KTiOPO4晶体的太赫兹光学声子振荡特性研究  

Optical Phonon Resonance of KTiOPO_4 Crystal Characterized by THz Time-domain Spectroscopy

作　　者：桑梅[1] 樊亮[1] 路鑫超 张伟力 

机构地区：[1]天津大学精密仪器与光电子工程学院光电信息技术科学教育部重点实验室,天津300072 [2]俄克拉荷马州立大学电子与计算机工程系,静水城74078

出　　处：《光子学报》2009年第6期1344-1348,共5页Acta Photonica Sinica

基　　金：国家自然科学基金(60377018)资助

摘　　要：采用超快半导体光电导开关的宽带太赫兹时域频谱系统,研究了KTiOPO4晶体在0.5～2.0THz波段的光学声子振荡特性;在晶体z轴平行于THz波电场振动方向时发现了明显的吸收峰.利用晶体中晶格振动模式(光学声子)对光谱的选择性吸收特性和多洛仑兹振子伪谐振介电模型,很好地拟合了KTP晶体的复介电常量曲线,得到了对应晶格弱振动的光学声子的频谱参量值.研究结果表明,位于ω1/2π=1.76THz的吸收峰是KTP晶体中沿z轴排列的K+相对于PO4和TiO6晶格振动造成的光学外振动模.同时也说明THz波对于晶格弱振动非常敏感,对于微弱的光学声子吸收峰的频谱分析更加精准.Utilizing uhrafast femtosecond pulses to pump photoconductive switches in the terahertz timedomain spectroscopy system, the optical phonon oscillation characteristics of KTiOPO4 crystal were studied in the 0. 5-2. 0THz range. An obvious absorption peak was found when the z-axis of the crystal was parallel to the polarization of the terahertz electric field. With the crystal lattice vibration selective absorption principle and pseudo harmonic dielectric model, the complex dielectric constant curves fit well and the spectroscopic parameters of a weak optical phonon resonance were achieved. The optical external mode at ω1/2π= 1.76THz,which attributed to the K ions vibration relative to the screw of PO4 tetrahedral and TiO6 octahedral,was confirmed. These results show that the THz time-domain spectroscopy is more sensitive and precise to weak lattice vibrations.

关 键 词：太赫兹波 时域频谱 KTiOPO4晶体 光电导开关 光学声子 

分 类 号：O433.1[机械工程—光学工程]