单周期结构极化晶体同时产生二倍频和三倍频光场研究  

Simultaneous Generation of Second Harmonic and Third Harmonic in Single-period Structural Polarized Crystals

作　　者：付祯玮 张超霞 王宇 郝景晨 杨荣国[1,2] FU Zhen-wei;ZHANG Chao-xia;WANG Yu;HAO Jing-chen;YANG Rong-guo(Department of Electronics and Information Technology,Shanxi University,Taiyuan 030006,China;State Key Laboratory of Quantum Optics and Quantum Optics Devices,Institute of Opto-Electronics,Shanxi University,Taiyuan 030006,China)

机构地区：[1]山西大学物理电子工程学院,山西太原030006 [2]量子光学与光量子器件国家重点实验室,山西大学光电研究所,山西太原030006

出　　处：《量子光学学报》2023年第3期37-43,共7页Journal of Quantum Optics

基　　金：国家自然科学基金(11874248,11874249,62027821)。

摘　　要：二阶非线性光学参量过程的上转换和下转换过程是扩展激光波长范围的一种手段,其中上转换过程中的倍频与和频可以有效产生短波长激光。本文提出利用1 438.9 nm的基频光场注入内置一块单周期结构的极化铌酸锂晶体(PPLN)的双端光学腔,在极化晶体的同一周期内,产生719.45 nm的二倍频光场和479.63 nm的三倍频光场,得到的两束光场分别从双端倍频腔两端输出。研究设计了晶体的周期结构,使得二倍频和三倍频的两个非线性光学过程在PPLN晶体的同一极化周期内同时性满足准相位匹配条件,实现二倍频和三倍频光场同时产生。并计算分析晶体极化周期,基频光波长和温度三个参数之间的关系,得到的结论可为单激光在单周期结构极化晶体中产生双波长激光提供理论参考价值。The up-conversion and down-conversion process of the second-order nonlinear optical parametric process is a means to expand the laser wavelength range,in which the second harmonic generation and sum frequency generation in the up-conversion process can effectively produce short-wavelength visible lasers with high power and high optical quality.In this paper,an experimental model of injecting the fundamental frequency light field with polarization direction of e and wavelength of 1 438.9 nm into a double-ended optical cavity with a single-period structure(15.69 μm) is proposed theoretically.The fundamental frequency light passes through the crystal many times,which can improve the conversion efficiency of the output dual-wavelength laser.Class 0 quasi-phase matching with the largest second-order nonlinear polarization tensor is selected.In the same period of the polarized crystal,at the proper working temperature of the crystal,the second-harmonic light field of 719.45 nm and the third-harmonic light field of 479.63 nm can be generated,and the obtained two light fields are output from both ends of the double-ended frequency doubling cavity respectively.The periodic structure of the crystal is designed,and the phase difference caused by the dispersion phenomenon when the interacting light waves propagate in the crystal is well solved by using the quasi-phase matching technology,so that the two nonlinear optical processes corresponding to the second-harmonic light field and the third-harmonic light field meet the first-order quasi-phase matching and third-order quasi-phase matching conditions respectively in the same crystal polarization period.By using the refractive index equation,thermal dispersion coefficient equation and nonlinear optical phase matching condition and other related theories,the relationship between crystal polarization period,fundamental wavelength and temperature is calculated and analyzed.The conclusions obtained can not only provide a theoretical reference value for a single laser to generat

关 键 词：非线性光学 周期极化晶体 准相位匹配 倍频 和频 

分 类 号：O43[机械工程—光学工程]