矽基主動與被動介電質微碟共振腔之製作

Abstract

在本篇論文中，我們製作出不同材料之介電質微碟共振腔。首先，氮化矽微碟面臨兩個問題，分別為量子點訊號消失與氮化矽材料在高功率激發下受損。另外，苯環丁烯微碟則是在製作時，量子點因持續高溫導致變質。故我們利用漸細光纖耦合量測系統來探討其被動微碟共振腔之特性，其結果為20微米微碟Q值約為1300、30微米微碟Q值約1400~1500、40微米微碟Q值約1900~2000。並且，我們亦有探討光纖與微碟耦合位置和模態間之關係。當光纖在微碟圓周附近耦合時，其量測到之頻譜為迴音廊模態徑向量子數mR=1，同時也觀察到徑向量子數mR=2的迴音廊模態。若持續將光纖往微碟內部靠近則會觀察到mR=2之徑向模態，並隨著光纖越靠近微碟內部mR=2之模態耦合影響越明顯。且隨光纖往微碟內部靠近其強度會衰減。其原因為基板折射率較高，光藉由柱子耦合進基板，造成整體強度下降。

In this thesis, we fabricated dielectric microdisks using different dielectric materials. Regarding silicon nitride microdisks, there are two problems, i.e. disappearance of quantum dot signal and damage of silicon nitride at high power excitation. On the other hand, the problem of benzocyclobutene (BCB) microdisks is that quantum dots will be damaged due to continuous processes at higher temperature. Therefore, we use a tapered-fiber measurement system to investigate the characteristics of passive BCB microdisk cavity. The quality factor of BCB microdisks with 20μm in diameter is about 1300, and that of 30μm microdisks is about 1400 to 1500, and that of 40μm microdisks is about 1900 to 2000. Moreover, we also investigate the characteristics of BCB microdisk cavities by changing tapered-fiber coupling position. The whispering gallery mode (WGM) with radial quantum number mR=1 is observed when the tapered-fiber is around the circumference. The WGM with mR=2 is also observed in this case. The whispering gallery mode which is observed is mR=2 as tapered-fiber continuing close to post. if tapered -fiber be moved close to the post, mR=2 mode coupling effect is more obvious. And, the overall signal intensity decrease as tapered -fiber be moved close to the post, because substrate is high refractive index. So, the light coupled into the substrate through the post, resulting in the overall intensity decrease.