Optomechanical Technologies


The H2020 Marie Sklodowska-Curie Action emOptomechanical Technologies (OMT)/em is a European Training Network (ETN) targeting the successful training and research experience of the leading European research groups working in the field of cavity optomechanics. Our ENT unites a total of 14 leading groups in the field, of which two are major industrial players that utilize MEMS and NEMS - Bosch and IBM. The main goal of the project is to exploit optomechanical interactions in views of novel functionality and possible applications of cavity optomechanical systems that were envisioned by consortium partners during their previous research activities. The possible applications include for instance MEMS sensors based on two-dimensional materials like graphene, quantum limited microwave amplifiers, and low noise optical to microwave frequency photon converters. While the majority of the experiments will firmly reside in the realm of classical, albeit weak, signals or fields, the aspired performance will also allow exploiting schemes in scenarios where quantum nature of the signal is relevant.pIn particular, the Konstanz node of the ETN focusses on cavity optomechanics with atomically thin two-dimensional (2D) membranes such as BN or MbS2. The 2D membranes are processed in a device architecture suitable for insertion in a high finesse fiber based Fabry-Perot cavity. Dispersive and dissipative optomechanical interaction will be explored. In particular, dynamical backaction leading to self-oscillation and cooling will be investigated, shedding light on the use of atomic-scale mechanical resonators for optomechanical technologies.

  • Department of Physics
  Ashour, Mohamed (2021): Efficient refractive index modulation in an open access silicon photonic platform

Efficient refractive index modulation in an open access silicon photonic platform


Optical modulators are one of the critical components of integrated photon-ics. Modulators enable control of light phase through an external excitation. This excitation can take different forms, including mechanical or electrical excitation. The maximum phaseshift, the bandwidth, power consumption as well as area footprint of the modulator are the most important key per-formance parameters of optical modulators. Bandwidth and phaseshifting efficiency are common to be of top priority in the telecom industry. This thesis focuses on the realization of highly efficient optical modulators in a silicon photonic open access platform. The modulators discussed within this work aim at achieving specific key performance indicators for application in an optical phased antenna array. An optical phased antenna array allows for full solid state laser beam steering. Its applications cover a diverse set of solutions within mobility, smart wearables, high precision measurement and meteorology industries. Unlike modulators for the telecom industry, an optical phased antenna ar-ray does not require a high operation bandwidth. As such an array involves a large number of optical modulators. Power consumption is a critical param-eter. This is implied by ensuring a low power density to prevent unwanted thermal effects. In this thesis, design and proposal as well as the experimental realization of novel concepts of integrated optical modulators is pursued. Fabrication of proposed designs is primarily done using an open access standard technol-ogy. The term open access refers to a standard industrial process, that is available to use publicly, under specific conditions, and usually for paying a considerable participation fee. However, such technologies largely ensure re-producibility and mass-producible industrially compatible designs. The work focuses on two approaches. The first is the optomechanical modulation, and the second is the electro-optic modulation. The optomechanical modulator poses a larger fabrication challenge, due to requiring free-standing nanophotonic waveguides to function. This, in turn, requires developing a releasing process, which is heavily discussed in this work. The electro-optic modulators in this work are realized by direct fab-rication in an open access technology without further processing. In the framework of this thesis, a fundamentally novel electro-optic modulator was proposed. This is the bi-junction electro-optic modulator. This modulator implements an implant profile, that is almost identical to the implant profile commonly found in a bipolar junction transistor, however, implemented in an optical waveguide. The phaseshifting performance of these modulators significantly exceeds the reported phaseshifting performance of the commonly reported lateral and interleaved modulators. Also, in some cases, the bi-junction modulators achieve lower or slightly higher optical losses. The phaseshift/optical loss figure of merits are calculated from experimental measurements. The NPN polarity of the bi-junction modulator achieves more than 200 % increase over the stander PN-lateral modulator and 8.3 % increase over the interleaved modulator. Interestingly, in this run, the losses were limited by employing a specific electrical contacts layout that added 1 dB of optical losses to the bi-junction modulators. Removal of such lossy elements can improve the performance gains to 50 % and 300 % more than interleaved and lateral modulators respectively. The bi-junction electro-optic modulator achieves these performance in-dicators under an operation bandwidth of almost 2 MHz and an electrical power consumption of less than 1 nW. These modulators are thought to be-come disruptive modulation devices for optical phased antenna arrays, which are currently a very hot topic in silicon photonics.

Origin (projects)

Funding sources
Name Finanzierungstyp Kategorie Project no.
Europäische Union third-party funds research funding program 675/16
Further information
Period: 01.10.2016 – 30.09.2020