Linear-mode characters of near-infrared wavelength InGaAs APDs for optical communication

Abstract

Recent developments in three-dimension imaging, quantum cryptography, and time-resolved spectroscopy have stimulated interest in Linear-Mode and Geiger-Mode detecting avalanche photodiodes operating in the short wavelength. A linear-mode detector based on an InGaAs avalanche photodiode (APD) has been investigated for use at near infrared communication wavelengths. In the experiments of this paper, sine gate signals coupled with DC biased voltage were applied to two APDs with the same semiconductor material and structure for detecting the pulse light signal. As the avalanche signals were mixed with sine wave background, a transformer-based method was applied to eliminate the background noise and improve the detection sensitivity of light induced signal. In order to test the maximum detection sensitivity, the sine pulse was delayed by a delay module before being applied to laser source, thus the pulse light signal and the sine pulse coupled to the detector were synchronized. From the performance tests, the frequency response from 10MHz to 100MHz is tested and the suitable range of biased voltage was acquired. Detection sensitivity and photoelectric gain were investigated in detail at 1.55um infrared wavelengths. In a word, the linear-mode APD working in gate-mode and mutual-differencing method can be widely used in optical communication such as Non-line-of-sight communication, free space communication, fiber communication, deep space communication, and satellite optical network communication.