HIGH-POWER MONOLITHIC PHASE-LOCKED ARRAYS OF ANTIGUIDED SEMICONDUCTOR DIODE-LASERS

All-monolithic phase-locked arrays of antiguided diode lasers have recently demonstrated exceptionally high diffraction-limited powers: 0.5 W continuous wave (CW) and 2.1 W peak pulsed. An overview of theoretical and experimental work to date is presented. The performance of antiguided arrays is compared to the best results from conventional array types (evanescent-wave, Y-junction, diffraction). The two basic types of array modes: evanescent-wave and leaky-wave are discussed. Resonant leaky-wave coupling in antiguided arrays is explained and interpreted. One key new insight is revealed: when gain is placed in the low-index regions of large arrays (greater-than-or-equal-to 10 elements) the array mode favoured to lase is the leaky mode (in-phase or out-of-phase) closest to its respective resonance. Thus the 'classic' prediction of coupled-mode theory that high gain in low-index regions automatically favours in-phase mode operation is incorrect. The intrinsic array modal discrimination mechanisms (mode overlap with the gain regions [i.e. the GAMMA-effect]; edge radiation loss, and interelement loss) as well as Talbot-type spatial filtering are briefly explained, and their respective effects on resonant and nonresonant devices are discussed. Results of rigorous modelling of antiguided arrays using two-dimensional analysis are discussed and compared, for the first time, to results obtained via the effective-index method. Finally, key electro-optical characteristics of 20- and 40-element arrays are described.