Frequency conversion in external cavity semiconductor lasers exposed to optical injection

A simultaneous application of delayed feedback and optical injection to semiconductor laser produces frequency conversion in the nearly degenerate tuning range. The frequency conversion occurs through four-wave mixing, and through multiwave mixing with the production of a cascade of higher harmonic generated signals. External feedback narrows the linewidth of the signal and affects conversion efficiency. Efficiency is maximum when the frequency of the injected signal matches external cavity conditions. Feedback parameters control the detuning range of frequency conversion.