Revealing the frequency-dependent oscillations in the nonlinear terahertz response induced by the Josephson current  

作　　者：Sijie Zhang Zhiyuan Sun Qiaomei Liu Zixiao Wang Qiong Wu Li Yue Shuxiang Xu Tianchen Hu Rongsheng Li Xinyu Zhou Jiayu Yuan Genda Gu Tao Dong Nanlin Wang 

机构地区：[1]International Center for Quantum Materials,School of Physics,Peking University,Beijing 100871,China [2]State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics,Tsinghua University,Beijing 100084,China [3]Condensed Matter Physics and Materials Science Department,Brookhaven National Lab,Upton,NY 11973,USA [4]Beijing Academy of Quantum Information Sciences,Beijing 100913,China

出　　处：《National Science Review》2023年第11期105-112,共8页国家科学评论（英文版）

基　　金：supported by the National Natural Science Foundation of China (11888101);the National Key Research and the Development Program of China (2022YFA1403901).;supported by the US Department of Energy,Office of Basic Energy Sciences (DOE-sc0012704);supported by the China Postdoctoral Science Foundation (2020M680181).;supported by a startup grant from the State Key Laboratory of Low-Dimensional Quantum Physics and Tsinghua University

摘　　要：Nonlinear responses of superconductors to intense terahertz radiation has been an active research frontier.Using terahertz pump-terahertz probe spectroscopy,we investigate the c-axis nonlinear optical response of a high-temperature superconducting cuprate.After excitation by a single-cycle terahertz pump pulse,the reflectivity of the probe pulse oscillates as the pump-probe delay is varied.Interestingly,the oscillatory central frequency scales linearly with the probe frequency,a fact widely overlooked in pump-probe experiments.By theoretically solving the nonlinear optical reflection problem on the interface,we show that our observation is well explained by the Josephson-type third-order nonlinear electrodynamics,together with the emission coefficient from inside the material into free space.The latter results in a strong enhancement of the emitted signal whose physical frequency is around the Josephson plasma edge.Our result offers a benchmark for and new insights into strong-field terahertz spectroscopy of related quantum materials.

关 键 词：high-temperature superconducting cuprates nonlinear optics time-domain tarahertz spectroscopy 

分 类 号：O511.3[一般工业技术—材料科学与工程]