Effect of optical injection on bias voltage and spectrum of a semiconductor laser

The effect of a mild form of optical injection on the bias voltage and optical spectrum of a Fabry-Perot-type AlGaAs laser has been studied. At small frequency detuning between the injection and the injected laser, injection locking is observed. The change in bias voltage, as a function of detuning, is dispersive-like and asymmetric, From the asymmetry, the α-parameter of the laser is determined. When the detuning is increased beyond the locking range, the effect of optical injection on bias voltage remains noticeable. Additional dispersive-like structures appear around the relaxation oscillation frequency. In the optical spectrum, four-wave mixing and reduced damping of the relaxation oscillations are observed