Phase-sensitive femtosecond time-resolved four-wave mixing with spatial light modulators

利用液晶空间光调制器（SLM）实现了相敏飞秒脉冲整形装置，该装置已商业化用于投影仪。SLM是具有640 × 480像素的有源矩阵TFT扭曲的液晶SLM，每个像素可以由个人计算机以256灰度独立控制。建立了迈克尔逊干涉仪，用于测量在256级中的每一级上透射通过SLM的光的振幅和相位变化。掩模图案和所产生的波形由新编写的模拟退火计算机程序计算，该程序结合了实验获得的幅相关系。利用GaAsP光电二极管中的双光子感应电流，建立了一种干涉互相关测量装置。当用压电作动器调制光程长度时，获得了高质量的数据。本文还提出了利用光电倍增管中双光子感生光电流的互相关测量技术。使用上述技术对所产生的波形的测量已经证实了所构造的脉冲整形设备的能力。还对所产生的波形进行相位控制。

Phase-sensitive femtosecond pulse shaping apparatus has been constructed using a liquid crystal spatial light modulator (SLM) with is commercialized for use in projectors. The SLM was an active-matrix TFT twisted nematic liquid crystal SLM with 640x 480 pixels, each of which can be controlled independently by a personal computer in 256 greyscale. A Michelson interferometer was built for the measurement of the amplitude and phase change of the light transmitted through the SLM at each of the 256 levels. Mask patterns and the generated waveforms were calculated by a newly written simulated annealing computer program which incorporated the experimentally obtained amplitude-phase relation. An interferometric cross-correlation measurement apparatus was constructed which used two-photon-induced current in a GaAsP photodiode. God quality of data was obtained when the path length was modulated by a piezo-electric actuator. Another cross-correlation measurement technique using two- photon-induced photocurrent in a photomultiplier tube has also been developed. Measurements of the generated waveforms using the technique described above have confirmed the ability of the constructed pulse shaping apparatus. Phase control of the generated waveforms was also performed.