Injection Locked Wavelength De-Multiplexer for Optical Comb-Based Nyquist WDM System

We report a standalone four-output wavelength de-multiplexer (de-mux) using optical injection locking for simultaneous comb tone separation, amplification and power equalization. Optical amplification from -30 to 5 dBm per output wavelength is achieved. We illustrate the flexibility of the de-mux by separating two input combs with tone spacing of 12.5 and 6.25 GHz into 12.5-GHz spaced outputs. The system performance of the de-mux is demonstrated in a 100-km Nyquist ultra-dense wavelength division multiplexed network where the de-multiplexed comb tones are each encoded with 12-GBd Nyquist polarization division multiplexed quadrature phase shift keying. Experimental results indicate a worst case 1.5-dB receiver sensitivity penalty at 1.5e-2 bit error ratio for the transmitted comb tone channels when compared with the 400-kHz linewidth comb source seeding laser.