Engineering Research Equipment Grant: Mode-Locked Q-Switched Picosecond Nd: Yag Laser System for Nonlinear Optical Processes with Organic Crystals and Semiconductors

该工程研究设备拨款将为皮秒激光系统（Nd:Yag，锁模，调q 1.06um，二次谐波0.53um， 35ps脉冲能力）提供资金。主要目标是将目前NSF资助的液晶非线性过程项目扩展到相对未开发的皮秒范围，其中最近开发了几种具有重要应用潜力的新基波混频过程。特别是，理论和实验表明，在任何高度非线性的克尔介质中，由于产生高阶绕射波，两波相互作用都可以实现大量的光束放大。这种效应已经在液晶、有机聚合物和半导体中得到了从连续波到纳秒的实验证明。无腔光逻辑门和光调制效应最近也在纳秒激光脉冲中得到了证明。皮秒激光系统将首次研究这些波混合过程的动力学，以及各种半导体和有机材料物理参数（如重组、扩散、激子形成、分子取向、带间和带内跃迁修正、分子大小、电子超极化率等）所起的作用。这项研究可能会产生一些基本的重要效应和新的非线性光学器件原理。

This Engineering Research Equipment Grant will provide funds for a picosecond laser system (Nd:Yag, mode-locked, Q-switched 1.06um with second harmonic 0.53um capability 35ps pulses). The main objective is to expand the current NSF funded project on nonlinear processes in liquid crystals into the relatively unexplored picosecond regime where several new fundamental wave mixing processes of important applied potentials have been developed recently. Specially, theory and experiment have shown substantial beam amplication can be realized in any highly nonlinear Kerr media by two-wave interaction, owing to the generation of higher order diffracted waves. The effect has been experimentally demonstrated from the cw to the nanosecond regime in liquid crystals, organic polymers and semiconductors. Cavity-less optical logic gates and opto-optical modulation effects have also been recently demonstrated with nanosecond laser pulse. The picosecond laser system will enable study for the first time of the dynamics of these wave mixing processes, and the roles played by various semiconductor and organic material physical parameters such as recombinations, diffusions, excitonic formations, molecular orientations, corrections inter- and intra-band transitions, molecular sizes, electronic hyperpolarizability, etc. Several fundamental important effects and new nonlinear optical devices principals could emerge from this study.