Study on Talbot phase-locking conditions of tapered semiconductor laser chip array

Based on the analysis of Talbot phase-locking theory of edge emitting semiconductor lasers, a method to obtain a single in-phase mode on a tapered laser chip is proposed. A phase-locked model with 1/2 Talbot spatial filter cavity for mode selection placed between 8 emitters on each facet is set up. Based on the mode coupling rate equation theory, the parallel coupling phase-locking conditions with different fill factors is analyzed. The results show that the stable parallel coupling phase lock can be achieved for 8 emitters with the pitch of 20 um, when the fill factor is set between 0.06 and 0.12, and the phase-locking time is about 3 ns. The supermode threshold gains are also calculated under different fill factors. In the phase-locked model, when the fill factor is approximately 0.1, the threshold gain difference between the in-phase mode and out-phase mode could reach the maximum, which is around 78cm-1 . Therefore, single in-phase mode output of this novel laser with Talbot cavity becomes more robust. The simulation analysis provides a reliable theoretical support for the preparation of a coherent array laser with a single in-phase mode output.