回音廊模態增強氧化鋅奈米柱的隨機雷射

Abstract

本論文主要目的在於研究利用回音廊模態增強氧化鋅奈米柱的隨機雷射。為了探討其中的運作原理，我們研究了二氧化矽奈米球修飾氧化鋅奈米線的雷射特性。我們發現在二氧化矽奈米球的幫助下，放射光譜裡有數個半高寬小於0.3奈米的雷射尖峰，而隨機雷射的微分量子效率也增加了七倍。拿來做修飾的奈米球不但可以做為回音廊模態的共振腔、增強發光強度，也可以做為一個散射中心。透過我們元件的二維的陰極發光影像、圓形迴音廊模態的理論計算、不同大小氧化矽奈米球的使用，我們進一步地驗證了提出的理論。這樣獨特的雷射特性將可以利用在製作高效率的光電元件。

Whispering-gallery-mode (WGM) resonance enhanced random laser action has been proposed and demonstrated. To illustrate the working principle, lasing characteristics of ZnO nanorods decorated with SiO2 nanospheres have been investigated. It is found that with the assistance of SiO2 nanospheres, the emission spectrum exhibits a very narrow background signal with few sharp lasing peaks and a very small full width at half maximum of less than 0.3 nm. The differential quantum efficiency (ηd) of random laser action can be greatly enhanced by up to 735 %. The decorated nanospheres not only enable to generate WGM resonance and enhance the emission intensity, but also can serve as scattering centers. Cathodoluminescence mapping images of nanorods decorated with nanospheres and theoretical calculation based on the spherical cavity were utilized to confirm our proposed mechanism. The unique lasing behavior shown here may open up a new approach for the creation of highly efficient optoelectronic devices.