Low-Complexity Phase-and-Polarization-Diversity Coherent Receiver with High Spectral Efficiency for UDWDM

We propose a phase-and-polarization-diversity coherent heterodyne receiver with lowcost 3x3 coupler optical front-end. Using simple DSP, the image-frequency band is rejected, and the receiver sensitivity is improved by 3dB, compared with conventional heterodyne detection.