基于KTP晶体的斯塔克啁啾快速绝热通道波长转换

Wavelength conversion of KTP crystal based Stark-chirped rapid adiabatic passage

通过近似类比原子绝热布居理论,建立了基于KTP晶体的斯塔克啁啾快速绝热通道理论的波长转换模型,系统研究了晶体耦合调制中的耦合迟延参数和宽度参数、泵浦强度、温度、入射波长等因素对转换效率的影响.结果表明在KTP晶体中能实现入射光能量到出射光能量近乎完全的转换,同时转换过程中中间光能量保持极低.离最优晶体耦合调制参数越远,转换效率越低.转换效率先随泵浦强度的增大不断增大,当转换效率达到最大值,增大泵浦强度对转换效率几乎无影响.温度和入射波长的变化对转换效率影响较小.研究结果表明基于KTP晶体的斯塔克啁啾快速绝热通道理论的波长转换具有很好的鲁棒性.该研究可为紫外到中红外光源的获取以及光子器件的制造提供理论依据.

The nonlinear wavelength conversion can generate the laser wavelengths which are not directly available,thereby broadening the laser spectrum range.However,the phase mismatch greatly limits the development and application of nonlinear optical technology.The wavelength conversion schemes in a manner analogous to population transfer in atomic rapid adiabatic passage,stimulated Raman adiabatic passage(STIRAP),and Stark chirped rapid adiabatic passage(SCRAP)provide feasible solutions for efficient and broadband wavelength conversion.The SCRAP uses the Stark shift caused by the Stark field to generate energy level crossings,therefore,the population in initial state can be efficiently converted into the target state.It does not require the two-photon resonance,and can be applied to multi-photon transition.In this paper,by approximate analogy to the adiabatic population theory,a wavelength conversion model with the KTP crystals based SCRAP is established,the influence of the coupling delay parameters,width parameters,pump intensity,temperature,and incident wavelength on the conversion process are systematically studied.The results show that the signal laser energy can be almost converted into output laser energy,while the intermediate laser energy is kept extremely low in the conversion process.The conversion process is sensitive to changes in coupling delay parameters,width parameters,and pump intensity.The farther away fromits optimal value the coupling delay parameter,the lower the conversion efficiency is.When the width parameter d_(2)^(2) is fixed,as the width parameter d_(1)^(2) increases,the conversion efficiency first increases to a maximum value,and then slowly decreases.At the same time,the greater the value of the width parameter d_(2)^(2),the greater the achievable maximum conversion efficiencies,and the greater the bandwidth that can achieve high-efficiency wavelength conversion.The conversion efficiency increases as the pump intensity increases.When the conversion efficiency value reaches a maximum value,the increase in pump intensity has almost no effect on the conversion efficiency.However,changes in temperature and incident wavelength have little effect on the conversion efficiency.The above research can provide a theoretical basis for the acquisition of ultraviolet to mid-infrared light sources and the manufacture of photonic devices.