HIGH-POWER, NEAR-DIFFRACTION-LIMITED LARGE-AREA TRAVELING-WAVE SEMICONDUCTOR AMPLIFIERS

Operating characteristics of high-power large-active-area GaAlAs ampli fiers configured in double-pass and single-pass traveling-wave arrange ments are described. Single-pass broad-area amplifiers with a 600 mum stripe width generated up to 21 W of near diffraction-limited emission under pulsed operation when injected with 500 mW from a Ti:Al2O3 lase r, and 11.6 W when injected with 100 mW from a laser diode master lase r. In CW operation, a broad-area amplifier output of 3.3 W was demonst rated. Tapered-stripe large-area amplifiers emitted up to 4.5 W CW in a near diffraction-limited beam when injected with 150 mW from a Ti:Al 2O3 laser. The physical mechanisms causing degradation of the output b eam phase front and intensity uniformity at high output power levels, including thermal lensing and filamentation, are presented.