Quasi-Continuous Symbol Rate Tunability for Maximum Capacity in Links Constrained by ROADM Filtering

Using real-time transceivers with symbol rates up to 72 GBd, we investigate the impact of ROADM filtering on optimum symbol rate and fractional m-QAM modulation required to maximize channel capacity. Granularity below 5 GBd is shown to yield maximum margin for a given link passband.