新材料太赫兹参量源研究

Terahertz parametric sources are important terahertz sources. They have outstanding advantages such as laser-like properties, tunable operation, narrow spectral line width, room-temperature operation, long lifetime, and so on. The disadvantage is that only MgO:LiNbO3 crystal has been the practical material for the terahertz parametric sources in the past more than 20 years. The main tunable spectral range is 0.9-3.1 THz and the reported maximum pulse energy so far is several micro joules. So, it is necessary to study the terahertz parametric sources with other materials. This project will research on the terahertz parametric sources of some materials including KTiOPO4 (KTP), KTiOAsO4 (KTA), RbTiOPO4 (RTP), RbTiOAsO4 (RTA). These materials have been grown for some time, but their applications in the terahertz wave parametric sources are new. Our recent experiment and others have shown the feasibility of KTP, KTA and RTP as the nonlinear materials for terahertz parametric sources. The characteristics of the terahertz parametric sources of these materials will be investigated intensively. The goal tunable spectral range is 1-10 THz and the goal pulse energies at about 3.8 THz is more than 30 micro joules. Moreover, some methods for crystal users to judge whether a crystal is suitable for terahertz parametric sources will be given. Some clues for crystal growers to grow crystals for terahertz parametric sources will be supplied.

太赫兹(THz)参量源是重要的THz辐射源之一，具有类激光特性、可调谐运转、谱线宽度窄、室温运转、长久耐用等突出优点，缺点是20多年来实用晶体只有铌酸锂，主要调谐范围为0.9-3.1 THz，最高脉冲能量为几个微焦水平，研究其他材料THz参量源很有必要。本项目拟研究四种材料的THz参量源，包括磷酸钛氧钾(KTP)、砷酸钛氧钾(KTA)、磷酸钛氧铷(RTA)、砷酸钛氧铷(RTA)，属于老晶体新应用。KTP、KTA和RTA应用于THz参量源的可行性已经由我们和其他研究组的实验证实。将研究这些材料的THz参量源特性，获得THz波调谐范围达到1-10 THz，并在3.8 THz附近获得THz单脉冲能量达到30 µJ以上，同时，为晶体使用者迅速诊断一种晶体是否适合于太赫兹参量源提供规律性依据，为晶体生长者生长优质太赫兹参量源晶体提供思路。

太赫兹(THz)参量源是重要的太赫兹辐射源之一，具有类激光特性、可调谐运转、谱线宽度窄、室温运转、长久耐用等突出优点，缺点是20多年来实用晶体只有铌酸锂，主要调谐范围为0.9-3.1 THz，研究其他材料THz参量源很有必要。本项目研究了基于磷酸钛氧钾(KTiOPO4，KTP)、砷酸钛氧钾(KTiOAsO4，KTA)、磷酸钛氧铷(RbTiOPO4, RTP)的太赫兹参量源的特性，属于老晶体新应用。确定了KTP、KTA、RTP晶体中各个具有红外和拉曼双活性的横光学极性振动模在产生THz波过程中所起的作用，确定了基于具有多个光学极性振动模的非线性晶体的太赫兹波参量源的运转特性。利用KTP、KTA、RTP晶体获得太赫兹波调谐范围在3.0-7.1 THz（不连续可调）。利用KTP晶体在新的波段获得大能量太赫兹脉冲，在5.7 THz处获得太赫兹波脉冲能量最大为 17.0 微焦。推导了内腔泵浦的太赫兹参量振荡器的速率方程，并在该速率方程的指导下设计了内腔泵浦的KTP及RTP太赫兹参量振荡器，在3.85 THz处获得平均功率为367微瓦的高重复率太赫兹波。