Injection quantum-well laser with external optical feedback

An investigation was made of the influence of the parameters of an external optical feedback loop and of the pump current on the emission characteristics of injection quantum-well lasers and of lasers with a "conventional" three-dimensional active region. Five lasing regimes were observed. The critical feedback, at which a strong noise was observed and a catastrophic broadening of the lasing line took place, was found to rise rapidly on reduction in the length of the external resonator. The spectrum of the noise generated by the external feedback loop could be divided into hf and lf components, with characteristic frequencies governed by the length of the external resonator, as well as a very-low-frequency component with the spectrum of the ν ^–ρ type (where ρ = 2) due to random hopping of the external resonator modes.