11 November 2014 Terahertz gas sensing based on high Q one-dimensional photonic crystal cavity
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We present a terahertz gas sensor based on a simple one-dimensional photonic crystal cavity. Although the manufacture process is quite easy, this cavity exhibits quite high quality factors for assisting the realization of very high sensitivity in the gas refractive index sensing. Transmission measurements of the one dimensional photonic crystal cavity under different gaseous environments showed that the resonant frequency depends linearly on the refractive index of the ambient gas. In our experiment, a change of the refractive index by 1.4×10-5 leads to a shift of the resonant frequency by 4 MHz, which corresponds to 6% of the change of hydrogen concentration in air. By using the former reported quality factor of ~1.1×104, a refractive index change as small as 7×10-6 can be expected.
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Tao Chen, Tao Chen, Zhanghua Han, Zhanghua Han, Jianjun Liu, Jianjun Liu, Zhi Hong, Zhi Hong, "Terahertz gas sensing based on high Q one-dimensional photonic crystal cavity", Proc. SPIE 9275, Infrared, Millimeter-Wave, and Terahertz Technologies III, 92750C (11 November 2014); doi: 10.1117/12.2071750; https://doi.org/10.1117/12.2071750


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