Polarization-diversity Stokes-analyzer-based coherent receiver

Since the conventional coherent transceiver is costly to be deployed in short-reach networks due to its complicated receiver structure, it is desired to simplify the structure itself. In this paper, we propose a simple polarization-diversity coherent receiver structure by exploiting the concept of the Stokes analyzer. Compared to the conventional architecture, the number of the photodiodes (PDs) is reduced from eight to six without relying on complicated analog circuits. In addition, splitters and combiners for dual-polarization (DP) signals can be replaced with only one polarization beam splitter or combiner (PBS/C). For evaluation of the proof-of-concept (PoC), we developed a prototype of the receiver using free-space optical components. We demonstrate the transmission of 120-Gb/s DP quadrature phase-shift keying (QPSK) and DP 8-ary quadrature-amplitude modulation (8QAM) signals over a 100-km single-mode fiber (SMF). We believe that the demonstrated architecture could potentially be integrated monolithically on silicon-photonic or InP platforms to realize compact and low-cost coherent transceivers for short-reach applications.