Study On Mode Characteristics For Semiconductor Microdisk Resonators

Semiconductor microcavity laser has a lot of merit such as ultrasmall volumn,ultralow threshold current and so on,so it has great application potential in optical communication,optical interconnection and optical neural networks.As the earliest developed microcavity laser, Microdisk laser has attracted researchers' great attention all over the world.It is known that the numerical value analysis of Semiconductor laser is the basis of devices production.In this thesis,2-dimensional(2-D) and 3-dimensional(3-D) microdisk lasers are analysed by using the Analytical Method and the Finite-Difference Time-Domain technique, (FDTD) and some important results are achieved as follows:By using Analytical Method,the properties of the mode for the 2-dimensional(2-D) microdisk are investigated.As for the microdisk with the refractive index of n₁= 2.56 in the air,the TE mode's changes according to azimuthal quantum number v and radial mode number l is given.In addition,the mode field distributions tends to be limited within the circle with the increasing of the azimuthal mode number v and radial mode number l. By using 3-D Finite-Difference Time-Domain technique as well as with the aid of FULLWAVE,the properties of the mode for the microdisk with a vertical refractive index distribution of n_air/3.4/n_sub are investigated.The map of TE mode and vertical mode is obtained by 3D-FDTD simulation for the microdisk with a thickness of 0.2μm,and a radius of 1μm,when the refractive index is n_air=1.0,the refractive index n_sub is varied from 2.0 to 3.17,from which we can obtain the conclusion about the mode properties of the microdisk laser.From the map we can find the main optical mode in the microcavity is a special mode-whisper Gallery Mode with high quality factor,transmitting circularly on the edge of microdisk.When the refractive index n_sub is minimums,because the light wave is fully reflected on the interface between the disk and the substrate,the light wave is limited within the disk,transmitting along the disk.corresponding to an increasing horizontal radiation loss,when refractive index n_sub is similar to active regions refractive index.For the microdisk with a thickness of 0.2μm,a radius of 1μm and the vertical refractive index distribution of n_air/3.4/n_sub,the two modes' wavelengths tend to be identical--a mode across coupling trend is observed between the fundamental and the first order modes when the refractive index n_sub change from 2.0 to 3.17.when n_sub=2.0,n_sub=2.5, the two modes are limited horizontally and vertically in Cylindrically microcavity--both of the Optical-Field Distribution will possess of quite good whispering-gallery modes characteristic,if wanting to get the Optical-Field Distribution with the whispering-gallery modes characteristic,we must try to magnify the difference.When n_sub=2.8,n_sub=3.17,the vertical limit to the option is decling--the loss of the optical energy is obviously increasing at the substrate,and when n_sub=3.17,the TE₀₁ mode gradually deviates from the features of the whispering-gallery modes.Furthermore,compared with fundamental mode,high mode is much easier to form the whispering-gallery modes. The results of the optical field distribution in chapter 3 and chapter 4 are compared only to find the quite close results.The above-mentioned conclusions will have a practical significance to the design of the semiconductor microcavity lasers.