光纖和微碟共振腔耦合之特性研究

Abstract

在本論文中，利用光纖側收量測砷化銦量子點的微碟共振腔所發出的螢光。特定模態與光纖的耦合可使螢光效率比傳統正向收光高達10倍左右。另外借由有限差分時域法模擬波導和微碟共振腔耦合的情形，對照實驗所觀察的現象進行解釋。 本論文也利用近場光學技術研究微碟共振腔的空間場強分佈，進而了解耳語廊模態以駐波的形式存在於微碟共振腔中。另外，不同徑向模態數 的空間分佈亦被探討。最後，微碟共振腔盤面的光瓣數為m個。顯示近場所掃描出的場強分布並非只由耳語廊模所貢獻，而是由砷化鎵量子點的場與耳語廊模態的場互相疊加後的結果。

We used optical fiber tip to collect emissions from the sidewall of microdisk cavities with embedding InAs/GaAs quantum dots. By using optical fiber tip, the collection efficiency of some particular whispering-gallery modes (WGMs) can be improved by a factor of 10. Finite-difference time-domain simulations are used to calculate waveguide coupled microdisk cavity. Scanning near-field optical microscopy (SNOM) is also used to study optical modes of microdisk cavity. Near-field images show that WGMs are standing wave in microdisk cavity. WGMs with different radial mode numbers are also investigated. Finally, we found that near-field images of the WGMs reveal m azimuthal maxima around the disk circumference. The results explain the intensity imaging arises from the superposition between the WGMs and InAs QDs field.