Research On Active Waveguide With Inverted Ridge Structure

The rapid development of communication technology and widely used of Dense Wavelength Division Multiplexing (DWDM) technology cause that fiber is not only widely used in backbone network, but also extend to the Metro Access Network (MAN) and the access network and gradually go deepening into the Fiber To The Home (FTTH). In the optical domain, optical switch can achieve many functions directly, such as self-healing protection of optical network and routing capabilities. It can overcome the limitation of photoelectric conversion in the communication network. And it also can reflect the characteristics of the large-capacity optical networks, the high-speed transmission and switching.Optical switch with waveguide structure has many advantages, such as short switching time, small size, and easy-to-integrate. Thus, it is an important direction. At present, optical switching technology is moving toward a practical stage abroad. Although there are still large gaps between inland and foreigner's research, we have achieved some important breakthrough after so many years of efforts.A good deal of research has been made in the laboratory for the optical switch too, for example, a type of the organic-inorganic hybrid materials used in our experiment has good stability and good electric-optical properties, but the inorganic material is difficult to etch in the oxygen reactive ion etching (RIE) process. It can't make up the waveguide device by the technological process of the ridge-waveguide or rectangular-waveguide. At the same time, because of its inherent nature of the material, the film thickness is limited by sol-gel method. These problems are too serious to achieved waveguide structure. Thus, this will have to need to introduce a new type waveguide with inverted ridge waveguide structure.In order to verify the feasibility of implementing device with inverted ridge waveguide structure, several commonly used optical waveguide numerical analysis method is used to simulate and analyze this structure and the optical switch structure with the inverted ridge in this thesis.The effective refractive index law is used to get a detailed analysis of its effective refractive index and the size and pattern of the relationship. At the same time, the structure of the inverted ridge waveguide dimensions has been optimized as follows: a = 6μm, b = 1.6μm, h = 0.6μmThe succeeding simulation analysis is based on the dimensions of the waveguide above. Two-dimensional waveguide can be equivalent to the plate waveguide structure through the effective refractive index law's equivalent; the approximate equivalent of combining with the BPM method can effectively reduce the amount of computation. However, the equivalent of the plate waveguide is not able to describe accurately the optical field distribution of its cut-view. On the other hand, the inverted ridge waveguide structure will be equivalent to a rectangular waveguide structure by using the approximate equivalent refractive index law. Although this can get the optical field distribution of its cut-view, the description of the field is not so accurate obviously after the equivalence to the rectangular waveguide.Then, the two-dimensional finite element method is used to analysis the inverted ridge waveguide. The functional expression being fit to the finite element method in the waveguide optical field is deducted by using of mathematical physics methods. F is the functional expression's matrix of the Helmholtz equation;Φis the shape function of finite element triangle unit; K is the matrix of coefficients of the linear system of equations made up byBased the gain of the functional expression, we can achieve the finite element analysis on inverted ridge waveguide structure through computer programming. The program is the same with calculating the formula waveguide structure. Finally, we have got the optical field distribution of the inverted ridge waveguide structure. From the inverted ridge waveguide's optical field distribution, we can see that the strong position lies in the inverted ridge position near the plate. In this way, in the actual preparation of the waveguide, we should try to ensure compliance with inverted ridge of the morphology, namely: to maintain the basic formation of the inverted ridge waveguide structure on the surface.In the programming process, I completed several commonly used method programming in C# - including: Jet color of the algorithm, variable step Simpson of double integral, the whole Consumers PCA Gaussian method of linear equations, the solution for the general determinant. These are widely used in other process of numerical analysis.Finally, the inverted ridge waveguide structure is analyzed in the optical field of two kinds of optical switches (M-Z and orient coupling type) by using the BPM software and the field-intensity map of their optical transmission. It is proven perfectly in this thesis that it is feasibility to achieve waveguide device with the inverted ridge waveguide structure.