ENHANCED STABILITY OF MFA-MOPA SEMICONDUCTOR-LASERS USING A NONLINEAR, TRUMPET-SHAPED FLARE

Monolithically integrated flared amplifier master oscillator power amp lifier (MFA-MOPA) lasers are studied using a high-resolution computati onal model that resolves time as well as longitudinal and transverse s pace dependences and includes Lorentzian gain and dispersion dynamics. By altering the linear hare 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 similar to 2 f or single-longitudinal, single-transverse mode operation and similar t o 3 for single-transverse mode operation. This enables the MOPA to mai ntain a stable, near-diffraction limited output beam for higher curren ts before the onset of transverse instabilities. Thus the trumpet-flar ed MOPA emits an output beam of significantly higher power and brightn ess. This increased stability is due to a large reduction in feedback from the output facet of the trumpet shaped MFA-MOPA.