Interelement coupling in gain-guided diode laser arrays

Abstract

Below-threshold studies of an injection-locked gain-guided diode laser array show a far-field emission pattern with several lobes whose angular widths decrease with increasing frequency of the injected radiation. The concurrent increase in the far-field emission angle with the frequency of the injected radiation provides strong evidence that the interelement coupling in a gain-guided diode laser array depends upon the tilt of the wave front in the array cavity. These results provide insight into the coupling mechanism that dominates gain-guided array behavior and strongly suggest that these devices should be viewed as perturbed broad-area devices in which plane waves are undergoing multiple reflections between facets. This contrasts sharply with the coupled-mode picture, which is more appropriate for index-guided arrays.