Investigation Of Optical Thin Films On Saturable Absorber Graphene And SESAM

With the development of optics and optical coating technology,there are various applications of optical thin films in various fields such as lasers,communication,national defense,energy,medicine and social life.Semiconductor saturable absorption mirror(SESAM),carbon nanotubes,graphene,graphene oxide,topological insulators,transition metal sulfides and black phosphorus as solid-state pulsed laser generating pulse device,are widely used passive mode-locked device.However,some problems with these materials have not yet been solved.For example,the instability of the material itself leads to a low damage threshold and low transmittance.Based on the above problems,this paper separately plated high-reflective film and anti-reflective film on SESAM to obtain SESAM devices with different structures;in addition,the saturable absorber material graphene and anti-reflective film were combined to reduce the reflectivity of the device.So that more light can penetrate the saturated absorber material,it can also play a protective role.1.Introduce the electromagnetic theory basis and design theory of SESAM,the saturable absorber material graphene,optical film,TFCalc simulation software and the experimental methods and instruments used in this paper.2.The effects of light transmittance and the annealing temperature of a single layer dielectric film as well as the effects of double layer antireflection films made of Ta₂O₅/SiO₂ and Ta₂O₅/MgF₂ on the transmittance and the annealing temperature were investigated.3.Ta₂O₅,SiO₂,MgF₂ film materials and graphene optical constants are extracted.TFCalc is used to design the film system.Based on the glass with graphene material attached,the anti-reflection film is simulated and the coating experiment is performed.The results show that the average reflectance of the substrate is 6.08%and the average reflectance of the two-layer anti-reflection film is 4.34%.This shows that the plated optical film has an anti-reflective effect.4.Based on SESAM,Ta₂O₅/SiO₂ is used as the dielectric film to simulate the anti-reflective film and Ta₂O₅/MgF₂ is used as the dielectric film to simulate the high-reflective film;refer to the simulation results for coating.The experimental results are as follows.The average reflectance of SESAM is 22.6%.After the anti-reflective coating is applied,the average reflectance is 6%.After the high-reflective coating is applied,the reflectance increases to 78.2%,indicating that the high-reflective and anti-reflective coatings we prepared Obvious effects have appeared.However,this result is partially deviated from the simulation,At the end of the article,the reasons for possible errors in experiment and simulation are analyzed.