Phase locking of laser array

In this paper, we discussed different mechanisms which are proved to ensure phase locking in a laser array. We also reported the phase locking in solid-state (crystal) laser array and fiber laser array by using the self-imaging confocal resonator which provides high feedback efficiency, quite insensitive to power variations among the pump beams, simply modal profile and also can achieve phase locking passively. A passive approach is to utilize the process of self-adjustment in lasing frequency to adapt to changes in the optical path lengths. The phase-locked mode is highly stable despite the phase variations in the individual elements caused by thermal and mechanical effects.