Study Of High Power Semiconductor Laser Cavity Surface Coating

With the application and development of the technology of semiconductor pumping solid laser, the higher power laser is needed. Simultaneity, the performance of the thin film is also one of the bottlenecks of the development of higher-power or higher-energy lasers. So the manufacture of high-quality laser films with low optical loss plays important role in the field of laser technology. Our job focused on designing and depositing of high-reflectivity film system and half-reflectivity outputting film system with low optical-lose applied to the high-power quasi-CW quantum laser emitting at 808nm , to make sure that the laser has a good output property .The theoretical study and experimental investigation come to the conclusion that the key technology of developing high-performance films on the cavity facets of the laser lies in optimization of the film system design and developing film materials with low optical-loss. The main work is followed:1: According to the property of laser such as wavelength, power and etc, several kinds of proper conventional film materials and one kind of mixed film material have to be chosen. The request of the design of the film is put forward that: the low absorption and scatting loss, the high laser damage threshold, and the request for the reflectivity of the high-reflectivity film system and half-reflectivity outputting film.2: According to the theory of thin-film optics, we designed half-reflectivity outputting film made by single-layer irregular SiO₂ and by bi-layer GZrO₂SiO₂A. At the same time we analyzed the distribution of standing-wave field and the absorption and scatting optical-loss of high-reflectivity film system , and compared the difference between two film systems of G(LH)^s A and G(HL)^s HA.3: With the native equipments and technology of vacuum sublimation, we had researched on how to decrease the optical-loss of the film on the facets in material preparation, substrate processing and film depositing process. Combining the theory and analyzing with spectrophotometer, bi-layer quarter GZrO₂SiO₂A is chosen as half reflectivity outputting film system at last. The high-reflectivity film system is G(HL)^s HA film system which is composed by mixed material and silicon oxide alternatively deposited.Through the repeated experiments, we deposited the high-reflectivity film system with the reflectivity 99.501% made by mixed material, and half-reflectivity outputting film with the reflectivity 10.08% made by quarter film of GZrO2SiO2A. Reliability satisfied the request of industrial production. With the application to the laser, the property of output near the center wavelength is good, and the satisfying effect is gained.