基于百太瓦级激光系统驱动的高能量13 nm波段高次谐波产生  

High-Energy High-Order Harmonic Generation Around 13 nm Wavelength Based on Hundred-Terawatt-Level Laser System

作　　者：高记星 娄智远 杨帆 杨晓骏 许毅[1,2] 冷雨欣 郑颖辉[3] 曾志男 李儒新 Gao Jixing;Lou Zhiyuan;Yang Fan;Yang Xiaojun;Xu Yi;Leng Yuxin;Zheng Yinghui;Zeng Zhinan;Li Ruxin(State Key Laboratory of High Field Laser Physics,Shanghai Institute of Optics and Fine Mechanics,Chinese Academy of Sciences,Shanghai 201800,China;Center of Materials Science and Optoelectronics Engineering,University of Chinese Academy of Sciences,Beijing 100049,China;Zhangjiang Laboratory,Shanghai 201210,China)

机构地区：[1]中国科学院上海光学精密机械研究所强场激光物理国家重点实验室,上海201800 [2]中国科学院大学材料科学与光电工程中心,北京100049 [3]张江实验室,上海201210

出　　处：《光学学报》2024年第2期221-228,共8页Acta Optica Sinica

基　　金：国家自然科学基金(11127901,91950203,11874374);中国科学院战略性先导科技专项(XDB16)。

摘　　要：利用百太瓦级激光系统在氖气(Ne)中得到基于高次谐波产生的极紫外脉冲。通过松聚焦结构在13 nm波段产生单级次单脉冲能量为13.5 nJ(13.1 nm波长)和11.1 nJ(13.5 nm波长)的高次谐波辐射,转换效率为3.6×10^(-7)和3.0×10^(-7),谐波发散角的半高全宽为0.32 mrad和0.33 mrad。对含时薛定谔方程进行数值求解,得到单原子偶极发射谱,结合麦克斯韦方程组模拟传播效应,同时考虑气体对谐波的吸收效应,理论模拟得到的信号强度随气压和光强的变化趋势与实验结果基本符合。实现相位匹配的谐波光束质量很好,纵向空间分布为高斯型。结合相位匹配条件和空间分布的分析得到了目前激光参数下的最优相位匹配条件。这种基于高次谐波机制的高能量相干极紫外光源在作为自由电子激光的种子光源以及超快非线性实验和半导体工业检测等方面具有广阔的应用前景。Objective With the rapid development of high-order harmonic extreme ultraviolet coherent light sources and attosecond pulses,they have caught widespread attention in free electron laser seed injection,time-resolved angular resolved photoelectron spectroscopy measurement,and nondestructive nanostructure detection.There are many ways to generate extreme ultraviolet light sources,including synchrotron radiation,laser produced plasma,and free electron lasers,which can also be employed to generate high-energy extreme ultraviolet light sources.Compared to other light sources,highorder harmonics feature good coherence,short pulse duration,and device miniaturization.Currently,the high-order harmonic mechanism has been widely adopted to generate coherent light sources in the extreme ultraviolet region.We utilize a self-developed 200 TW titanium sapphire laser system with a maximum single pulse energy that can reach 8 J,and a main pulse energy of 7.9 J after beam splitting is transported to the free electron laser experiment for generating an electron beam source based on the acceleration mechanism of laser wakefield.The second laser beam is leveraged for highorder harmonic generation experiments.Both experiments are conducted synchronously to facilitate the simultaneous injection of electron beams and extreme ultraviolet seed beams into the oscillators in the future.Methods As shown in Fig.1(a),the whole system is placed in a vacuum chamber to avoid strong absorption of extreme ultraviolet pulse,and the vacuum system maintains the background pressure of 10^(-3) Pa.The driving laser parameters include a center wavelength of 800 nm,repetition rate of 1 Hz,pulse width of 30 fs,and energy of 35 mJ.A plano-convex mirror with a focal length of 5000 mm and a focal spot diameter of about 400μm is adopted.The length of the Ne-filled gas cell is 50 mm.The harmonic radiation propagates with the residual driving laser and then transmits through the iris to the measurement section.Two Mo mirrors and a 350 nm-thick Zr filter are place

关 键 词：极紫外 高次谐波 相位匹配 空间分布 

分 类 号：O437[机械工程—光学工程]