Compact All-InP Laser-Vector-Modulator for Generation and Transmission of 100-Gb/s PDM-QPSK and 200-Gb/s PDM-16-QAM
01 January 2013
A compact InP-based integrated transmitter assembly consisting of a tunable laser and a double-nested Mach- Zehnder modulator (vector modulator) was successfully used for the generation of Nyquist-prefiltered quadrature phase shift keying (QPSK) and 16-ary quadrature amplitude modulation (16-QAM) signals at 32 Gbaud. With external polarization division multiplexing (PDM) emulation and digital coherent detection, we realized data rates of 128 Gb/s with PDM-QPSK and 256 Gb/s with PDM-16QAM from a commercially available small-form factor device originally designed for 40-Gb/s directdetection differential QPSK applications. We transmitted these two signals over 8000 km and 960 km of standard single mode fiber (SSMF), respectively. We also compared the performance of the integrated transmitter with a LiNbO3 based vector modulator, using a high-performance 100-kHz external-cavity laser and a low-cost 200-kHz to 400-kHz integrated laser assembly as optical local oscillators. The all-InP integrated laservector- modulator transmitter was found to be a viable solution for long-haul 100-Gb/s and 200-Gb/s coherent optical transmission systems.
