兆赫輻射(THz)為頻率介於0.1THz到10THz之間的電磁波。在本論文中，我們利用光電導模式(photoconductive mode)與自由空間電光取樣(FSEOS)的方法來產生與偵測兆赫輻射。首先利用改變激發光強度之方法，研究在InAlAs SIN+結構的樣品中，其臨界電場、樣品內存能量及光吸收飽和(optical absorption saturation)極限對於兆赫輻射效益之關係。並以不同兆赫輻射機制的樣品(如InAlAs SIN+、InAlAs SIP+及InAs)，研究在高激發光強度下，導致兆赫輻射減弱之原因。最後針對共軛高分子材料(DB-PPV)導致N型砷化鎵晶圓的兆赫輻射訊號增強的現象做一探討。

The terahertz (THz) radiation is the electromagnetic wave with frequency between 0.1THz to 10THz. In this thesis, we employ the photoconductive mode and the free-space electro-optical sampling to generate and detect the terahertz radiations. Terahertz radiation from InAlAs SIN+ and InAlAs SIP+ hetrostructures and InAs wafer are measured at different pump power. The critical electric field, stored energy and optical absorption saturation in the emitters have played important roles in the amplitude of terahertz radiation. The decrease of terahertz radiation under the high pump power involves various radiation mechanisms. Finally, the enhancement of terahertz radiation by conjugate polymers (DB-PPV) deposited on n-doped GaAs wafer is observed and discussed.

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