Experimental Analysis of Locking and Unlocking Regimes in Laterally Coupled Diode Lasers

The emission characteristics of laterally coupled diode lasers have been theoretically studied by many authors. However, little experimental work has been done on the locking and unlocking regimes of these coupled lasers. Analyzing both the spectrally resolved far field and the relative intensity noise (RIN) spectrum, the authors have observed the presence of locking and unlocking operation regimes. In the locking regime the device is phase locked emitting only the out-of-phase lateral mode and no RF tone in the RIN spectrum is observed. By changing the bias conditions, lateral mode locking is observed with both in-phase and out-of-phase lateral modes lasing. In this case a RF tone in the RIN spectrum is observed at the frequency separation between the lateral modes. The unlocking regime is characterized by an absence of phase relation between the fields emitted by each one of the laser waveguides.