
Proceedings Paper
High-sensitivity gas sensing through plasmonic spectrometry (Conference Presentation)
Paper Abstract
Detection of faint fluxes of photons at terahertz frequencies is crucial for various applications including biosensing, medical diagnosis, chemical detection, atmospheric studies, space explorations, high-data-rate communication, and security screening. Heterodyne terahertz spectrometers based on cryogenically cooled superconducting mixers have so far been the only instruments that can provide high spectral resolution and near-quantum-limited sensitivity levels. The operation temperature, bandwidth constraints, and complexity of these terahertz spectrometers have restricted their use to mostly astronomy and atmospheric studies, limiting the overall impact and wide-spread use of terahertz technologies. Here we introduce a spectrometry scheme that uses plasmonic photomixing for frequency downconversion to offer quantum-level sensitivities at room temperature for the first time. Frequency downconversion is achieved by mixing terahertz radiation and a heterodyning optical beam with a terahertz beat frequency in a plasmonics-enhanced semiconductor active region. We demonstrate spectrometer sensitivities down to 3 times the quantum-limit at room temperature. Our presented spectrometry scheme can be applicable to resolve both the high-resolution spectra of gas molecules and mid-resolution spectra of condensed phase samples over a total operable bandwidth of 0.1-5 THz. As an example, we use the presented spectrometer to resolve the spectral information of ammonia, which has a number of narrowband absorption peaks over the 0.1-5 THz frequency range. With a versatile design capable of broadband spectrometry, this plasmonic photomixer has broad applicability to quantum optics, chemical sensing, biological studies, medical diagnosis, high data-rate communication, as well as astronomy and atmospheric studies.
Paper Details
Date Published: 9 September 2019
PDF
Proc. SPIE 11081, Active Photonic Platforms XI, 1108125 (9 September 2019); doi: 10.1117/12.2524432
Published in SPIE Proceedings Vol. 11081:
Active Photonic Platforms XI
Ganapathi S. Subramania; Stavroula Foteinopoulou, Editor(s)
Proc. SPIE 11081, Active Photonic Platforms XI, 1108125 (9 September 2019); doi: 10.1117/12.2524432
Show Author Affiliations
Mona Jarrahi, Univ. of California, Los Angeles (United States)
Semih Cakmakyapan, Univ. of California, Los Angeles (United States)
Semih Cakmakyapan, Univ. of California, Los Angeles (United States)
Yen-Ju Lin, Univ. of California, Los Angeles (United States)
Ning Wang, Univ. of California, Los Angeles (United States)
Ning Wang, Univ. of California, Los Angeles (United States)
Published in SPIE Proceedings Vol. 11081:
Active Photonic Platforms XI
Ganapathi S. Subramania; Stavroula Foteinopoulou, Editor(s)
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