200 Gb/s transmission using a dual-polarization O-Band silicon photonic intensity modulator for Stokes vector direct...

We present a dual-polarization O-band silicon photonic (SiP) transmitter for intra-datacenter optical interconnects. The transmitter is built using two identical O-band traveling wave Mach-Zehnder modulators with an average VπL and a bandwidth at 1.5 V bias voltage of 2.88 V.cm and 24.5 GHz, respectively. We experimentally demonstrate the transmitter in a Stokes vector direct-detection (SV-DD) system for dual-polarization intensity modulated signals with 2-level and 4-level pulse amplitude modulation (DP-PAM2 and DP-PAM4) formats. The direct-detection Stokes vector receiver (DD-SVR) followed by offline digital signal processing (DSP) is implemented for SOP de-rotation. We characterize the performance of the SV-DD system versus number of taps, received signal power, state of polarization (SOP), reach, and bit rate. Results reveal that 112 Gb/s DP-PAM2 can be transmitted over 10 km of single mode fiber (SMF) at a bit error rate (BER) below 10^-5 at -1 dBm received signal power irrespective of the SOP. Moreover, a 168 Gb/s (42 Gbaud) DP-PAM4 signal can be transmitted over 2 km and 10 km at a BER below the 7% hard-decision forward error correction (HD-FEC) threshold (i.e., 3.8 × 10^-3) at 0 dBm and 2 dBm, respectively. Furthermore, 224 Gb/s and 200 Gb/s DP-PAM4 are successfully received at a BER below the HD-FEC in the back-to-back and 2 km cases, respectively. Finally, we compare the performance of the 6 × 2 multiple-input multiple-output (MIMO) equalization to a simpler 4 × 2 MIMO equalization and explain the superior performance of the 6 × 2 in the presence of SVR imperfections.