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

• 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
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-07650401/
• 关键词: femtosecond laser; amplitude shaping; phase shaping; coherent phonon; coherent function shaping; multiplexed holography; フェムト秒光パルス; フーリェ波形整形; 液晶空間光変調器; 周波数チャープ; フーリエ波形整形; シミュレーティド・アニーリング法

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.利用IBM-PC控制的商用液晶空间光调制器(SLM)，通过傅里叶变换合成产生了任意形状的飞秒激光脉冲。该调制器由128个单独可编程的像素组成，每个像素宽100微米，每个元件之间的间隙为3微米。脉冲整形装置由放置在焦距为15 cm的单位放大率共焦透镜对焦面上的一对光栅组成。(1)利用模拟退火法对任意形状的幅度和相位时间历程设计了实验中SLM形成的纯相位掩模。即使是时间域中的非对称形状也可以用0、(]sy.+-四个灰度级来合成。[)pi/2和pi。(2)在实验中，我们成功地整形了-100ps的输入激光脉冲，如用7长M序列整形的太赫兹脉冲串、不对称的脉冲串和线性频率啁啾脉冲。用我们的脉冲整形装置合成了太赫兹脉冲串，在铋中激发了选择性相干声子模。利用该脉冲整形装置，我们成功地整形了光谱宽度为-17 nm的超发光二极管输出的连续光的相干函数。作为飞秒光谱全息的初步实验，用空间位相编码的方法记录了多路复用全息图。由用准噪声相位图案和单瓣形成图案编码的光束记录的全息图仅当用相同的准噪声相位图案编码读出光束时才成功地产生单瓣光束图案。

项目成果

K.Takasago: "Accurate Pulse Shaping of Femtasecond Lasers Using Programmable Phase-only Modulator" Japanese J.Applied Phys.Vol.35 No.11A. L1430-L1433 (1996)

K.Takasago：“使用可编程纯相位调制器实现飞秒激光器的精确脉冲整形”日本 J.Applied Phys.Vol.35 No.11A。

K. Takasago, T. Itoh, M. Takekawa, K. Utoh, F. Kannari: "Design of Frequency-Domain Filters for Femtosecond Pulse Shaping" Japanese Journal of Applied Physics. 35(未定). (1996)

K. Takasago、T. Itoh、M. Takekawa、K. Utoh、F. Kannari：“飞秒脉冲整形频域滤波器的设计”日本应用物理学杂志 35（待定）。

K.Takasago: "Accurate Pulse Shaping of Femtosecond Lasers Using Programmable Phase-only Modulator" Japanese J.Appied Phys.vol.35, No.11A. L1430-1433 (1996)

K.Takasago：“使用可编程纯相位调制器实现飞秒激光器的精确脉冲整形”日本 J.Appied Phys.vol.35，No.11A。

K.Takasago: "Accurate pulse shaping of femtosecond lasens using programmable phase-only modurator" Japanese J.Appl.Physics. Vol.35 No.11A. L1430-L1433 (1996)

K.Takasago：“使用可编程纯相位调制器对飞秒激光进行精确脉冲整形”日本 J.Appl.Physics。

K.Takasago: "Design of Frequency-Domain Filters for Femtosecond Pulse Shaping" Japanese J.Applied Phys.Vol.35 No.2A. 624-629 (1996)

K.Takasago：“用于飞秒脉冲整形的频域滤波器的设计”日本 J.Applied Phys.Vol.35 No.2A。