光波导中反射光强及其Goos-Hanchen位移的双稳态特性和应用研究

Optical bistability, which stems from the combined effect of the optical nonlinearity and the feedback mechanism, is a cornerstone of the all-optical exchange devices, such as optical switch and optical logic, and is a key technology for realizing the ultra-high speed all-optical information processing. In spite of considerable progress, there is no report about the experimental investigation of ultra-low threshold optical bistability based on the optical waveguide. Recently, it was demonstrated that the double metal-cladding optical waveguide is extremely sensitive to optical parameters (e.g. refractive index) of the guiding layer and can achieve a 1.5mm giant Goos-H?nchen (GH) shift. These properties have already been used to develop the biochemical sensors with high sensitivity. Moreover, our recent experiments revealed that the incident light intensity can be enlarged as much as two orders in the double metal-cladding optical waveguide. Based on the high sensitivity, light enhancement effect and the giant GH shift, we conjecture that a mutational double metal-cladding optical waveguide whose guiding layer is nonlinear material can be utilized to obtain the reflection intensity and GH shift optical bistability within an ultra-low energy threshold. Our project may provide an effective method to integrate the light transmission and optical exchange. The aims of the project are listed below:.1).Using the analytical transfer matrix method, we will derive an exact formula for the optical bistability..2).Based on the nonlinear double metal-cladding optical waveguide, we will experimentally explore the all-optical and electro-optical characteristics of the reflection intensity and the GH shift bistability. .3).We will experimentally investigate the magnetic-optical bistability characteristics in the double metal-cladding optical waveguide whose guiding layer is the magnetic fluid.

由光学非线性和反馈机制共同作用产生的光学双稳态可用于制作光开关、光逻辑等全光交换器件，是实现超高速全光信息处理的核心技术，受到了国内外广泛关注。但是尚无基于光波导达到超低阈值光学双稳态的实验报道。近年来，双面金属包覆光波导已被证实对导波层的光学参量（如折射率）极其灵敏，适用于生化传感器的研发；且被验证能得到1.5毫米的超大Goos-H?nchen位移。在前期研究中，我们发现此类光波导对入射光强具有极大的增强效应（两个数量级）。考虑到高灵敏特性、光增强效应及超大GH位移，我们推测非线性材料为导波层的双面金属包覆光波导可实现超低阈值的反射光强及GH位移光学双稳态，这可能是集光传输与光交换为一体的一种新方法。本项目拟：.1）运用分析转移矩阵推导光学双稳态的解析公式.2）研究非线性双面金属包覆光波导的反射光强及GH位移的全光、电光双稳态特性.3）研究磁流体为导波层的双面金属包覆光波导的磁光双稳态

光学双稳态是由光学非线性和反馈机制共同作用产生的一种以输入—输出曲线具有双稳滞后回线为特征的非线性光学现象。目前的研究目标之一是如何进一步降低阈值功率。在本研究课题中，我们利用双面金属包覆光波导的高灵敏度（即精细度高）、光增强效应和超大GH位移等特性，将非线性kerr介质、压电材料引入双面金属包覆光波导内作为导波层，实现了低阈值的全光、电光控制的反射光强和GH位移的光学双稳态。实验研究了入射角、导波层厚度等因素对双稳态阈值和双稳区域的影响。除实现项目的预期目标外，还取得了如下成果：. 1) 我们利用FDTD软件模拟了微米尺度双面金属包覆波导的场强分布和GH位移影响因素。发现：场强在导波层中得到了极大的增强；当导模被激发时，GH位移也能得到极大的增强。. 2) 我们将纳米磁流体注入双面金属包覆波导中，实现了自组装的可调谐一维磁流体的周期性链状结构，发现信号光的反射光强和GH 位移均可被泵浦光全光调控，且其响应时间为秒量级。利用光捕获效应，我们提出了一种形成环状光栅的简易方案。. 3) 利用双面金属包覆波导反射光强、GH 位移及最小反射率对光学参量极其灵敏的特性， 开展了多种物理量的传感研究。 如：手性液体传感中，柠檬油精和香芹酮的最小可测对映体过量值分别为1.2 %和2.1%；气体浓度传感中，对苯和甲苯的传感极限分别是9.5 ppm和28.5 ppm、环境湿度传感中，实现了0.12%相对湿度变化的测量、环境温度传感中，灵敏度约为5e-3 oC、草甘磷溶液浓度传感中，测量极限为4.2 nM/L。. 4) 项目实施期间，项目成员出版学术专著2部，在Scientific Reports, Applied Physics Letters, Optics Letters, Optics Express等SCI期刊发表论文12篇，申请发明专利1项，参加国际会议1次，国内会议3次，培养研究生8名。