Adaptive Pre-Compensation of ROADMs in Coherent Optical Transponders

We propose a novel adaptive pre-compensation method to correct for the filtering effects caused by cascading optical reconfigurable optical add drop multiplexers (ROADMs). The improvement is achieved without using additional hardware (HW) on the link or within a typical coherent signal processor in the transponders. With our method, using an estimate of the adaptive common response of all the branches of the adaptive equalizer at the receiver, we show an improvement of up to 0.6 dB in required optical signal-to-noise ratio (R-OSNR).