无曲率奇点的光波导短程透镜的设计

在Ｓｏｔｔｉｎｉ等人提出的求解非球面光波导短程透镜一般解析方法的基础上，研究了卷边函数对透镜旋转母线曲率的影响。指出具有连续二阶导数的母线，可有效地消除曲率奇点，从而在理论上能够减小由于波导弯曲造成的导光损耗。基于这种观点，提出了一种新的卷边函数，求得了透镜轮廓的表达式，进而求得了透镜深度，并与Ｓｏｔｔｉｎｉ等人的解进行了比较。     

优化的波导短程透镜研究

对光波导短程透镜进行优化。在无曲率奇点理想波导短程透镜的基础上，选取一般形式卷边函数，以无弯曲损耗为目标，讨论了透镜过渡区不同卷边函数形式的曲率分布，选取了最优卷边函数并给出透镜母线的特解。经过数值计算得到了优化的理想波导短程透镜的母线函数数值，完成了非球面面型的精细加工，研制出优化的理想波导短程透镜。实验测试结果表明，短程透镜在通光孔径8mm内消球差，对4mm宽的平面波束，焦距20mm的短程透镜，其焦点束斑宽度小于4μm。     

无球差非球面短程透镜的研究

用光线追迹迭代法和解析法设计无球差非球面波导短程透镜的母线,用单点金刚石超精加工和凹面波导制备工艺,研制成孔径和有效孔径分别为8和6mm的LiNbO3导短程透镜.实验表明,器件在有效孔径内无球差;对4mm宽的输入平面波光束,焦点衍射光斑半宽度为4μm;透镜插入损耗为～1dB.     

短程透镜问题的最优解

本文给出了带卷边短程透镜问题的一个最优解,透镜子午线光滑无奇点,在透镜边缘处卷边的曲率半径趋于无穷大,具有使该点弯曲损耗达到极小的最优卷边形状.最优解优于已有的短程透镜其他解析形式解,完善了设计短程透镜的解析法.     

光在有缺陷存在的斐波那契准晶中的透射特性

利用传输矩阵方法,模拟研究了FC(N)准晶链排列的多层介质膜中存在不同缺陷情形时,光在其中传播的透射规律.结果表明,当Fibonacci准晶中存在缺陷时,引入了缺陷模,而且其缺陷模具有与自身结构相关的特点.还进一步模拟研究了存在负折射率吸收缺陷媒质时的FC(N)准晶链的透射系数,出现了共振透射率大于1的情形.同时还研究了负折射率缺陷媒质的虚部对禁带中共振透射峰大小的影响,发现并不是所有引入负折射率吸收缺陷媒质的准晶都会出现共振透射率大于1的现象.     

新面型短程透镜的制备研究

根据解析理论新的精确公式进行设计并用单点金刚石超精切削加工制备,研制出一种优化的非球凹面短程透镜.透镜含光滑无奇点圆边,与平面连接的边缘曲率半径为无限大.样品制备在45×20×2.5mm3的LiNbO3衬底上,每片有两个孔径8mm、焦距8mm的无球差非球面短程透镜,利用670nm波长的半导体激光器端面耦合入样品一端,在另一端测得焦点光斑半宽度为2.9μm.     

Universal evolution of perfect lenses

This Letter is a theoretical attempt to answer two questions. First how long does it takes for perfect lensing to be observed, and second how does loss diminish the performance of a general perfect lens. The method described in this Letter is universal, in the sense that it can be applied to perfect lenses of any arbitrary geometry. We shall show that the dynamics of perfect lensing is equivalent to the dynamics of 2 coupled simple harmonic oscillators. Moreover we shall derive quantitatively, the effects of losses on a compact perfect lens.     

The cosmological constant and the gravitational light bending

The solution of the null non-radial geodesic in a Schwarzschild-de Sitter background is revisited. The gravitational bending of a light ray is affected by the cosmological constant, in agreement with the findings of some previous investigations. The present study confirms that the leading correction term depends directly not only on Λ but also on the impact parameter and on the angular distance to the source. Using the resulting lens equation, the projected mass of the lens was estimated for several systems displaying Einstein rings. Corrections on the masses due to Λ are, on the average, of the order of 2%, indicating that they are not completly negligible for lens systems at cosmological distances.     

基于全场干涉测量方法的透镜三维轮廓测量

为了满足高精度透镜加工工艺的要求,设计了一套基于全场干涉测量方法的透镜三维轮廓测量系统。已标定的透镜三维轮廓测量系统利用分布式反馈激光二极管对透镜进行波数扫描,对CCD相机采集到的干涉图像依次进行随机采样傅里叶变换和解卷绕算法,最终通过计算得出透镜的三维轮廓数据。实验结果表明:该系统横向和纵向的分辨率均为0.011 3 mm/pixels,深度方向的测量均方根误差为±19.8 nm。系统结构简单、稳定性高,对透镜没有任何接触,不会对透镜表面造成损伤,适用于透镜的高精度轮廓测量。     

四种解析解设计的短程透镜卷边对损耗的影响

根据光波导短程透镜母线曲率半径与光传输损耗的关系,利用数值计算的方法,通过计算不同母线参数条件下,四种解析解设计的短程透镜母线曲率半径,研究比较了短程透镜卷边对其损耗的影响,得出了短程透镜损耗与其有效区半径关系的曲线图,发现透镜凹面半径一定时,有效区半径越小,即卷边越大时,光传输损耗越小;短程透镜的解析改进解和最优解设计的透镜卷边存在曲率奇点.并由此得出了四种解析解设计的短程透镜有效区半径选取原则及其满足低损耗条件的取值范围.     

Hyperboloid cylinder-plane lens for shaping laser diode array beam

A high coupling efficiency, simple structure refractive lens was designed; a hyperboloid cylinder-plane lens was proposed to reduce the divergence angle of the laser diode array beam in the fast axis direction. Based on the ray-tracing method, the shape of the input refractive surface of the designed lens is determined by numerical analysis, and designed as aspherical profile in one direction. When the beam from source point reaches the input surface of the lens, it is refracted and becomes a parallel output beam in the fast axis direction. The expressions for describing the irradiance behind the lens are also derived.     

波导短程透镜的实验研究

波导透镜是集成光路〔IO〕中的最基本元件,它在IO中的作用类似体光学光路中的透镜.IO光信号处理系统如集成光学声光频谱分析器、导波声光卷积器、相关器、调频脉冲压缩器和矩阵乘法器等.系统中都需要用波导透镜.波导短程透镜较其它形式的波导透镜具有孔径大、旋转对称、无色差和插入损耗小的特点,所以特别引人注意.     

Instability of the Randall-Sundrum Model and Exact Bulk Solutions

Five dimensional geodesic equation is used to study the gravitational force acted on a test particle in the bulk of the Randall-Sundrum two-brane model. This force could be interpreted as the gravitational attraction from matters on the two branes and may cause the model to be unstable. By analogy with star models in astrophysics, a fluid RS model is proposed in which the bulk is filled with a fluid and this fluid has an anisotropic pressure to balance the gravity from the two branes. Thus a class of exact bulk solutions is obtained which shows that any 4D Einstein solution with a perfect fluid source can be embedded in y = constant hypersurfaces in the bulk to form an equilibrium state of the brane model. By requiring a 4D effective curvature to have a minimum, the compactification size of the extra dimension is discussed.     

The development of a portable line-shaping optical system for silicon surface treatment

This study proposes a beam shaper for converting a circle beam profile generated with a Gaussian intensity distribution by an 808 nm diode laser into a line beam profile for silicon surface treatment applications. To produce a hand-held and low-cost device with a large spot-size laser, this study uses a portable optical system consisting of a diode laser source, a collimator, a cylindrical lens, and a plano-convex lens to generate an approximately 40 × 3:5mm² line beam profile at a working distance of 200 mm. The silicon surface treated by the line-shaped laser beam has significantly reduced reflectance spectra. The proposed system is also suitable for the surface cleaning of materials.     

光刻物镜中透镜高精度支撑结构的设计及分析

光刻投影物镜中透镜的面形精度是影响光学系统成像质量的关键因素之一。为实现透镜面形精度均方根(RMS)值优于2nm的高精度指标,提出一种轴向多点挠性支撑、径向三点可调式定位的光学透镜支撑结构。基于自重变形对支撑结构进行优化设计,深入分析在此支撑结构下自重和热载荷对透镜面形影响。结果表明,重力引起的透镜上表面面形RMS值为0.186nm,下表面面形RMS值为0.15nm。热载荷引起的上表面面形RMS值为0.55nm,下表面面形RMS值为0.54nm。采用这种透镜的支撑结构,能够满足光刻投影物镜中透镜的高精度面形要求。     

A method to overcome the limitations of G.O. in axis-symmetric dielectric lens shaping

The design of a cylindrically symmetric dielectric lens antenna is presented for the case of a very squeezed fan-beam. One makes use of geometrical optics (G.O.) to establish the profile of the lens in a first step. A half-integrated solution of Green's formula for bodies with cylindrical symmetry and circularly polarized surface fields is then derived to calculate the radiation pattern. Since the use of G.O. is restricted to some conditions which were observed unsatisfied in our study, a two-steps procedure to reach an acceptable lens shape is then presented. The first step is based on weighting the source beam of the antenna; and the second one is based on simple geometrical interpolation. Prototypes provided experimental results that are consistent with the predicted radiation characteristics and interesting features of such antennas are pointed out.     

像散椭球高斯光束的理论分析与实验模拟

从理论上讨论了具有简单像散特必的椭 图 束的处理方法,在实验中利用两个正交的柱透镜模拟球面双轴透镜对半导体激光器的输出光束进行变换,得较为理想的结果,即把椭圆高斯光束自理为近似圆高斯光束。     

波导短程透镜的优化理论设计研究

本文给出了非球面短程透镜的优化理论设计。卷边与平面波导连接处的曲率半径为无限大,卷边与实际透镜连接处的曲率半径为较大的有限值。完善了短程透镜的一般解析法。     

Morse lens [Invited]

In this Letter, we find that Morse potential(proposed about 90 years ago) could be connected to Coulomb potential(or Newton potential) and harmonic potential(or Hooke potential) by conformal mappings. We thereby design a new conformal lens from Morse potential, Eaton lens, and Luneburg lens and propose a series of generalized Eaton/Luneburg lenses. We find that this Morse lens is a perfect self-focusing asymmetric lens that differs from a Mikaelian lens. Our theory provides a new insight to Morse potential and other traditional potentials, and revisits their classical applications on designing lenses.