Injection locking of a highly coherent and high-power diode laser at 1.5 microm

Injection locking has been employed to improve the coherence of a high-power diode laser at 1.5 microm. The injected high-power laser emitted in a single mode with a side-mode suppression ratio of larger than 30 dB and an output power of 40 mW. The FM noise of the slave laser was nearly the same as that of the submegahertz-linewidth master laser. We have also demonstrated the coherent addition of the master and the injection-locked slave laser with a residual phase error of deltaø < 0.2 rad.