飞秒时间分辨取样光谱仪的研制

Investigation of Femtosecond Time-resolved Boxcar Spectrometer

研制的飞秒(10^(-15)s)时间分辨取样光谱仅由三部分组成:①飞秒激光探针弥散补偿光学系统,②氩激光泵浦掺钛兰宝石飞秒激光系统,③信号探测、数据采集分析处理系统。掺钛兰宝石飞秒激光器在7W氩激光全线泵浦下,能输出平均功率400mW、持续期50fs到300fs的光脉冲。其光谱可在750nm到920nm范围内调谐,经LBO晶体倍频,能得到375nm到460nm的二次谐波。整体取样光谱仪的时间分辨为90fs到320fs,光谱分辨率好于0.1nm,泵浦一探测差异吸收灵敏度达到10^(-6)～10^(-7)量级。该光谱仪已用于"八五"国家攀登计划"飞秒激光技术与超快过程研究"项目中的光合作用PSⅡ反应中心原初电荷分离等超快过程研究。

A femtosecond time-resolved Boxcar pump-probe difference absorption spectrometer is developed. It has three major components: a dispersion compensated optics system of femtosecond laser probe, an argon laser pumped Ti: sapphire femtosecond laser system and a signal detection and analysis system. A two-wavelength tunable Ti: sapphire femtosecond laser system is employed to meet the repuirement of wavelength change of both the pump and the probe. The laser output is tunable from 750 nm to 920 nm and the frequency doubling output is tunable from 375 nm to 460 nm. The minimum time resolution of total Boxer spectrometer is 90 fs and spectral resolution is less than 0.1 nm. The detection sensitivity is about 10^(-6)～10^(-7). Light at 400 nm is used for pump pulses and light at 800 nm is used for probe pulses. This spectrometer has been used to determine the charge separation rate for photosynthesis PSⅡ reaction center D_1-D_2-cyt-b559, a charge separation time of 3.2 ps is obtained.