In-Phase/Quadrature Imbalance Mitigation in 100Gb/s Coherent Passive Optical Network Based on Alamouti-Ofdm Modulation

Simplified coherent detection technology has the potential to deliver higher receiver sensitivity in future high-speed passive optical networks (PONs) while maintaining a low-cost profile. In this paper, we present a channel equalization algorithm tailored for Alamouti-Coded orthogonal frequency division multiplexing (OFDM) signals in a simplified coherent detection framework. This algorithm is capable of simultaneously compensating for both channel impairments and in-phase/quadrature (IQ) imbalance distortions. The effectiveness of the proposed algorithm is experimentally verified in a 100-Gb/s coherent PON system. The results indicate that, in the presence of significant IQ imbalance impairments, the proposed channel equalization algorithm can achieve at least a 5-dB improvement in power budget margin compared to conventional equalization method.