We increased the bit rate of PSK synchronous coherent systems to 2 Gbit/s. The receiver was implemented with a pin/100-Ω photodiode and a 1320 nm diode-pumped miniature Nd:YAG laser as a local oscillator. The receiver used an optical phase-locked loop and exhibited the sensitivity of −41.7 dBm or 225 photons/bit after 50 km of single-mode fibre transmission.