【作者】 余天一；

【导师】 曹庄琪；

【作者基本信息】 上海交通大学 ， 光学， 2009， 硕士

【摘要】 古斯汉欣位移最早在1947年被提出。其描述的是全反射过程中,反射光会经历一个侧向位移,而从非几何光学指出的反射点出射。自从古斯汉欣效应提出以来,关于其产生原因和相关属性的理论研究不断发展,同时发现了古斯汉欣位移在不同情况下的增强效应。基于以下几个因素,本文提出了基于双面金属包覆波导中古斯汉欣效应的位移传感方法。首先,反射光经历的古斯汉欣位移对于导波层厚度具有很高的灵敏度。其次,双面金属包覆波导中古斯汉欣位移的增强效应非常显著,达到几百微米,如果利用一维位置敏感探测器进行观测,可以获得极高的探测精度。同时,亚毫米尺度的双面金属包覆波导中的超高阶导模对导波层厚度也具有极高的灵敏度,这进一步增强了最终的传感精度。最后,观测古斯汉欣效应与入射光能量波动无关,使得传感器的信号噪声得以降低。本文利用双面金属包覆波导的电磁场模型对于其中的导波模式进行了分析,并利用静态相位法和高斯光束数值模拟方法对双面金属包覆波导中的古斯汉欣位移增强效应进行了理论计算。由此,推导出了增强的古斯汉欣位移对导波层厚度变化的灵敏度,并进行了定量的数值模拟。而后,本文给出了具体的传感器设计和实验方案,在实验中验证了数值模拟的结果。随着双面金属包覆波导中古斯汉欣位移的增强效应被越来越多的应用于光器件的设计当中,进一步认识反射光束在发生古斯汉欣位移时的具体行为十分必要。因此,本文基于以往对双面金属包覆波导中古斯汉欣位移的研究,对反射光斑内的能量分布进行了高斯光束数值模拟。我们发现,当古斯汉欣位移被增强到束腰宽度的尺度,即出现了明显的形变,其表现为反射光斑内的能量分布出现双峰结构。这和以往对于其他多层结构表面的古斯汉欣位移的研究结果是非常相似的。为了直观的认识反射光斑能量分布的演化,我们利用CCD直接观测了波长调谐下反射光斑能量分布的变化,实验结果与理论分析十分吻合。光束形变的研究对于深入认识古斯汉欣位移以及基于此的光器件设计具有建设性。更多还原

【Abstract】 Goos-H?nchen effect was first discovered in 1947. It describes a phenomenon that the reflected beam in total reflection experiences a lateral shift from the incident point. Since it was discovered, the researches regarding the intrinsic reason of GH shift and its property have being reported continuously. Meanwhile, researchers have found the enhancement effect of GH shift under various conditions.We present the displacement sensing using GH shift in the Double Metal Cladding Waveguide (DMCW) based on the following factors: Firstly, the GH shift of reflected beam is sensitive to the thickness change of guiding layer. Then, the enhancement effect of GH shift in DMCW is significant, which research a scale of several hundred microns. If a one dimensional Position Sensitive Detector (PSD) is used to monitoring the GH shift, a very high degree of accuracy can be obtained. At the same time, the ultra-high modes in the sub-millimeter scale DMCW are highly sensitive to the thickness change of guiding layer. Finally, the energy fluctuation of incident light will not affect the proposed sensor since the GH shift is irrelevant to the incident energy. In this thesis, we begin the electromagnetic field model of DMCW to analyze the guided modes. Further, Stationary Phase method and Gauss Beam model are applied in the theoretical calculation to evaluate the enhancement effect of GH shift. The sensitivity of proposed sensor is derived from the previous analysis, and numerical simulation is performed to get the quantitative result. After that, we carry out the experiment based on the parameters in the simulation. The experimental result shows good accordance to the theoretical prediction.As the enhancement effect of GH shift in DMCW is applied to optical device design more frequently, it is necessary to further understand the beam behavior during the GH shift. Therefore, we use the Gauss Beam model to simulate the practical energy distribution inside the reflected beam spot. We find from the simulation that when the GH shift is enhanced to the scale of beam waist width, obvious beam distortion appears, the reflected spot changes into a double-peak shape. This is very similar to previous researches about the GH shift on multilayered structures. In order to observe the evolution of the reflected beam spot, we use CCD to monitor the reflected beam during wavelength tuning. Experimental result turns out to be good verification to our theoretical analysis. The research regarding beam distortion is a contribution to the understanding of GH shift and the related optical device designs.更多还原