Characteristics Of Resonantly Pumped Ho:SSO Laser

Lasers emitting at 2?m locates in the spectrum of atmospheric window and the region safe to human eyes,also it covers the absorption peaks of many atoms and molecules.By shifting wavelengths with the use of optical parametric oscillators?OPOs?,it is possible to provide very broad wavelength-tuning ranges.Lasers emitting at 2?m have an extensive application in a variety of scientific and technical applications.Thus,in this paper,researches on Ho:SSO laser and its 2 ?m output characteristics were carried out.Firstly,the development status and application prospect of 2?m band laser were expounded.Through the introduction and comparison of Ho³⁺ solid lasers with different matrices,the advantages of 2?m solid-state lasers with silicate as matrix were introduced.At the same time,the developed history of Q-switched technology has been described.The value of application and the developing potential of Cr²⁺:ZnS crystal as passive Q-switch in 2?m lasers was pointed out.Secondly,the physical and chemical properties as same as spectral properties of Ho:SSO crystal were investigated.According to its absorption spectra and emission spectra,the absorption and emission cross sections were obtained.The spectral parameters of Ho:SSO crystal were calculated based on Judd-Ofelt theory.And the possible oscillation wavelength was discussed.The quasi-four-level rate equation model of Ho:SSO laser was established theoretically,which lays the theoretical foundation for the design of single-ended pumped Ho:SSO lasers.Thirdly,the influence of the cavity length and the output mirror curvature on the distribution of the oscillating spot in the resonator of Ho:SSO laser was discussed.The theoretical basis for the design of single-ended pumped Ho: SSO lasers was provided.Combined with the theoretical calculation,the pump laser and resonator of single-ended pump Ho:SSO laser were designed.The influence of output mirror transmittance,resonant cavity length and the temperature of Ho:SSO on the output performance of laser was discussed by taking the control variable method.With the output mirror of T=20%,R=-100 mm,the resonant cavity length L=60mm and the crystal temperature of 290 K,the maximum output power was 1.71W;Unchanged the resonant cavity parameter,at the crystal temperature of 281 K,the maximum output power was 2.1W.Continuous operation laser output wavelength of 2113.5nm.Finally,the output characteristics of passive Q-switched Ho:SSO laser was investigated.Firstly,the physical and chemical properties as same as spectral properties of the saturable absorber Cr²⁺:ZnS crystal were introduced,and the feasibility of Cr²⁺:ZnS as a passive Q-switched at 2?m laser was analyzed.And then theoretically established the rate equation model of Ho³⁺ passive Q-switched laser,and analyzed the working process of passive Q switch.In the experiment,the trend of the average output power,pulse width and repetition frequency with the pump power change during the passive Q-pulse operation of Ho:SSO laser was explored.At the experimental temperature T = 284 K,the maximum pump power?14.1W?,the minimum pulse width of 615.56 ns,the maximum frequency of 24.54 kHz were achieved..