Experimental observations on the nonlinear behaviors of DFB semiconductor lasers under external optical injection

In this paper, the nonlinear dynamic characteristics of the distributed feedback semiconductor lasers (DFB-SL) subject to external optical injection have been investigated experimentally, and the output dynamical characteristics are mapped as a function of the injection power and the detuning frequency between the injection frequency and the free-running frequency of the unperturbed DFB-SL. Experimental results show that DFB-SL under external optical injection is very sensitive to external perturbation and can exhibit various nonlinear dynamical characteristics. Especially, when the laser exhibits the complex dynamical characteristic, its power spectrum is continuous spectrum with several peaks whose frequencies are independent on the power and the frequency of the injection light.