基于相位采样光栅的双波长光纤激光器

提出一种基于相位采样的分布反馈式双波长光纤激光器,在不同的空间化置同时引入相位和采样周期的突变.通过理论分析,这种结构能够实现谐振腔的分离,使不同波长的光波利用不同空间位置的增益介质,克服增益介质均匀加宽引起的模式竞争,实现双波长激射.采用准分子激光器和均匀相位模板,在掺铒光纤上制作波长差为0.46 nm的舣波长光纤激光器,能够实现舣波长激射.通过实验,对激光器输出功率和光栅强度的关系进行研究,表明输出功率和光栅强度成反比.     

双波长光纤光栅的矩阵分析

本文在分析双波长光栅特征的基础上,结合耦合模理论和矩阵分析方法,提出了分析双波长光栅的一种数学模型,并在此基础上,采用矩阵分析方法对双波光栅进行了理论分析,得到的结果与实验结果基本吻合。     

对衍射光栅测波长的分析

一、问题的提出目前,各大专院校多开设了光栅衍射的实验。而且,一般都在分光计上进行。此实验既可对光栅常数进行测量,也可测量光源的波长。就测量光源的波长而言,有多种方法.常用的方法是令入射角ψ=O,此时光栅方程变为dsinθ=mλ的简单形式,只需测量一个角度——衍射角θ即可求出波长λ。所以此方法具有原理、调节和测量都简单的     

双波长非水溶性光致聚合物全息光栅的研究

介绍了一种对488 nm蓝光和632.8 nm红光均敏感的双色非水溶性光致聚合物制成的二重全息光栅.理论分析得出此光栅的分辨率＞5 000 line/mm,温度变化时中心波长的漂移几乎为零.实验仪器测得光栅的衍射效率最高达到90%以上,而且该光栅具有成本低和一次成型的优点,适合制作波分复用器.与单波长的二重光栅相比,它解决了由于光的相干性出现的串扰问题,串扰更小,所以在制作光栅时两束光不但可以选择角度入射也可以选择平行入射,同时具有良好的波长选择性和角度选择性.     

紫外双光栅光谱仪结构设计与波长精度分析

为了满足太阳光谱在170～380 nm波段的精确观测需求,设计了波长重复性精度优于±0.02 nm的紫外双光栅光谱仪。波长扫描机构是双光栅光谱仪的关键组件,根据凹面光栅色散原理,将光学设计指标转换为波长扫描机构设计的输入参数,分析了影响光谱仪波长重复性精度的误差源。根据分析结果得知,丝杠的重复定位误差是影响波长重复性的主要误差源。选用重复定位精度为±2μm的丝杠设计了波长扫描机构,并对光谱仪整机进行了设计。以汞灯光源对光谱仪的波长重复性指标进行了验证实验。实验结果表明,设计的光谱仪波长重复性介于-0.005～+0.007 nm之间,满足波长重复性优于±0.02 nm的指标要求。     

X射线光栅相位成像的理论和方法

通过对X射线光栅相位衬度成像实验装置的理论分析,提出了光栅位移曲线的表达式,推导出了X射线光栅相位衬度成像方程.根据该成像方程,提出了基于光栅成像相位提取方法.这些理论结果将简化光栅相位衬度成像实验步骤,提高信息获取效率,并为X射线光栅相位衬度成像和计算机断层成像的结合,进一步提出光栅相位衬度CT的简化理论奠定基础.关键词：X射线相位衬度成像光栅衍射Talbot效应     

用于ICF驱动器谐波分离的亚波长光栅优化设计

针对惯性约束聚变(ICF)驱动器对谐波分离的苛刻要求,利用基于矢量衍射理论开发的商用软件Gsolver,在布拉格(Bragg)入射角下,设计满足分光要求的光栅参数,并根据对影响谐波分离性能的亚波长光栅的各个参数进行了分析,研究了实现谐波分离的亚波长光栅的优化设计方法,并设计得到了满足谐波分离要求的亚波长光栅。研究结果为亚波长光栅用于谐波分离提供了理论支持。     

用于谐波分离的三角形槽亚波长光栅设计

根据亚波长光栅的导模共振异常特性,提出三角形槽亚波长光栅实现惯性约束聚变驱动器谐波分离的技术方案.定义了用于描述谐波分离性能优劣的谐波分离品质函数,对影响三角形槽亚波长光栅的谐波分离品质函数的光栅参量进行了详细的分析,基于矢量衍射理论设计了能够实现谐波分离的三角形槽亚波长光栅,确定了用于谐波分离的三角形槽亚波长光栅的设计思路和方法.     

用于谐波分离的三角形槽亚波长光栅设计

根据亚波长光栅的导模共振异常特性,提出三角形槽亚波长光栅实现惯性约束聚变驱动器谐波分离的技术方案.定义了用于描述谐波分离性能优劣的谐波分离品质函数,对影响三角形槽亚波长光栅的谐波分离品质函数的光栅参量进行了详细的分析,基于矢量衍射理论设计了能够实现谐波分离的三角形槽亚波长光栅,确定了用于谐波分离的三角形槽亚波长光栅的设计思路和方法.     

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 encoder based on Fractional-Talbot effect using two-dimensional phase grating

This work presents an optical encoder that uses a two-dimensional phase grating. Rather than using a four-windowed scanning grating, this design with a special two-dimensional phase index grating generates two sinusoidal signals that are mutually phase-shifted by 180°. Afterwards, two large-areas, specially structured index grating generates the four 90° electrically phase-shifted scanning signals. The special design of the two-dimensional phase index grating provides more accuracy of phase-shift by using the fact that the  + 1 and −1 diffraction orders are intrinsically phase-shifted from one another by 180°. The gap between the phase index grating and mail scale was increased to three quarters of Talbot distance. The tolerance of gap between the index and main grating is 0.1 mm. The tolerance of yaw motion is ± 0.25°.     

利用光栅测量任意入射角方式下的光波波长

以光栅衍射方程为理论依据,讨论了在任意入射角方式下,如何利用光栅和分光计对光波波长进行测量并同时能得到未知入射角的值。给出了理论推导和实验结果。结果表明：该方法的所得到的光波波长的相对误差为0．21％。     

Aberrations in fractional-Talbot images of periodic binary gratings

We discuss the ray-optical aberrations which appear in the fractional-Talbot image of a periodic binary grating with coherent illumination. First we examine the complex amplitude of an aberration-free imaging field at a fractional-Talbot plane. We then trace the path of a diffracted ray of specific order which contributes to the fractional-Talbot imaging. Next we formulate the focus-shift and third-order aberrations which arise from a focusing error and a fourth-order approximation of the path length, respectively. We then evaluate the amplitude and phase of an aberrated imaging field that are represented in terms of aberration functions. When the grating period decreases to approach the optical wavelength, the aberrations of lower-order rays are shown to be more influential on the fractional-Talbot imaging field than those of higher-order rays. The theory of aberration discussed here could be very useful in evaluating the fractional-Talbot image of a periodic binary grating.     

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.     

Talbot experiment re-examined: demonstration of an achromatic and continuous self-imaging regime

In the original Talbot experiment, a grating made of thin slits was illuminated in polychromatic light. Reconstituting this simple experiment, we have observed that at a certain distance from the grating, achromatic lines are formed whose transverse-resolution remains unaffected over a wide propagation-distance range. To our knowledge, this phenomenon has never been reported before. A theoretical explanation of this achromatic and continuous self-imaging regime is given and experimental results are reported.     

Analysis on diffraction properties of the transmission phase grating

Diffraction properties of the transmission phase grating are analyzed in terms of the Fourier optics theory. The analysis results show that the diffraction intensity distribution of the transmission phase grating is closely related to the optical thickness of the grating and the wavelength of the incident light, and not only determined by the grating's period and slit width. For monochromatic incident light, more than 80% of the diffraction energy will concentrate to the first diffraction order under certain conditions. For white incident light, the energy of the first order of diffraction spectrum may be much higher than other orders. Based on these results, some possible applications of the transmission phase grating are discussed.     

光栅移动法检校光束准直性的探讨

本文探讨了一种检校光束准直性的新方法。它只需移动光栅,观察叠栅条纹是否变化。该法装置简单,操作方便。     

莫尔偏折术中栅距差的影响研究

分析了莫尔偏折术中光栅付栅距差对测量精度的影响,提出了用减小栅距差来提高精度的结构措施。