在极化声子共振区基于级联差频产生高频太赫兹波  

High-Frequency Terahertz Wave Generation with Cascaded Difference Frequency Generation at Polariton Resonance

作　　者：李忠洋 颜钤泽 张格格 赵佳 焦彬哲 孙向前 邴丕彬 袁胜 姚建铨[2] Li Zhongyang;Yan Qianze;Zhang Gege;Zhao Jia;Jiao binzhe;Sun Xiangqian;Bing Pibin;Yuan Sheng;Yao Jianquan(College of Electric Power,North China University of Water Resources and Electric Power,Zhengzhou,Henan A500A5,China;College of Precision Instrument and Opto-Electronics Engineering,Institute of Laser and Opto-Electronics,Tianjin University,Tianjin 300072,China)

机构地区：[1]华北水利水电大学电力学院,河南郑州450045 [2]天津大学精密仪器与光电子工程学院,激光与光电子研究所,天津300072

出　　处：《中国激光》2022年第7期171-180,共10页Chinese Journal of Lasers

基　　金：国家自然科学基金(3167158,61735010)。

摘　　要：提出了一种在晶体极化声子共振区利用级联差频在Mg O∶Li Nb O_(3)平板波导中产生高频太赫兹波的方法。不同于传统的基于两束近红外光直接差频产生太赫兹波,本文首先利用两束近红外光在周期极化铌酸锂(PPLN)晶体中产生低频太赫兹波和一系列级联光,然后将上述级联光耦合导入平板波导中,通过改变平板波导的尺寸优化各阶差频的相位失配分布,经级联差频高效产生高频太赫兹波。借助Mg O∶Li Nb O_(3)晶体极化声子共振区巨大的非线性光学系数,以及Mg O∶Li Nb O_(3)平板波导中被降低的太赫兹波吸收系数,在室温下通过输入两束强度均为100 MW/cm^(2)的差频光,得到了频率为5 THz的高频太赫兹波,太赫兹波强度为88.2396 MW/cm^(2),能量转换效率为44.12%。本文为产生高频、高功率太赫兹波提供了一种全新方法,可以推动高频太赫兹波在未来高速无线通信领域的应用。Objective Terahertz technologies have attracted significant attention in various fields,such as imaging,spectral analysis,security inspections,biomedicine and communications.Wireless transmission at several hundred Gb/s rates can be realised with high-frequency terahertz waves(>5 THz),especially in the field of high-speed wireless communications.For such wireless communications,a high-power,high-efficiency,inexpensive and compact source of high-frequency terahertz waves is required.Electronic methods(e.g.travelling wave tube,backward wave oscillator and nanoklystron)and optical methods(e.g.photoconductive antenna,optical rectification,terahertz wave parametric oscillator,difference frequency generation and quantum cascade laser)cannot efficiently generate high-frequency terahertz waves.In this study,we present a novel scheme for generating high-frequency terahertz waves in Mg O∶Li Nb O_(3)slab waveguides with optimised cascaded difference frequency generation at polariton resonance.Such a terahertz source exhibits excellent advantages,such as high-efficiency,high-power,compactness and room temperature operation.We believe that the proposed novel scheme can boost terahertz wave applications in high-speed wireless communications.Methods Two infrared pump wavesω0 of 291.76 THz andω1 of 291.26 THz interact in a PPLN crystal,generating a terahertz waveωT1 of 0.5 THz and a series of cascaded optical waves by cascaded difference frequency generation.Then,the generated cascaded optical waves with frequency intervalωT1 further interact in an Mg O∶Li Nb O_(3)slab waveguide,generating a high-frequency terahertz waveωT2 of 5 THz through the optimised cascaded difference frequency generation.The phase mismatches optimised by changing the dimensions of the Mg O∶Li Nb O_(3)slab waveguide in cascaded Stokes processes is equal to zero one by one from the first-order Stokes process to high-order Stokes processes.The phase mismatches in cascaded anti-Stokes processes are enlarged simultaneously;thereby,enhancing cascaded

关 键 词：非线性光学 太赫兹波 级联差频 极化声子共振区 平板波导 

分 类 号：O437.3[机械工程—光学工程]