Ho I-Chen, Guo Xiaoyu, Zhang X-C
Center for Terahertz Research, Rensselaer polytechnic Institute, Troy, NY 12180-3590, USA.
Opt Express. 2010 Feb 1;18(3):2872-83. doi: 10.1364/OE.18.002872.
When a sample being tested is optically opaque or has a high absorption coefficient, a reflective measurement is often more suitable than a transmission measurement. We report the design and evaluation of a reflective terahertz time-domain spectroscopy (R-THz-TDS), using air as THz wave emitter and sensor, together with air-biased-coherent-detection (ABCD) method for the first time. With an 85 fs pulse amplified laser, we demonstrate a usable bandwidth from 0.5 THz to 12 THz, together with a peak dynamic range (DR) better than 2000:1 and a peak THz electrical field greater than 30 kV/cm. With a 32 fs pulse amplified laser, the usable bandwidth is remarkably expanded to a continuous 35 THz. Several far-infrared optical properties in various samples are reported. Furthermore, the time-resolved optical pump-THz probe experiment is performed. Finally, the uniqueness and advantage of this spectrometer are comprehensively compared with traditional THz-TDS and Fourier transform infrared (FTIR) spectroscopy.
当被测试的样品是光学不透明的或具有高吸收系数时，反射测量通常比透射测量更合适。我们首次报告了一种反射式太赫兹时域光谱仪（R-THz-TDS）的设计与评估，该光谱仪使用空气作为太赫兹波发射器和传感器，并采用空气偏置相干检测（ABCD）方法。利用一台85飞秒脉冲放大激光器，我们展示了从0.5太赫兹到12太赫兹的可用带宽，以及优于2000:1的峰值动态范围（DR）和大于30 kV/cm的峰值太赫兹电场。使用32飞秒脉冲放大激光器时，可用带宽显著扩展至连续的35太赫兹。报告了各种样品中的几种远红外光学特性。此外，还进行了时间分辨光泵浦-太赫兹探测实验。最后，将该光谱仪的独特性和优势与传统太赫兹时域光谱仪（THz-TDS）和傅里叶变换红外（FTIR）光谱仪进行了全面比较。
