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The REDFINCH project involves building three fully-integrated, PIC-based, chemical sensor demonstrators for: Process gas analysis at refineries, Gas leak detection at petrochemical plants, Liquid sensing for protein analysis in the dairy industry.

Published on 16 August 2021

REDFINCH: mid infraRED Fully Integrated CHemical sensors

The REDFINCH project involves building three fully-integrated, PIC-based, chemical sensor demonstrators for: Process gas analysis at refineries, Gas leak detection at petrochemical plants, Liquid sensing for protein analysis in the dairy industry.


Starting date : Dec 2017 > Jun 2021

Lifetime: 42 months

Program in support :


Status of project : in progress

CEA-Leti's contact :                             

> Jean-Guillaume Coutard

> Laurent Fulbert       



Project Coordinator: CEA-Leti 


  • AT: TU Wien
  • CZ: Argotech
  • DE: Endress Hauser, Fraunhofer IPM
  • FR: mirSense, Univsersité de Montpellier
  • IE: CIT


Investment: € 3.9 mi

EC Contribution€ 3.9 mi


«Photoacoustic cell on silicon for mid-infrared QCL-based spectroscopic analysis», J.-G. Coutard, A. Glière, J.-M. Fedeli, O. Lartigue, J. Skubich, G. Aoust, A. Teulle, T. Strahl, S. Nicoletti, M. Carras, L. Duraffourg, Best paper award photonic west 2019 : MOEMS and miniaturized system XVIII.


Promotional Video


  • Photoacoustic (PA) spectroscopy is among the most sensitive methods used to monitor chemical emission or detect gas traces. In the mid-infrared, where most gases of interest have their strongest absorption lines, this technique takes advantage of the high optical power and room temperature operation of Quantum Cascade Lasers (QCLs). We have recently demonstrated that centimeter-size PA cells can compete with bulky commercial systems for gas sensing without any compromises on performances. 
  • This year, CEA-Leti has taken a new step towards cost reduction, extreme integration and mass deployment of such PA sensors with a miniaturized silicon PA-cellfabricated on standard CMOS tools.

  • This new sub-centimeter PA cell built on a silicon platform has been designed, fabricated and characterized. Initially, the component was designed using a detailed physical model accounting for viscous and thermal losses and metamodel-based optimization techniques. 

  • It has been subsequently fabricated on CEA-Leti’s 200 mm CMOS pilot line. Several wafers have been released and diced. Single chips have been assembled with commercial capacitive microphones; these have been characterized on the CEA-Leti reference gas bench. The results of the photoacoustic simulations and acoustics experiments agree closely and the tiny PA cell exhibits a sensitivity down to ppm level for CO2 at 2300 cm-1 and for CH4 at 3057 cm-1, even in a gas flow.

  • Heterogeneous integration of QCL sources on silicon is starting to stabilize. The main objective is to reduce the cost of these sources to ensure wide availability of their intrinsic qualities. the-art performance.Basically, one can relate the cost of MIR lasers to the costs associated with 1) epitaxy, 2) manufacturing yield and 3) packaging. CEA-Leti has fabricated several wafers on its CMOS pilot line. Thousands of QCL sources have been characterized and have exhibited excellent fabrication yield and stateof-


  • Mid-infrared photonic integrated circuits (mid-IR PICs) are the subject of increasing interest due to the large number of sensing applications in the 2-20 μm wavelength range. Most molecules exhibit absorption fingerprints in the mid-IR range corresponding to their rotational/vibrational energies. 
  • Tunable diode laser absorption spectroscopy thus allows detection and concentration measurements of many biological and chemical species. This is of crucial interest for many societal applications including health monitoring and diagnosis, detection of biological compounds, monitoring of toxic gases or of greenhouse gas emissions responsible for global warming. However, state-of-the-art sensing systems are large and delicate, which greatly hampers potential applications.

  • The REDFINCH project involves hybrid and monolithic integration of III-V diode and Interband Cascade/Quantum Cascade materials with silicon to create high-performance, cost effective sensors based on Photonic Integrated Circuits.
  • Integration creates extremely robust systems, in which discrete components are replaced by on-chip equivalents, prompting simultaneous improvement in ease of use and reduced cost. Silicon photonics leverages the advantages of high-performance CMOS technology, offering low cost mass manufacturing, high fidelity reproduction of designs and access to high refractive index contrasts enabling high-performance nanophotonics.


  • The two outcomes of the REDFINCH project represent major steps towards dissemination of MIR technologies. Regarding photoacoustics, they have been obtained thanks to close cooperation with the Fraunhofer Institute’s teams and may be exploited by mirS and EH. The REDFINCH website, conference communications and press releases have made it possible to establish preliminary contacts with industrials such as BP, BAE systems, Thorlabs and the US Naval Research Laboratory.