高功率GaAs/AlGaAs單一量子井雷射端面之高反射率及抗反射率鍍膜

Abstract

在這篇論文裡，我們介紹高功率雷射端面鍍膜上的研究。藉由在半導體雷 射的端面上鍍一層或多層介電質薄膜以改變反射率；我們可以改善半導體 雷射的特性，增加輸出功率。採用單層四分之一波長厚的二氧化矽當抗反 射膜可以將反射率由原來31%改變為5%。而使用三對四分之一波長厚的二 氧化矽及二氧化鈦可將反射率提高為92%。雷射端面經過高反射及抗反射 鍍膜，抗反射面輸出功率幾乎為未鍍膜前的兩倍， s瘢入電流2.5安培時 ，輸出功率可達2瓦、臨界電流由235毫安增加為260毫安、單面外部量子 效益 (external quantum efficiency) 由0.37增加為0.72、電光轉換效 益(wall plug efficiency)由0.225增加為0.37。 In this thesis, we present our study on the facet coating of high power GaAs/AlGaAs lasers. Performance of the high power lasers is improved by coatings the combination of AR and HR to the two facets using E-beam evaporation. Anti-reflectivity coating which consist of a single (/4 thick SiO2 film is deposited to the front facet (the emission facet) to reduce its reflectivity from 31% (as-cleaved facet) to 6%. High reflectivity coating which consists of 3 pairs of quarter wave SiO2/TiO2 stacks on the back facet to increases the reflectivity to more than 92%. The combination of AR and HR coating increases the differential quantum efficiency of light output from the front facet from the uncoated value 0.55 W/A to 1.1 W/ A. The output power reaches as high as 2W at room temperature at 2.5 A. The threshold current changes only slightly from 235 mA to 260 mA. The front facet external quantum efficiency has increased from 0.37 to 0.72. The front facet wall plug efficiency has increased from 0.225 to 0.37.