利用摻碲硒化鎵晶體產生兆赫波輻射

Abstract

在本論文中，我們利用超短脈衝雷射激發摻碲硒化鎵晶體產生中心波長可調之寬頻兆赫波，其中心波長可透過樣品厚度來調變，而輸出功率可達至少1.36 μW，至於在硒化鎵晶體中所摻雜之碲原子則可提高兆赫波之產生效率。其中最引人注意的特性為其兆赫波輸出功率隨著激發功率增加而線性增加，在本實驗中並未觀察到飽和的現象，這意味著摻碲的硒化鎵晶體利用光整流效應所產生之兆赫波可做為高功率兆赫輻射之應用。除此之外，我們量測摻雜不同碲元素濃度之硒化鎵晶體從可見光到遠紅外光波段的光學特性，並利用兆赫波時間解析光譜技術分析摻碲硒化鎵晶體在遠紅外光波段之折射率與吸收係數作為理論模擬的依據。

In this thesis, we demonstrate the generation of central wavelength-tunable (Δλc > 84.8 nm ) and high-output power (>1.36 µW) terahertz radiation on Te-doped GaSe crystals by using femtosecond laser pulses. The dopant, Te atoms, in GaSe crystals significantly enhances the efficiency of THz generation. The wide-range linearity between the optical pumping power and THz radiation power on Te-doped crystals promises them to be the potential materials for high-power THz applications via optical rectification method. Furthermore, we also measured the optical properties of Te-doped GaSe crystals in the range from visible to far-IR. For the range of far-IR, the index of reflection and absorption coefficient of Te-doped GaSe crystals can be directly obtained by terahertz time-domain spectroscopy.