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 1550nm 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 184mV to 162mV.