高非线性光子晶体光纤中优化产生宽带紫外三次谐波

发布时间：2018-06-19 22:04

本文选题：高非线性光子晶体光纤 + 三次谐波　；参考：《物理学报》2017年04期

【摘要】：通过非线性光学频率转换技术产生不同频率的脉冲辐射是实现具有短波波长的激光光源的有效手段.近年来,光子晶体光纤技术的发展为解决传统的基于非线性晶体的频率转换系统面临的难以维护、转换效率低、不易推广等问题带来了新的解决思路.在频率转换研究领域中,紫外光波段的脉冲辐射产生一直以来都受到学者的广泛关注.国外已报道过利用超短脉冲抽运光子晶体光纤实现三次谐波产生,从而输出具有高灵敏度和高分辨率的窄带紫外脉冲辐射,但其紫外光转换效率较低,且光谱的可调谐能力有限,而这些缺陷恰恰可以由宽带紫外脉冲辐射的获得来改善.宽带紫外脉冲辐射的有效获得不仅意味着紫外光转换效率可大幅提高,并且若加以合适的滤波手段,还可获得内任意波长下的窄带宽的脉冲辐射,从而增加窄带紫外脉冲辐射的可调谐度,但目前相关报道较为有限.本文将中心波长为1035 nm,脉冲重复频率为50 MHz的飞秒激光耦合至一定长度的高非线性光子晶体光纤中,将其产生的拉曼自频移孤子作为三次谐波产生的抽运源,通过相位匹配作用,在深紫外波段产生高阶模式传导下的三次谐波.随后让超短脉冲以偏离光纤轴心一定角度入射,可进一步激发出具有更短波长的超高阶紫外光模式.通过激发多个邻近的超高阶紫外光模式,在一定连续范围内实现相位匹配,获得超高阶紫外光模式传输下紫外光转换效率为3.6%的宽带(32—360 nm)深紫外脉冲激光.实验结果与理论模拟结果相一致.
[Abstract]:The generation of pulse radiation with different frequencies by nonlinear optical frequency conversion technique is an effective means to realize the laser light source with short wave length. In recent years, the development of photonic crystal fiber (PCF) technology has brought a new solution to the problems of the traditional frequency conversion system based on nonlinear crystal which is difficult to maintain, low conversion efficiency and difficult to popularize. In the field of frequency conversion, the generation of ultraviolet pulse radiation has been widely concerned by scholars. It has been reported that ultrashort pulse pumped photonic crystal fiber is used to generate third harmonic wave, which can output narrow band ultraviolet pulse radiation with high sensitivity and high resolution, but its UV conversion efficiency is low. The spectral tunability is limited, and these defects can be improved by the broadband ultraviolet pulse radiation. The effective acquisition of broadband ultraviolet pulse radiation not only means that the conversion efficiency of ultraviolet light can be greatly improved, but also that the pulse radiation with narrow bandwidth at any wavelength can be obtained if the appropriate filtering means are applied. Therefore, the tunability of narrowband ultraviolet pulse radiation is increased, but the relevant reports are limited. In this paper, a femtosecond laser with a central wavelength of 1035 nm and a pulse repetition rate of 50 MHz is coupled to a high nonlinear photonic crystal fiber of a certain length. The Raman self-frequency shift soliton generated by the laser is used as a pumping source for the third harmonic generation. By phase matching, the third harmonic wave is generated in the deep ultraviolet band under high order mode conduction. The ultrashort pulse is then incident at a certain angle from the axis of the fiber, which can further excite the ultra-high order ultraviolet mode with shorter wavelength. By exciting several adjacent ultra-high order ultraviolet (UHUV) modes, the phase matching is realized in a certain continuous range, and a wideband 32-360 nm deep UV pulse laser with an UV conversion efficiency of 3.6% under UHUV mode transmission is obtained. The experimental results are in agreement with the theoretical simulation results.
【作者单位】：天津大学精密仪器与光电子工程学院光电信息技术科学教育部重点实验室;
【基金】：国家自然科学基金(批准号:61535009,61675150) 教育部长江学者创新团队(批准号:IRT13033)资助的课题~~
【分类号】：TN253

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