Extending high-finesse cavity techniques to the far-infrared
Extending high-finesse cavity techniques to the far-infrared
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DOI：
10.1063/1.4813274
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发表时间：
2013-07-01
影响因子：
1.6
通讯作者：
Weaver, Susanna L. Widicus
中科院分区：
文献类型：
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作者：
DePrince, Bridget Alligood;Rocher, Blithe E.;Weaver, Susanna L. Widicus
涉及高精细法布里-珀罗腔的敏感光谱技术广泛应用于微波和近红外光谱领域，但硬件限制阻碍了它们扩展到远红外波长。虽然理论上对腔增强技术实用的频率区域没有限制，但这些方法的灵敏度确实明确地依赖于高反射光学的可用性，并且在腔振铃光谱的情况下，足够快的探测器。在这里，我们描述了一种新型的高精细腔，它使用线栅偏振器作为反射面。在250 GHz下实现了10(5)数量级的品质因数。在优化的腔体设计的基础上，研究了将腔体衰荡技术扩展到远红外波段的可行性。在目前商业上可用的技术下，我们发现光谱仪的性能受到可用光学元件和探测器的限制。在腔长为120厘米，探测器响应时间接近500 ns的情况下，我们预测最小可探测吸收系数α(Min)约为10(-7)cm(-1)量级。考虑到振铃测量的灵敏度和噪声要求，在光谱仪实际应用或在远红外波长对现有方法进行重大改进之前，需要更快、更灵敏的探测器。(C)2013 AIP出版有限责任公司。
Sensitive spectroscopic techniques involving high-finesse Fabry-Perot resonators are widely used in the microwave and near-infrared spectral regimes, but hardware limitations have hindered their extension to far-infrared wavelengths. While there is no theoretical limit to the frequency region where cavity-enhanced techniques are practical, the sensitivity of these methods does depend explicitly on the availability of highly reflective optics and, in the case of cavity ringdown spectroscopy, sufficiently fast detectors. Here, we describe a novel high-finesse cavity that uses wire-grid polarizers as the reflective surfaces. Quality factors on the order of 10(5) are achieved at 250 GHz. Based on the optimized cavity design, we investigate the feasibility of extending the cavity ringdown technique to far-infrared wavelengths. With the present commercially available technology, we find spectrometer performance to be limited by both the available optics and detectors. With a 120 cm cavity and a detector response time of similar to 500 ns, we predict a minimum detectable absorption coefficient, alpha(min), on the order of 10(-7) cm(-1). Given the sensitivity and noise requirements for the ringdown measurements, faster and more sensitive detectors are needed before implementation of the spectrometer is practical or offers any significant advances to existing methods at far-infrared wavelengths. (C) 2013 AIP Publishing LLC.