9B8 - Semiconductor laser amplifier

The infrared GaAs injection amplifiers described have gains as high as 2000 and give output powers of 150 milliwatts when operating at 77°K and driven by a single mode. Output efficiencies of 68 percent differentiial and 50 percent overall can be obtained if the amplifier is driven by light of spectral width equal to the band-pass of the amplifier (30 Å). Regenerative effects are minimized by coating the diodes with three-fourth wavelength coatings of SiO. Thresholds at liquid nitrogen temperature were raised by a factor of ten on some diodes after the coatings were applied. Experimental data obtained on gain, efficiency, spectra, beamwidth, and noise power of several amplifiers are summarized and presented.