基于光学参量振荡器的高分辨率CARS光谱研究

摘要

提出了一种基于三硼酸锂（LBO）晶体的飞秒绿色泵浦光学参量振荡器（OPO），其采用飞秒525 nm绿光光纤激光器作为泵浦源。OPO产生的信号光其可调谐的光谱范围由780～940 nm，光功率可达到250 mW以上；闲频光可调谐范围从1630～1190 nm，光功率可达到300 mW以上。利用本系统可在波数为1330 cm－1和6650 cm－1之间进行相干反斯托克斯拉曼散射（CARS）光谱测量。由于脉冲啁啾，光谱分辨率达到100 cm－1，与时间带宽限制脉冲激励源相比，分辨率达到后者的2.5倍。%A femtosecond green-pumped optical parametric oscillator (OPO)based on the LBO crystal is proposed,and 525 nm green fiber laser system is used as the pump source.The tunable spectral range of signal pulses generated by OPO is from 780 to 940 nm and optical power reaches up to 250 mW;the tunable spectral range of idler pulses is from 1630 to1 190 nm and optical power reaches up to 300 mW.The coherent anti-Stokes Raman scattering spectrum are measured between 1330 and 6650 cm-1 by using this system.Due to the pulse chirp,a spectral resolution of 100 cm-1 is achieved,whose resolution is 2.5 times higher compared to an excitation source with time-bandwidth limited pulses.