FDTD Calculation Of The Modes In An Equilateral Triangle Microcavity

Optical micro-cavities are optical dielectric resonators which the line is between 5um and 500 um. Recently, Optical micro-cavities have attracted great attention due to their unique properties such as high quality factors and low mode volume. It can be applied to the case in which requires superfine line width, extreme high energy density and brightness, or the superfine micro-detect-ability, such as narrowband optics filter and the extremely low threshold lasers. These characters of the optical micro-cavity come from its unique Whispering-Gallery mode. The micro-cavity of the WG structure is a tiny structure often composed of the active region of high refractive index which was surrounded by the restrictions (or air) with a low refractive index. The total reflection is formed due to the large refractive index difference inside and outside, after multiple reflections, the micro-cavity mode is limited to the cavity so that the so-called whispering gallery mode was formed. The large Q value can be usually achieved because the most of the energy is restricted in the cavity. The most common forms of this structure are micro-disk, micro-ring, micro-spheres, micro-pillar, polygon micro-cavities and so on.Because of the low output efficiency of the micro-disc, the micro-cavity structure of orthogonal polygon was gradually studied by the researchers. The nature of the regular polygon micro-cavity gets gradually closer to that in disk when the number of the regular polygon sides increased, but its symmetry decreased significantly when the number of the side is small, and then the nature of micro-cavity may be changed. Now the largest study is about the structures such as equilateral triangle, square, hexagonal and octagonal .In recent years, the mode characters in the equilateral triangle pattern of optical micro-cavity were studied deeply on the basis of Maxwell's equations. In China, discussion group Yong-Zhen HUANG researcher leading in the CAS Institute of Semiconductors used FDTD, studied the mode characteristic of Equilateral triangle micro-cavity deeply and achieved certain results.In this paper ,equilateral triangle resonators with the refractive index of 3.2 and the side length of 5 um is simulated by 2-D FDTD technique in Full WAVE 4.0 software and the fundamental mode field are analyzed .The result show that light occur nearly total reflection on the border if the fundamental mode exist in equilateral triangle resonators .However transmission on of light increase with the order of the mode ,largen energy loss gradually, it is very difficult to form a stable mode of distribution. Also the longitudinal mode TE and TM of equilateral triangle resonators are simulated and analysis numerical results. The result show that TE_2,17, TE_2,18 and TM_1,20 have high quality factor, it is possible that formed resonant mode is stable in the resonators.