New transmitter configuration for subcarrier multiplexed DPSK systems and its applications to chromatic dispersion monitoring.

We present a new transmitter configuration using a single dual-electrode Mach-Zehnder Modulator (DE-MZM) for generating DPSK signal and subcarrier simultaneously. We then apply this new configuration to monitoring chromatic dispersion (CD) in DPSK systems by detecting the RF power at both of the clock and subcarrier frequencies. Our investigations show that the method can greatly improve CD monitoring capability. The impact of subcarrier on the DPSK performance is also investigated. Results show that by simply selecting the subcarrier close to half of the DPSK data rate frequency, we can significantly suppress the subcarrier induced power penalty to DPSK signal.