Synthesis and Properties of Vanadium Dioxide Thin Films for use as Optical Switches

互联网主要运行在光纤通信网络上，只有光纤才能满足人们对互联网的需求。 增加了对带宽的需求。在光纤电缆的每一端都有各种设备， 操纵光束，包括光束多路复用器和其它操纵、切换和选择装置。 有各种各样的技术用于设计这些装置，例如MEMS、液晶、声光， 等最好的技术之一是利用其光学特性会随另一种材料而变化的材料。 电信号或光信号。例如，具有可变折射率的材料可用于光学系统中。 干涉仪从相长干涉变为相消干涉，从而实现光开关。或者在一种 光束选择器可以由反射率随电场变化的材料制成。材料的 与其它技术相比，这些装置是坚固的、快速作用的、小的并且制造相对简单。的 这个项目的整个想法是拥有新技术的光开关，它将由一个电子控制器控制。 输入.这些光开关将基于新技术（所描述的相变技术 下文）并且将增强光网络中的光交换的效率。过渡金属氧化物 (MO)在本项目中特别感兴趣的材料系统是钒的氧化物。氧化钒 存在于许多化学计量中。二氧化物VO 2具有从单斜晶到 在340 K下，四斜相是绝缘的，并且四斜相是金属的。 在VO 2中的金属-绝缘体转变也可以通过外加电场诱导。因此，VO 2是一个质数， 用于电子控制光开关的候选物。本研究将分为三个部分： 二氧化钒薄膜，表征，原型器件的开发和测试。准备工作将由 真空沉积-在氧气存在下从钒靶溅射。沉积VO 2薄膜 通过溅射和它们的光学性质将被检查与没有电场，以探索 这些器件中的场感应光开关。

The internet primarily runs on optical fibre communication networks; only optical fibers can satisfy the ever increasing demands for bandwidth. At each end of the fibre optic cable are a variety of devices for manipulating the light beam including beam multiplexers and other steering, switching, and selecting devices. There are a variety of technologies for designing these devices such as MEMS, liquid crystals, acousto-optics, etc. One of the best technologies utilizes materials whose optical properties change in response to another electrical or optical signal. For example, a material with a variable index of refraction can be used in an interferometer to change from constructive to destructive interference thereby effecting an optical switch. Or, a beam selector can be made from a material whose reflectivity changes with electric field. Materials based devices are robust, fast-acting, small, and relatively simple to manufacture compared to other technologies. The whole idea in this project is to have new-technology optical switches that will be controlled by an electrical input. These optical switches would be based on a new technology (phase transition technology described below) and would be enhancing the efficiency of optical switching in optical networks. Transition metal oxide (MO) material system that is of particular interest in this project is the oxides of vanadium. Vanadium oxide exists in a number of stoichiometries. The dioxide VO2 has a crystalline phase transition from monoclinic to tetragonal at 340K; the (low-temperature) monoclinic phase is insulating and the tetragonal phase is metallic. The metal-insulator transition in VO2 can also be induced by an applied electric field. Thus VO2 is a prime candidate for use in an electronically controlled optical switch. The research will have three parts: preparation of VO2 thin films, characterization, and prototype device development and testing. The preparation will be by vacuum deposition - sputtering from a vanadium target in the presence of oxygen gas. VO2 films be deposited by sputtering and their optical properties will be examined with and without an electric field to explore the field induced optical switching in these devices.