BLOCH-FUNCTION ANALYSIS OF RESONANT ARRAYS OF ANTIGUIDED DIODE-LASERS

Bloch-function analysis of antiguided laser arrays provides closed-form expressions for key parameters in array design, and allows new insights in device behavior. It is found that as the gain is preferentially placed in the low-index array regions (i.e., antiguide cores) the array mode favored to lase is the resonant leaky mode: in-phase type. That is, the prediction of coupled-mode theory that high gain in low-index regions always favors single-lobe phase-locked operation is incorrect. The The intermodal discrimination is found to be strongly asymmetrical with respect to resonance: the resonant mode is preferred to lase over a much wider range in index step, DELTA-n, variation on the high-DELTA-n side of resonance than on the low-DELTA-n side of resonance. Devices with Talbot-type spatial filters invariably operate in-phase except for DELTA-n values well below resonance, when out-of-phase-like modes take over.