Theoretical and experimental investigation of inter-channel crosstalk mitigation by assist light in a TOAD de-multiplexer

In the present work we have investigated experimentally and theoretically inter-channel crosstalk in an all-optical de-multiplexer at 50 Gbps using a terahertz optical asymmetric de-multiplexer (TOAD) in presence of continuous wave (CW) assist light. CW assist light substantially reduces gain recovery time and gain depletion in the non linear element present in the TOAD. We found that with assist light `on´, power penalty in the de-multiplexing device is reduced and dynamic range of input probe power is raised to 10 dB. Assist light also removes Bit-Error-Rate (BER) floor due to crosstalk and distortion. Lastly the optimum CW assist light wavelength is found to be at the edge of 3-dB gain peak of semiconductor optical amplifier for minimum crosstalk. The experimental results are validated with the theoretical investigation.