Asymmetrical bidirectional optical wireless communication system based on a transmissive 1D LC-SLM for NG-PON2

An asymmetric bidirectional optical wireless communication (B-OWC) system using optical fibers as the transmitter and receiver and capable of wavelength switching is proposed for next generation passive optical network stage two (NG-PON2) extension to home area network (HAN), without optical/electrical (O/E) and electrical/optical (E/O) conversions, which is based on a transmissive "floating" pixel size one-dimensional (1D) liquid crystal spatial light modulator (LC-SLM) at the access node (AN) and a modulated retroreflector (MRR) at the terminal user (TU). The utilization of a reflective grating element and a low-cost LC-SLM in the AN offers a high flexibility of beam steering and wavelength selection in the scenario of B-OWC. Instead of a light source used at conventional TU, a MRR was employed at a TU in order to improve the problems of the power consumptions, alignment difficulties, wavelength contentions, and cost of the TUs. Downlink and uplink data transmissions at a link speed over 2.5 Gbits/s, using wavelengths between 1590∼1603nm and 1524∼1544nm, respectively, corresponding to the downlink and uplink wavelengths specified by the NG-PON2 standard, have been experimentally demonstrated successfully, with quality factors (Q-factors) beyond the forward error correction limit (Q-factor=16.9dB, bit error rate=10^-12).