研究了小角度情况下基于光谱角色散(ASD)方式的非共线光参量啁啾脉冲放大(OPCPA)实现啁啾激光脉冲频谱整形的方法。详细讨论了角色散率对信号光各频率成分相位失配量、转换效率及放大后频谱分布的影响。当信号光中心波长为800 nm,带宽为20 nm,在532 nm抽运作用下,对耦合波方程组进行了数值模拟。其结果显示:在最佳角色散率情况下,采用ASD方式的光参量放大后,得到了约28 nm带宽的双峰整形频谱。计算结果也表明:角色散率对整体的转换效率以及放大后整形的频谱分布有较大影响,适当调节抽运光与信号光之间的时延可调整放大后信号光频谱的频移。整形后的频谱分布可在一定程度上克服增益窄化、光谱红移等效应。

The spectrum shaping approach of chirped laser pulse is studied based on the non-colinear optical parametric chirped pulse amplification (OPCPA) with angular spectral dispersion (ASD). The effect of angular dispersion ratio on the phase mismatching of each signal frequency component, the conversion efficiency and the spectral distribution after amplification is discussed in detail. The coupled wave equations are simulated numerically when signal pulse is pumped by 532 nm with the central wavelength of 800 nm and the bandwidth of 20 nm. The results show that the bimodal spectrum with 28 nm bandwidth is obtained by use of the non-colinear OPCPA with ASD, under the optimal angular dispersion ratio. The results also indicate that the angular dispersion ratio has a considerable effect on the overall conversion efficiency and the shaped spectrum of the signal pulse after the amplification. Furthermore, the frequency-shift of signal spectrum after amplification could be modulated by adjustment of the time-delay variation between the pump and the signal pulse properly. The shaped spectrum is available to compensate the gain narrowing and spectroscopic redshift effect to some extent.