Research On The Novel Rare-Earth-Doped Laser With Thin Gain Medium

Dioded pump solid state lasers have been widely used in fieds of fundamental science,defense,industrial process and environmental monitoring.Hundreds of kilo watts output has been achieved by solid state lasers with thin gain mediun,thickness of which is micro-nano scale.The thin gain medium has quite high SVR（Surface to Volume Ratio）and rapid heat dissipation.The thesis studied two kind of thin medium laser:one is the longitudinally pumped and lasing PWL（Planar Waveguide Laser）.Nowadays,large scale PWLs can be fabricated through the non-aqueous tape casting method,which is easier to control the gain medium dimension and realize ustainable production,so it is important to inveitgate lasing behavior of the ceramic PWL.Another candidate for high-power solid-state laser is the vertically lasing laser,which has large mode area and better beam quality.However,the limited gain medium thickness casues lower absorption and gain coefficient,so an effective method to break through the limit is neccesary for higher output power and laser efficiency.We prepared a YAG/Yb:YAG/YAG ceramic PWL using the non-aqueous tape casting and vacuum sintering method in the thesis.Duirng the sintering process,Yb³⁺ions diffuse into YAG layers,so refractive index of the ceramic PWL is gradual.A propagation model is built up based on the BPM（Beam Propagation Method）,which despicts the pump beam distribution in the waveguide.In this model,beam quality is poor and the sample factors are fixed,pump source parameters are optimized to achive higher pump efficiency.Furthermore,this model can be generalized to other PWL fabricated by other methods,improve the pump and laser efficiency.A YAG/Yb:YAG/YAG ceramic continuous-wave PWL is set up in the paper.The maximum output power is about 58 W and the tempreture rise is about 50 K.We design a reflectively pump and lasing membrane laser based on the grating waveguide structure.A numerical simulation is carried out based on the RCWA（Rigorous Coupled-Wave Analysis）.Parameters of the gratign waveguide are optimized,so pump and lasing beam could generize GMR effect simultaneously.Stimulated absorption and emission are ehanced becaused of the localized light field.On the other hand,a resonator can be set up by the high reflection,so lasing at a certain angle can be realized.The effective absorption cross section,Purcell factor are obtained according to the simulation results.Introducing these factors into rate equations,we analyzed the lasing performances with GMR effect.Calculation results show that the optimized grating waveguide structure could improve optical effciceincy of the refecltively emission membrane laser,at the same time,time respond performance is affected apparately either.A stimulated emission measurement platform is set up.Gain film in the experiment is fabricated by blending Nd2O3 and TiO2 nanoparticles.By changing the volume fraction,refractive index of the gain film is adjusted.Furthermore,size of the nanoparticles is smaller than 5 nm,so scattering loss is quite low.Collosol of these nanoparticles are spin coated on the grating substrate to form a grating waveguide structure.When the incident pump angle and detection angle are adjusted separeately,emission intensity increased largely at a certain pump angle.On the other hand,emission intensity is enhanced apparately either when detector is set at a certain angle.Experimental results verified the absorption and emission effect caused by GMR and formed the basis of a reflectively emission membrane laser.A reflective amplifier module is designed in Chapt 5,basic parameters of the grating waveguide are optimized through numerical simulation.A MW output MOPA system is designed,power scaling and temperature performance is eatimated meanwhile structural parameters are predicated.