Metal-clad Symmetrical Plane Uniaxial Crystal Waveguide Mode Field

In recent ten years, the great progress has been made in the application of the planar crystal waveguide polarizers in integrated optics, Various suggestions have been made for the structures of such polarizers. Among those different methods, the metal-clad planar crystal waveguide polarizer is the most interesting. As a result, it results in the requirement for studying the propagation properties of the electromagnetic field in the metal-clad planar anisotropic media waveguide. But it was common that discussion was limited to the most non-symmetric metal-clad waveguide that one of two interfaces of the planar anisotropic medium waveguide is metal-cladding. Because of its complexity, no analytic solution can be got. To better understand the propagation characteristics of the waveguide, it is necessary that analytic solution should be got for simpler structure.Based on the background, in this paper, we discuss the propagation characteristic of ray in the planar symmetric metal-clad uniaxial waveguide (The waveguide layer is uniaxial crystal. Two interfaces of waveguide are metal) by using metal-clad waveguide and uniaxial's character and linking Maxwell's equations and the boundary conditions on the metal interfaces from three different things. The most achievement is that we firstly obtain the analytic accurate solution of the modal fields of the waveguide structure and find some available character:(1) the different uniaxial crystal materials have the different propagation properties;(2) When the optical axis of the crystal is on the plane that is made up of the normal direction of the waveguide plane and the propagation, there are TE mode and TM mode in thisspecial waveguide, but the principal mode is different of the character of the uniaxial crystal, the principal mode is the principal mode of TE mode for the negative uniaxial crystal, but the one of TM mode for the positive uniaxial crystal;(3) When the crystal optical-axis parallel to the waveguide plane, For the positive uniaxial crystal material, the principal mode of the waveguide is a TE wave, which can be excited by the light at any frequency; when the light frequency satisfies a single mode propagation condition, there will be only the principal mode propagating in the waveguide, otherwise some of the higher order modes can be excited, which are neither TE modes, nor TM modes, but the hybrid guided modes. For the negative uniaxial crystal material, the principal mode is a hybrid guided mode, which can also be excited by the light at any frequency, but when the single mode propagation condition can not be satisfied, some of the higher order hybrid guided modes will exist in the waveguide.