超短激光脉冲对比度的三阶相关测量

Contrast Measurement of Ultrashort Laser Pulse with Third Order Correlation Technique

在超强超短激光脉冲与物质相可作用过程中,良好的激光脉冲对比度是一个非常重要的参数指标。为了扩大对超短激光脉冲对比度的测量范围,准确地测量超短激光脉冲的对比度,利用非线性品体对激光脉冲强度变化十分敏感的特性,研究了超短激光脉冲三阶相关信号的产生过程,并在此基础上,研制了一台三阶相关仪,对一台飞秒激光振荡器进行了脉冲对比度的测量研究。测量结果表11月,通过在测量光路中加入聚焦透镜进行聚焦准直,可以有效提高激光脉冲的倍频效率,从而大幅提高该二阶相关仪的可测动态范围。该测量系统目前可实现的可测动态范围达到约108。

High laser pulse contrast ratio is one of the most important terms during the interaction of ultrashort laser pulse and substance. In order to enlarge the range of the pulse contrast measurement, a third-order correlator based on the technique of cross-correlation between the fundamental and second harmonic waves of ultrashort lasers is built. Using this correlator, the contrast ratio of ultrashort laser pulses from a typical Ti.. sapphire oscillator is measured. The results show that the conversion efficiency of second harmonic and third harmonic of ultrashort laser pulse can be enhanced, and the dynamic range in pulse contrast measurement can be made much wider by using convex lenses, and the correlator＇s widest dynamic range in pulse contrast measurement is about 10^8.