基于DAST晶体的连续太赫兹差频辐射源研究  

Tunable continuous-wave terahertz generator based on difference frequency generation with DAST crystal

作　　者：王泽龙 王与烨[1,2] 李海滨 张敬喜 徐德刚[1,2] 姚建铨[1,2] WANG Zelong;WANG Yuye;LI Haibin;ZHANG Jingxi;XU Degang;YAO Jianquan(School of Precision Instrument and Optoelectronics Engineering,Tianjin University,Tianjin 300072,China;Key Laboratory of Optoelectronic Information Technology(Ministry of Education),Tianjin University,Tianjin 300072,China)

机构地区：[1]天津大学精密仪器与光电子工程学院,天津300072 [2]天津大学,光电信息技术教育部重点实验室,天津300072

出　　处：《物理学报》2025年第3期118-126,共9页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:62175182,62275193,U22A20123,U22A20353)资助的课题。

摘　　要：基于DAST晶体的太赫兹差频辐射源具有宽调谐、室温运转等优点,但DAST晶体熔点低、热导率低的特性使其在连续泵浦条件下热积累严重、晶体易损伤,这限制了其实际应用.本文理论研究了基于金刚石衬底的DAST晶体的热分布特性,实验分析了金刚石衬底对DAST晶体中热效应的改善.进一步,基于连续单频激光器与金刚石衬底DAST晶体搭建了差频太赫兹辐射源,其太赫兹波频率调谐范围为1.1—3 THz,在2.493THz处获得最大输出功率为3.39 nW,30 min内太赫兹波的功率不稳定度为2.19%.该窄线宽、可调谐太赫兹辐射源在高精度光谱检测等领域具有较高的应用潜力.Terahertz(THz)waves have been widely investigated recently due to their ability to reflect the fingerprint characteristics of samples.As a promising method,THz technology has aroused great interest in various applications,especially biological imaging,environmental monitoring,non-destructive evaluation,spectroscopy and molecular analysis.In order to reveal the intramolecular vibration/rotation information of various compounds,the linewidths of their absorption lines are usually in a range of GHz or even MHz,and THz waves with wide tunability,narrow linewidth,high frequency accuracy,and high power stability are required.Currently, the linewidth with GHz level and low SNR at higher frequency still limit its further applications inreveal intramolecular information. In this work, the thermal distribution characteristics of DAST crystals basedon diamond substrates under continuous laser pumping conditions are theoretically studied by COMSOLMultiphysics, and the effectiveness of diamond substrates in dissipating heat from DAST crystals isexperimentally verified. Then, a narrow-linewidth and tunable organic-crystal continuous-wave terahertz sourceis demonstrated. Two narrow-linewidth continuous-wave (CW) fiber lasers are used as the pump sources forgenerating difference frequency. The terahertz wave is continuously tunable in a range of 1.1–3 THz. Themaximum output power of 3.39 nW is obtained at 2.493 THz. The power fluctuation in 30 min is measured tobe 2.19%. In addition, the generated THz wave has a high polarization extinction ratio of 9.44 dB. Using thisCW-THz source for high-precision spectral detection of air with different humidity, the results correspond wellwith the gas absorption spectral lines in the Hitran database, proving that the CW-THz source has narrowlinewidth, high frequency accuracy and stability. Therefore, it can promote the practical application of tunableCW-THz source, thus having good potential in THz high-precision spectroscopic detection and multispectralimaging.

关 键 词：连续太赫兹源 差频产生 DAST晶体 

分 类 号：O441.4[理学—电磁学]