Title: Advanced Infrared Detector Development for Space lidar applications
Presenting Author: Xiaoli Sun
Organization: NASA GSFC
Co-Author(s):

Abstract:
Detector technologies play a vital role in the space lidar design and directly affect the instrument performance, size, mass, power, and cost. Many lidar measurements for Earth science studies and environmental monitoring need to be performed over short wave infrared (SWIR) and mid-wave infrared (MWIR) laser wavelength where more favorable spectral absorption lines are available and solar background light become lower. However, there has been a lack of sensitive lidar detectors at SWIR and MWIR wavelength. All single photon lidar detectors work in the visible and near infrared wavelength. Most of the existing SWIR and MWIR detectors are imaging sensors and not suitable for detecting short laser pulses. A few infrared SWIR photon detectors such as InGaAs avalanche photodiodes (APD) have various nonlinear effects which seriously limit the instrument performance. NASA Goddard Space Flight Center (GSFC) been developing advanced SWIR and MWIR lidar detectors with Leonardo DRS, Electro-Optical Infrared Systems, Dallas TX, under ESTO IIP, ACT, InVEST and QRS programs. A new type of HgCdTe APD arrays has been developed with high and noiseless APD gain and >90% quantum efficiency from 0.9 to 4.3 µm wavelength. They are near ideal lidar detectors with single photon sensitivity, wide linear dynamic range, and sufficiently high speed. The new detectors in laborarory cryo-coolers have been successfully used in the airborne CO2 and CH4 lidars by GSFC and Langley Research Center (LaRC). One of detector has been used in a passive spectrometer experiment by the Jet Propulsion Laboratory (JPL). DRS also successfully developed an integrated detector cooler assembly (IDCA) with a 2x8 pixel HgCdTe APD array and a mini-Stirling tactical cooler. ESTO also funded studies of HgCdTe APD arrays from other infrared detector developers, including Raytheon Vision Systems in Santa Barbara, CA, and Leonardo Airborne and Space Systems, Southampton, UK. A series of radiation damage tests have also been performed, also funded by ESTO, and the results showed the devices are radiation tolerant for a multi-year near Earth orbit science mission. A radiation damage annealing technique has also been found if the damage become apparent. These HgCdTe APD arrays have filled the gap in SWIR and MWIR lidar detectors and opens up many opportunities for lidar remote sensing, not just for Earth science but also planetary science studies. In this presentation, we give an overview of the HgCdTe APD developments under various ESTO programs and show the latest results.