晶体的连续双折射双反射及1×N电光开关的应用
文献类型:学位论文
作者 | 任海霞 |
学位类别 | 博士 |
答辩日期 | 2004 |
授予单位 | 中国科学院上海光学精密机械研究所 |
导师 | 刘立人 |
关键词 | 双折射 双反射 1×N电光开关 集成 优化设计 |
其他题名 | Double refraction and reflection of sequential interfaces in a crystal and application to integration of 1*N electro-optic switch |
中文摘要 | 自由空间光交换是目前国际上最主要的发展方向之一,趋向实用化的要求之一就是集成化。近年来在光通信中使用的1火N电光开关,大多是用分立元件级联构成的。由分立元件组成的器件存在着装配成本高、插入损耗大以及易受环境影响等缺点,在实际应用中受到很大程度上的限制。而电光集成器件具有结构紧凑、稳定可靠、并行处理、可级联等优点,是实际应用的一个重要方向。单块集成结构的高速光开关是全光网络通信的关键器件,主要用于光通讯和光计算信号的空间光开关或光交换。虽然对晶体的双折射效应已有大量的研究,但都只关注于单个界面上的双折射双反射,没有适用于多个界面的连续双折射双反射的情况。本论文对晶体的连续双折射双反射进行了研究,并在基础上提出了单晶集成的1xN电光开关,主要包括:(1)孑开究了光轴在入射面内的单轴晶体的连续双折射双反射。在惠更斯定理的基础上,对从空气到扉:体的折射、从晶体到空气的折射、近光轴入射的晶体全内反射和近光轴反射的晶体全内反射这四种单个界面上的双折射双反射情况,给出了同时适用于。o光和e光的光线方向和光波法线方向的普遍公式。在此基础上,分析了前一界面输出量和后一界面输入量之间的联系,可以计算两个界面上的连续双折射双反射。多个界面上的连续双折射双反射可以看成是两个界面上的连续双折射双反射的级联,因此能够计算光在晶体内多次折射或反射后最终的光线方向和光波法线方向。给出了适用于任何级联形式的数学解,使得我们能够更好地了解包含晶体元件的光学系统的特性及最大极限,为晶体元件的设计及光学系统的集成提供了有力的工具。(2)为了使光学系统更加紧凑化和稳定化,提出了一种单晶集成的1×N电光开关:它有2个折射面,4个互相垂直的全内反射面,和N-1个电光调制器。该利l结构使入射的o光依次通过这N-1个电光调制器。给一个电光调制器上加半波电压,就对应着一个输出角位置。我们还得到了该种1×N电光开关的构成条件:发生两相邻反射的反射i丽必须互相垂直。并对I晃.体的结构进行了优化,通过调榷光束输出而与光4=lll的夹角来改变光束出射角,使得接收端易于接收输出的光信号。选择适当的屏.体尺寸以避免光从品体中逸出。分析了有限面积电极板的边缘电场强度,可以得到当电极对的长度为5mm、宽度为2mm、板间距离为2mm时,离开电极板边缘3mm处的电场强度就已经降到了电极板中心处的5%左右,可忽略不计此时的电场弧度对其他光通道的影响了。本论文提出的单晶集成1×N电光开关具有结构简单紧凑,插入损耗小,抗干扰能力强的优点。(3)研究了光轴方向任意的单轴晶体的连续双折射双反射。根据惠更斯定理和边界连续条件,分析了单个界而_上的双折射与全内双反射,给出了光线方向和光波法线方向f内普遍公式。该公式适用于任意入射方向和任意光轴方向的情况,简单且易于计算机编程计算。并讨论了光在晶体内沿多个界面的连续双折射双反身。在此菇础土,适当地选取l显:体的界而参数,相当于选取光轴方向,可以使晶体器件某些参数的选择范围更大。在斜入射2×2电光开关中改变出射面的光轴方向,可以使o光和e光的分离角△oe。更大。光轴方向任意的晶体连续双折射双反射对晶体器件的最优化设计非常有帮助。 |
英文摘要 | Optical cross-connects in free-space is one of the current topics in the world and its integration is one of the keys for practical applications. In the recent years, most of electro-optical switches are assembled from discrete elements, which are difficult to fabrication, have high insert loss, and are sensitive to environment. The integration of elements has the advantages of compactness, stability, cascaded connection and parallel processing. It is thus apparent that the integration of elements is important for practical applications. The electro-optical switch in a single-block crystal is the key element of all-optical cross-connects, and is mainly used for switching or exchanging optical signals in optical communication and optical computing. Various methods have been developed to evaluate such double refraction and reflection effects at a single crystal surface in uniaxial crystals. However, double refraction and reflection along the sequential interfaces in a crystal have rarely been discussed, The aim of this paper is to reach a mathematical solution to double refraction and internal double reflection in a uniaxial crystal along the sequential interfaces, and on this basis to develop a technique to assemble an E-0 device of modulators and slabs in a single block of crystal. The details are listed in the following: Double refraction and reflection of sequential interfaces in a crystal when the optic axis contained in the incident plane are discussed. First, based on Huygens' principle, formulas for double refraction and internal double reflection with different directions of propagation vector and wave vector are given. For such a single refraction or reflection interface, we highlight four cases: refraction from air to crystal, refraction from crystal to air, reflection in the crystal from a direction near the optic axis, and reflection in the crystal to a direction near the optic axis. Then with the relations between the output of interface 1 and the input of interface 2, double refraction and/or double internal reflection in a crystal along two successive interfaces can be calculated. Double refraction and/or double internal reflection in a crystal along multiple successive interfaces can be seen as a cascade of that along two successive interfaces, and thus may also be calculated. The information obtained with these formulas in this paper should lead to a better understanding of the performance and the ultimate limits of optical systems that contain birefringent crystal elements and provide a valuable means of designing crystal devices and integrating optical systems. For enhanced compactness and stability, a new 1xN electro-optic switch is presented, which is a single crystal slab of 2 refractive interfaces for beam input and output, 4 reflective interfaces for total-internal reflection, and N-1 E-0 modulators with pairs of electrodes. Each of the 4 reflective interfaces is perpendicular to the next, which makes it possible for the input ordinary beam pass through the N-1 E-0 modulators. A voltage on the n pair of electrodes will induce output beam onto the n angular position. Then the requirement for this new type of lxN switch is found that the interface for k + 1th reflection must be perpendicular to the interface for kth reflection. And we can make a simple modification by choosing the angle between the normal of output face and the optic axis appropriately to obtain a good arrangement with output positions for receiving output signals. Additionally, selection of crystal size is discussed to avoid the input signal walking off. The electric field distribution is analyzed for finite-size planar electrodes in this lxN switch. For calculation, the electric field at the point 3mm from the edge of the electrodes decreased to about 5% compare with the center point when the electrode width is 2mm, the length is 5mm and the distance between the electrodes is 2mm. Therefore, it can be concluded that the edge of electric Held can't affect the other optical signal. The suggested lxN switch is simple and compact in construction, low in loss and insensitive to environment. (3) Double refraction and reflection of sequential crystal interfaces with arbitrary orientation of the optic axis are discussed. The general formulation of double refraction or internal double reflection at a single interface is analyzed in terms of Huygens' principle and surface boundary conditions, The formulas for any direction of incidence and arbitrary orientation of the optic axis are simple and directly amenable for computer programming. Then double refraction and double reflection along the sequential interfaces in a crystal are discussed. On this basis, if the parameters of the interface are chosen appropriately, the range of some interests may be larger. In the 2x2 electro-optic switch with oblique incidence, the angular separation △oe between the ordinary ray and extraordinary ray can be much greater if the output end interface are properly designed. The formulas we obtain allow us to draw the optimum design of crystal elements. |
语种 | 中文 |
源URL | [http://ir.siom.ac.cn/handle/181231/15432] ![]() |
专题 | 上海光学精密机械研究所_学位论文 |
推荐引用方式 GB/T 7714 | 任海霞. 晶体的连续双折射双反射及1×N电光开关的应用[D]. 中国科学院上海光学精密机械研究所. 2004. |
入库方式: OAI收割
来源:上海光学精密机械研究所
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