Terahertz Bragg Resonator Based on a Mechanical Assembly of Metal Grating and Metal Waveguide

You, Borwen; Takaki, Ryohei; Hsieh, Chen-Chiung; Iwasa, Ryuji; Lu, Ja-Yu; Hattori, Toshiaki

doi:10.1109/jlt.2020.2973247

Cited by 3 publications

(2 citation statements)

References 21 publications

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“…Alternatively, a THz waveguide-based sensor of relatively short length can be designed using various resonant elements in their structures (e.g., Bragg gratings, asymmetric directional couples, integrated Fabry-Perot resonant cavities, and coherent scattering elements [25][26][27][28][29][30][31]). Due to the low bandwidth nature of resonant devices, one can then monitor the gaseous analyte RI (mostly its real part) by tracking the spectral position of various singularities using cost-effective THz sources (e.g., resonant tunneling diodes).…”

Section: Introductionmentioning

confidence: 99%

“…Although high sensitivities are readily achievable by both one-dimensional (e.g., photonic crystal cavity on silicon wafer [26]) and two-dimensional resonators (e.g., pillar arrays [29]), it is noted that for most reported optical sensors, the gaseous analyte delivery infrastructure comes as an afterthought. In contrast, in this work, this crucial component is co-engineered with optical ones, thus ensuring the independent efficient operation of both with minimal mutual intrusion for gas sensing.…”

Section: Introductionmentioning

confidence: 99%

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Resonant Gas Sensing in the Terahertz Spectral Range Using Two-Wire Phase-Shifted Waveguide Bragg Gratings

Cao,

Nallappan,

et al. 2023

Sensors

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The development of low-cost sensing devices with high compactness, flexibility, and robustness is of significance for practical applications of optical gas sensing. In this work, we propose a waveguide-based resonant gas sensor operating in the terahertz frequency band. It features micro-encapsulated two-wire plasmonic waveguides and a phase-shifted waveguide Bragg grating (WBG). The modular semi-sealed structure ensures the controllable and efficient interaction between terahertz radiation and gaseous analytes of small quantities. WBG built by superimposing periodical features on one wire shows high reflection and a low transmission coefficient within the grating stopband. Phase-shifted grating is developed by inserting a Fabry–Perot cavity in the form of a straight waveguide section inside the uniform gratings. Its spectral response is optimized for sensing by tailoring the cavity length and the number of grating periods. Gas sensor operating around 140 GHz, featuring a sensitivity of 144 GHz/RIU to the variation in the gas refractive index, with resolution of 7 × 10−5 RIU, is developed. In proof-of-concept experiments, gas sensing was demonstrated by monitoring the real-time spectral response of the phase-shifted grating to glycerol vapor flowing through its sealed cavity. We believe that the phase-shifted grating-based terahertz resonant gas sensor can open new opportunities in the monitoring of gaseous analytes.

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