Bi-directional fiber-IVLLC convergence with parallel/orthogonally polarized dual-sideband operation and two RSOAs scheme

A 128-Gb/s (downstream)/10-Gb/s (upstream) bi-directional fiber-invisible laser light communication (IVLLC) convergence with parallel/orthogonally polarized dual-sideband operation and two reflective semiconductor optical amplifiers (RSOAs) scheme is proposed and practically demonstrated. To the best of our knowledge, this study is the first one that adopts parallel/orthogonally polarized dual-sideband operation and two RSOAs scheme in a bi-directional fiber-IVLLC convergence. For downlink transmission, the channel capacity is increased to four times by way of vestigial sideband (VSB)-four-level pulse amplitude modulation (PAM4) modulation and parallel/orthogonally polarized dual-sideband operation [1-2]. For uplink transmission, the upstream performance presents apparent enhancement by means of two RSOAs scheme [3] to effectively erase the modulated data. The RSOA1 is deployed at the receiver side to erase the downstream data and remodulate the upstream data, whereas the RSOA2 is deployed at the transmitter side to further erase the modulated data and produce a pure optical carrier to seed the RSOA1. BER (downstream/upstream) and VSB-PAM4 (downstream)/NRZ (upstream) eye diagrams perform well over a 25-km single-mode fiber (SMF) transport with a 120-m free-space transmission.