You are here : Home > HOLDON: HgCdTe APD Optimization for Lidar Detection Of greeNhouse gas

Europe | Tools & research instruments


Published on 22 April 2021

HOLDON: HgCdTe APD Optimization for Lidar Detection Of greeNhouse gas

The HOLDON project aim is to develop a highly sensitive LIDAR detector module for atmospheric surveillance of greenhouse gases (CO2, CH4). This detector will be assessed in relation to its potential capacity for integration into mini-satellites for future operation.


Starting date : Jan 2018 > Jun 2021

Lifetime: 48 months

Program in support :


Status of project : in progress

CEA-Leti's contact :                             

> Jérome Le Perchec

> Laurent Fulbert 

> Pierre Castelain  



Project Coordinator:



  • CH: IDQuantique
  • DE: Deutsches Zentrum für Luft- und Raumfahrt
  • ES: Alter Technology
  • FR: Absiskey, Airbus Defence and Space, Ecole Polytechnique
  • Laboratoire de Météorologie Dynamique

Investment: € 2.5 mi

EC Contribution€ 2.5 mi



  • CEA-Leti is manufacturing the detection module to be integrated into the full LIDAR chain. During the first year of project, CEA-Leti and its technical partners drew up the full specifications for the HOLDON detector (APD, ROIC, optical and electronic interfaces) specifically for greenhouse gases and LIDAR altimetric measurements. These specifications were validated after analyzing relevant space and ground atmospheric LIDAR scenarios for 350 nm to 2 μm wavelengths embracing a wide dynamic range between 10^6 and 10^12 photons/s for limited signal detection of a shot noise.

  • CEA-Leti has now launched development of the detector module technological bricks, which will be based on HgCdTe APDs hybridized with specifically designed CMOS ROIC. The combination will be packaged in a cryo-cooler). HgCdTe APDs have the unique advantage of combining high quantum efficiency over a broad spectral window with a close to deterministic avalanche gain, which allows amplification of the signal to a level higher than the electronic amplifier noise with almost negligible information loss.

  • Regarding the specifications, CEA-Leti has studied different potential ROIC architectures and conducted simulation campaigns. The ROIC architecture has now been frozen, offering a dual operation mode with different possible gains covering the required wide dynamic range. The two modes are continuous for conventional sampling on proximity electronics or switchable on-chipsampling with variable observation time, gain and accumulation capabilities.

  • CEA-Leti has defined the APD architecture and the mask set specifications for the technological process of forthcoming batches and has undertaken epitaxial growth of the high quality HgCdTe layers.

  • The APD performance characteristics will be optionally maximized, while minimizing response time and dark current, by optimizing optical coupling to the APD with micro-lenses, which will be directly machined on the side of the APD chips, which will be illuminated by the laser echo.


  • LIDAR remote sensing of the Earth’s atmosphere is a key tool for monitoring the effects and causes of global warming caused by greenhouse gas emission. LIDAR is the acronym of «Light Imaging, Detection and Ranging». It refers to a surveying method that measures distance to a target by illuminating the latter with pulsed laser light and measuring the reflected pulses with a sensor. 
  • With regard to atmospheric monitoring, today’s LIDAR applications are all installed at large satellite platforms because of the size of the telescope and high energy laser modules required to ensure sufficient light intake and separate the return signal from detector noise.
  • The purpose of the HOLDON project is to develop a new, versatile detection chain, which will improve LIDAR performance, and to reduce LIDAR payload for future mini-satellites. Increased performance is obtained by optimizing high quantum-efficiency HgCdTe Avalanche PhotoDiodes (APD) to be hybridized to a specially designed CMOS readout circuit (ROIC) offering two operating modes. 
  • The devices are expected to meet the most stringent specifications for LIDAR applications implementing ultra-violet to near-infrared wavelengths in terms of sensitivity, dynamic range and temporal resolution (high dynamic range down to single photon sensitivity). Seven European partners (CEA-Leti, DLR, AIRBUS, IDQ, LMD, ALTER and ABSISKEY) are cooperating to take up the following three challenges:

  1. Design and manufacturing of a cutting edge, photon noise-limited LIDAR detection chain
  2. Demonstration of the improvement achieved with the detection chain for greenhouse gas detection (especially CO2 andCH4)
  3. Validation of the adequacy between LIDAR detection key performance characteristics and future space mission requirements.


  • The ambitious specifications for the HOLDON LIDAR module outperform the state of the art. We expect to foster scientific excellence in Europe, in particular by maintaining Europe’s leadership in the physics and applications of HgCdTe APDs and by enabling new cooperations. 
  • Furthermore, a versatile detection chain offering low payload will pave the way towards a European commercial offer for atmospheric and space LIDAR applications fulfilling similar needs and potential industrial exploitation by a number of interested companies.