Minimizing Noise in Distributed Reflector Laser Types Under Optical Injection Locking

Complex coupled distributed feedback (DFB) lasers and sampled grating distributed Bragg reflector (SGDBR) lasers under optical injection locking are investigated to determine lowest noise operation. A noise reduction (frequency and intensity combined) of up to 15 dB was measured utilizing detuned optical injection locking at the relaxation oscillation frequency. Furthermore, 4 dB improvement in frequency noise at 10 kHz offset for higher coupling coefficient DFBs under injection locking was measured. The DFB lasers show more sensitivity to injection locking and have a lower need of injection power while exhibiting better signal to noise ratio compared to an SGDBR.