High-efficiency color separation method based on fractional Talbot effect for color liquid crystal display

Based on the fractional Talbot effect of Talbot grating, a new method with high light efficiency for color separation in color liquid crystal displays (LCDs) is proposed. The light efficiency of 85% and 89% are obtained by three- and four-step Talbot gratings, respectively, which are rather higher than that of using color filter, the traditional color separation method in color LCDs. This method has large tolerance to the position error of the color separation plane, the wavelength changes of red, green and blue colors, and the step height errors of the gratings.     

高斯光束照射下的近似Talbot自成像效应及其两种新应用

本文讨论了高斯光束照明下的Talbot近似自成像的性质.提出了利用Talbot自成像测量高斯光束发散角的简便方法;也提出在满足一定条件下,可得到自成像的超高倍放大率.     

Talbot effect under illumination of double femtosecond laser pulses

The Talbot effect under illumination of double femtosecond laser pulses has been reported. Spectrums of double femtosecond laser pulses with phase differences are quite different from that of one single femtosecond laser pulse. Therefore, the Talbot images of the double femtosecond laser pulses with phase differences are different from that of one single femtosecond laser pulse. Specifically, for the phase difference corresponding to π, the Talbot image shows the largest difference from that of one single pulse. Experimental results are in good agreement with the theoretical analysis. The behaviors of Talbot images under double femtosecond laser pulses illumination cannot be obtained under one femtosecond laser pulse, monochromatic or polychromatic light illumination. Therefore, it is a new interesting optical phenomenon for the Talbot effect which should have potential applications.     

Texture Image Segmentation Using Talbot Effect

ＴｅｘｔｕｒｅＩｍａｇｅＳｅｇｍｅｎｔａｔｉｏｎＵｓｉｎｇＴａｌｂｏｔＥｆｆｅｃｔ￥ＷＡＮＧＷｅｎｌｕ；ＪＩＮＧｕｏｆａｎ；ＹＡＮＹｉｎｇｂａｉ；ＷＵＭｉｎｘｉａｎ（Ｄｅｐｔ．ｏｆＰｒｅｃｉｓｉｏｎＩｎｓｔｒｕｍｅｎｔｓ，ＴｓｉｎｇｈｕａＵｎｉｖｅｒ...     

二维阵列光场衍射自成像效应的倒格矢分析

基于衍射的角谱理论,分析了一般二维周期阵列光场的衍射特性.提出了一种用阵列光场的倒格矢来研究和描述衍射自成像（或泰伯效应）的方法.给出了用倒格矢表示的一般衍射自成像条件.在此基础上,对典型的非正交六方型二维周期阵列光场的泰伯效应和分数泰伯效应进行了定量分析和计算机模拟.     

The influence of the polarization effect in Talbot self-imaging of high-density gratings

The Talbot self-imaging of high-density gratings with different period at half Talbot distance for different polarization is analyzed with the finite-difference time-domain (FDTD) method. The numerical results indicate that the Talbot self-imaging of high-density gratings is obviously different for different polarization when the period d of the grating between 2λ and 3λ, which is verified through experimental results with the scanning near-field optical microscopy (SNOM) technique. Furthermore, the Fourier spectrum (far field) generated by the gratings is also given with the rigorous coupled-wave method, which is in agreement with the near field.     

Influence of the size of the grating on Talbot effect

The Fresnel theory of the Talbot effect of the grating is reviewed in this paper, and the general formula of the Fresnel diffraction of the grating with finite aperture size is presented. The aperture effect of the grating on the Talbot image is discussed and a number of numerical calculations are performed. The variation rule of the diffraction intensity distribution at the Talbot distance with the aperture size of the grating and the case at different Talbot distances are obtained through the calculations, and the corresponding explanations of these phenomena are given in this paper. We think that these discussions provide the theoretic basis for the practical application of the Talbot effect of the actual grating.     

Optical Texture Super-Lattices Produced by Talbot Effect at Superimposed Gratings

Fresnel diffraction on periodic gratings results in a two-dimensional periodic distribution of light intensity, also known as the Talbot effect. Here this approach is extended to the family of superimposed structures with translational symmetry, which consist of superposed spatial harmonics. The Talbot effect is demonstrated to be valid for superimposed gratings. The considered superimposed gratings provide a wide range of textures of optical super-lattices. These texture super-lattices represent a Talbot carpets with a complex motif, which can be varied by choosing structure parameters. These results provide a new functionality for structuring optical lattices and can find potential applications in a wide range of light–matter interactions.     

Talbot effect of a high-density grating under femtosecond laser illumination

The Talbot effect of a high-density grating under femtosecond laser illumination is analyzed with rigorous electromagnetic theory which is based on the Fourier decomposition and the rigorous coupled-wave analysis (RCWA). Numerical simulations show that the contrast of the Talbot images steadily decreases as the transmitted femtosecond laser pulses propagate forward and with wider spectrum width of the femtosecond laser pulses. The Talbot images of high-density gratings have much higher sensitivity of the spectrum widths of the incident laser pulses than those of the traditional low-density gratings. In experiments, the spectrums and the pulse widths of the incident pulses are measured with a frequency-resolved optical grating (FROG) apparatus. The Talbot images are detected by using a Talbot scanning near-field optical microscopy (Talbot-SNOM) technique, which are in coincidence with the numerical simulations. This effect should be useful for developing new femtosecond laser techniques and devices.     

Experimental study of the Talbot effect under femtosecond laser illumination

Experimental results of the Talbot effect of an amplitude grating under femtosecond laser illumination are reported. Compared with Talbot image under continuous wave (CW) illumination, Talbot images under femtosecond laser illumination are different due to the wide spectral bandwidth and the Talbot images are more distorted at longer Talbot distances. The spectrums and the pulsewidths of femtosecond laser pulses are measured with the frequency-resolved optical gating (FROG) apparatus. Experimental results are in good agreement with the theoretical analysis.     

Spectral Talbot phenomena in sampled arbitrarily chirped Bragg gratings

We derive the general conditions for which spectral Talbot phenomena, both integer and fractional self-imaging, can be observed in sampled arbitrarily chirped fiber Bragg gratings. These results are a generalization of those previously reported in [C. Wang, J. Azaña, L.R. Chen, Opt. Lett. 29(14) (2004) 1590] in which spectral Talbot phenomena were observed in sampled linearly chirped fiber Bragg gratings. We confirm our theoretical derivations with numerical simulations.     

利用保角变换实现环形光栅的Talbot效应

Talbot效应是一种近场自成像效应,通常只有周期光栅可以产生Talbot效应,而环形光栅无法产生.本文通过引入保角变换,发现可以在环形光栅外部设计适当的折射率渐变层介质,使得其中也能够产生严格的Talbot效应,并计算了对应的自成像半径表达式.本文利用FDTD软件分别将一个环形光栅放置在真空中以及人工设计的折射率渐变层中进行了模拟,并对二者的结果进行了比较分析,发现这种折射率渐变层介质确实对点光源入射的环形光栅的自成像情况有着很好的改善.希望这一工作能够推广Talbot效应的应用范围.     

基于泰伯效应的高斯光束尺寸测量

光栅用在高斯光束参数测量中的突出优点是方法简单，成本较低，全息光栅由于其制备容易，无周期误差而比一般光栅具有更多的优点。在用光栅进行光斑测量的实验中，观察到由全息光栅引起的泰伯（Ｔａｌｂｏｔ）效应携带有关光斑参数的有用信息，本文提出了一种基于泰伯效应的测量方法，只需测定条纹间隔就能确定高斯光束尺寸，因此降低了对光源或光栅定位精度，电路和光源稳定性的要求，文中聚焦高斯光束照明全息光栅时光场分布，及其     

畴腐蚀掺镁铌酸锂可调阵列光分束器的研究

研究了不同畴腐蚀深度的掺镁铌酸锂二维六角可调阵列光分束器的分数Talbot效应.对不同Talbot分数β和不同畴腐蚀深度的阵列光分束器Talbot衍射像进行了数值模拟理论研究.模拟结果表明,Talbot分数β可以改变Talbot衍射像的周期及结构分布,而畴腐蚀深度可有效调制衍射像的光强分布.在理论研究的基础上,设计并制备了具有不同畴腐蚀深度的掺镁铌酸锂二维六角阵列光分束器,对其在不同Talbot分数β条件下的分数Talbot效应进行了通光实验研究,实现了畴腐蚀阵列光分束器对近场Talbot衍射光强分布的调制,实验结果与理论研究结果一致.     

Application of source encoding to incoherent Talbot imaging and the Lau effect

We demonstrate a technique to generate Talbot images by a spatially incoherent source using a source encoding technique. We further show that a Talbot image can be formed in the optical set-up for the Lau effect following source encoding theory.     

超短脉冲激光照射下光栅Talbot效应的实验研究

理论上研究了超短脉冲激光照射下光栅的Talbot效应,得到了超短脉冲激光照射下光栅Talbot图像的性质.实验上采用严格的实验方法(频率分辨光学开关装置测量超短脉冲激光、反射式扩束系统对超短脉冲进行扩束)很好地验证了理论分析结果.理论分析和实验结果表明,超短脉冲激光照射下光栅的Talbot图像的对比度会显著下降,而且超短脉冲激光的脉宽越短,Talbot距离越大,Talbot图像的对比度会进一步下降.     

Efficiency Enhancement of Components Based on Talbot Effect

Two ways to improve efficiency of components based on Talbot effect are considered in the present paper. One way is based on optimization of waveguide wall impedance, another one consists in modification of waveguide cross-section shape. Both methods allow correction of waveguide modes spectrum and lead to efficiency enhancement. For the important application of Talbot effect-remote steering antenna of a wavebeam in plasma-the steering band is expanded by 40–50%.     

泰伯效应的共轭现象

介绍了观察泰伯（Ｔａｌｂｏｔ）像的共轭虚像的实验原理及方法，并给出实验结果及扼要的理论解释，作者首次提出可把泰伯自成像公式的ｍ值扩展的负值。     

云纹技术测量透镜焦距和折射率

本文给出会聚球面波光场下Talbot长度的计算公式和用云纹技术测量透镜焦距和折射率的一种新方法,避免了近两年来提出的方法不足之处。     

Temporal Talbot effect applied to determine dispersion parameters

The space–time duality theory and the temporal selfimaging phenomenon (or Talbot effect) are used to propose a method for determining dispersion parameters associated with an optic fiber link. From the space–time analogy, the actions of free-space propagation and phase curvatures taking place in the general spatial Talbot effect are implemented for time-varying wavefields. Using the temporal selfimaging conditions, a relationship is derived for determining the second-order dispersion coefficient of a given dispersive medium under test. As a particular application, we analyze the feasibility of the measuring approach using a linearly chirped fiber grating as the dispersive component under test. Some simulations are carried out in order to study the sensitivity and accuracy of the developed method.