GaP波导型发射器产生频率可调谐太赫兹脉冲

报道了利用脉宽可调的光子晶体光纤飞秒激光放大器抽运矩形波导结构的GaP晶体太赫兹(THz) 发射器产生频率可调谐的超快THz脉冲.非线性晶体中光整流过程产生的THz辐射频率随抽运光脉冲宽度而 变化. GaP波导THz发射器可通过波导的几何尺寸来控制色散,以达到增加有效作用长度和提高输出功率的目的. 不同横截面尺寸的波导型发射器的THz辐射峰值频率随相位匹配条件的改变而改变,加以脉宽调节技术, 可以在大频谱范围获得频谱精细可调的THz脉冲.实验中在1 mm×0.7 mm的波导型THz发射器中获得了 频率可调谐的THz脉冲.提出实现THz辐射频率大范围调谐的GaP波导型阵列发射器的实施方案.     

EXPERIMENTAL STUDY ON THE SELF-MODE-LOCKED Ti:SAPPHIRE LASER

The role of gain aperture in self-mode-locked Ti:sapphire laser was verified in our experiments. The observation of self-Q switching of self-mode-locked Ti:sapphire laser is reported. And tuning pulse duration from 50fs to 14.5ps was achieved.     

采用双石英棱镜对的掺钛蓝宝石自锁模激光器

给出了双棱镜对二、三阶色散的解析式。报道了采用双石英棱镜对的掺钛蓝宝石自锁模激光器的实验结果，获得与理论分析一致的结论。     

TW(1012W)飞秒激光作用下的超连续光谱的实验研究

利用飞秒脉冲啁啾放大系统所产生的TW级飞秒强光脉冲,以液体介质为研究对象,研究了不同介质长度(作用长度)、不同泵浦强度、介质的基频和倍频飞秒光脉冲的超连续光谱特性,在液体中实现了具有光谱“平台”效应的高转换率宽光谱,边缘光谱强度仅低于中心1个数量级,同时还研究了超连续谱形成过程中自相位调制(SPM)效应与四光子参量效应的作用。     

GROUP-VELOCITY DISPERSION IN CHIRPED-PULSE AMPLIFIER

By using the pulse propagation equation in the nonlinear dispersive medium, the effects of second- and third-order group-velocity dispersion on pulse evolution in the stretching, amplification and compressing are studied when chirped pulse am-plification is applied to the pulses of a width <30fs, and the optimum dispersion-compensated conditions among the stretcher, amplifier and compressor are deter-mined. From the standpoint of dispersion compensation and control and the com-pressor adjustment, it is proposed that low-groove-density gratings (≤800 line/mm) are the better choices for stretching and compressing the pulses of a width <30fs in chirped-pulse amplification. It is also shown that, with a proper adjustment of the compressor incident angle and grating separation, an exact null in both second- and third-order dispersions can be achieved without any additional dispersion- compensated elements.     

Compact and high-power broadband terahertz source based on femtosecond photonic crystal fiber amplifier

We present a review of the development of a compact and high-power broadband terahertz (THz) source optically excited by a femtosecond photonic crystal fiber (PCF) amplifier.The large mode area of the PCF and the stretcher-free configuration make the pump source compact and very efficient.Broadband THz pulses of 150 μW extending from 0.1 to 3.5 THz are generated from a 3-mm-thick GaP crystal through optical rectification of 12-W pump pulses with duration of 66 fs and a repetition rate of 52 MHz.A strong saturation effect is observed,which is attributed to pump pulse absorption;a Z-scan measurement shows that three-photon absorption dominates the nonlinear absorption when the crystal is pumped by femtosecond pulses at 1 040 nm.A further scale-up of the THz source power is expected to find important applications in THz nonlinear optics and nonlinear THz spectroscopy.     

THz波的小波变换频谱分析

将小波变换引入THz波时域光谱技术.将水蒸气的THz波时域信号通过小波变换转化为二维的时间-频率平面，得到了和文献报道数据相一致的水蒸气的吸收谱线.同时发现了THz波频谱的时域分布特性，这将有利于进一步研究THz波与物质相互作用的内在机理. 关键词： THz波 频谱分析 小波变换     

飞秒互相关时间选通技术用于光学层析成像的实验研究

利用飞秒互相关二次谐波信号时间选通技术。实现了对埋藏在高度散射介质中物体的透射成像和反射以析成像。互相关选通门有效地选出携带物体信息的弹道光子和蛇行光子，排除了给成像带来背景噪声的温射光子，分别获得了散射介质中物体的二次谐波一维和二维图像。     

采用光谱展宽技术的钛宝石飞秒激光放大器

报道了飞秒激光啁啾脉冲放大器中的激光脉冲光谱展宽技术，实验中使用了几种光谱展宽元件，结果表明使用激光光谱展宽元件能有效地将飞秒激光脉冲 光谱展宽，抑制了飞秒激光放大器中常见的激光脉冲光谱增益窄化现象，从飞秒放大系统的振荡级输出28fs种子脉冲，放大后得到了重复频率为10Hz、峰值功率为1．6TW、脉冲宽度37．5fs的超短强飞秒激光脉冲 。