High-power, near-diffraction-limited large-area traveling-wave semiconductor amplifiers

Operating characteristics of high-power large-active-area GaAlAs amplifiers configured in double-pass and single-pass traveling-wave arrangements are described. Single-pass broad-area amplifiers with a 600- mu m stripe width generated up to 21 W of near-diffraction-limited emission under pulsed operation when injected with 500 mW from a Ti:Al/sub 2/O/sub 3/ laser, and 11.6 W when injected with 100 mW from a laser diode master laser. In CW operation, a broad-area amplifier output of 3.3 W was demonstrated. Tapered-stripe large-area amplifiers emitted up to 4.5 W in a near-diffraction-limited beam when injected with 150 mW from a Ti:Al/sub 2/O/sub 3/ laser. The physical mechanisms causing degradation of the output beam phase front and intensity uniformity at high output power levels, including thermal lensing and filamentation, are presented.>