The Study Of High-power Semiconductor Laser Diode Facet Coatings

High-power semiconductor lasers based on semiconductor materials as lasermaterials laser, With the advantages of small volume, high efficiency, simplestructure and low price, Thus been widely developed. The high power semiconductorlaser has a high output laser density, which will cause the laser cavity surfacesuffering catastrophic optical damage. Usually in order to improve the laser damagethreshold, the output optical power density and electro-optical conversion efficiencyof the high-power semiconductor lasers, protection film is coated at the cleavagesurface. Protective film can not only protect the laser cavity surface from subjecting tooxidation and corrosion, but also prolong the life of the lasers.This paper based on the cavity surface coating technology of high-powersemiconductor laser, starting from the optical film, describes the growth of thin film,ion-assisted electron beam evaporation technique used in cavity surface-coated films,the various properties of optical thin film and some commonly material used incoating. And in accordance with the theory of HR film and AR film, applying the filmdesign software the film systems were simulated and optimized. Using the designedfilm systems, the thin films were prepared on the experimental wafer and cavitysurface of high-power semiconductor laser by the equipment of vacuum coating. Thenthe reflectivity of coated thin films was tested and analysis, as well as the deviceperformance of high-power semiconductor laser. The detail contents of the study areas follow:(1) Starting from the theory of HR film and AR film, selecting the appropriatecoating materials, the film systems used in the cavity surface of808nm and980nmhigh-power semiconductor laser were designed, including single AR film, multilayerAR film, specific reflectivity multilayer AR film and HR film. In order to makehigh-power semiconductor lasers prepared for the job in a larger current, using thechanging rule between the optimum operating point and parameters related to cavitysurface reflectivity such as threshold current, the film systems used in the cavitysurface of980nm semiconductor laser were further optimized and chosen. (2) Using vacuum coating machine of ion-assisted and electron beam evaporation,by monolayer experiments, the effects of technological conditions on film qualitywere analyzed. The technological conditions studied include vacuum, ion-assistedevaporation rate and wafer temperatures.(3)According to the designed film systems, the wafers were coated, tested andanalyze for reflectivity. Then InGaAs/GaAs/AlGaAs980nm high-power laser diodesof4mm cavity length were prepared, and cavity surface of laser diodes was coatedaccording to the optimized film systems. The laser diodes were tested and analyzedfor the impact of their slope efficiency, conversion efficiency and COD threshold.