Supermode control and phase front measurements of phase-locked offset-coupled laser arrays with a large optical waveguide structure

Phase-locked array lasers with large optical waveguide structures are demonstrated. The refractive index guides of each laser are evanescently coupled with and without offset-coupling structure. An evanescently coupled three-element laser array without offset coupling regions emits up to 200 mW and an offset-coupled laser array with a 4/5 element emits up to 150 mW under pulsed operation. Both laser arrays emit with all elements in-phase locked and produce a single narrow far-field lobe. The full widths at half maximum of the three-element and 4/5-element laser arrays are 5° and 2.5°, respectively. In phase measurements of the lobe of the 4/5-element laser array, we find that the root-mean-square aberration is less than 0.11λ under pulsed operation. This phase aberration is constant with varying power from 75 to 150 mW.