中文摘要：

针对飞秒激光光谱学研究中对微弱光信号的多通道光谱分析的需求,提出了一种32通道光纤阵列-锁相放大光谱分析仪（OSA）设计方案。32通道光纤阵列用于传输线型分布光谱信号,经光电探测器（PD）转换的电信号由32通道同步数字锁相放大器进行处理。基于现场可编程门阵列（FPGA）设计的32通道同步数字锁相放大器,实现了各路独立的微弱光谱信号同时检测功能。针对飞秒激光光谱测量中重复频率为1kHz的强干扰,设计1kHz陷波器,提高信号测量的动态范围。设计的OSA的测量光谱范围为400-1100nm,通道光谱间隔为4nm。实验结果表明：32通道光纤阵列OSA的通道隔离度大于80dB,输入光噪声密度为37.9fW/槡Hz,各通道极限检测灵敏度可达18.9fW,动态储备达到120dB。应用于飞秒时间分辨荧光光谱测量,对超荧光干扰抑制效果明显,同时极大地提高了测量灵敏度并缩短动力学测量时间至6 min。本文实现的OSA具有灵敏度高、体积小和性价比高等优点,适用于对微弱光谱信号的高灵敏与快速检测分析。

英文摘要：

To meet the need of multi-channel optical spectrum analysis of weak light signals in spectro seopic studies, a design scheme of 32-channel fiber array and lock-in amplifier based optical spectrum analyzer is presented. 32-channel fiber array is used for transmitting the linear light signals,and the detec ted signals converted by photodetectors are processed by a 32-channel synchronous digital lock-in amplifier. The field programmable gate array （FPGA） based 32-channel synchronous digital lock-in amplifier is designed to realize the function of detection for weak light signals simultaneously. Considering the strong interference whose frequency is 1 kHz in measurement of femtosecond laser spectroscopy, a notch filter with the center frequency of 1 kHz is designed to improve the dynamic range of signal measurement. The designed spectrum analyzer has a spectral range from 400 nm to l 100 nm and a spectrum interval of 4 nm. Experimental results show that the 32-channel fiber array input optical spectrum analyzer can run with a channel isolation up to 80 dB,input light noise of 37.9 fW/√Hz, sensitivity limitation as low as 18.9 fW and dynamic reser;ze up to 120 dB. The designed optical spectrum analyzer is applied for the measurement of femtosecond time resolved fluorescence spectroscopy,and the strong ability of suppression for super fluorescence is presented. Meanwhile; the sensitivity is improved and the measurement time is reduced to 6 rain. The designed optical spectrum analyzer can achieve multi-channel synchronous detection and spectrum analysis of weak light signals, with the advantages of high sensitivity, small size and low cost.