自拉曼混频黄绿波段三波长可切换激光  

Triple wavelength-switchable lasing in yellow-green based on frequency mixing of self-Raman operation

作　　者：孙瑛璐 段延敏[1] 程梦瑶 袁先漳 张立 张栋[1] 朱海永[1] Sun Ying-Lu;Duan Yan-Min;Cheng Meng-Yao;Yuan Xian-Zhang;Zhang Li;Zhang Dong;Zhu Hai-Yong(Institute of Laser and Optoelectronic Technology,Wenzhou University,Wenzhou 325035,China)

机构地区：[1]温州大学激光与光电子技术研究所,温州325035

出　　处：《物理学报》2020年第12期37-42,共6页Acta Physica Sinica

基　　金：浙江省自然科学基金(批准号:LY19F050012);国家自然科学基金(批准号:61505147);温州市公益性科技计划(批准号:G20180013)资助的课题。

摘　　要：报道了高效的Nd:YVO4晶体自拉曼结合二阶非线性光学混频实现黄绿波段三波长可选输出.从改善热效应和增加拉曼介质长度出发,设计双端键合的YVO4/Nd:YVO4/YVO4晶体用于自拉曼变频.考虑混频转换效率和混频波长切换的便捷性,选用临界相位匹配的BaB2O4(BBO)晶体作为二阶非线性光学混频晶体.只需微调BBO晶体匹配角度在1.4°内,就可成功实现基频光和一阶斯托克斯光之间的倍频与和频,获得高效的532 nm绿光、559 nm黄绿光和588 nm黄光三个波长可切换输出.在19.5 W抽运功率和60 kHz的重复频率下,三个波长激光的最高平均输出功率分别为4.37 W,2.03 W和3.43 W,对应抽运光到可见光的转换效率分别达22.4%,10.4%和17.6%,对应脉冲宽度分别为36 ns,12.2 ns和12.7 ns.可见波段波长可切换激光器可满足激光医疗、显示、光谱成像和生物光子学等领域对多种波长激光的应用需求.An efficient Nd:YVO4 crystal self-Raman laser combined with second-order nonlinear frequency conversion is demonstrated to achieve an switchable output of three wavelengths in the yellow-green band.In order to improve the thermal effect and increase the length of Raman medium,a three-stage diffusion-bonded YVO4/Nd:YVO4/YVO4 crystal is designed for high power and efficient self-Raman laser operation.Selective frequency mixing mechanisms between the fundamental wave and the first Stokes wave using the LiB3O5(LBO)and BaB2O4(BBO)crystals are comparatively studied by temperature tuning and angle tuning,respectively.Considering the frequency mixing conversion efficiency and a relatively fast wavelength switching,the BBO crystal with critical phase matching is selected as the second order nonlinear optical crystal for frequency conversion.It only needs to fine-tune the phase match angle of BBO crystal within 1.4°,and thus successfully realizing all second harmonic and sum frequency generation between the fundamental wave and the first Stokes wave.Therefore the efficient-switchable output of the three wavelengths of 532 nm green light,559 nm lime light and 588 nm yellow light is obtained.Under the incident pump power of 19.5 W and the pulse repetition rate of 60 kHz,maximum average output power of 4.37 W at 532 nm,2.03 W at 559 nm,3.43 W at 588 nm are achieved.The conversion efficiency values of the corresponding pump light to visible light are 22.4%,10.4%and17.6%,respectively.The corresponding pulse widths are 36 ns,12.2 ns and 12.7 ns,respectively.The results show that the selective frequency mixing of self-Raman operation is an efficient approach to achieving the wavelength-switchable emission in visible waveband.This wavelength-switchable laser source has important applications in the areas of laser therapy,visual display,spectral imaging and biological medicine.

关 键 词：自拉曼 ND:YVO4晶体 可见光 波长可切换 

分 类 号：O734[理学—晶体学] TN24[电子电信—物理电子学]