Photon Counting Optical Time Domain Reflectometry Applying a Single Photon Modulation Technique

Photon-counting optical time domain reflectometry (v-OTDR) is typically used in a mode with spatial resolution in the centimeter range. Here we demonstrate a 1550 nm v-OTDR system to optimize the discriminate voltage of a single photon avalanche detector using a single photon modulation and demodulation technique, which shows obvious improvement in the signal intensity. The intensity of signal is doubled when the discriminator voltage is optimized from 184 mV to 162 mV.