The Study On Laser Induced Damage Threshold Of Cavity Surface Film On Semiconductor Laser

Because its advantages of small size,simple structure,low input energy,high conversion efficiency,long service life,easy modulation,economical and practical,semiconductor laser has become the core technology of semiconductor optoelectronics.The output power of semiconductor laser on the cavity surface continuously improve the reliability and the cavity surface laser damage threshold requirements are increasingly higher,many scholars have studied the cavity surface film of semiconductor laser,they found that the different preparation process and the choice of the thin film materials are closely related to the laser damage of the cavity surface film.In this paper,we prepared the cavity surface film of semiconductor laser by ion beam assisted electron beam evaporation.In order to study the anti-laser damage ability of semiconductor laser cavity surface film,we mainly studied the following contents:1.With 980nm semiconductor laser as an example,according to the theory of optical thin film,in order to improve the anti-laser damage ability of semiconductor laser cavity surface film.First we optimized the structure of laser cavity surface film,the reflectivity of antireflection film reaches to 2.8%,the reflectivity of the high reflective film is up to 97%,to meet the design requirements of semiconductor laser cavity surface film;2.We mainly studied the anti-laser damage ability of the rear cavity surface film.The damage threshold of the TiO₂ film which is easy to form low oxide film in the process of preparation was studied.And the damage threshold comparison test was studied with the Ta₂O₅ film with higher refractive index,the results show that the laser damage threshold of TiO₂ film is higher than that of Ta₂O₅ film.3.For the TiO₂ films with higher damage threshold,we optimized the process of preparation.In order to reduce the oxygen loss of TiO₂ thin film during evaporation process,we changed the flow of oxygen to 16.7sccm and 20.7sccm respectively under the same oxygen pressure.The laser damage threshold was tested,and the damage threshold of TiO₂ film with oxygen flow rate of 20.7sccm was reaching to 2.75 J/cm²,which was higher than that of TiO₂ film with oxygen flow rate of 16.7sccm,which was about 2.66 J/cm².4.In order to further improve the laser damage threshold of TiO₂ film,the TiO2films with higher damage threshold?oxygen flow rate of 20.7sccm?were annealed.The purpose is to reduce the defects in the films,improve the stoichiometric ratio of the film,and make the film more dense,laser damage threshold higher.From the optical properties,including the refractive index,reflectivity and the absorption spectrum of TiO₂ films before and after annealing,we found that the damage threshold of the film with oxygen flow of 20.7sccm have increased to 3.52 J/cm² after annealing,increased by 27.8%compared with that before annealing.In summary,we focused on the preparation process of anti-laser damage threshold of the 980nm semiconductor laser cavity surface film.Through annealing,we reduced the film defects and absorption,improved the laser damage threshold of TiO₂ film,and improved the reliability of semiconductor laser cavity surface films.