Tamm 電漿子紫外光雷射的設計與製作

Abstract

當電子與電洞藉由庫倫作用力結合所形成的激子能態與光子能態非常接 近時會分裂成兩個不同的極激子分支，我們稱為上能級激子與下能級激子。 而這種激子-極化子擁有相當小的有效質量且擁有玻色子特性，因此可以不用在絕對低溫下就能觀察玻色-愛因斯坦冷凝效應。 藉由動態冷凝物來形成激子-極化子雷射是一種擁有相當低閾值的新穎光源。在此論文，我們用 Tamm 電漿極化子結合氧化鋅來實現作用在紫外光的雷射。由於 Tamm 電漿極化子可以提供強局域電場在激子形成的作用 層中，因此我們可以材料放置在強電場處來達到強激子-極化子耦合效果。 而氧化鋅是一種擁有直接能隙以及束縛能高達 60 meV 的材料，且他的作用波段在紫外光波段，而目前作用在紫外光波段的雷射數量並不多，因此此子外波段雷射可以應用在生醫方面，例如殺菌、癌細胞治療等等。 在實驗結果中，我們可以在 373 nm 處觀察到激子-極化子強耦合且rabi splitting 達到 140 meV。並且我們透過雷射閾值、線寬以及變角度色散曲線來辨別相對應的雷射特性。這些結果也提供了解激子-Tamm 極化子的雷射機制。

Electrons and holes coupled by the Coulomb force in semiconductors could form the quasi-particle, which is so called exciton. The exciton strongly couples with photon and produce the exciton-polariton. The coupling would split to two polariton branches: upper polariton branch (UPB) and lower polariton branch(LPB). Exciton-polaritons have the small effective mass and has the similar properties of bosons. Therefore, it can be an ideal candidates to observe the Bose–Einstein condensation at room temperature. The exciton-polariton laser generated by dynamical condensates is a low threshold novel coherent light source. In this study, the ZnO based Tamm plasmon polariton (TPP) ultraviolet laser is realized. TPP provides the strong electric field confinements in the active layer with excitons. The strong coupling of exciton polariton is at 373 nm and the large Rabi-splitting about 140 meV is observed. The corresponding lasing behaviors, such as threshold energy, linewidth, angular dispersion curve are verified. These results afford a basis to understand the exciton-Tamm polaritons lasing mechanisms.