Fast-Tuning Coherent Burst-Mode Receiver for Metropolitan Networks

We demonstrate a fast wavelength-tunable burst-mode receiver for coherent 28 GBaud DP-QPSK signals using a commercially available DS-DBR laser as the local oscillator. We find that the frequency drift and linewidth of the local oscillator (LO) must be precisely controlled to prevent bit-error-ratio (BER) penalties when the signal undergoes transmission distances typical of metropolitan-area networks. We demonstrate reduction of the LO frequency drift and linewidth after wavelength switching by compensation using the phase section of the laser and achieve negligible BER penalty with burst-mode reception for single-mode fiber transmission up to 1280 km. We also measure the sensitivity of the receiver to LO detuning when multiple wavelength-division multiplexed channels are received simultaneously as in a broadcast-and-select network architecture.