GW/cm^2量级飞秒脉冲倍频的宽谱谐波产生  

Broadband Second Harmonic Generation of Femtosecond Pulses at Magnitude of GW/cm^2

作　　者：黄章超[1] 张文定[2] 林洪沂[1] 许英朝[1] 沈汉鑫[1] 阮剑剑[1] 孙栋[1] 王衡[2] 朱文章[1] 

机构地区：[1]厦门理工学院光电与通信工程学院福建省光电技术与器件重点实验室,厦门市LED照明应用工程技术研究中心,福建厦门361024 [2]西北工业大学理学院空间应用物理化学教育部重点实验室,陕西省光信息技术重点实验室,陕西西安710072

出　　处：《光学学报》2017年第3期373-381,共9页Acta Optica Sinica

基　　金：国家自然科学基金(11404263,61675169,11304259);中央高校基本科研业务费专项资金(3102015ZY060);福建省自然科学基金(2016J01683);福建省中青年教师教育科研项目(JA15387);厦门理工学院科学技术研究项目(YKJ13035R)

摘　　要：使用含镁摩尔分数为5%的掺镁铌酸锂晶体对57.4fs脉冲在1550nm通信波段进行了Ⅰ型(o+o-e)和0型(e+e-e)的倍频对比实验。对于Ⅰ型倍频,在4.3GW/cm^2的峰值功率密度下得到了谱宽为28nm、脉宽为79fs的谐波脉冲,转换效率最高达54%;对于0型倍频,在3.7GW/cm^2的峰值功率密度下得到了谱宽为2.1nm的谐波脉冲,转换效率最高为40%。分别从飞秒脉冲多波长成分的相位匹配(频域)和基波与谐波脉冲的群速度匹配(时域)两个角度,对倍频过程中基波脉冲和谐波脉冲的演变进行了详细分析。发现同时满足多波长成分相位匹配时,传播中谐波的谱宽能维持不变;而仅满足中心波长相位匹配时,谐波光谱则随着传播长度的增加而逐渐变窄。The experiments of second harmonic generation（SHG）of 57.4fs pulses at 1550 nm wavelength for typeⅠ（o＋o-e）and type 0（e＋e-e）are achieved using Mg-doped lithium niobate crystal with mole fraction of 5% of magnesium.For SHG of typeⅠ,the second harmonic pulse with spectrum width of 28 nm and pulse width of 79 fs is obtained at the peak density of 4.3GW/cm^2,and the conversion efficiency is up to 54%.For SHG of type 0,the second harmonic pulse with spectrum width of 2.1nm is obtained at the peak density of 3.7GW/cm^2,and the conversion efficiency is up to 40%.The key points of the evolution for fundamental pulse and second harmonic pulse in SHG process are analyzed,which are the phase-match of femtosecond pulse multi-wavelength components of fundamental wave in frequency domain and the group-velocity-match of fundamental pulse and second harmonic pulse in time domain.It is found that the spectral width can keep constant in the propagation when the phase-match of multi-wavelength components is satisfied.However,the spectral width will gradually become narrower with the increase of the propagation distance when the phase-match of the center wavelength is satisfied only.

关 键 词：超快光学 Ⅰ型倍频 飞秒脉冲 群速度匹配 掺镁铌酸锂 

分 类 号：O437[机械工程—光学工程]