Low-crosstalk bidirectional optical transceiver based on phase-sensitive parametric de-amplification for ultra-high-loss links.

We propose a low-crosstalk transceiver architecture based on optical parametric amplifiers (OPAs) for ultra-high-link-loss bidirectional transmission over Rayleigh-backscattering-free links, such as free space. This architecture suppresses crosstalk within transceivers by exploiting the gain contrast between the downstream signal and upstream-signal-induced crosstalk through phase-sensitive de-amplification. We demonstrate crosstalk suppression for the same-wavelength bidirectional transmission condition using polarization-diverse OPAs with periodically poled lithium niobate waveguides. A crosstalk tolerance improvement of 15 dB for a 64-Gbaud DP-PCS-64QAM signal is achieved.