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Reference : UMR8520-STEBAR-003
Workplace : VILLENEUVE D ASCQ
Date of publication : Thursday, September 9, 2021
Type of Contract : FTC Scientist
Contract Period : 24 months
Expected date of employment : 1 February 2022
Proportion of work : Full time
Remuneration : From 2675 euros gross per month
Desired level of education : PhD
Experience required : Indifferent
Context. Applications relying on mid-infrared (MIR, 3-12 m) radiation have progressed at a very rapid pace in recent years, stimulated by scientific and technological breakthroughs. MIR cameras have propelled the field of thermal imaging. The invention of the quantum cascade laser (QCL) has been another milestone, which has enabled a vast range of civilian, and defense-related applications. All the recent breakthrough advances stemmed from the development of transformative optical components.
In addition to the generation and detection of light, a key functionality for most photonics systems is the possibility to electrically control the amplitude, phase, and polarization state of an optical beam up to ultra-short time scales. Fast amplitude and phase modulation are essential for a large number of applications, including laser amplitude/frequency stabilization, coherent detection, FM/AM spectroscopy and sensing, mode-locking, optical communications, military countermeasures, etc.
Contrary to the visible and near-IR range, in the MIR range broadband modulators with modulation bandwidth of several tens of GHz do not exist, which hampers the progress of MIR photonics.
Objective. The goal of this project is the demonstration of a power-efficient, broadband (up to ~40 GHz bandwidth) and integrated semiconductor-based MIR amplitude and phase-modulator. The modulator will be optimized for operation at =10m, since this wavelength (i) matches an important atmospheric window for free space communications, and (ii) because it is ideal for spectroscopy and gas sensing applications. The envisaged device exploits the electro-optical properties of Gallium Arsenide (GaAs) in a double waveguide allowing the simultaneous propagation of MIR radiation and of the microwave modulating signal.
During the project, the development of the device will be done schematically in three steps: (i) a first phase of device design based on FDTD simulations; (ii) a second phase of device fabrication in clean room environment, and measurement of the optical properties of the grown materials (permittivity, losses etc) using FTIR spectroscopy ; (iii) a final stage of characterization of the MIR waveguides, after which the modulator will be characterized optically and electrically using an ultra-broadband MIR detector recently developed in our laboratory . In the final part of the project, we plan to carry out a dedicated experiment to evaluate the performance of the modulator for telecom applications in free space. All the project phases, including fabrication and characterization, will be carried out at IEMN facilities.
 M. Hakl, et al., “Ultrafast quantum well photodetectors operating at 10m with flat frequency response up to 70GHz at room temperature”, ACS Photonics https://pubs.acs.org/doi/10.1021/acsphotonics.0c01299
Required profile For this project we seek a motivated post-doctoral student with a PhD in Physics/Electrical Engineering, and solid background in semiconductor physics, optoelectronics and/or material science. The student will be involved in all the aspects of the project, with a special emphasis on device fabrication. Experience in III-V semiconductor processing, mid-infrared optics and/or semiconductor device characterization will definitely be a plus.
The project will be carried out within the THz Photonics Team of the IEMN Laboratory. The team has a long experience in the design and realization of optoelectronic devices (sources, detectors, etc.) in the frequency range from sub-mm to infrared.
This project will be done in collaboration with Laboratoire C2N (Palaiseau-France) and Laboratoire LPL (Villetaneuse-France).
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