A Broadband Near-IR Detector Based on a Large-Area InGaAs Photodiode for Time-Resolved Detection of Singlet Oxygen

A broadband near-IR photodetector based on a large-area G12180-250A InGaAs photodiode (Hamamatsu) with a 5-mm-diameter photosensitive area was developed and tested. It is designed for detecting the IR luminescence of singlet oxygen. A circuit for signal amplification is assembled on the basis of broadband low-noise operational amplifiers with the subsequent filtering of a signal with an adjustable passband $f$ varied from 15 to 600 kHz, thus allowing one to obtain a time resolution of better than 1 $\mu$s, a sensitivity level of 107$-$109 V/W, and a noise equivalent power NEP [W/Hz^1/2] ≈ 1.4 x 10^-14 $\lambda$^-1[$\mu$m] $f$[kHz] in a frequency band of 15$-$600 kHz.