Ultrafast Quantum Physics in Amplitude and Phase - UltraPhase, ERC Advanced Grant

Beschreibung

Ultrafast phenomena related to and/or accessible only via the absolute temporal phase of electronic, vibrational and spin coherent excitations in condensed matter are studied via electromagnetic transients in the multi-terahertz regime. The project also includes innovative aspects of quantum optics, femtosecond lasers and terahertz technology. Four central objectives are as follows:p align="left"(i) Establishing rapid quantum oscillatory motion as the earliest regime in the dynamics and transport of electrons in solids. Fundamental phenomena like the temporal buildup of effective mass in semiconductors and Zitterbewegung in graphene are accessed directly.p align="left"(ii) Studying nonclassical light emission predicted to emerge after non-adiabatic perturbation of ultrastrongly coupled systems of light and matter. The quantum properties of radiation released by such processes are investigated at the uncertainty limit between amplitude and phase of the light field.p align="left"(iii) Observation and control of charge and spin electronic properties of solids under extremely high transient electric or magnetic bias provided by a novel source of phase-locked multi-terahertz pulses allowing analysis with a resolution significantly below half a cycle of light.p align="left"(iv) Field-resolved photon-echo studies in the mid infrared. Unprecedented insights into complex phenomena like the interplay between low-energy degrees of freedom in high-temperature superconductors and intermolecular motion in liquids are envisioned.p align="left"New developments in ultrabroadband terahertz technology will enable the experiments:p align="left"(a) Generation of phase-locked electromagnetic transients with precisely controlled shape of the electric field like quasi-monopolar terahertz shock waves or single-cycle pulses with field amplitudes up to 30 MV/cm.p align="left"(b) Coherent detection of electric fields with bandwidth up to 200 THz and sensitivity at the uncertainty limit, giving access to the quantum properties of electromagnetic waves in amplitude and phase.

Institutionen
  • AG Leitenstorfer (Experimentalphysik mit SP Ultrakurzzeitphysik und Quantenoptik)
Publikationen
    Schmidt, Christian; Bühler, Johannes; Heinrich, Alexander-Cornelius; Allerbeck, Jonas; Podzimski, Reinold; Berghoff, Daniel; Meier, Torsten; Schmidt, Wolf Gero; Reichl, Christian; Wegscheider, Werner; Brida, Daniele; Leitenstorfer, Alfred (2018): Signatures of transient Wannier-Stark localization in bulk gallium arsenide Nature Communications. 2018, 9(1), 2890. eISSN 2041-1723. Available under: doi: 10.1038/s41467-018-05229-x

Signatures of transient Wannier-Stark localization in bulk gallium arsenide

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Many properties of solids result from the fact that in a periodic crystal structure, electronic wave functions are delocalized over many lattice sites. Electrons should become increasingly localized when a strong electric field is applied. So far, this Wannier-Stark regime has been reached only in artificial superlattices. Here we show that extremely transient bias over the few-femtosecond period of phase-stable mid-infrared pulses may localize electrons even in a bulk semiconductor like GaAs. The complicated band structure of a three-dimensional crystal leads to a strong blurring of field-dependent steps in the Wannier-Stark ladder. Only the central step emerges strongly in interband electro-absorption because its energetic position is dictated by the electronic structure at an atomic level and therefore insensitive to the external bias. In this way, we demonstrate an extreme state of matter with potential applications due to e.g., its giant optical non-linearity or extremely high chemical reactivity.

Forschungszusammenhang (Projekte)

    Yerebakan, Talha; Demirbas, Umit; Eggert, Stefan; Bertram, Rainer; Reiche, Peter; Leitenstorfer, Alfred (2017): Red-diode-pumped Cr:Nd:GSGG laser : two-color mode-locked operation Journal of the Optical Society of America B. 2017, 34(5), pp. 1023-1032. ISSN 0740-3224. eISSN 1520-8540. Available under: doi: 10.1364/JOSAB.34.001023

Red-diode-pumped Cr:Nd:GSGG laser : two-color mode-locked operation

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We have investigated in detail the continuous-wave (cw) and mode-locked performance of a diode-pumped Cr:Nd:GSGG laser. State-of-the-art single-mode and multimode laser diodes around 665 nm were used as pump sources. In cw operation, we have demonstrated lasing thresholds as low as 14 mW, slope efficiencies as high as 23.4%, and output powers up to 738 mW. The free running emission wavelength was 1061 nm. Lasing could also be obtained at 1051, 1058, 1065, 1068, 1072, 1103, and 1111 nm lines. A saturable Bragg reflector was used to initiate and sustain mode-locking where the Cr:Nd:GSGG laser produced 6-ps-long pulses around 1061 nm with an average power of 160 mW. The repetition rate was 142.65 MHz, resulting in pulse energies of 1.1 nJ and peak powers of 175 W. An off-surface optical axis quartz birefringent filter (BRF) was inserted inside the laser cavity at Brewster’s angle to obtain two-color cw and mode-locked laser operation at the 1051 and 1058 nm and 1058 and 1061 transition pairs, resulting in cw powers up to 60 mW and cw mode-locked average powers up to 45 mW. Unlike many other methods applied for two-color mode-locked laser operation, usage of the BRF enabled regulation of the ratio of the power in each line by fine adjustment of its rotation angle. The method could potentially be used for other gain media as well, which could simplify development of multicolor solid-state laser systems.

Forschungszusammenhang (Projekte)

    Riek, Claudius; Seletskiy, Denis V.; Leitenstorfer, Alfred (2017): Femtosecond measurements of electric fields : from classical amplitudes to quantum fluctuations European Journal of Physics. 2017, 38(2), 024003. ISSN 0143-0807. eISSN 1361-6404. Available under: doi: 10.1088/1361-6404/aa53a2

Femtosecond measurements of electric fields : from classical amplitudes to quantum fluctuations

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Ultrabroadband electro-optic sampling is presented as an extremely sensitive technique to detect electric field amplitudes in free space. The temporal resolution provided by few-femtosecond laser pulses results in a bandwidth exceeding 100 THz, potentially covering the entire infrared spectral range. A pedagogic introduction to the operational principle of the method is given along the lines of a classical coherent input field and a zincblende-type electro-optic sensor. We then show that even the bare vacuum fluctuations of the electric field in the quantum ground state may be detected. This time-domain approach to quantum physics operates directly on sub-cycle scales where no local energy conservation holds. Therefore, signals may be obtained from purely virtual photons without amplification to finite intensity.

Forschungszusammenhang (Projekte)

    Riek, Claudius; Sulzer, Philipp; Seeger, Maximilian; Moskalenko, Andrey S.; Burkard, Guido; Seletskiy, Denis V.; Leitenstorfer, Alfred (2017): Subcycle Quantum Electrodynamics Nature. 2017, 541(7637), pp. 376-379. ISSN 0028-0836. eISSN 1476-4687. Available under: doi: 10.1038/nature21024

Subcycle Quantum Electrodynamics

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dc.contributor.author: Riek, Claudius; Sulzer, Philipp; Seeger, Maximilian; Moskalenko, Andrey S.; Burkard, Guido; Seletskiy, Denis V.; Leitenstorfer, Alfred

Forschungszusammenhang (Projekte)

  Leitenstorfer, Alfred (2017): Subcycle quantum physics (Conference Presentation) BETZ, Markus, ed., Abdulhakem Y. ELEZZABI, ed.. Ultrafast Phenomena and Nanophotonics XXI. Bellingham: SPIE, 2017, 1010216. SPIE Proceedings. 10102. ISSN 0277-786X. eISSN 1996-756X. ISBN 978-1-5106-0645-6. Available under: doi: 10.1117/12.2254953

Subcycle quantum physics (Conference Presentation)

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A time-domain approach to quantum electrodynamics is presented, covering the entire mid-infrared and terahertz frequency ranges. Ultrabroadband electro-optic sampling with few-femtosecond laser pulses allows direct detection of the vacuum fluctuations of the electric field in free space [1,2]. Besides the Planck and electric field fundamental constants, the variance of the ground state is determined solely by the inverse of the four-dimensional space-time volume over which a measurement or physical process integrates. Therefore, we can vary the contribution of multi-terahertz vacuum fluctuations and discriminate against the trivial shot noise due to the constant flux of near-infrared probe photons. Subcycle temporal resolution based on a nonlinear phase shift provides signals from purely virtual photons for accessing the ground-state wave function without amplification to finite intensity. Recently, we have succeeded in generation and analysis of mid-infrared squeezed transients with quantum noise patterns that are time-locked to the intensity envelope of the probe pulses. We find subcycle temporal positions with a noise level distinctly below the bare vacuum which serves as a direct reference. Delay times with increased differential noise indicate generation of highly correlated quantum fields by spontaneous parametric fluorescence. Our time-domain approach offers a generalized understanding of spontaneous emission processes as a consequence of local anomalies in the co-propagating reference frame modulating the quantum vacuum, in combination with the boundary conditions set by Heisenberg’s uncertainty principle. [1] C. Riek et al., Science 350, 420 (2015) [2] A. S. Moskalenko et al., Phys. Rev. Lett. 115, 263601 (2015)

Forschungszusammenhang (Projekte)

    Liehl, Andreas; Fehrenbacher, David; Sulzer, Philipp; Leitenstorfer, Alfred; Seletskiy, Denis V. (2017): Ultrabroadband out-of-loop characterization of the carrier-envelope phase noise of an offset-free Er:fiber frequency comb Optics Letters. 2017, 42(10), pp. 2050-2053. ISSN 0146-9592. eISSN 1539-4794. Available under: doi: 10.1364/OL.42.002050

Ultrabroadband out-of-loop characterization of the carrier-envelope phase noise of an offset-free Er:fiber frequency comb

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Recent demonstrations of passively phase-locked fiber-based combs motivate broadband characterization of the noise associated with the stabilized carrier-envelope offset frequency. In our study, we analyze the phase noise of a 100 MHz Er:fiber system in a wide range spanning from microhertz to the Nyquist frequency. An interferometric detection method enables analysis of the high-frequency output of an f-to-2f interferometer. The dominant contribution of a broadband white noise floor at high frequencies attests quantum-limited performance. An out-of-loop measurement of the carrier-envelope phase reveals its jitter to be as low as 250 mrad when integrated over 12 orders of magnitude of the radio-frequency spectrum.

Forschungszusammenhang (Projekte)

  Leitenstorfer, Alfred (2017): Time-domain Quantum Electrodynamics CLEO : Science and Innovations : Proceedings Conference on Lasers and Electro-Optics. Washington, DC: optica publishing, 2017, SM2J.1. ISBN 978-1-943580-27-9. Available under: doi: 10.1364/CLEO_SI.2017.SM2J.1

Time-domain Quantum Electrodynamics

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Ultrabroadband electro-optic sampling with few-femtosecond laser pulses allows direct detection of electric-field vacuum fluctuations. Subcycle analysis of multi-terahertz squeezed light is introduced as a first application of this new type of quantum metrology.

Forschungszusammenhang (Projekte)

    Rybka, Tobias; Ludwig, Markus; Schmalz, Michael; Knittel, Vanessa; Brida, Daniele; Leitenstorfer, Alfred (2016): Sub-cycle optical phase control of nanotunnelling in the single-electron regime Nature Photonics. 2016, 10(10), pp. 667-670. ISSN 1749-4885. eISSN 1749-4893. Available under: doi: 10.1038/NPHOTON.2016.174

Sub-cycle optical phase control of nanotunnelling in the single-electron regime

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dc.contributor.author: Rybka, Tobias; Ludwig, Markus; Schmalz, Michael; Knittel, Vanessa; Brida, Daniele; Leitenstorfer, Alfred

Forschungszusammenhang (Projekte)

    Filipovic, Milena; Belzig, Wolfgang (2016): Photon-assisted electronic and spin transport in a junction containing precessing molecular spin Physical Review B. 2016, 93(7), 075402. ISSN 2469-9950. eISSN 2469-9969. Available under: doi: 10.1103/PhysRevB.93.075402

Photon-assisted electronic and spin transport in a junction containing precessing molecular spin

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We study the ac charge and -spin transport through an orbital of a magnetic molecule with spin precessing in a constant magnetic field. We assume that the source and drain contacts have time-dependent chemical potentials. We employ the Keldysh nonequilibrium Green’s functions method to calculate the spin and charge currents to linear order in the time-dependent potentials. The molecular and electronic spins are coupled via exchange interaction. The time-dependent molecular spin drives inelastic transitions between the molecular quasienergy levels, resulting in a rich structure in the transport characteristics. The time-dependent voltages allow us to reveal the internal precession time scale (the Larmor frequency) by a dc conductance measurement if the ac frequency matches the Larmor frequency. In the low-ac-frequency limit the junction resembles a classical electric circuit. Furthermore, we show that the setup can be used to generate dc-spin currents, which are controlled by the molecular magnetization direction and the relative phases between the Larmor precession and the ac voltage.

Forschungszusammenhang (Projekte)

  Brida, Daniele; Fischer, Jonathan; Storz, Patrick; Leitenstorfer, Alfred (2016): High-power Yb:amplifiers seeded by a femtosecond Er:Fiber laser 2016 International Conference Laser Optics (LO). Piscataway: IEEE, 2016, pp. R1-R27. ISBN 978-1-4673-9737-7. Available under: doi: 10.1109/LO.2016.7549647

High-power Yb:amplifiers seeded by a femtosecond Er:Fiber laser

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We present two alternative implementations of high-power Yb:amplifiers designed for advanced applications in ultrafast science. The seed is generated by ultrabroadband Er:fiber laser technology. Our fiber-based setup produces pulses at 1030 nm with energies of 6 μJ at a repetition rate of 10 MHz and duration of 145 fs. The thin-disk amplifier is operated at 3 kHz repetition rate and generates 655-fs pulses with energies up to 17 mJ.

Forschungszusammenhang (Projekte)

    Fischer, Jonathan; Heinrich, Alexander-Cornelius; Maier, Simon; Jungwirth, Julian; Brida, Daniele; Leitenstorfer, Alfred (2016): 615  fs pulses with 17  mJ energy generated by an Yb:thin-disk amplifier at 3  kHz repetition rate Optics Letters. 2016, 41(2), pp. 246-249. ISSN 0146-9592. eISSN 1539-4794. Available under: doi: 10.1364/OL.41.000246

615  fs pulses with 17  mJ energy generated by an Yb:thin-disk amplifier at 3  kHz repetition rate

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A combination of Er/Yb:fiber and Yb:thin-disk technology produces 615 fs pulses at 1030 nm with an average output power of 72 W. The regenerative amplifier allows variation of the repetition rate between 3 and 5 kHz with pulse energies from 13 to 17 mJ. A broadband and intense seed provided by the compact and versatile fiber front-end minimizes gain narrowing. The resulting sub-ps performance is ideal for nonlinear frequency conversion and pulse compression. Operating in the upper branch of a bifurcated pulse train, the system exhibits exceptional noise performance and stability.

Forschungszusammenhang (Projekte)

    Schmidt, Christian; Bühler, Johannes; Mayer, Bernhard; Pashkin, Alexej; Leitenstorfer, Alfred; Seletskiy, Denis V. (2016): Controlled polar asymmetry of few-cycle and intense mid-infrared pulses Journal of Optics. 2016, 18(5), 05LT01. ISSN 2040-8978. eISSN 2040-8986. Available under: doi: 10.1088/2040-8978/18/5/05LT01

Controlled polar asymmetry of few-cycle and intense mid-infrared pulses

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We demonstrate synthesis of ultrabroadband and phase-locked two-color transients in the multi-terahertz frequency range with amplitudes exceeding 13 MV cm−1. Subcycle polar asymmetry of the electric field is adjusted by changing the relative phase between superposed fundamental and second harmonic components. The resultant broken symmetry of the field profile is directly resolved via electro-optic sampling. Access to such waveforms provides a direct route for control of low-energy degrees of freedom in condensed matter as well as non-perturbative light–matter interactions under highest non-resonant electric bias.

Forschungszusammenhang (Projekte)

  Riek, Claudius; Sulzer, Philipp; Seeger, Maximillian; Seletskiy, Denis V.; Leitenstorfer, Alfred (2016): Carrier-Envelope Phase Control and Subcycle Analysis of Mid-Infrared Squeezed States of the Light Field CLEO: Science and Innovations : part of CLEO: 2016 : 5-10 June 2016, San Jose, California, United States. Washington, D.C.: OSA, 2016, JTh4A.6. ISBN 978-1-943580-11-8. Available under: doi: 10.1364/CLEO_AT.2016.JTh4A.6

Carrier-Envelope Phase Control and Subcycle Analysis of Mid-Infrared Squeezed States of the Light Field

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We generate few-cycle nonclassical transients by optical rectification of femtosecond pulses and subsequent index modulation in the multi-THz range. Subcycle analysis of quantum statistics by ultrabroadband electro-optic sampling reveals substantial squeezing below the vacuum level.

Forschungszusammenhang (Projekte)

  Fischer, Jonathan; Storz, Patrick; Heinrich, Alexander-Cornelius; Maier, Simon; Jungwirth, Julian; Brida, Daniele; Leitenstorfer, Alfred (2016): Sub-ps Pulses with multi-mJ Energy at kHz Repetition Rate from an Yb:YAG Thin-disk Amplifier Conference on Lasers and Electro-Optics. Washington, D.C.: OSA, 2016, SF2I.5. ISBN 978-1-943580-11-8. Available under: doi: 10.1364/CLEO_SI.2016.SF2I.5

Sub-ps Pulses with multi-mJ Energy at kHz Repetition Rate from an Yb:YAG Thin-disk Amplifier

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Combined Er/Yb:fiber and Yb:thin-disk technology produces 615 fs pulses at 1030 nm with an energy of 17 mJ at 3 kHz repetition rate. The sub-ps duration allows efficient white-light generation and optical parametric amplification.

Forschungszusammenhang (Projekte)

  Riek, Claudius; Sulzer, Philipp; Seeger, Maximillian; Seletskiy, Denis V.; Leitenstorfer, Alfred (2016): Simultaneous Sampling of Electric Field Quadratures in the Time Domain Conference on Lasers and Electro-Optics. Washington, D.C.: OSA, 2016, SM1L.1. ISBN 978-1-943580-11-8. Available under: doi: 10.1364/CLEO_SI.2016.SM1L.1

Simultaneous Sampling of Electric Field Quadratures in the Time Domain

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We directly detect the multi-terahertz vacuum field and analyze its dependence on the probed space-time volume. A scheme for sensing the time derivative of the field enables timedomain quantum tomography with simultaneous sampling of both quadratures.

Forschungszusammenhang (Projekte)

  Leitenstorfer, Alfred (2016): Subcycle Quantum Physics 2016 41st International Conference on Infrared, Millimeter, and Terahertz waves (IRMMW-THz). Piscataway, NJ: IEEE, 2016. eISSN 2162-2035. ISBN 978-1-4673-8485-8. Available under: doi: 10.1109/IRMMW-THz.2016.7758539

Subcycle Quantum Physics

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dc.contributor.author: Leitenstorfer, Alfred

Forschungszusammenhang (Projekte)

  Storz, Patrick; Fischer, Jonathan; Tauch, Jonas; Wunram, Marcel; Leitenstorfer, Alfred; Brida, Daniele (2016): Generation of UV Harmonics in Solids with Intense and Phase-Locked Few-Cycle Pulses at High Repetition Rate Conference on Lasers and Electro-Optics. Washington, D.C.: OSA, 2016, SF1I.3. ISBN 978-1-943580-11-8. Available under: doi: 10.1364/CLEO_SI.2016.SF1I.3

Generation of UV Harmonics in Solids with Intense and Phase-Locked Few-Cycle Pulses at High Repetition Rate

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We demonstrate carrier-envelope phase control of even and odd harmonics in solids up to fifth order with intense 2.3-cycle pulses from a near-infrared optical parametric amplifier operated at 10 MHz repetition rate.

Forschungszusammenhang (Projekte)

  Rybka, Tobias; Ludwig, Markus; Schmalz, Michael; Knittel, Vanessa; Brida, Daniele; Leitenstorfer, Alfred (2016): Optical phase control of single-electron nanotunneling Conference on Lasers and Electro-Optics. Washington, D.C.: OSA, 2016, FTh4B.2. ISBN 978-1-943580-11-8. Available under: doi: 10.1364/CLEO_QELS.2016.FTh4B.2

Optical phase control of single-electron nanotunneling

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We exploit the carrier-envelope phase of near-infrared 1.4-cycle pulses with picojoule-level energy to drive and control single-electron transport across the 8 nm tunneling gap of a gold nanoantenna.

Forschungszusammenhang (Projekte)

    Riek, Claudius; Seletskiy, Denis V.; Moskalenko, Andrey S.; Schmidt, Jan; Krauspe, Philipp; Eckart, Sebastian; Eggert, Stefan; Burkard, Guido; Leitenstorfer, Alfred (2015): Direct sampling of electric-field vacuum fluctuations Science. 2015, 350(6259), pp. 420-423. ISSN 0036-8075. eISSN 1095-9203. Available under: doi: 10.1126/science.aac9788

Direct sampling of electric-field vacuum fluctuations

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The ground state of quantum systems is characterized by zero-point motion. Those vacuum fluctuations are generally deemed an elusive phenomenon that manifests itself only indirectly. Here, we report direct detection of the vacuum fluctuations of electromagnetic radiation in free space. The ground-state electric field variance is found to be inversely proportional to the four-dimensional space-time volume sampled electro-optically with tightly focused few-femtosecond laser pulses. Sub-cycle temporal readout and nonlinear coupling far from resonance provide signals from purely virtual photons without amplification. Our findings enable an extreme time-domain approach to quantum physics with nondestructive access to the quantum state of light. Operating at multi-terahertz frequencies, such techniques might also allow time-resolved studies of intrinsic fluctuations of elementary excitations in condensed matter.

Forschungszusammenhang (Projekte)

    Schmidt, Christian; Bühler, Johannes; Heinrich, Alexander-Cornelius; Leitenstorfer, Alfred; Brida, Daniele (2015): Noncollinear parametric amplification in the near-infrared based on type-II phase matching Journal of Optics. 2015, 17(9), 094003. ISSN 2040-8978. eISSN 2040-8986. Available under: doi: 10.1088/2040-8978/17/9/094003

Noncollinear parametric amplification in the near-infrared based on type-II phase matching

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Noncollinear parametric amplification based on type-II phase matching for the generation of ultrabroadband and tunable spectra in the near infrared is investigated. In a noncollinear geometry the group velocity matching condition between signal and idler can be obtained in frequently used crystals such as β-barium borate (BBO) even for wavelengths fully located in the anomalous dispersion region. The extremely broadband operation, peculiar tuning possibilities and straightforward experimental implementation with the standard BBO crystal pave the way for a versatile NIR source in ultrafast spectroscopy.

Forschungszusammenhang (Projekte)

  Kampfrath, Tobias; Battiato, Marco; Sell, Alexander; Freimuth, Frank; Leitenstorfer, Alfred; Wolf, Martin; Huber, Rupert; Oppeneer, Peter M.; Münzenberg, Markus (2015): Ultrafast Spin Precession and Transport Controlled and Probed with Terahertz Radiation BIGOT, Jean-Yves, ed., Wolfgang HÜBNER, ed., Theo RASING, ed., Roy CHANTRELL, ed.. Ultrafast Magnetism I : Proceedings of the International Conference UMC 2013 Strasbourg, France, October 28th - November 1st, 2013. Cham: Springer International Publishing, 2015, pp. 324-326. Springer Proceedings in Physics. 159. ISBN 978-3-319-07742-0. Available under: doi: 10.1007/978-3-319-07743-7_100

Ultrafast Spin Precession and Transport Controlled and Probed with Terahertz Radiation

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dc.contributor.author: Kampfrath, Tobias; Battiato, Marco; Sell, Alexander; Freimuth, Frank; Leitenstorfer, Alfred; Wolf, Martin; Huber, Rupert; Oppeneer, Peter M.; Münzenberg, Markus

Forschungszusammenhang (Projekte)

  Fehrenbacher, David; Sulzer, Philipp; Seletskiy, Denis V.; Leitenstorfer, Alfred (2015): A Passively Phase-Locked Er:Fiber Frequency Comb:Free-Running Performance and Active Linewidth Narrowing CLEO: 2015, OSA Technical Digest (online). Optical Society of America, 2015, STh1N.1. ISBN 978-1-55752-968-8. Available under: doi: 10.1364/CLEO_SI.2015.STh1N.1

A Passively Phase-Locked Er:Fiber Frequency Comb:Free-Running Performance and Active Linewidth Narrowing

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An offset-free frequency comb generated by difference frequency mixing is established and characterized. mHz-level direct locking of the repetition rate to 85Rb and reference-limited linewidth narrowing via an extra-cavity electro-optic modulator are demonstrated.

Forschungszusammenhang (Projekte)

  Kim, Kyung Wan; Porer, Michael; Pashkin, Alexej; Sell, Alexander; Kampfrath, Tobias; Leitenstorfer, Alfred; Huber, Rupert (2015): THz Spin Dynamics : Phonon-Induced Spin Order BIGOT, Jean-Yves, ed., Wolfgang HÜBNER, ed., Theo RASING, ed., Roy CHANTRELL, ed.. Ultrafast Magnetism I : Proceedings of the International Conference UMC 2013 Strasbourg, France, October 28th - November 1st, 2013. Cham: Springer International Publishing, 2015, pp. 327-330. Springer Proceedings in Physics. 159. ISSN 0930-8989. eISSN 1867-4941. ISBN 978-3-319-07742-0. Available under: doi: 10.1007/978-3-319-07743-7_101

THz Spin Dynamics : Phonon-Induced Spin Order

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dc.contributor.author: Kim, Kyung Wan; Porer, Michael; Pashkin, Alexej; Sell, Alexander; Kampfrath, Tobias; Leitenstorfer, Alfred; Huber, Rupert

Forschungszusammenhang (Projekte)

    Fehrenbacher, David; Sulzer, Philipp; Liehl, Andreas; Kälberer, Thomas; Riek, Claudius; Seletskiy, Denis V.; Leitenstorfer, Alfred (2015): Free-running performance and full control of a passively phase-stable Er:fiber frequency comb Optica. 2015, 2(10), pp. 917-923. eISSN 2334-2536. Available under: doi: 10.1364/OPTICA.2.000917

Free-running performance and full control of a passively phase-stable Er:fiber frequency comb

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Optical frequency combs based on erbium-doped fiber lasers are attractive tools in precision metrology due to their inherent compactness and stability. Here we study a femtosecond Er:fiber comb that passively eliminates the carrier–envelope phase slip by difference frequency generation. Quantum statistics inside the all-fiber soliton oscillator governs its free-running performance. Active stabilization of the repetition rate supports a subhertz optical linewidth and does not necessitate additional intracavity elements. Direct locking to an optical atomic frequency standard enables generation of a 100 MHz microwave signal with a stability of 3.4 mHz maintained over 15 min.

Forschungszusammenhang (Projekte)

    Mayer, Bernhard; Schmidt, Christian; Grupp, Alexander; Bühler, Johannes; Oelmann, Jannis; Marvel, Robert E.; Haglund, Richard F.; Oka, Takashi; Brida, Daniele; Leitenstorfer, Alfred; Pashkin, Alexej (2015): Tunneling breakdown of a strongly correlated insulating state in VO2 induced by intense multiterahertz excitation Physical Review B. 2015, 91(23), 235113. ISSN 1098-0121. eISSN 1550-235X. Available under: doi: 10.1103/PhysRevB.91.235113

Tunneling breakdown of a strongly correlated insulating state in VO2 induced by intense multiterahertz excitation

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We directly trace the near- and midinfrared transmission change of a VO2 thin film during an ultrafast insulator-to-metal transition triggered by high-field multiterahertz transients. Nonthermal switching into a metastable metallic state is governed solely by the amplitude of the applied terahertz field. In contrast to resonant excitation below the threshold fluence, no signatures of excitonic self-trapping are observed. Our findings are consistent with the generation of spatially separated charge pairs and a cooperative transition into a delocalized metallic state by THz field-induced tunneling. The tunneling process is a condensed-matter analog of the Schwinger effect in nonlinear quantum electrodynamics. We find good agreement with the pair production formula by replacing the Compton wavelength with an electronic correlation length of 2.1 Å.

Forschungszusammenhang (Projekte)

    Soavi, Giancarlo; Grupp, Alexander; Budweg, Arne; Scotognella, Francesco; Hefner, Timo; Hertel, Tobias; Lanzani, Guglielmo; Leitenstorfer, Alfred; Cerullo, Giulio; Brida, Daniele (2015): Below-gap excitation of semiconducting single-wall carbon nanotubes Nanoscale. 2015, 7(43), pp. 18337-18342. ISSN 2040-3364. eISSN 2040-3372. Available under: doi: 10.1039/C5NR05218A

Below-gap excitation of semiconducting single-wall carbon nanotubes

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We investigate the optoelectronic properties of the semiconducting (6,5) species of single-walled carbon nanotubes by measuring ultrafast transient transmission changes with 20 fs time resolution. We demonstrate that photons with energy below the lowest exciton resonance efficiently lead to linear excitation of electronic states. This finding challenges the established picture of a vanishing optical absorption below the fundamental excitonic resonance. Our result points towards below-gap electronic states as an intrinsic property of semiconducting nanotubes.

Forschungszusammenhang (Projekte)

    Moskalenko, Andrey S.; Riek, Claudius; Seletskiy, Denis V.; Burkard, Guido; Leitenstorfer, Alfred (2015): Paraxial Theory of Direct Electro-Optic Sampling of the Quantum Vacuum Physical Review Letters. 2015, 115(26), 263601. ISSN 0031-9007. eISSN 1079-7114. Available under: doi: 10.1103/PhysRevLett.115.263601

Paraxial Theory of Direct Electro-Optic Sampling of the Quantum Vacuum

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Direct detection of vacuum fluctuations and analysis of subcycle quantum properties of the electric field are explored by a paraxial quantum theory of ultrafast electro-optic sampling. The feasibility of such experiments is demonstrated by realistic calculations adopting a thin ZnTe electro-optic crystal and stable few-femtosecond laser pulses. We show that nonlinear mixing of a short near-infrared probe pulse with the multiterahertz vacuum field leads to an increase of the signal variance with respect to the shot noise level. The vacuum contribution increases significantly for appropriate length of the nonlinear crystal, short pulse duration, tight focusing, and a sufficiently large number of photons per probe pulse. If the vacuum input is squeezed, the signal variance depends on the probe delay. Temporal positions with a noise level below the pure vacuum may be traced with subcycle resolution.

Forschungszusammenhang (Projekte)

    Wunram, Marcel; Storz, Patrick; Brida, Daniele; Leitenstorfer, Alfred (2015): Ultrastable fiber amplifier delivering 145-fs pulses with 6-μJ energy at 10-MHz repetition rate Optics Letters. 2015, 40(5), pp. 823-826. ISSN 0146-9592. eISSN 1539-4794. Available under: doi: 10.1364/OL.40.000823

Ultrastable fiber amplifier delivering 145-fs pulses with 6-μJ energy at 10-MHz repetition rate

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A high-power femtosecond Yb:fiber amplifier operating with exceptional noise performance and long-term stability is demonstrated. It generates a 10-MHz train of 145-fs pulses at 1.03 μm with peak powers above 36 MW. The system features a relative amplitude noise of 1.5⋅10−6  Hz−1/2 at 1 MHz and drifts of the 60-W average power below 0.3% over 72 hours of continuous operation. The passively phase-stable Er:fiber seed system provides ultrabroadband pulses that are synchronized at a repetition rate of 40 MHz. This combination aims at new schemes for sensitive experiments in ultrafast scientific applications.

Forschungszusammenhang (Projekte)

  Cihan, Can; Beyatli, Ersen; Canbaz, Ferda; Chen, Li-Jin; Sumpf, Bernd; Erbert, Götz; Leitenstorfer, Alfred; Kärtner, Franz X.; Sennaroglu, Alphan; Demirbas, Umit (2015): Gain-Matched Output Couplers for Efficient Kerr-Lens Mode-Locking of Low-Cost and High-Peak Power Cr:LiSAF Lasers IEEE journal of selected topics in quantum electronics. 2015, 21(1), 1100712. ISSN 1077-260X. Available under: doi: 10.1109/JSTQE.2014.2359540

Gain-Matched Output Couplers for Efficient Kerr-Lens Mode-Locking of Low-Cost and High-Peak Power Cr:LiSAF Lasers

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We present a detailed investigation of Kerr-lens mode-locking in diode-pumped Cr:LiSAF lasers employing gain-matched output couplers (GMOCs). Single-mode diodes (660 nm, 130 mW) and tapered diodes (685 nm, 1 W) were investigated as diode pump sources. We have shown that, by reducing the gain-filtering effect, GMOC enhances the effective self-amplitude modulation depth and provides a significant improvement in both efficiency and robustness of KLM operation. From the single-mode diode pumped system, 13 fs pulses with an average power of 25 mW and a peak power 25 kW have been generated at an incident pump power of only 120 mW (21% optical-to-optical conversion efficiency). The tapered diode pumped Cr:LiSAF oscillator provided pulses as short as 14.5 fs with 106-mW average power and 60-kW peak power at an incident pump power of 940 mW (11% optical-to-optical conversion efficiency). A femtosecond tuning range extending from 807 to 919 nm was also realized with sub-50-fs long pulses. To our knowledge, demonstrated optical-to-optical conversion efficiencies, peak powers and fs tuning ranges are record results for Cr:LiSAF laser oscillators. The obtainable pulsewidth and fs tuning range are currently limited by the dispersion/reflectivity bandwidth of the available optics.

Forschungszusammenhang (Projekte)

  Mayer, Bernhard; Schmidt, Christian; Bühler, Johannes; Fischer, Jonathan; Seletskiy, Denis V.; Brida, Daniele; Pashkin, Alexej; Leitenstorfer, Alfred (2015): Tailoring of High-Field Multi-THz Waveforms with Sub-Cycle Precision YAMANOUCHI, Kaoru, ed., Steven T. CUNDIFF, ed., Regina DE VIVIE-RIEDLE, ed., Makoto KUWATA-GONOKAMI, ed., Louis DIMAURO, ed.. Ultrafast Phenomena XIX. Cham: Springer International Publishing, 2015, pp. 805-808. Springer Proceedings in Physics. 162. ISBN 978-3-319-13241-9. Available under: doi: 10.1007/978-3-319-13242-6_197

Tailoring of High-Field Multi-THz Waveforms with Sub-Cycle Precision

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Shaping of extremely intense mid-infrared transients by means of time-domain slicing and frequency-domain synthesis is demonstrated. We achieve phase-stable transients at multiple MV/cm peak fields with single-cycle duration and strong polar asymmetry.

Forschungszusammenhang (Projekte)

  Grupp, Alexander; Mayer, Bernhard; Schmidt, Christian; Oelmann, Jannis; Marvel, Robert E.; Haglund, Richard F.; Leitenstorfer, Alfred; Pashkin, Alexej (2015): Ultrafast Insulator-Metal Transition in VO2 Driven by Intense Multi-THz Pulses YAMANOUCHI, Kaoru, ed., Steven T. CUNDIFF, ed., Regina DE VIVIE-RIEDLE, ed., Makoto KUWATA-GONOKAMI, ed., Louis DIMAURO, ed.. Ultrafast Phenomena XIX. Cham: Springer International Publishing, 2015, pp. 637-640. Springer Proceedings in Physics. 162. ISBN 978-3-319-13241-9. Available under: doi: 10.1007/978-3-319-13242-6_157

Ultrafast Insulator-Metal Transition in VO2 Driven by Intense Multi-THz Pulses

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We demonstrate sub-100 fs metallization of VO2 induced by few-cycle electric transients at frequencies around 25 THz. Interband tunneling is identified as an instantaneous excitation mechanism.

Forschungszusammenhang (Projekte)

  Storz, Patrick; Wunram, Marcel; Brida, Daniele; Leitenstorfer, Alfred (2015): Ultrastable and High-Power Yb:Fiber Amplifier for Nonlinear Frequency Conversion at High Repetition Rate OSA, The Optical Society, ed.. CLEO: Science and Innovations : part of Conference on Lasers and Electro-Optics ; 10 - 15 May 2015, San Jose, California, United States ; [including the] Symposium - Advanced Optical Microscopy for Brain Imaging, Symposium - OPA/OPCPA Next Generation of Ultra-Short Pulse Laser Technology, Symposium - Remote Atmospheric Lasing, Symposum - Breaking Limits with Unconventional Optical Fields. Washington, DC: OSA, The Optical Society, 2015, SM1P.5. OSA technical digest (online). ISBN 978-1-55752-968-8. Available under: doi: 10.1364/CLEO_SI.2015.SM1P.5

Ultrastable and High-Power Yb:Fiber Amplifier for Nonlinear Frequency Conversion at High Repetition Rate

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We demonstrate an ultrastable Yb:fiber amplifier delivering 145 fs pulses with 6 µJ energy at 10 MHz repetition rate. The Er:fiber seed laser provides inherently synchronized broadband continua whose power is boosted via optical parametric amplification.

Forschungszusammenhang (Projekte)

  Seletskiy, Denis V.; Fehrenbacher, David; Sulzer, Philipp; Leitenstorfer, Alfred (2015): Passively phase-locked Er:Fiber frequency comb URSI Atlantic Radio Science Conference (URSI AT-RASC). Piscataway, New Jersey: IEEE, 2015. ISBN 9789090086286. Available under: doi: 10.1109/URSI-AT-RASC.2015.7303014

Passively phase-locked Er:Fiber frequency comb

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Modern precision metrology ever more strongly relies on the availability of optical frequency combs. We review our approach to passive stabilization of the carrier envelope phase (CEP) of a pulse train at full repetition rate via difference frequency generation. Using this approach, we demonstrate a inherently offset-free Er:fiber comb directly locked onto an optical reference ( 85 Rb) together with a possibility of an actively narrowed sub-500 mHz linewidth. This performance highlights an attractive potential of robust all-fiber comb systems toward applications in ultrahigh-precision metrology.

Forschungszusammenhang (Projekte)

  Mayer, Bernhard; Schmidt, Christian; Buhler, Johannes; Seletskiy, Denis V.; Brida, Daniele; Pashkin, Alexej; Leitenstorfer, Alfred (2014): Sub-cycle slicing of high-field multi-THz transients 39th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz), 2014 : 14 - 19 Sept. 2014, The University of Arizona, Tucson, Arizona, USA. Piscataway: IEEE, 2014, pp. 1-2. ISBN 978-1-4799-3877-3. Available under: doi: 10.1109/IRMMW-THz.2014.6956035

Sub-cycle slicing of high-field multi-THz transients

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We demonstrate ultrafast temporal slicing of phase-locked multi-THz pulses using a photoinduced electron-hole plasma in germanium. This approach enables us to extract single-cycle transients with a peak electric field of 10 MV/cm from a multi-cycle waveform at a carrier frequency of 24 THz.

Forschungszusammenhang (Projekte)

  Grupp, Alexander; Mayer, Bernhard; Schmidt, Christian; Oelmann, Jannis; Marvel, R. E.; Haglund, R. F.; Leitenstorfer, Alfred; Pashkin, Alexej (2014): Femtosecond Insulator-Metal Transition in VO2 Induced by Intense Multi-THz Transients 2014 Conference on Lasers and Electro-Optics (CLEO). Piscataway, NJ: IEEE, 2014, pp. 679-680. 2014 Conference on Lasers and Electro-Optics. 1. ISBN 978-1-4799-5335-6

Femtosecond Insulator-Metal Transition in VO2 Induced by Intense Multi-THz Transients

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dc.title:


dc.contributor.author: Grupp, Alexander; Mayer, Bernhard; Schmidt, Christian; Oelmann, Jannis; Marvel, R. E.; Haglund, R. F.; Leitenstorfer, Alfred; Pashkin, Alexej

Forschungszusammenhang (Projekte)

  Riek, Claudius; Schmidt, Jan; Eckart, Sebastian; Seletskiy, Denis V.; Leitenstorfer, Alfred (2014): Direct and Ultrabroadband Detection of the Vacuum Field CLEO: QELS-Fundamental Science : part of CLEO ; 8 - 13 June 2014, San Jose, California, United States. Washington, DC: Optical Society of America, 2014, FTh5A.6. ISBN 978-1-55752-998-5. Available under: doi: 10.1364/CLEO_QELS.2014.FTh5A.6

Direct and Ultrabroadband Detection of the Vacuum Field

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Electro-optic sampling at center frequency and bandwidth around 70 THz allows measuring the vacuum fluctuations of the electric field in free space. Distinction from detector shot noise is accomplished by modifying the space-time volume probed.

Forschungszusammenhang (Projekte)

  Brida, Daniele; Krauss, Günther; Sell, Alexander; Leitenstorfer, Alfred (2014): Ultrabroadband Er:fiber lasers Laser & Photonics Reviews. 2014, 8(3), pp. 409-428. ISSN 1863-8880. eISSN 1863-8899. Available under: doi: 10.1002/lpor.201300194

Ultrabroadband Er:fiber lasers

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The state of the art of ultrafast Er:fiber technology is reviewed. Such lasers are increasingly used for generation of ultrabroadband and widely tunable pulse trains. Er:fiber sources prove to be flexible, compact and robust with important applications in fundamental and interdisciplinary sciences. After a short overview of different oscillator and amplifier designs the discussion focuses on coherent and tailored supercontinuum generation in highly nonlinear germanosilicate fibers. This approach enables a tuning range spanning from the visible to the mid infrared, synthesis of single-cycle light pulses and passive locking of the carrier-envelope phase.

Forschungszusammenhang (Projekte)

    Pashkin, Alexej; Leitenstorfer, Alfred (2014): Particle physics in a superconductor Science. 2014, 345(6201), pp. 1121-1122. ISSN 0036-8075. eISSN 1095-9203. Available under: doi: 10.1126/science.1257302

Particle physics in a superconductor

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The recent discovery of the Higgs boson has created a lot of excitement among scientists. Celebrated as one of the most fundamental results in experimental physics (1), the observation of this particle confirms the existence of the associated Higgs field that plays a pivotal role in the Standard Model of particle physics. Because of the Higgs boson's large mass (about 125 GeV), it could be detected only in the world's largest and most powerful accelerator—the Large Hadron Collider at CERN, Geneva. Although it sounds strange, the theoretical proposal of the Higgs mechanism was actually inspired by ideas from condensed matter physics, which typically works at much lower energies (a few electron volts or less). In 1958, Anderson discussed the appearance of a coherent excited state in superconducting condensates with spontaneously broken symmetry (2). Later, this approach was advanced by Nambu (3). The existence of superconducting condensates has been firmly established. In contrast, unambiguous experimental evidence for the coherent excited state (called the Higgs mode) had been missing. On page 1145 of this issue, Matsunaga et al. (4) report direct observation of the Higgs mode in the conventional superconductor niobium nitride (NbN) excited by intense electric field transients.

Forschungszusammenhang (Projekte)

    Mayer, Bernhard; Schmidt, Christian; Bühler, Johannes; Seletskiy, Denis V.; Brida, Daniele; Pashkin, Alexej; Leitenstorfer, Alfred (2014): Sub-cycle slicing of phase-locked and intense mid-infrared transients New Journal of Physics. 2014, 16(6), pp. 063033. ISSN 1367-2630. eISSN 1367-2630. Available under: doi: 10.1088/1367-2630/16/6/063033

Sub-cycle slicing of phase-locked and intense mid-infrared transients

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We demonstrate sub-cycle manipulation of mid-infrared optical waveforms in the time domain. This goal is accomplished via efficient reflection at a semiconductor surface induced by femtosecond interband excitation. The ultrafast response of this process allows slicing of high-field multi-terahertz transients down to the single optical cycle. Ultrabroadband and phase-stable transients with peak amplitudes beyond 10 MVcm-1 are obtained, paving the way for efficient coherent control of light–matter interaction in the non-perturbative regime. The microscopic analysis of electron–hole plasma generation in germanium reveals a decisive role of two-photon absorption allowing efficient slicing up to midinfrared frequencies.

Forschungszusammenhang (Projekte)

    Leitenstorfer, Alfred; Nelson, Keith A.; Reimann, Klaus; Tanaka, Koichiro (2014): Focus on nonlinear terahertz studies New Journal of Physics. 2014, 16, 045016. eISSN 1367-2630. Available under: doi: 10.1088/1367-2630/16/4/045016

Focus on nonlinear terahertz studies

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Resulting from the availability of improved sources, research in the terahertz (THz) spectral range has increased dramatically over the last decade, leading essentially to the disappearance of the so-called 'THz gap'. While most work to date has been carried out with THz radiation of low field amplitude, a growing number of experiments are using THz radiation with large electric and magnetic fields that induce nonlinearities in the system under study. This 'focus on' collection contains a number of articles, both experimental and theoretical, in the new subfield of THz nonlinear optics and spectroscopy on various systems, among them molecular gases, superconductors, semiconductors, antiferromagnets and graphene.

Forschungszusammenhang (Projekte)

  Seletskiy, Denis V.; Mayer, Bernhard; Schmidt, Christian; Bühler, Johannes; Fischer, Jonathan; Brida, Daniele; Pashkin, Alexej; Leitenstorfer, Alfred (2014): Generation and detection of tailored high-field mid-infrared waveforms with sub-cycle precision THEODORE E. SIMOS, , ed. and others. International Conference of Computational Methods in Sciences and Engineering 2014. AIP Conference Proceedings, 2014, 80. Conference collection. 1618. ISSN 0094-243X. eISSN 1551-7616. ISBN 978-0-7354-1255-2. Available under: doi: 10.1063/1.4897680

Generation and detection of tailored high-field mid-infrared waveforms with sub-cycle precision

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We review our methods for shaping of high-field multi-THz transients by means of complementary techniques of time-domain slicing and frequency-domain synthesis. In the first approach, mid-infrared waveforms are manipulated by slicing the pulse duration down to a single-cycle regime while maintaining peak field amplitude of 10 MV/cm. In the second approach, functional mid-infrared transients with controlled polar asymmetry are demonstrated. Access to these waveforms offers a robust experimental platform for investigation of fundamental light-matter interactions in novel condensed matter systems.

Forschungszusammenhang (Projekte)

    Schmidt, Christian; Mayer, Bernhard; Junginger, Friederike; Rebholz, Marc; Grupp, Alexander; Brida, Daniele; Huber, Rupert; Leitenstorfer, Alfred; Pashkin, Alexej (2013): Ultrafast low-energy dynamics of graphite studied by nonlinear multi-THz spectroscopy CHERGUI, Majed, ed. and others. XVIIIth International Conference on Ultrafast Phenomena : Lausanne, Switzerland, July 8-13, 2012. Les Ulis: EDP Sciences, 2013, 04023. EPJ Web of Conferences. 41. eISSN 2100-014X. ISBN 978-2-7598-0956-1. Available under: doi: 10.1051/epjconf/20134104023

Ultrafast low-energy dynamics of graphite studied by nonlinear multi-THz spectroscopy

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Ultraintense few-cycle THz pulses are employed to study the nonlinear response of graphite. A phase sensitive 2D spectroscopy setup is capable of detecting pump-induced transient changes as well as multi-wave mixing processes. The observed strong THz-pump THz-probe signals provide insight into ultrafast dynamics and the spectral response of the low-energy carriers. Here we report the observation of a pump-induced transmission in graphite. The relaxation dynamics shows three distinct time scales, which are assigned to carrier thermalization, phonon emission and a slow cooling down back to equilibrium.

Forschungszusammenhang (Projekte)

    Kim, Kyungwan; Pashkin, Alexej; Schäfer, Hanjo; Beyer, Markus; Porer, Michael; Wolf, Thomas; Bernhard, Christian; Demsar, Jure; Huber, Rupert; Leitenstorfer, Alfred (2013): Transient Spin Density Wave Order Induced in the Normal State of BaFe2As2 by Coherent Lattice Oscillations CHERGUI, Majed, ed. and others. XVIIIth International Conference on Ultrafast Phenomena : Lausanne, Switzerland, July 8-13, 2012. Les Ulis: EDP Sciences, 2013, 03012. EPJ Web of Conferences. 41. eISSN 2100-014X. ISBN 978-2-7598-0956-1. Available under: doi: 10.1051/epjconf/20134103012

Transient Spin Density Wave Order Induced in the Normal State of BaFe2As2 by Coherent Lattice Oscillations

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We trace the ultrafast dynamics of the spin density wave gap of the pnictide system BaFe2As2 probing resonantly with broadband multi-terahertz pulses. The photoexcitation in the low-temperature ground state leads to a fast suppression of the spin order followed by a slower recovery process. Surprisingly, in the normal state, we observe periodic oscillations of the spin density wave feature at a frequency as high as 5.5 THz. Our results indicate a transient development of a macroscopic order driven by a coherent lattice oscillation and attest to a pronounced spin–phonon coupling in pnictides.

Forschungszusammenhang (Projekte)

    Mayer, Bernhard; Junginger, Friederike; Schmidt, Christian; Mährlein, Sebastian; Schubert, Olaf; Pashkin, Alexej; Huber, Rupert; Leitenstorfer, Alfred (2013): Non-perturbative four-wave mixing in InSb with intense off-resonant multi-THz pulses CHERGUI, Majed, ed. and others. XVIIIth International Conference on Ultrafast Phenomena : Lausanne, Switzerland, July 8-13, 2012. Les Ulis: EDP Sciences, 2013, 04004. EPJ Web of Conferences. 41. eISSN 2100-014X. ISBN 978-2-7598-0956-1. Available under: doi: 10.1051/epjconf/20134104004

Non-perturbative four-wave mixing in InSb with intense off-resonant multi-THz pulses

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High-field multi-THz pulses are employed to analyze the coherent nonlinear response of the narrow-gap semiconductor InSb which is driven off-resonantly. Field-resolved four-wave mixing signals manifest the onset of a non-perturbative regime of Rabi flopping at external amplitudes above 5 MV/cm per pulse. Simulations based on a two-level quantum system confirm these experimental results.

Forschungszusammenhang (Projekte)

    Kumkar, Sören; Krauss, Günther; Brida, Daniele; Leitenstorfer, Alfred (2013): Fully coherent spectral broadening of femtosecond pulses from an Er:fiber system CHERGUI, Majed, ed. and others. XVIIIth International Conference on Ultrafast Phenomena : Lausanne, Switzerland, July 8-13, 2012. Les Ulis: EDP Sciences, 2013, 10015. EPJ Web of Conferences. 41. eISSN 2100-014X. ISBN 978-2-7598-0956-1. Available under: doi: 10.1051/epjconf/20134110015

Fully coherent spectral broadening of femtosecond pulses from an Er:fiber system

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Coherence properties of the ultrabroadband output from a highly nonlinear germanosilicate fiber pumped by a femtosecond Er:fiber source are investigated. Conditions necessary to achieve full spectral coherence are demonstrated experimentally and analyzed theoretically.

Forschungszusammenhang (Projekte)

    Filipovic, Milena; Holmqvist, Cecilia; Haupt, Federica; Belzig, Wolfgang (2013): Spin transport and tunable Gilbert damping in a single-molecule magnet junction Physical Review B. 2013, 87(4). ISSN 1098-0121. eISSN 1095-3795. Available under: doi: 10.1103/PhysRevB.87.045426

Spin transport and tunable Gilbert damping in a single-molecule magnet junction

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We study time-dependent electronic and spin transport through an electronic level connected to two leads and coupled with a single-molecule magnet via exchange interaction. The molecular spin is treated as a classical variable and precesses around an external magnetic field. We derive expressions for charge and spin currents by means of the Keldysh nonequilibrium Green’s functions technique in linear order with respect to the time-dependent magnetic field created by this precession. The coupling between the electronic spins and the magnetization dynamics of the molecule creates inelastic tunneling processes which contribute to the spin currents. The inelastic spin currents, in turn, generate a spin-transfer torque acting on the molecular spin. This back-action includes a contribution to the Gilbert damping and a modification of the precession frequency. The Gilbert damping coefficient can be controlled by the bias and gate voltages or via the external magnetic field and has a nonmonotonic dependence on the tunneling rates.

Forschungszusammenhang (Projekte)

    Pashkin, Alexej; Junginger, Friederike; Mayer, Bernhard; Schmidt, Christian; Schubert, Olaf; Brida, Daniele; Huber, Rupert; Leitenstorfer, Alfred (2013): Quantum Physics with Ultrabroadband and Intense Terahertz Pulses IEEE Journal of Selected Topics in Quantum Electronics. 2013, 19(1), pp. 8401608-8401608. ISSN 1077-260X. Available under: doi: 10.1109/JSTQE.2012.2202216

Quantum Physics with Ultrabroadband and Intense Terahertz Pulses

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We present recent advances in the generation of highly intense multiterahertz transients and their application to nonlinear spectroscopy of bulk semiconductors. An optimized scheme of parametric amplification results in broadband single- or few-cycle terahertz transients with peak electric fields up to 10 or 25 MV/cm, respectively. Time-resolved four-wave mixing terahertz spectroscopy of InSb far away from the interband resonance demonstrates clear signatures of a nonperturbative regime of Rabi flopping. We qualitatively explain the observed behavior within a model of a quantum two-level system. In addition, we demonstrate the dynamical Franz-Keldysh effect in InP resolved on a subcycle timescale. The field-induced modulation of the interband optical absorption at the second harmonic of the driving terahertz field is observed in full agreement with theoretical predictions.

Forschungszusammenhang (Projekte)

  Kumkar, Sören; Wunram, Marcel; Storz, Patrick; Fehrenbacher, David; Brida, Daniele; Leitenstorfer, Alfred (2013): High-power Yb- and Tm-doped fiber amplifiers seeded by a femtosecond Er:Fiber system 2013 Conference on Lasers & Electro-Optics Europe & International Quantum Electronics Conference CLEO EUROPE/IQEC. Piscataway, New Jersey: IEEE, 2013. ISBN 978-1-4799-0594-2. Available under: doi: 10.1109/CLEOE-IQEC.2013.6801344

High-power Yb- and Tm-doped fiber amplifiers seeded by a femtosecond Er:Fiber system

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Summary form only given. The generation of ultrafast optical pulses that are used for many applications is increasingly based on Er:fiber lasers. The inherent advantages of this technology are compactness, stability, and turn-key operation. Tm- and Yb-doped fiber systems are promising candidates for reaching microjoule pulse energies [1,2,3].We present a setup exploiting the well-established Er:fiber technology that provides a femtosecond pulse train suitable for coherent seeding of both Yb: and Tm:amplifiers. A seed source generates pulses with a wavelength centered at 1550 nm. Four parallel amplification branches each provide 8 nJ pulse energy at a repetition rate of 40 MHz. This source implements also a passive phase-locking scheme [4]. The pulses are compressed in a silicon prism pair and then coupled into a highly nonlinear fiber (HNF). This scheme allows us to generate tailor-cut spectra with components spanning from 800 to 2300 nm that can be finely tuned by material insertion in the prism sequence [5]. The solitonic part of the spectrum is centered at 1970 nm and optimized to cover the entire gain bandwidth of Tm:silica. The dispersive part of a second HNF is designed to fit the gain maximum of Yb-doped fibers at a wavelength of 1030 nm. The benefit of Er:fiber seeding has been proven experimentally by confirming the full coherence of the spectral components generated in the HNFs [6].MHz and the transform limit for the pulse duration is 110 fs. The Er:fiber system acts as seed source for the parallel Yb: and Tm:fiber amplifiers. We reduce the repetition rate to 10 MHz via electro-optic modulators. To amplify the spectrum delivered by the HNF at a center wavelength of 1030 nm, we stretch the pulses with a grating pair to a temporal duration of 340 ps. The amplification occurs in a first Yb:fiber preamplifier pumped at a wavelength of 976 nm. The energy is then boosted in a 1.5 m long Yb-doped photonic crystal fiber (PCF) amplifier stage. The PCF double cladding structure enables pumping with high-power multimode laser diodes. At a pump power of 40 W, we measured pulse energies of 2.2 μJ. The spectrum after amplification has a bandwidth of 12 nm (FWHM) centered at 1032 nm (see Fig. 1.a). Recompression of these pulses leads to a pulse duration of 185 fs (see SHG FROG characterization in Fig. 1.b). The seed for the Tm:amplifier is stretched in 30 m of single-mode fiber directly spliced to the HNF. In a monolithic and truly single-mode Tm:fiber amplifier pumped at 796 nm, we demonstrate pulse energies of 250 nJ at a repetition rate of 10 MHz [6]. Fig. 1.c shows the pulse spectrum after amplification. It is centered at a wavelength of 1950 nm with a bandwidth of 50 nm. Both amplifiers are operating in a linear regime and there are no signs of a significant influence of nonlinear effects. The combination of high-energy, sub 200-fs pump pulses together with passive carrier-envelope phase stability of ultrabroadband seed pulses for parametric amplification paves the way towards extremely nonlinear optics and attosecond technology at unprecedented repetition rates and stability.

Forschungszusammenhang (Projekte)

  Schmidt, Christian; Mayer, Bernhard; Bühler, Johannes; Seletskiy, Denis V.; Brida, Daniele; Pashkin, Alexej; Leitenstorfer, Alfred (2013): Temporal Slicing of Intense Multi-THz Transients Using an Ultrafast Semiconductor Switch Conference on Lasers and Electro-Optics Europe and International Quantum Electronics Conference (CLEO Europe/IQEC), 2013 : 12 - 16 May 2013, Munich, Germany ; at the World of Photonics Congress 2013. Piscataway, NJ: IEEE, 2013. ISBN 978-1-4799-0594-2. Available under: doi: 10.1109/CLEOE-IQEC.2013.6801033

Temporal Slicing of Intense Multi-THz Transients Using an Ultrafast Semiconductor Switch

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Advances in the femtosecond THz opto-electronics have set the stage for a novel class of nonlinear optical experiments exploiting the extreme limits of light-matter interaction. The spectral range of phase-stable multi-THz transients generated by means of difference frequency mixing spans over a multi-octave frequency window. Simultaneously, field-sensitive electro-optic detection provides full access to the temporal pulse shape. Currently, phase-locked multi-THz transients range from multi-cycle waveforms with highest peak electric fields in excess of 100 MV/cm [1] down to a single oscillation of the carrier wave with maximum field above 10 MV/cm [2]. Generally, the interaction length within the emitter crystal yields a trade-off between peak electric field and spectral bandwidth [2]. It would be desirable to combine the advantages of highest peak electric fields and short pulse durations in a single waveform. A promising tool for this purpose is a switching technique based on an ultrafast plasma mirror (UPM)Here, we present a scheme that employs an ultrafast plasma mirror (UPM) to slice intense multi-THz transients from our high-field THz laser source with a sub-cycle precision. For the first time, to the best of our knowledge, the fastest temporal slicing of multi-THz transients is observed using a field-resolved electro-optic detection scheme.

Forschungszusammenhang (Projekte)

  Porer, Michael; Sell, Alexander; Junginger, Friederike; Mayer, Bernhard; Schmidt, Christian; Mährlein, Sebastian; Pashkin, Alexej; Wolf, Martin; Leitenstorfer, Alfred; Huber, Rupert (2013): Multi-THz nonlinear optics and sub-cycle control of charge and spin CLEO : QELS_Fundamental Science : Part of Conference on Lasers and Electro-Optics. Washington, DC: optica publishing, 2013, JF1K.6. ISBN 978-1-55752-972-5. Available under: doi: 10.1364/CLEO_QELS.2013.JF1K.6

Multi-THz nonlinear optics and sub-cycle control of charge and spin

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Strong THz electric and magnetic fields are harnessed to coherently control charge and spin in solids with sub-cycle resolution. Exploiting coherent THz phonons we transiently induce and destroy spin density wave order in pnictides.

Forschungszusammenhang (Projekte)

  Seletskiy, Denis V.; Schmidt, Christian; Mayer, Bernhard; Pashkin, Alexej; Leitenstorfer, Alfred (2013): Few-cycle Synthetic Multi-THz Waveforms with Asymmetric Temporal Envelope OSA, The Optical Society, ed.. CLEO: QELS-Fundamental Science : part of Conference on Lasers and Electro-Optics ; 9 - 14 June 2013, San Jose, California, United States. Washington, DC: OSA, The Optical Society, 2013, JF1K.2. ISBN 978-1-55752-972-5. Available under: doi: 10.1364/CLEO_QELS.2013.JF1K.2

Few-cycle Synthetic Multi-THz Waveforms with Asymmetric Temporal Envelope

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Intense few-cycle synthetic multi-THz waveforms with strongly symmetry-broken temporal envelope are generated and field-resolved. Access to these waveforms sets an exciting platform for novel experiments in THz nonlinear optics.

Forschungszusammenhang (Projekte)

  Kumkar, Sören; Wunram, Marcel; Storz, Patrick; Fehrenbacher, David; Brida, Daniele; Leitenstorfer, Alfred (2013): High-power Yb: and Tm:fiber amplifiers seeded by a femtosecond passively phase-stable Er:system 2013 Conference on Lasers and Electro-Optics (CLEO 2013) : San Jose, California, USA, 9 - 14 June 2013. Piscataway, NJ: IEEE, 2013, 2122. ISBN 978-1-4799-0960-5. Available under: doi: 10.1364/CLEO_SI.2013.CW1M.4

High-power Yb: and Tm:fiber amplifiers seeded by a femtosecond passively phase-stable Er:system

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dc.title:


dc.contributor.author: Kumkar, Sören; Wunram, Marcel; Storz, Patrick; Fehrenbacher, David; Brida, Daniele; Leitenstorfer, Alfred

Forschungszusammenhang (Projekte)

  Grupp, Alexander; Mayer, Bernhard; Schmidt, Christian; Maehrlein, S.; Leitenstorfer, Alfred; Pashkin, Alexej (2013): Depletion of the Superconducting Condensate in Bi2Sr2CaCu2O8+δ Induced by Intense Multi-THz Pulses 2013 Conference on Lasers and Electro-Optics (CLEO 2013) : San Jose, California, USA, 9 - 14 June 2013 / [APS Division of Laser Science; IEEE Photonics Society; Optical Society of America] ; 4. Piscataway, NJ: IEEE, 2013, 2551. ISBN 978-1-4799-0960-5

Depletion of the Superconducting Condensate in Bi2Sr2CaCu2O8+δ Induced by Intense Multi-THz Pulses

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dc.contributor.author: Grupp, Alexander; Mayer, Bernhard; Schmidt, Christian; Maehrlein, S.; Leitenstorfer, Alfred; Pashkin, Alexej

Forschungszusammenhang (Projekte)

    Pelletier, Etienne; Sell, Alexander; Leitenstorfer, Alfred; Miller, RJ Dwayne (2012): Mid-infrared optical parametric amplifier based on a LGSe crystal and pumped at 1.6 μm. Optics Express. 2012, 20(25), pp. 27456-27464. eISSN 1094-4087. Available under: doi: 10.1364/OE.20.027456

Mid-infrared optical parametric amplifier based on a LGSe crystal and pumped at 1.6 μm.

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We demonstrate the generation of 22.6 μJ of combined energy at 3 μm for sub-300fs pulses at a repetition rate of 1 kHz using a LGSe optical parametric amplifier (OPA). The LGSe OPA is pumped by the 140-fs 1.6 μm pulses from a 300-mW KTA optical parametric chirped pulse amplifier (OPCPA) based on an all-optical synchronization scheme. By using a highly-nonlinear fiber, the output of an erbium-doped fiber laser operating at 1560 nm is shifted to 1050 nm in order to coherently seed a Nd:YLF regenerative amplifier. The LGSe OPA is seeded using the MIR coming from the amplification of the 1.6 μm in the OPCPA.

Forschungszusammenhang (Projekte)

    Kim, Kyung Wan; Pashkin, Alexej; Schäfer, Hanjo; Beyer, Markus; Porer, Michael; Wolf, Thomas; Bernhard, Christian; Demsar, Jure; Huber, Rupert; Leitenstorfer, Alfred (2012): Ultrafast transient generation of spin-density-wave order in the normal state of BaFe2As2 driven by coherent lattice vibrations Nature Materials. 2012, 11(6), pp. 497-501. ISSN 1476-1122. eISSN 1476-4660. Available under: doi: 10.1038/nmat3294

Ultrafast transient generation of spin-density-wave order in the normal state of BaFe2As2 driven by coherent lattice vibrations

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The interplay among charge, spin and lattice degrees of freedom in solids gives rise to intriguing macroscopic quantum phenomena such as colossal magnetoresistance, multiferroicity and high-temperature superconductivity. Strong coupling or competition between various orders in these systems presents the key to manipulate their functional properties by means of external perturbations such as electric and magnetic fields or pressure. Ultrashort and intense optical pulses have emerged as an interesting tool to investigate elementary dynamics and control material properties by melting an existing order. Here, we employ few-cycle multi-terahertz pulses to resonantly probe the evolution of the spin-density-wave (SDW) gap of the pnictide compound BaFe(2)As(2) following excitation with a femtosecond optical pulse. When starting in the low-temperature ground state, optical excitation results in a melting of the SDW order, followed by ultrafast recovery. In contrast, the SDW gap is induced when we excite the normal state above the transition temperature. Very surprisingly, the transient ordering quasi-adiabatically follows a coherent lattice oscillation at a frequency as high as 5.5 THz. Our results attest to a pronounced spin-phonon coupling in pnictides that supports rapid development of a macroscopic order on small vibrational displacement even without breaking the symmetry of the crystal.

Forschungszusammenhang (Projekte)

  Junginger, Friederike; Schmidt, Christian; Mayer, Boris; Maehrlein, S.; Schubert, O.; Pashkin, A.; Huber, Rupert; Leitenstorfer, Alfred (2012): Non-perturbative Four-wave Mixing in Bulk InSb Driven by Intense Off-resonant THz Pulses OSA, The Optical Society, ed.. Conference on Lasers and Electro-Optics 2012. Washington: OSA, 2012, QTu1H.6. ISBN 978-1-55752-943-5. Available under: doi: 10.1364/QELS.2012.QTu1H.6

Non-perturbative Four-wave Mixing in Bulk InSb Driven by Intense Off-resonant THz Pulses

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A high-field multi-THz source is used to study the nonlinear response of InSb under off-resonant excitation. Field-resolved four-wave mixing signals demonstrate clear signatures of a non-perturbative regime in agreement with numerical simulations.

Forschungszusammenhang (Projekte)

  Kumkar, Sören; Krauss, Günther; Wunram, Marcel; Fehrenbacher, David; Demirbas, Umit; Brida, Daniele; Leitenstorfer, Alfred (2012): Tm:fiber amplifier coherently seeded by femtosecond Er:fiber technology OSA, The Optical Society, ed.. Quantum Electronics and Laser Science Conference : [part of] Conference on Lasers and Electro-Optics 2012 ; 6 - 11 May 2012, San Jose, California, United States. Piscataway: IEEE, 2012, SI.2012.CM1B.6. ISBN 978-1-55752-943-5. Available under: doi: 10.1364/CLEO_SI.2012.CM1B.6

Tm:fiber amplifier coherently seeded by femtosecond Er:fiber technology

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Broadband seeding of a femtosecond Tm:fiber amplifier based on passively phase-locked Er:fiber technology is demonstrated. Excellent coherence properties of the seed are observed experimentally and analyzed theoretically.

Forschungszusammenhang (Projekte)

    Demirbas, Umit; Eggert, Stefan; Leitenstorfer, Alfred (2012): Compact and efficient Cr:LiSAF lasers pumped by one single-spatial-mode diode : a minimal cost approach Journal of the Optical Society of America B. 2012, 29(8), pp. 1894-1903. ISSN 0740-3224. eISSN 1520-8540. Available under: doi: 10.1364/JOSAB.29.001894

Compact and efficient Cr:LiSAF lasers pumped by one single-spatial-mode diode : a minimal cost approach

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dc.contributor.author: Demirbas, Umit; Eggert, Stefan; Leitenstorfer, Alfred

Forschungszusammenhang (Projekte)

    Junginger, Friederike; Mayer, Bernhard; Schmidt, Christian; Schubert, Olaf; Mährlein, Sebastian; Leitenstorfer, Alfred; Huber, Rupert; Pashkin, Alexej (2012): Nonperturbative Interband Response of a Bulk InSb Semiconductor Driven Off Resonantly by Terahertz Electromagnetic Few-Cycle Pulses Physical Review Letters. 2012, 109(14). ISSN 0031-9007. eISSN 1079-7114. Available under: doi: 10.1103/PhysRevLett.109.147403

Nonperturbative Interband Response of a Bulk InSb Semiconductor Driven Off Resonantly by Terahertz Electromagnetic Few-Cycle Pulses

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dc.title:


dc.contributor.author: Junginger, Friederike; Mayer, Bernhard; Schmidt, Christian; Schubert, Olaf; Mährlein, Sebastian; Leitenstorfer, Alfred; Huber, Rupert; Pashkin, Alexej

Forschungszusammenhang (Projekte)

Mittelgeber
Name Finanzierungstyp Kategorie Kennziffer
Sonstige EU Drittmittel Forschungsförderprogramm 839/11
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Laufzeit: 01.01.2012 – 31.12.2016