Cross-correlation method for noise measurements of photodetectors used for laser absorption spectroscopy

Abstract

The paper presents noise measurements of low-resistance photon detectors with a specially developed system. These measurements are significant for many applications. This issue is particularly critical for laser absorption spectroscopy systems to detect trace amounts of gases. In these systems, the detection limit is determined by noise origins, e.g., light source, background, and detector noise and its readout electronics. The use of some specially designed components of the system (low-noise - 3.6 × 10-19 V2/Hz for f >1 kHz) cross-correlation signal processing provides to obtain a measuring floor noise below 10-18 V2/Hz for f > 10 Hz and below 10-19 V2/Hz for f > 1 kHz after ten minutes’ analysis. Measurements of some reference resistors have verified the system’s performance. Finally, the system was also applied to determine the spectral noise density of the II -Type SuperLattice photodetector made of InAs / InAsSb.

Keywords

• noise
• infrared detectors
• infrared absorption spectroscopy
• superlattice detectors