Enhanced stability of MFA-MOPA semiconductor lasers using a nonlinear, trumpet-shaped flare

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Abstract
Monolithically integrated flared amplifier master oscillator power amplifier (MFA-MOPA) lasers are studied using a high-resolution computational model that resolves time as well as longitudinal and transverse space dependences and includes Lorentzian gain and dispersion dynamics. By altering the linear flare of the power amplifier into a nonlinear, trumpet-shaped flare to overlap the gain region to the expanding field, the instability threshold of the MOPA is increased by /spl sim/2 for single-longitudinal, single-transverse mode operation and /spl sim/3 for single-transverse mode operation. This enables the MOPA to maintain a stable, near-diffraction limited output beam for higher currents before the onset of transverse instabilities. Thus the trumpet-flared MOPA emits an output beam of significantly higher power and brightness. This increased stability is due to a large reduction in feedback from the output facet of the trumpet shaped MFA-MOPA.