Enhancement of Chaotic Signal Bandwidth in VCSELs Induced by Polarized Optical Injection

In this paper, we present a theoretical study of bandwidths of broadband chaotic signals generated by a single-mode vertical-cavity surface-emitting laser subjected to optical injection and feedback. Both parallel and orthogonal optical injections are considered. Bandwidths of the linearly polarized and total signals are analyzed for different values of the linear dichroism and frequency of the injected field. For the case of parallel optical injection, our results are in agreement with recent experimental results of Hong et al. Both linear polarizations are excited when orthogonal optical injection is considered. In this case, the dependence of the orthogonal polarization bandwidth on the frequency detuning is similar to that found in the case of parallel injection. We also predict that the selection of the orthogonal polarization can give a much larger value of the chaotic bandwidth than that obtained in the total emitted power.