Emission line width of a single-mode injection laser with optoelectric feedback

An analysis is made of the feasibility of narrowing the lasing line of a single-mode semiconductor laser by suppressing part of the frequency noise due to nonisochronism. It is suggested that this suppression may be achieved by optoelectric feedback using a signal from a photodiode, recording the amplitude fluctuations, to modulate the pump current. It is shown that fluctuation levels of the amplitude and frequency, and also the lasing line width may be altered substantially by such feedback.