Exploration Research Of Optically Pumped Metastable Rare Gas Laser

Diode pumped alkali vapor laser(DPAL)has great potential in single-aperture power scaling due to its intrinsic physical characteristics,e.g.the high quantum efficiency,efficient heat management by flowing the gaseous medium,and electrically driven compact system.But the highly reactive nature of alkali atoms decreases the operability of such kinds of lasers.To solve this problem,a new type of DPAL-like optically pumped gas laser,named as the optically pumped metastable rare gas laser(OPRGLs),was proposed at 2012,which is hopeful to inherit DPAL's advantages and overcome its problems.Due to the potential of OPRGLs,we have made exploratory researches on this new kind of lasers.The main contents are presented as follows:1.The basic principle of OPRGL is briefly introduced.The transmittance characteristics of metastable Ar,Kr,and Xe in atmosphere propagation were calculation by HITRAN,which indicate that metastable Ar has comparatively highest transmittance and is suitable for long-distance atmosphere propagation.Therefore,we choose the Ar species as research object in this thesis.2.A multi-level rate equation based model of OPRGL is established and the corresponding numerical approach is developed.A qualitative agreement between simulation and Rawlins et al.'s experimental result shows the validity of the model.The key parameters' influences and energy distribution characteristics are theoretically studied.The results shows that Ar metastable laser has a theoretically optical conversion efficiency ~50-60% under conditions of moderate pump intensity(2-5 kW/cm2)and relatively low He pressure(~1atm).Due to the complex energy levels and population relaxation channels,the waste heat fraction of Ar metastable laser is much higher(~25%)than the quantum defect(11%).so more efficient convective thermal management was needed.3.The physical model of dielectric barrier discharge(DBD)in argon / helium at ~1atm pressure level is introduced,and the characteristics and parameters of the dielectric barrier discharge are simulated by COMSOL.Based on the theoretical study,an apparatus of dielectric barrier discharge is designed and constructed.By using such apparatus,a spatial uniform discharge between dielectric barriers is realized,and some parameter influences are studied.The fluorescence spectra were measured and the energy levels transitions were analyzed via the fluorescence spectra.4.We try to detect the metastable argon atom(1s5)concentration in the discharge region by using the absorption spectrometry.Both tunable diode laser and the super continuous spectrum were used as detection light sources,and the mixed gases were further purified.But there was no obvious absorption signal being detected.The analysis indicated that DBD may not be effective to produce enough concentrations of metastable argon atoms,and it is also possible for some other factors,and the further research schemes are proposed.5.By use of Littrow configuration external cavity on a diode laser array,we realize 1.5 W output with linewidth ~0.15 nm,the tuning range is 6 nm and efficiency is 57%,which can be used for high efficiency pump argon metastable laser.