Hybrid Optomechanical Technologies

Description

The H2020 FET Proactive project emHybrid Optomechanical Technologies (HOT)/em is pursued by a consortium of 17 major European research institutions, including 4 industrial players, which will explore the potential of hybrid-nano-optomechanical systems. The project will lay the foundation for a new generation of devices, which connect, or indeed contain, several platforms at the nanoscale in a single ”hybrid” system. As hybrid interfaces they will allow to harness the unique advantages of each subsystem within a nano-scale footprint, while as integrated hybrid devices they will enable entirely novel functionalities. A particular focus will be on nano-optomechanical devices that comprise electrical, microwave or optical systems with micro- and nano-mechanical systems. Research in the past decade, in particular by European groups, has shown the significant technological potential that such nano-optomechanical systems can offer, in particular by establishing a new way in which optical, radio-frequency and microwave signals can be interfaced. The project focusses on hybrid opto- and electro-mechanical devices operating at the physical limit for conversion, synthesis, processing, sensing and measurement of EM fields, comprising radio, microwave frequencies to the terahertz domain. These spectral domains open realistic applications in the existing application domains of medical (e.g. MRI imaging), security (e.g. Radar and THz monitoring), positioning, timing and navigations (Oscillators) and for future quantum technology. The research aims at specific technological application, with realistic operating conditions and seeks to develop actual system demonstrators. In addition, it will explore how these hybrid transducers can be fabricated within standard CMOS processing, and thereby be made compatible with current manufacturing methods. The HOT devices will thereby impact today’s technology and likewise address potential future need for the manipulation of quantum signals.pIn particular, the Konstanz node of HOT will target multimode nanoelectromechanical devices consisting of arrays of resonators. The linear and nonlinear dynamics as well as coherent control of these nanomechanical networks will be investigated. This will enable insights into parametric effects in coupled oscillators or synchronization phenomena, and could even pave the way towards a better understanding of topological mechanical nanostructures.

Institutions
  • Department of Physics
Publications
  Le, Anh Tuan; Brieussel, Alexandre; Weig, Eva M. (2021): Room temperature cavity electromechanics in the sideband-resolved regime Journal of Applied Physics. American Institute of Physics (AIP). 2021, 130, 014301. ISSN 0021-8979. eISSN 1089-7550. Available under: doi: 10.1063/5.0054965

Room temperature cavity electromechanics in the sideband-resolved regime

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We demonstrate a sideband-resolved cavity electromechanical system operating at room temperature. The mechanical resonator, a strongly pre-stressed silicon nitride string, is dielectrically coupled to a three-dimensional microwave cavity made of copper. The electromechanical coupling is characterized by two measurements, the cavity-induced eigenfrequency shift of the mechanical resonator and the optomechanically induced transparency. While the former is dominated by dielectric effects, the latter reveals a clear signature of the dynamical backaction of the cavity field on the resonator. This unlocks the field of cavity electromechanics for room temperature applications.

Origin (projects)

  Bückle, Maximilian; Klaß, Yannick S.; Nägele, Felix B.; Braive, Rémy; Weig, Eva M. (2021): Universal Length Dependence of Tensile Stress in Nanomechanical String Resonators Physical Review Applied. American Physical Society (APS). 2021, 15(3), 034063. eISSN 2331-7019. Available under: doi: 10.1103/PhysRevApplied.15.034063

Universal Length Dependence of Tensile Stress in Nanomechanical String Resonators

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We investigate the tensile stress in freely suspended nanomechanical string resonators, and observe a material-independent dependence on the resonator length. We compare strongly stressed string resonators fabricated from four different material systems based on amorphous silicon nitride, crystalline silicon carbide as well as crystalline indium gallium phosphide. The tensile stress is found to increase by approximately 50% for shorter resonators. We establish a simple elastic model to describe the observed length dependence of the tensile stress. The model accurately describes our experimental data. This opens a perspective for stress engineering the mechanical quality factor of nanomechanical string resonators.

Origin (projects)

  Ochs, Jana Simone; Seitner, Maximilian; Dykman, Mark I.; Weig, Eva M. (2021): Amplification and spectral evidence of squeezing in the response of a strongly driven nanoresonator to a probe field Physical Review A. American Physical Society. 2021, 103(1), 013506. ISSN 2469-9926. eISSN 2469-9934. Available under: doi: 10.1103/PhysRevA.103.013506

Amplification and spectral evidence of squeezing in the response of a strongly driven nanoresonator to a probe field

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Because of their small decay rates, nanomechanical modes enable studying strongly nonlinear phenomena for a moderately strong resonant driving. Here we study the response of a driven resonator to an additional probe field. We experimentally demonstrate resonant amplification and resonant absorption of the probe field. The corresponding spectral peaks lie on the opposite sides of the strong-drive frequency. Even though the fluctuation-dissipation theorem does not apply, we show that the response to the probe field allows us to characterize the squeezing of fluctuations about the stable states of forced oscillations. Our two-tone experiment is done in the classical regime, but our findings should equally apply to quantum fluctuations as well. In quantum terms, the observed response is due to multiphoton processes. The squeezing parameter extracted from the spectra of the response is in excellent agreement with the calculated value with no free parameters.

Origin (projects)

  Yang, Fan; Hellbach, Felicitas; Rochau, Felix; Belzig, Wolfgang; Weig, Eva M.; Rastelli, Gianluca; Scheer, Elke (2020): Persistent Response in an Ultrastrongly Driven Mechanical Membrane Resonator Physical Review Letters. American Physical Society (APS). 2020, 127(1), 014304. ISSN 0031-9007. eISSN 1079-7114. Available under: doi: 10.1103/PhysRevLett.127.014304

Persistent Response in an Ultrastrongly Driven Mechanical Membrane Resonator

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We study experimentally and theoretically the phenomenon of persistent response in ultra-strongly driven membrane resonators. This term denotes the development of a vibrating state with nearly constant amplitude over an extreme wide frequency range. We reveal the underlying mechanism of the persistent response state by directly imaging the vibrational state using advanced optical interferometry. We argue that the persistent state is related to the nonlinear interaction between higher order flexural modes and higher-order overtones of the driven mode. Finally, we propose a stability diagram for the different vibrational states that the membrane can adopt.

Origin (projects)

  Yang, Fan (2020): Investigation of the Interaction, Nonlinear and Dissipation Effects in Nano-Membrane Resonators by Optical Interferometry

Investigation of the Interaction, Nonlinear and Dissipation Effects in Nano-Membrane Resonators by Optical Interferometry

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Nanomechanical membrane resonators are extensively used in a variety of applications due to their high quality factor and sensitive response in the linear working range. The quantitative characterization of mechanical properties of nanomechanical resonators paves the way to understand the vibrational dynamics of nanomechanical systems and provides the opportunity to extend the application into nonlinear regime. In the nonlinear regime, the nanomechanical systems present tremendous vibrational and coupling behavior which can provide massive information beyond the linear regime. Thus extending the investigation into nonlinear is significantly important. In this thesis, we present experimental studies of the bending waves of freestanding silicon nitride (SiN) nanomembrane resonators in different dynamic regimes by using optical profilometry, such as Imaging White Light Interferometer (IWLI) and Michelson Interferometer (MI), in varying environments such as pressure and temperature.
To quantitatively characterize the basic mechanical properties of nanomembrane resonators, we introduce a method, named Vibrometry in Continuous Light (VICL) that enables us to disentangle the response of the membrane from that of the excitation system, thereby giving access to the eigenfrequency and the quality (Q) factor of the membrane by fitting a damped driven harmonic oscillator model to the experimental data. We verify the performance of the method by studying two modes of a 478 nm thick SiN freestanding membrane and find Q factors of 2 \times 10444 for both modes at room temperature. Finally, we observe a linear increase of the resonance frequency of the ground mode with temperature which makes nanomembrane resonators suitable for high-sensitive temperature sensors.
In the second phase of experiments, we study the vibrational motion of mechanical resonators in the strong nonlinear regime. By imaging the vibrational state of rectangular SiN membrane resonators and by analyzing its frequency response using optical interferometry, we show that upon increasing the driving strength, the membrane adopts a peculiar deflection pattern of concentric rings superimposed onto the drum head shape of its fundamental mode. Such a circular symmetry cannot be described as a superposition of a small number of excited linear eigenmodes. Furthermore, different parts of the membrane vibrate at different multiples of the drive frequency, an observation that we term "localization of overtones". We introduce a phenomenological model based on the coupling between effective nonlinear resonators to represent different parts of the membrane, which agrees well with the experimental observations.
Further more, we investigated the phenomenon of persistent response in ultra-strongly driven membrane oscillators. The term "persistent response" denotes the development of a vibrating state with nearly constant amplitude over a very wide frequency range (up to 50% of the drive frequency). We reveal its underlying mechanism by directly imaging the vibrational state of membrane resonators. Beyond the spatial modulation, at even larger driving strength nonlinear interaction and sub-harmonically driven parametric resonance between different exural modes and their localized overtones govern the persistent response. Our result is important for understanding nonlinear resonance behavior appearing in different fields of physics as well as for the development of amplitude-stable mechanical resonators with broadband tunable frequency.

Origin (projects)

    Ochs, Jana Simone; Rastelli, Gianluca; Seitner, Maximilian; Kölbl, Johannes; Belzig, Wolfgang; Dykman, Mark I.; Weig, Eva M. (2020): Spectral evidence of squeezing of a weakly damped driven nanomechanical mode Physical Review X. American Physical Society (APS). 2020, 10, 021066. eISSN 2160-3308. Available under: doi: 10.1103/PhysRevX.10.021066

Spectral evidence of squeezing of a weakly damped driven nanomechanical mode

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Because of the broken time-translation symmetry, in periodically driven vibrational systems fluctuations of different vibration components have different intensities. Fluctuations of one of the components are often squeezed, whereas fluctutions of the other component, which is shifted in phase by π/2, are increased. Squeezing is a multi-faceted phenomenon, it attracts much attention from the perspective of high-precision measurements. Here we demonstrate a new and hitherto unappreciated side of squeezing: its direct manifestation in the spectra of driven vibrational systems. With a weakly damped nanomechanical resonator, we study the spectrum of thermal fluctuations of a resonantly driven nonlinear mode. In the attained sideband-resolved regime, we show that the asymmetry of the spectrum directly characterizes the squeezing. This opens a way to deduce squeezing of thermal fluctuations in strongly underdamped resonators, for which a direct determination by a standard homodyne measurement is impeded by frequency fluctuations. The experimental and theoretical results are in excellent agreement. We further extend the theory to also describe the spectral manifestation of squeezing of quantum fluctuations.

Origin (projects)

    Gajo, Katrin; Rastelli, Gianluca; Weig, Eva M. (2020): Tuning the nonlinear dispersive coupling of nanomechanical string resonators Physical Review B. American Physical Society (APS). 2020, 101(7), 075420. ISSN 2469-9950. eISSN 2469-9969. Available under: doi: 10.1103/PhysRevB.101.075420

Tuning the nonlinear dispersive coupling of nanomechanical string resonators

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We investigate nonlinear dispersive mode coupling between the flexural in- and out-of-plane modes of two doubly clamped, nanomechanical silicon nitride string resonators. As the amplitude of one mode transitions from the linear response regime into the nonlinear regime, we find a frequency shift of two other modes. The resonators are strongly elastically coupled via a shared clamping point and can be tuned in and out of resonance dielectrically, giving rise to multimode avoided crossings. When the modes start hybridizing, their polarization changes. This affects the nonlinear dispersive coupling in a non-trivial way. We propose a theoretical model to describe the dependence of the dispersive coupling on the mode hybridization.

Origin (projects)

    Yang, Fan; Rochau, Felix; Ochs, Jana Simone; Brieussel, Alexandre; Rastelli, Gianluca; Weig, Eva M.; Scheer, Elke (2019): Spatial Modulation of Nonlinear Flexural Vibrations of Membrane Resonators Physical Review Letters. 2019, 122(15), 154301. ISSN 0031-9007. eISSN 1079-7114. Available under: doi: 10.1103/PhysRevLett.122.154301

Spatial Modulation of Nonlinear Flexural Vibrations of Membrane Resonators

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We study the vibrational motion of mechanical resonators under strong drive in the strongly nonlinear regime. By imaging the vibrational state of rectangular silicon nitride membrane resonators and by analyzing the frequency response using optical interferometry, we show that, upon increasing the driving strength, the membrane adopts a peculiar deflection pattern formed by concentric rings superimposed onto the drum head shape of the fundamental mode. Such a circular symmetry cannot be described as a superposition of a small number of excited linear eigenmodes. Furthermore, different parts of the membrane vibrate at different multiples of the drive frequency, an observation that we denominate as "localization of overtones." We introduce a phenomenological model that is based on the coupling of a small number of effective nonlinear resonators, representing the different parts of the membrane, and that describes the experimental observations correctly.

Origin (projects)

    Paulitschke, Philipp; Keber, F.; Lebedev, Andrej; Stephan, Jürgen; Lorenz, Heribert; Hasselmann, Sebastian; Heinrich, Doris; Weig, Eva M. (2019): Ultraflexible Nanowire Array for Label- and Distortion-Free Cellular Force Tracking Nano letters. 2019, 19(4), pp. 2207-2214. ISSN 1530-6984. eISSN 1530-6992. Available under: doi: 10.1021/acs.nanolett.8b02568

Ultraflexible Nanowire Array for Label- and Distortion-Free Cellular Force Tracking

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Living cells interact with their immediate environment by exerting mechanical forces, which regulate important cell functions. Elucidation of such force patterns yields deep insights into the physics of life. Here we present a top-down nanostructured, ultraflexible nanowire array biosensor capable of probing cell-induced forces. Its universal building block, an inverted conical semiconductor nanowire, greatly enhances both the functionality and the sensitivity of the device. In contrast to existing cellular force sensing architectures, microscopy is performed on the nanowire heads while cells deflecting the nanowires are confined within the array. This separation between the optical path and the cells under investigation excludes optical distortions caused by cell-induced refraction, which can give rise to feigned displacements on the 100 nm scale. The undistorted nanowire displacements are converted into cellular forces via the nanowire spring constant. The resulting distortion-free cellular force transducer realizes a high-resolution and label-free biosenor based on optical microscopy. Its performance is demonstrated in a proof-of-principle experiment with living Dictyostelium discoideum cells migrating through the nanowire array. Cell-induced forces are probed with a resolution of 50 piconewton, while the most flexible nanowires promise to enter the 100 femtonewton realm.

Origin (projects)

    Bückle, Maximilian; Hauber, Valentin C.; Cole, Garrett D.; Gärtner, Claus; Zeimer, Ute; Grenzer, Jörg; Weig, Eva M. (2018): Stress control of tensile-strained In1−xGaxP nanomechanical string resonators Applied Physics Letters. 2018, 113(20), 201903. ISSN 0003-6951. eISSN 1077-3118. Available under: doi: 10.1063/1.5054076

Stress control of tensile-strained In1−xGaxP nanomechanical string resonators

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We investigate the mechanical properties of freely suspended nanostrings fabricated from tensile-stressed, crystalline In1−xGaxP. The intrinsic strain arises during epitaxial growth as a consequence of the lattice mismatch between the thin film and the substrate, and is confirmed by x-ray diffraction measurements. The flexural eigenfrequencies of the nanomechanical string resonators reveal an orientation dependent stress with a maximum value of 650 MPa. The angular dependence is explained by a combination of anisotropic Young's modulus and a change of elastic properties caused by defects. As a function of the crystal orientation, a stress variation of up to 50% is observed. This enables fine tuning of the tensile stress for any given Ga content x, which implies interesting prospects for the study of high Q nanomechanical systems.

Origin (projects)

    Gajo, Katrin; Schüz, Simon; Weig, Eva M. (2017): Strong 4-mode coupling of nanomechanical string resonators Applied Physics Letters. 2017, 111(13), 133109. ISSN 0003-6951. eISSN 1077-3118. Available under: doi: 10.1063/1.4995230

Strong 4-mode coupling of nanomechanical string resonators

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We investigate mechanical mode coupling between the four fundamental flexural modes of two doubly-clamped, high-Q silicon-nitride nanomechanical string resonators. Strong mechanical coupling between the strings is induced by the strain mediated via a shared clamping point, engineered to increase the exchange of oscillatory energy. One of the resonators is controlled dielectrically, which results in strong coupling between its out-of-plane and in-plane flexural modes. We show both, inter-string out-of-plane-in-plane and 3-mode resonance of the four coupled fundamental vibrational modes of a resonator pair, giving rise to a simple and a multimode avoided crossing, respectively.

Origin (projects)

Funding sources
Name Finanzierungstyp Kategorie Project no.
Europäische Union third-party funds research funding program 706/16
Further information
Period: 01.01.2017 – 31.12.2020