Encoding and decoding of amplitude or phase informations with a liquid-crystal array on femtosecond light pulses

使用飞秒光脉冲上的液晶阵列对幅度或相位信息进行编码和解码

基本信息

批准号：
07650401
负责人：
KANNARI Fumihiko
金额：
$ 1.28万
依托单位：
Keio University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1995
资助国家：
日本
起止时间：
1995 至 1996
项目状态：
已结题

项目摘要

1. Arbitrarily shaped femtosecond laser pulses are produced with a Fourier-transform synthesis using a commercially available liquid-crystal spatial light modulator (SLM) controlled by a IBM-PC.The modulator consists of 128 individually programmable pixels of 100 mum wide with a 3 mum gap between each elements. The pulse-shaping apparatus consists of a grating pair placed at the focal planes of a unit magnification confocal lens-pair with a focal length of 15cm.(1) Phase-only masks formed with the SLM in the experiments were designed with simulated annealing optimization algorithm for arbitrarily shaped amplitude and phase time histories. Even asymmetric shapes in time domain can be synthesized with four gray levels of 0, (]SY.+-。[)pi/2, and pi.(2) Successful shaping of -100 fs input laser pulse was obtained in our experiments such as THz pulse trains shaped with 7-length M-sequence, unsymmetrical pulse trains, and linearly frequency-chirped pulses.2. Selective coherent phonon mode was excited in Bi with THz pulse trains synthesized with our pulse shaping apparatus.3. Utilizing this pulse shaping apparatus, we succeeded to shape coherent function of a cw light from a super luminescent diode with a spectrum width of -17nm.4. Multiplexed holograms were recorded with spatial phase encoding method as a preliminary experiments of femtosecond spectrum holography. Holograms recorded by a beam encoded with a quasi-noise phase pattern and a single lobe formation pattern, successfully produce a single lobe beam pattern only when a read beam is encoded with the same quasi-noise phase pattern.

1. 使用由 IBM-PC 控制的市售液晶空间光调制器 (SLM)，通过傅里叶变换合成产生任意形状的飞秒激光脉冲。调制器由 128 个 100 μm 宽、3 个像素的独立可编程像素组成。每个元件之间的间隙很小。脉冲整形装置由位于单位放大倍率共焦透镜对焦平面上的一对光栅组成，其焦距为15cm。（1）实验中用SLM形成的纯相位掩模是通过模拟退火优化算法设计的，用于任意形状的幅度和相位时间历史，甚至可以用四个0灰度级来合成时域中的不对称形状。 ]SY.+-. [)pi/2, pi.(2) 在我们的实验中成功地获得了-100 fs输入激光脉冲的整形，例如采用7长度M序列整形的非对称太赫兹脉冲串2．用我们的脉冲整形装置合成太赫兹脉冲串，在Bi中激发选择性相干声子模式。3．利用该脉冲整形装置，我们成功地形成了连续波的相干函数。光谱宽度为-17nm的超发光二极管。4．用空间相位编码方法记录了多路全息图，作为光束编码记录的飞秒光谱全息图的初步实验。具有准噪声相位图案和单瓣形成图案，仅当读取光束用相同的准噪声相位图案编码时才成功产生单瓣光束图案。