Cavity Surface Of Semiconductor Laser Based On ZnSe Thin Film Technology Research

With the continuous expansion of semiconductor laser applications,the requirements for device output power and reliability are getting higher and higher.The working stability of the laser cavity surface is an important factor that restricts the high power output and service life of the device.The catastrophic optical damage（COD）problem of the cavity surface will directly cause the device failure.At present,a variety of cavity surface treatment technologies have been developed,and the cavity surface passivation technology can effectively improve the damage resistance of the device.As an excellent cavity surface passivation film material,ZnSe has significant effects in suppressing cavity surface degradation and improving device stability.Among the optical film preparation technologies,electron beam evaporation is a technology with relatively low equipment,process requirements and good film quality.It is widely used in the preparation of optical films on the cavity surface of semiconductor lasers.However,the currently reported ZnSe thin film preparation mostly adopts chemical film forming method,and the research reports on electron beam evaporation deposition of ZnSe thin film and related cavity surface treatment technology are relatively scarce.This paper aims to improve the catastrophic damage resistance of the laser cavity surface,and conducts research on the cavity surface treatment technology based on electron beam evaporation deposition of ZnSe passivation film.The specific research contents are as follows:1.The mechanism of catastrophic optical damage on the cavity surface of semiconductor laser is discussed,the typical cavity surface treatment technology to suppress COD problem is introduced.Analyzed the main cause of the COD problem-the source of the surface state and its influence on the performance of the laser.The design theory and optical characteristics of anti-reflection film and high-reflection film are discussed,which provides a basis for the design and preparation of laser cavity optical film.2.The electron beam evaporation technology of ZnSe thin film has been studied.Through the analysis of the change law of the film microcrystalline structure,the influence of the substrate temperature and deposition rate on the ZnSe film formation process was discussed,the relationship between the key parameters of electron beam evaporation technology and the microstructure,optical properties,and surface morphology of ZnSe thin films has been mastered.The experimental results show that the increase of the substrate temperature is beneficial to improve the crystalline quality of the film and increase the optical band gap of the film.The optimization of the deposition rate can not only improve the crystalline properties of the film,but also increase the density of the film.The improvement of the above-mentioned film quality can enhance the laser damage resistance of the ZnSe film.3.Carried out research on argon plasma cleaning technology,the cavity surface optical film of 1064nm semiconductor laser has been designed and prepared.The argon plasma cleaning technology of the Ga As substrate surface was studied by electron beam evaporation coating equipment,and the influence of argon plasma cleaning treatment on the surface state of Ga As was analyzed.Based on the optical characteristics and laser damage characteristics of the laser cavity surface optical film,an Al₂O₃ anti-reflection film with a reflectivity of 2.2%and a HfO₂/TiO₂/SiO₂ high-reflection film with a reflectivity of 99%were designed and prepared.4.The cavity surface technology of semiconductor laser based on ZnSe thin film was studied.With the help of electron beam evaporation coating equipment,argon plasma cleaning treatment,in-situ deposition of ZnSe passivation film,and in-situ coating of optical thin films were carried out on the front and back cavity surfaces of 1064nm semiconductor lasers.The device test shows that the COD threshold power of the device after adopting the cavity surface treatment technology is increased by 29%,which proves that this technology has excellent cavity surface passivation effect.