The Effect of Relaxation Oscillations in Integrated Optical Comb Demultiplexers Based on Injection Locking

Narrowly spaced optical combs are being considered for use in future wavelength division multiplexing optical networks. Optical injection locking has been demonstrated as an effective method of demultiplexing these narrow optical combs, and recent research has shown monolithically integrable designs can achieve side mode suppression ratios of greater than 35 dB. We present an experimental and theoretical study on how the side mode suppression ratio of these demultiplexers varies with the injected comb frequency spacing, the detuning between the slave laser and the comb, and optical injection strength. We show that the performance of these demultiplexers depends strongly on the difference between the relaxation oscillation frequency and the frequency spacing of the injected comb.