Low power InP-based monolithic DFB-laser IQ modulator with SiGe differential driver for 32-GBd QPSK modulation
An optical transmitter incorporating a monolithically integrated laser and a traveling wave electrode in-phase and quadrature modulator is presented. A co-designed SiGe differential driver was co-packaged for highest quality push-pull modulation. With only 0.1-dB coupling loss between the laser and the modulator, and a low modulator switching voltage the transmitter power consumption was 1.1 W, which fits the CFP4 (analog coherent optics) ACO module overall budget of 6 W. Without DSP for precompensation, FEC or equalization, 32 GBd QPSK with 3 V-pp driving voltage and an error vector magnitude of <10% are presented. Operation with an optical signal-to-noise ratio larger than 14 dB is achieved before breaking the hard decision forward error correction threshold (3.8 x 10(-3)).