We report a first experimental study of the nonlinear dynamics appearing in a 1550 nm single-mode VCSEL subject to parallel and to orthogonal optical injection. For the first time to our knowledge we report experimentally measured stability maps identifying the boundaries between regions of different nonlinear dynamics for both cases of polarized injection. A rich variety of nonlinear behaviours, including periodic (limit cycle, period doubling) and chaotic dynamics have been experimentally observed.

We have performed a systematic experimental and simulation analysis of the optical frequency combs generated by gain-switching single mode laser diodes, either free-running or subjected to optical injection. The simulations have been produced with a dynamical model consisting of three rate equations that include stochastic noise terms. The model parameters have been extracted from experiments. An exhaustive comparison between the simulated and the experimental temporal profiles and optical spectra generated under a wide range of switching and optical injection conditions has been performed. The excellent quantitative agreement found in the entire range of the explored operating conditions supports the validity of the model for the analysis of the comb generation mechanisms. The detailed maps generated provide guidelines for selecting suitable operating conditions for specific comb characteristics.

A complete characterization of the working parameters of a long-wavelength vertical-cavity surface-emitting laser (VCSEL) is presented. A technique is described for extracting values for the parameters of semiconductor laser rate equations based on simple expressions for the laser power and linewidth as a function of the bias current. The differential carrier lifetime at threshold is estimated by using the linear relation between the laser linewidth and the bias current that is obtained for below threshold operation. High resolution CW optical spectrum measurements are performed to apply this technique for extraction of the parameters of a 1550-nm single-transverse mode VCSEL. Intensity noise spectrum analysis is used to complete our parameter extraction procedure and to compare with parameter values obtained from laser linewidth measurements.

An analysis has been undertaken of the effect of birefringence on the selection of polarization states of a weakly index guided vertical-cavity surface-emitting laser (VCSEL) supporting both a fundamental and a first-order transverse mode. It is shown that for small index steps polarization switching due to spatial-hole burning effects can occur. For larger index steps it is found that higher order modes can emerge which are orthogonally polarized to the dominant polarization of the fundamental mode.

A chaotic semiconductor laser subject to double optical feedback is characterised in terms of the statistical analysis, power spectrum analysis and forecast error analysis of the chaotic dynamics. Varying the relative lengths of the two external cavities, the dynamics are observed and compared to that of a single cavity. We show that in the case of integer multiple external-cavity lengths the round-trip time delays can be deduced from the forecast error analysis. In the case of fractional multiple cavity lengths, only the mean value of the cavity resonance frequencies can be deduced from the power spectra and hence the cavity time delays cannot be found. Cavity time delays that differ more than 0.4 ns can be obtained from the forecast error analysis. In the case of similar cavity lengths, the cavity time delays cannot be extracted. The results show that double optical feedback may offer particular advantages for enhancing security in chaos encryption.