Spectral Mode Analysis of an Injection-Locked Semiconductor Laser

We performed injection-locking by two independent semiconductor lasers and investigated the spectral modes of the injection-locked laser. From the observation of the saturated absorption spectrum in the 85Rb DI transition line, we have confirmed that the frequency of the injection-locked slave laser is synchronized by the frequency of the master laser, and the slave laser has a narrow linewidth after injection-locking. According to the intensity injected into the slave laser, we measured the variation of the injection-locking range and the mode of the injection-locked slave laser by using the confocal Fabry-Perrot interferometer. In the case of the incomplete injection-locking, we observed the competition between the free running mode of the slave laser and the mode of the master laser and analyzed the modes of the injection-locked slave laser.