Higher-order QAM data transmission using a high-coherence hybrid Si/III-V semiconductor laser.

We experimentally demonstrate the use of a high-coherence hybrid silicon (Si)/III-V semiconductor laser as the light source for a transmitter generating 20 Gbaud 16- and 64-quadrature amplitude modulated (QAM) data signals over an 80 km single-mode fiber (SMF) link. The hybrid. Si/III-V laser has a measured Schawlow-Townes linewidth of similar to 10 kHz, which is achieved by storing modal optical energy in low-loss Si, rather than the relatively lossy III-V materials. We measure a received bit error rate (BER) of 4.1 x 10(-3) when transmitting the 64-QAM data over an 80 km SMF using the hybrid laser. Furthermore, we measure a BER of <1 x 10(-4) with the Viterbi-Viterbi digital carrier phase recovery method when transmitting the 16-QAM data over an 80 km SMF using the hybrid Si/III-V laser. This performance is achieved at power penalties lower than those obtained with an exemplary distributed feedback laser and slightly higher than those with an exemplary narrow-linewidth external cavity laser. (C) 2020 Optical Society of America