基于预啁啾控制的极宽带光参量放大

Ultra-broadband optical parametric amplification based on pre-chirp controlling

在以飞秒钛宝石放大系统的倍频光为抽运光和超连续白光为信号光的光参量放大中,针对抽运光的宽带特点,分析了一种新的极宽带相位匹配方法.结果表明,10nm的抽运光带宽可得到近400nm的相位匹配带宽,若抽运光带宽达到20nm,相位匹配带宽就能达到近600nm.零色散波长为800nm的光子晶体光纤产生的超连续谱经光纤传输后为二次啁啾,宽带抽运光经棱镜对展宽具有线性啁啾,满足了极宽带相位匹配方法所需要的光谱分布.理论计算了对输入脉冲进行预啁啾控制应选择的光纤长度和棱镜对在光路中的插入量,为实现极宽带光参量放大提供了理论依据.

For optical parametric amplification with broadband pump coming from the second harmonic of an amplified Ti： sapphire laser syetem, a novel ultra-broad bandwidth phase-matching approach is investigated. The results show that an approximately 400 nm phase-matching bandwidth can be obtained by using a 10 nm pump bandwidth. Moreover, the phase-matching bandwidth can reach 600 nm when the pump bandwidth attains 20nm. In order to obtain temporal overlap of phase-matched spectral components, a linear chirp in the pump requires a quadratic chirp in signal. The photonic crystal fiber with a zero-dispersion wavelength of 800 nm generates a supercontinuum with a quadratic chirp. The broadband pump pulse is stretched to a linear chirped pulse by a prism pairs. Calculations concerning the appropriate length of fiber and prism sequence to be inserted in optical path for the pre-chirp controlling were performed, the results of which provide a theoretical basis for implementing the ultra-broadband optical parametric amplification.