FREQUENCY-CONVERSION IN EXTERNAL-CAVITY SEMICONDUCTOR-LASERS EXPOSED TO OPTICAL-INJECTION

We have investigated experimentally and theoretically the phenomenon o f frequency conversion in a semiconductor laser subjected simultaneous ly to delayed feedback and optical injection. We report observations o f frequency conversion in the nearly degenerate detuning range, even w ith the production of a cascade of higher harmonics, through the proce ss of multiwave mixing. We demonstrate that the external feedback exer ts a strong influence on the conversion process, by narrowing the line width of the converted signal and, mainly, by affecting the conversion efficiency. Maxima in the efficiency occur whenever the frequency of the injected signal fulfils the phase conditions imposed by the extern al cavity; moreover, the choice of the feedback parameters controls th e detuning range within which frequency conversion is allowed.