基于光谱增强技术实现对532 nm波长激光频率标定  

Realization of frequency calibration for 532 nm wavelength laser based on spectral enhancement technology

作　　者：赵瀚宇 曹士英[2,3] 戴少阳 杨涛 左娅妮 胡明列[1] Zhao Han-Yu;Cao Shi-Ying;Dai Shao-Yang;Yang Tao;Zuo Ya-Ni;Hu Ming-Lie(Key Laboratory of Opto-electronic Information Technology of the Ministry of Education,School of Precision Instruments and Opto-electronics Engineering,Tianjin University,Tianjin 300072,China;Division of Time and Frequency Metrology,National Institute of Metrology,Beijing 100029,China;Key Laboratory of State Administration for Market Regulation(Time Frequency and Gravity Primary Standard),National Institute of Metrology,Beijing 100029,China)

机构地区：[1]天津大学精密仪器与光电子工程学院,教育部光电子信息技术重点实验室,天津300072 [2]中国计量科学研究院,时间频率计量科学研究所,北京100029 [3]中国计量科学研究院,国家市场监管重点实验室(时间频率与重力计量基准),北京100029

出　　处：《物理学报》2024年第9期116-124,共9页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:61827821)资助的课题.

摘　　要：碘稳频532 nm Nd:YAG激光器在复现长度单位“米(m)”、绝对重力测量、引力波探测、精密光谱学、长度计量等领域有着重要应用,对其进行频率测量和标定对于激光器的性能评价具有重要意义.本文采用自行研制的掺Er光纤光学频率梳作为光源,对其扩谱后的1μm波段进行光谱增强并结合倍频晶体将光学频率梳输出的1.5μm波段光脉冲扩展到532 nm波段.其中掺Er光纤光学频率梳输出功率20 mW,首先经过掺Er光纤放大器将功率提到370 mW,经过脉冲压缩后脉冲宽度为45.7 fs,此后经过高非线性光纤扩谱实现光谱覆盖至1μm,输出功率为180 mW.扩谱后的1μm波段激光经过掺Yb光纤放大器放大至601 mW,经过压缩后脉冲宽度为84.6 fs,压缩后功率为420 mW.采用MgO:PPLN晶体对压缩后激光进行倍频得到155 mW的532 nm激光,倍频效率为36%.利用该系统分别对碘稳频532 nm Nd:YAG激光器输出的基频光1064 nm和倍频光532 nm进行拍频,获得了优于40 dB信噪比的拍频信号,后续进行了超过10 h的连续测量,测量结果与国际推荐值保持一致.The iodine frequency stabilized 532 nm Nd:YAG laser plays an important role in realizing the reproduction unit of length“meter(m)”,absolute gravity measurement,gravitational waves detection,precision spectroscopy,distance metrology,etc.Absolute frequency measurement and calibration of the laser are of great significance for evaluating the performance of laser.The previous method of extending the erbium-doped fiber optical frequency comb(Er-FOFC)to the wavelength of 532 nm was to first amplify the seed light,then realize frequency-doubled with a periodic polarization lithium niobate crystal,and finally couple it into a photonic crystal fiber to expand the spectrum to the 532 nm band.With such a technique,the a signal-to-noise ratio(SNR)of the beat signal between the iodine-stabilized 532 nm Nd:YAG laser and the Er-FOFC was approximately 30 dB.Moreover,the SNR of the beat signal was unstable,resulting in the errors in frequency measurement with a counter.This is not conducive to the long-term frequency measurement of the iodine-stabilized 532 nm Nd:YAG laser.Therefore,a method that can obtain both high SNR and long-term stable beat signals is required.In this paper,an Er-FOFC is developed.The spectral enhancement of its broadening at 1μm is carried out,and then expanded to the wavelength at 532 nm by using a frequency-doubling crystal.The output power of the Er-FOFC is 20 mW,which is first amplified to 370 mW by an Er-fiber amplifier and then compressed to a pulse width of 45.7 fs.Subsequently,the spectrum is extended to cover the wavelength at 1μm with a highly nonlinear fiber,resulting in an output power of 180 mW.The broadened spectrum at 1μm is amplified to 601 mW by a Yb-fiber amplifier,and the compressed power increases to 420 mW.Using an MgO:PPLN crystal,the compressed laser is frequency-doubled to produce a 532 nm laser output with 155 mW power and a doubling efficiency of 36%.Utilizing this system,the absolute frequency measurements are conducted on the fundamental frequency light at 1064 nm and the

关 键 词：光谱增强 频率测量 稳频激光 光学频率梳 

分 类 号：TN248[电子电信—物理电子学]