Extension of the concept of lasing-without-inversion to nonlinear optical processes

将无反转激光概念扩展到非线性光学过程

基本信息

批准号：
04452055
负责人：
HAKUTA Kohzo
金额：
$ 4.35万
依托单位：
University of Electro-Communications
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (B)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1994
项目状态：
已结题

项目摘要

This project aims to exploit a new method in nonlinear optical frequecy mixing processes, by extending an idea of "lasing without population inversion". The key idea is to strongly couple the upper two states in a three level system, leading to two dressed states which are decaying to an identical continuum. Using such dressed state system, optical responses of the atomic medium can obtain much more freedom than that for bare atomic system. We use the atomic hydrogen as a test medium, and have investigated the sumfrequency generation process, generating coherent 103 nm radiation.In this project, we have shown that strong coupling at the 3p-2s transition creates destructive interference to reduce the linear susceptibility at the resonant3p*Is transition. Simultaneously, two-photon coupling of the 2s and 1s states produces constructive interference to resonantly enhance the nonlinear susceptibility for sum-frequency generation at the 3p*1s (Lyman-beta) transition.Experimental results clearly demonstrate the theoretical predictions.When the Rabi frequency for the 3p-2s coupling exceeds the Doppler tail of the medium, the photoion signals on resonance are suppressed significantly because of induced transparency.The generated Lyman-beta radiation grows rapidly by a factor of 250 at an atom density of 10^<15> cm^<-3> and interaction length of 3.5 cm, resulting in a conversion efficiency of 2x10^<-4>.It has also shown that, when the coupling frequency is detuned from the resonance, the refractive index of the medium can be controlled to satisfy the phase-matching condition for sum-frequency generation.

该项目旨在通过扩展“没有种群反转的激光”的想法来利用非线性光学频率混合过程中的新方法。关键的想法是在三层系统中强烈将上两个状态融入上两个状态，从而导致两个穿着的状态腐烂到相同的连续体。使用这种着装状态系统，原子培养基的光学响应比裸露原子系统可以获得更多的自由。我们将原子氢用作测试介质，并研究了SumFreChency的生成过程，产生了连贯的103 nm辐射。在这个项目中，我们已经表明，在3p-2s过渡时进行强耦合会产生破坏性干扰，以降低在降低线性敏感的情况下，以降低线性敏感resonant3p*是过渡。同时，2s和1态的两光子耦合产生建设性干扰，以共同增强3p*1s（Lyman-Beta）过渡的总和频率产生的非线性敏感性。对于3p-2s耦合超过了介质的多普勒尾巴，由于透明度诱导的透明度，共振上的光子信号被大大抑制。产生的Lyman-Beta辐射在原子密度为10^<15>的原子密度下迅速增长250倍。 CM^<-3>和3.5 cm的相互作用长度，导致2x10^<-4>的转换效率。它还表明，当耦合频率从谐振中脱离时，介质的折射率可能会为受控以满足总和生成的相匹配条件。