Multi-Dimensional, Wide-Range, and Modulation-Format-Transparent Transceiver Imbalance Monitoring

We propose and experimentally demonstrate a dual-polarization (DP) transceiver imbalance monitoring scheme, which is applicable for the coherent system using square QAM signals. The scheme can separate/monitor various kinds of imbalances has technical advantages multi-dimension, wide range, modulation-format-transparency. In proposed polarization scrambler configured between transmitter (Tx) receiver (Rx). After detection, digital signal processing (DSP) modules are implemented to monitor based on received To simplify DSP modules, implementation sequence in reverse order compared impairments introduced. Firstly, Godard timing error detection (TED) Gram-Schmidt orthogonalization procedure (GSOP) used compensate Rx imbalances. compensating imbalances, Tx implemented. Complex/real maximum likelihood independent component analysis (ML-ICA) Godard-TED imbalance. Finally, amplitude ratios final output in-phase/quadrature (IQ) fed back mitigate interaction power improve accuracy. IQ x-polarization/y-polarization (XY) separated first time by frequency offset (FO) naturally existing continuous rotation induced scrambler. separation method combined with algorithm design ratio feedback mechanism makes achieve most multi-dimensional far. simulation experimental results verify that modulation-format-transparent within range.