| Semiconductor laser has the advantages of high reliability,which plays an important role in industry,communication and other fields.With the update of semiconductor technology,the performance of semiconductor laser is more superior.The high output power density of the semiconductor laser and the photothermal absorption of the resonator cause the optical catastrophic damage of the cavity surface.In this paper,the working principle of semiconductor laser and the research status of cavity surface damage and cavity film of semiconductor laser are introduced.By means of coating optical thin films on the cavity surface of semiconductor laser,the optical performance of the cavity surface of semiconductor laser is improved.Optical thin film can not only prevent the damage of the cavity surface,but also improve the efficiency of laser.It is of great significance for the development of semiconductor laser to plating optical thin film reasonably.In this paper,the damage and cavity coating of semiconductor laser cavity are studied.The damage of cavity surface and temperature characteristics of cavity film are studied,the mainly study are following as:（1）Based on the damage mechanism of semiconductor lasers,the cavity surface damage defects of semiconductor lasers are classified.The sphere defect model and the cuboid defect model are established respectively.The influence of different defect shapes and structural parameters on the light intensity of semiconductor lasers is analyzed.Different types and sizes of defects cause different light intensity enhancement.Taking light intensity enhancement as a bridge,the relationship between micro defects and light intensity enhancement is analyzed by establishing the light intensity distribution on the surface of defects.The results show that the light intensity enhancement is the largest when the defect size is similar to the wavelength of semiconductor laser,and the spherical defect can enhance the light intensity more than the rectangular defect.（2）Based on the principle of antireflection film and high reflection film,the appropriate film materials are selected.According to the different requirements of the reflectivity specification of the cavity surface of semiconductor laser,different films are coated on the front and back cavity surfaces of the laser respectively.In the design of the front cavity surface film,the material of the single layer film is Al2O3,the double layer film uses the combination of Al2O3 and Si O2,and the multilayer film is the superposition of the double layer film combination;In the design of the back cavity surface film,in order to improve the light reflectivity,the multilayer film composed of Ti O2and Si O2 was designed.In order to solve the optical catastrophic damage problem of laser cavity surface,the steady-state temperature field and transient temperature field of the thin film are studied.In the steady-state,the variation of temperature with the thickness of the thin film is analyzed.With the increase of the number of films,the temperature of the films increases.In the same film structure,the heat is absorbed evenly between the layers,and the temperature distribution is uniform and the gradient is small;In the transient analysis of the film temperature field,the film temperature increases with the increase of time.Due to the good heat dissipation between the film layers,the temperature tends to be stable in a few seconds.For antireflection film and high reflection film,finally,considering the requirements of temperature,stress and reflectivity,six films are selected to be plated on the front cavity surface of the laser,and nine films are selected to be plated on the back cavity surface of the laser. |
