Electrically-pumped mid-infrared spectrometer on silicon photonic circuits. (UNISON project)

Silicon photonics group / Univ Paris Sud


14 Nov 2023
Job Information

Silicon photonics group / Univ Paris Sud
Research Field
Physics » Optics
Researcher Profile
Recognised Researcher (R2)
Application Deadline
22 Dec 2023 – 12:00 (Europe/Paris)
Type of Contract
Job Status
Is the job funded through the EU Research Framework Programme?
Is the Job related to staff position within a Research Infrastructure?

Offer Description

Mid-infrared (mid-IR) spectroscopy is a nearly universal way to identify chemical and biological substances and to perform non-intrusive diagnostics. Indeed, the mid-IR spectral range contains the so-called “fingerprint” region (wavelength from 6 to 15 µm) in which most molecules have vibrational and rotational resonances. This wavelength range can, hence, be exploited to detect small traces of environmentally hazardous and toxic substances for a variety of applications including defense, security and industrial monitoring. A challenging task is to make mid-IR spectroscopy accessible in remote areas, driving the development of compact and cost-effective solutions to replace table-top systems .

            The post-doctoral position will occur in the framework of EU Pathfinder open UNISON project, whose objective is to demonstrate a highly scalable platform for infra-red spectroscopy that is both cost-effective and compact. The radically new technology is a compact and low-cost integrated spectrometer covering the whole mid-IR spectral range (from 3 to 12 μm wavelengths) and that can be integrated in the cramped space of an Internet of Things (IoT) device.

            To achieve this objective, UNISON will leverage on electrically pumped cascade lasers (QCL and ICL) and on silicon germanium (SiGe) mid-IR photonic circuits to demonstrate beyond state-of-the-art spectrometers. Beyond physical and technological challenges on each of the project cornerstone, the integration of QCL or ICL with SiGe photonics circuits is a major task that will be required for any of the project objective and that will be developed within this post-doctoral position. Different solutions will be explored :

  • The  monolithic integration of QCL source on SiGe photonics circuits will be investigated as it would allow a large-volume, wafer-level mid-IR photonic platform. However main challenges will have to be solved, related to the definition of structures compatible with the integration, keeping good material properties and device performances, while allowing efficient coupling from the laser to the SiGe waveguide. This solution will be investigated during the post-doctoral position, requiring numerical simulation, device design, process development, fabrication and characterization of the samples.
  • In parallel with the monolithic integration, for which the abovementioned challenges will have to be solved, a butt coupling strategy will be developed, allowing the combination of any kind of laser with SiGe-based photonic circuits for the development of an integrated mid-IR sensing platform. Mode size converters, integrated lenses and Anti-Reflection (AR) coatings will be developed to optimize the coupling transmission.



For each of these path, the research activity will include:

 – Numerical simulation and modeling of the devices, using commercially available software and developing home-made code (Matlab or python) for automating tasks

Design and fabrication of the devices in in-house clean room in collaboration with other group members.

Experimental characterizations of the devices, using mid-IR optical benches already developed in the group (participation to the set-up development and maintenance).


Profil of the candidate

We are looking for a candidate with experience in integrated optics, ideally in the mid-IR spectral range but this is not restrictive. Ideally, the candidate should have experience in simulation, clean room fabrication and optical characterization.

Furthermore, the candidate will work in a framework of EU Pathfinder project (2024-2028), starting in March 2024, with 7 international partners, C2N being the coordinator of the project. A strong involvement in the project is expected (presentation during project meetings, participation in the deliverables writing, participation in the  management, ….). The capability to communicate and share results in a multidisciplinary and multi-nationality environment is highly expected.


References related to the work

[1] M. Montesinos-Ballester, V. Vakarin, Q. Liu, X. Le Roux, J. Frigerio, A. Ballabio, A. Barzaghi, C. Alonso-Ramos, L. Vivien, G. Isella, D. Marris-Morini,Ge-rich graded SiGe waveguides and interferometers from 5 to 11 μm wavelength range, Optics Express, 28 (9), 12771 (2020). https://doi.org/10.1364/OE.391464

[2] J-M. Ramirez, Q. Liu, V. Vakarin, X. Le Roux, J. Frigerio, A. Ballabio, C. Alonso Ramos, E. Talamas Simola, L. Vivien, G. Isella, D. Marris-Morini, Broadband integrated racetrack ring resonators for long-wave infrared photonics, Optics Letters, 44 (2), 407 (2019). https://doi.org/10.1364/OL.44.000407

[3] M. Montesinos-Ballester, C. Lafforgue, J. Frigerio, A. Ballabio, V. Vakarin, Q. Liu, J. M. Ramirez, X. Le Roux, D. Bouville, A. Barzaghi, C. Alonso-Ramos, L. Vivien, G. Isella, and D. Marris-Morini, On-Chip Mid-Infrared Supercontinuum Generation from 3 to 13 μm Wavelength, ACS Photonics, 7, 3423-3429, (2020) https://dx.doi.org/10.1021/acsphotonics.0c01232

[4] T.H.N. Nguyen, N. Koompai, V. Turpaud, M. Montesinos-Ballester, J. Peltier, J Frigerio, A. Ballabio, R. Giani, J-R. Coudevylle, C. Villebasse, D. Bouville, C. Alonso-Ramos, L. Vivien, G. Isella, D. Marris-Morini, 1 GHz electro-optical silicon-germanium modulator in the 5-9 μm wavelength range, Optics Express, 30, (26), 47093 (2022). https://doi.org/10.1364/OE.476164

[5] T.H.N. Nguyen, N. Koompai, V. Turpaud, M. Montesinos-Ballester, J Frigerio, S. Calcaterra, A. Ballabio, X. Le Roux, J-R. Coudevylle, C. Villebasse, D. Bouville, C. Alonso-Ramos, L. Vivien, G. Isella, D. Marris-Morini, Room temperature integrated photodetector between 5 µm and 8 µm wavelength, Advanced Photonics Research, 2200237 (2022) http://doi.org/10.1002/adpr.202200237

[6] Natnicha Koompai, Thi Hao Nhi Nguyen, Victor Turpaud, Jacopo Frigerio, Virginia Falcone, Stefano Calcaterra, Luca Lucia, Adel Bousseksou, Raffaele Colombelli, Jean-Rene Coudevylle, David Bouville, Carlos Alonso-Ramos, Laurent Vivien, Giovanni Isella, Delphine Marris-Morini, Long wave-infrared integrated resonators in the 7.5-9 µm wavelength range, Applied Physics Letters,123 (3) (2023) 



Research Field
Physics » Optics
Education Level
PhD or equivalent

Additional Information
Work Location(s)

Number of offers available
C2N / Universite Paris Saclay

Where to apply

[email protected]


C2N, Palaiseau


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