基于光束偏转的扫描式宽带光参量啁啾脉冲放大

光参量啁啾脉冲放大(OPCPA)是超短激光脉冲领域的重要技术之一,增大增益带宽对提高OPCPA的转换效率、实现宽带光参量放大具有重要的意义.本文将光束偏转和非共线OPCPA有机结合,提出了基于光束偏转的扫描式宽带OPCPA模型.分析了通过光束偏转来时刻改变非共线角,以保证各频率成分的相位匹配,从而增大增益带宽的基本原理.采用提出的扫描式宽带OPCPA,针对800 nm中心波长、带宽约为100 nm信号光的光参量放大进行了数值计算.结果表明:经过扫描式OPCPA后,信号光的带宽与放大之前几乎相同,光谱没有窄化;扫描式OPCPA比固定非共线角方式的放大极大地增加了增益带宽和转换效率,实现了宽带的光参量放大;要满足信号光各频率成分的相位匹配,达到最大的增益带宽和转换效率,需要尽量减小加载到钽铌酸钾(KTa_(1-x) Nb_xO_3, KTN)电光晶体上的电压抖动和电压延时.

Scanning broadband optical parametric chirped pulse amplification based on optical beam deflection

One of the goals pursued in laser pulse is to achieve a laser with a shorter duration and higher intensity. In the past two decades, the laser pulse duration has been shortened by more than 7 orders of magnitude due to the development of Q-switched, Mode-locked and pulse compression technology. The peak power of laser pulse has been increased to PW, even EW and ZW from initial MW with the development of pulse amplification technology, whose focused intensity can reach to 10²³ W/cm². Thus, it provides unprecedented extreme conditions, and speeds up the laser applications in ultrafast nonlinear optics, strong field physics, fast ignition of laser nuclear fusion, optic communication, etc. The optical parametric chirped pulse amplification (OPCPA) is one of the important technologies in ultra-short laser pulse field. It is of great significance to increase the gain bandwidth for improving the conversion efficiency of OPCPA and achieving broadband optical parametric amplification. Combining the optical beam deflection and non-collinear OPCPA, a novel scanning broadband OPCPA model is proposed based on the optical beam deflection. The basic principle of increasing the gain bandwidth for the scanning broadband OPCPA is analyzed theoretically, which ensures the phase matching of each frequency component of signal by optical beam deflecting to change the non-collinear angle constantly. Namely, the non-collinear angles of incident frequency components of signal are different from each other, which, however, makes the whole phase matching of signal, i.e. momentum conservation in optics. The optical parametric amplification of signal pulse with 800 nm central wavelength and almost 100 nm bandwidth is simulated numerically by the proposed scanning broadband OPCPA. The results show that the bandwidth after being amplified is almost the same as before and there is no spectral narrowing, and the scanning broadband OPCPA increases the gain bandwidth and conversion efficiency greatly compared with the amplification with a constant given non-collinear angle, which leads to broadband optical parametric amplification. Finally, it is necessary to make sure that the on-load voltage to the KTN crystal matches with the frequency of signal pulse in time and reduces the unfavorable voltage deviation and time-delay for the maximizing gain bandwidth and conversion efficiency and ensuring the phase matching of each signal frequency component. The results of this paper not only provide an approach to increasing the gain bandwidth of OPCPA, but also supply some theoretical references and the basis for the experimental work of OPCPA in ultra-short laser pulse system.