耦合雙微碟共振腔之光學特性研究

Abstract

本論文探討由砷化銦量子點作為發光主動層之耦合雙微碟共振腔。將微碟轉移至藍寶石基板上，並且利用光纖探針製造耦合雙微碟。由顯微光激螢光系統可以看到許多很窄的譜線，即為耳語廊模態。透過電場偏振實驗與有限時域差分法，可確認實驗量測的耳語廊模態之方位角與徑向模態數。藉由穩定地改變其中一個微碟的折射率，可清楚地觀察束縛態與反束縛態的現象，證明耦合雙微碟為強耦合效應。我們發現當耳語廊方位角模態數越大時，其耦合強度越小。此現象為較高的等效位能屏障將電磁波侷限在微碟共振腔，使模態之間耦合減小。

The optical properties of microdisk microcavities with embedded InAs quantum dots (QD) in GaAs membrane are investigated. The microdisks are transferred to a sapphire substrate and fabricated closely spaced double microdisks by using a fiber tip. The emission spectra of the double microdisks are investigated by micro-photoluminescence (μ-PL) measurements. several sharp emission lines arise from the Whispering gallery modes (WGMs) of the microdisks have been observed. Polarization resolved μ-PL and finite-difference time-dominate simulation (FDTD) are used to identify the azimuthal and radial mode number of the measured WGMs. By continuously increasing the refractive index of one of the double microdisks using laser local heating, we observed clear molecular modes with bonding states and antibonding states due to a strongly coupling of the double microdisk. We found that the higher-order WGMs always have smaller coupling strengths. This phenomenon can be explained by the effective potential confining the electromagnetic wave in the microdisk microcavity.