Semiconductor Pumps for the Nd:YAG Laser.
Final rept. 1 Jul-31 Dec 71,
TEXAS INSTRUMENTS INC DALLAS COMPONENTS GROUP
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This report describes the major accomplishments and conclusions of a six-month program to develop light-emitting diodes suitable as pump sources for the NdYAG laser at room temperature. Work was concentrated on zinc-diffused Gal-xAlxAs 18-mil diameter dome emitters. Improved material and device technology resulted in an increased yield of emitters having a power efficiency of 4 to 5, an optical output power of 17 to 21mW at 250mA, a wavelength of 8070 or -50 A and a spectral half-width of 200A. The increased yields demonstrate the feasibility of fabricating high-power diode arrays which employ large numbers of GaAlAs emitters. The development of the materials technology enabled improved control, uniformity, and reproducibility of Al composition, Te doping concentration, and thickness for the GaAlAs epitaxial layers grown on GaAs substrates. Wavelength control was previously a major difficulty due to a large Al composition gradient in the grown GaAlAs materials. Increased absorption of the generated light due to the improved Al composition uniformity caused the typical device efficiencies to be less than the maximum values previously observed. The specific accomplishments for the device technology were the determination of the dependence of 1 device peak emission wavelength of GaAlAs crystal composition, 2 device efficiency on Te doping concentration, and 3 efficiency, output power, and thermal resistance on junction diameter. The best emitters degraded less than 10 during 7500 hours of continuous operation. Sample devices were delivered which essentially met the program goals of 20-mW output power with a 7 power efficiency. Author
- Lasers and Masers
- Electricity and Magnetism