Strong optical feedback effects on vertical cavity surface emitting lasers

An analysis is performed of the effects of strong optical feedback on the characteristics of single-transverse mode VCSELs. Consideration is given to the cases of short (1.5 cm) and long (15 cm) external cavities. When the laser is operated well above threshold in a short external cavity with high reflectivity a strong dependence on the accumulated external cavity phase is observed. Stable operation is found for an optimum phase while for other values of the phase chaotic dynamics is observed. Such behaviour is not seen near threshold where the laser output is stable for any accumulated phase. For the longer external cavity the influence of the phase term is found to be insignificant: chaotic behaviour is seen in the output over a wide range of operating currents.