Cost-effective DAC/ADC-induced impacts on DSP-enabled flexible ROADM free from O-E-O conversion and optical filter

Utilizing Hilbert-pair-based digital filtering, intensity modulation and passive optical coupling, DSP-enabled optical filter- and O-E-O conversion-free ROADMs have been reported to offer excellent flexibility, colorlessness, gridlessness, contentionlessness, adaptability and transparency to physical-layer network characteristics. In this paper, DAC/ADC-induced impacts on ROADM performances are, for the first time, extensively explored in various IMDD-based optical network nodes. Numerical results indicate that for optical and electrical filters-free network nodes, ROADM has excellent performance robustness against the DAC characteristic variations, however high-resolution ADCs are required to improve the ROADM drop performances. While when equipping the network nodes with electrical baseband filters, ROADM drop operation performance robustness against the DAC/ADC characteristic variations is considerably improved and the low-cost ADCs with much lower resolutions and sampling speeds are also tolerable to be used in demodulating the dropped signals.