New method for reducing distortion in directly modulated lasers in subcarrier-multiplexed systems

Abstract

In this paper we use small signal analysis to predict the intrinsic non-linear distortion of an injection-locked semiconductor laser diode directly driven by two subcarriers. We show that the second-order harmonic distortion may be reduced by between 12 and 27 dB over the free-running laser bandwidth of 3.4 GHz and that the third-order intermodulation distortion may be reduced by between 12 and 22 dB over a bandwidth of 5 GHz, for an injection ratio of 0.5.