Experimental evaluation of 40 Gb/s NRZ-DQPSK data amplification using a semiconductor optical amplifier

Abstract

DQPSK modulation has become particularly attractive in high-speed optical communications because of its resistance to fiber nonlinearities and its more efficient use of fiber bandwidth. We experimentally study the amplification of 40 Gbit/s (20 Gbaud) NRZ-DQPSK data by a semiconductor optical amplifier (SOA). The Q factors before and after amplification are measured. A bulk SOA with 21 dB gain and 10 dBm output saturation power is used. The Q factor of the demodulated data after amplification ranges from 5 to 7 with a maximum penalty of 0.7 dB compared to the back-to-back measurements.