Studies On Kinetics And Features Of Diode Pumped Rb-Kr Vapor Laser

As a hybrid solid-state/gas phase laser,exciplex pumped alkali vapor laser(XPAL)has advantages of high quantum efficiency,convenient thermal management and good beam quality.It has great potential in the fields of long-distance energy transmission and aerospace due to the near-infrared emission spectrum,which close to atmospheric transmission windows.Therefore,in-depth studies of kinetic processes,and explorations of pump configuration and operation having higher power and efficiency are significant for optimizing the design of XPAL.In Chapter 1,the fundamental principle,technical routes and research progresses in XPAL are introduced,and the classical experiments and theoretical models so far are briefly reviewed.In Chapter 2,a theoretical model is established to calculate the steady-state temperature distribution of CW end-pumped Rb-Kr XPAL by combining the thermal conduction equation,rate equations and power propagation equations.The temperature distribution of end-pumped Rb-Kr XPAL is simulated by solving the second-order differential equation of temperature.Based on the steady-state temperature field model,the influences of initial temperature,waist of pump light and Kr pressure on the radial optical path difference are analyzed,and the thermal effect is also discussed.In Chapter 3,we establish a kinetic model of CW end-pumped Rb-Kr XPAL,and make a comparison with Carroll’s model,which verified the validity of our model.Influences of pump intensity,temperature,reflectivity of output coupler and number density of Kr on the performances of Rb-Kr XPAL with uniform temperature distribution are considered.Besides,considered the heat accumulation,a model for endpumped CW Rb-Kr XPAL with a longitudinal flowing medium is established by combining the heat balance equation.Dependence of flow velocity on the optical-tooptical efficiency and temperature distribution of a Rb-Kr XPAL is calculated and analyzed.Results demonstrate tha increasing the flow velocity can reduce the thermal effect and improve the laser output performance.In Chapter 4,a theoretical model of CW side-pumped Rb-Kr XPAL is established by combining the four-level rate equations and power propagation equations.The output performances of single-pass and double-pass Rb-Kr XPAL are compared.Influences of temperature,pump intensity,length and width of the vapor cell,reflectivity of output coupler,and pressure of Kr on the performances of double-pass Rb-Kr XPAL are calculated and analyzed.The results provide theoretical references to design an efficient side-pumped Rb-Kr XPAL system.In Chapter 5,with the consideration of pulsed-pumped mode,a model for the temporal evolution of pulsed-pumped Rb-Kr XPAL is established by combining the rate equations,power propagation equations and heat conduction equation.In the long-pulse Rb-Kr XPAL,the effect of the initial temperature on the laser output feature is analyzed.In the multi-pulse mode,influences of initial temperature and pump pulse duration on temperature rise,optical-to-optical efficiency and laser power are calculated and analysed.With a pulsed-pumped duration less than hundreds of nanosecond,the QCW Rb-Kr XPAL with a repetition rate of more than 100 Hz is achieved.Based on the pulsed-pumped XPAL model,the effect of ethane pressure on the double-line five-level Rb-Kr XPAL is simulated.In the last chapter,the main works and innovations of this dissertation are summarized,and the outlook for the future work is suggested.