金属-电介质约束的半导体微盘激光器

Metallo-dielectric Confined Semiconductor Microdisk Lasers

设计了一种以半导体材料InGaAsP作为核心结构的器件表面蒸镀二氧化硅膜层,在其上蒸镀金膜层,构成金属-电介质半导体微盘激光器结构,盘面的厚度为2μm,盘面半径为6μm,盘壁侧表面与底面的夹角为45°.使用有限元法对该结构器件的回音壁模式进行数值研究,利用所谓"偏微分方程的弱项形式"有效地抑制了许多局域不变性相关的"伪解".通过数值求解弱项型矢量亥姆霍兹方程,得到微盘激光器回音壁模式的横磁场分布,在此基础上讨论了其品质因数(Q值)、模体积、不同金属和电介质膜厚度对器件品质因数的影响、盘的半径和其品质因素的关系等相关量.理论计算表明,这种结构的器件较直接在介质表面蒸镀金属膜层结构的器件的品质因数高2～3倍.实验还获得了基阶和高阶的表面等离子体波模式,以及品质因数最大达到约5 400的光学-电介质基模.

A novel metal-dielectric semiconductor microdisk laser structure with the thickness of 2 micrometer and the radius of 6 micormeter is designed by depositing a silica film and a noble metal gold film on the InGaAsP semiconductor microdisk. The angle between side-wall surface and the bottom plate is 45°. The whispering gallery mode of the device is numerically investigated by using a well-known Finite Element Method (FEM). The so-called weak-form of the partial differential equation is employed to effectively reduce the pseudo-solution associated with the local invariant, which exists in the FEM directly applying to Maxwell equations.The distribution of the cross magnetic field (TM) of the whispering gallery mode of the proposed microdisk laser is achieved based on the numerical solution of the weak-type vector Helmholtz equation. After that the quality factor (Q), the mode volume and other related quantities are discussed. Theoretical results show that the quality factor of the proposed microdisk laser with the sandwich-structure is 2~3 times more than the one with the structure directly deposited metal film in InGaAsP semiconductor microdisk. Furthermore, different thicknesses of the metal and the dielectric quality factor of the microdisk laser and the relationship between the disk radius and the quality factor are discussed. A fundamental mode and higher-order surface plasma wave mode, and a maximum quality factor of about 5 400 optical-dielectric of the fundamental mode are achieved.