Abstract

Fanout-type master oscillator power amplifier (MOPA) devices based on “free space" diffraction have recently been developed as promising candidates for high- power (>0.5 W) coherent sources.^1-3 In these devices, external lenses are required to obtain a collimated, diffraction-limited beam because of the curved phasefront. Sincc the propagation is unguided, phasefront distortions occur due to refractive-index variations caused by thermal gradients and injected carriers. As a result, phase corrections via external lenses are drive-dependent.^1-3 In addition, the devices have a tendency to break into filaments^4,5 for linewidth enhancement factors, α, greater than 2.

© 1994 Optical Society of America