title: A terahertz plastic wire based evanescent field sensor for high sensitivity liquid detection.
abstract: A highly sensitive detection method based on the evanescent wave of a terahertz subwavelength plastic wire was demonstrated for liquid sensing. Terahertz power spreading outside the wire core makes the waveguide dispersion sensitive to the cladding index variation, resulting in a considerable deviation of waveguide dispersion. Two liquids with transparent appearances, water and alcohol, are easily distinguished based on the waveguide dispersion, which is consistent with theoretical predictions. A melamine alcohol solution with various concentrations is identified successfully, and the detection limit is up to 20ppm, i.e. equivalent to the index variation on the order of 0.01.
authors.affiliation: Institute of Electro-Optical Science and Engineering and Advanced Optoelectronic Technology Center, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan, R.O.C.
authors.forename: Borwen
authors.initials: B
authors.lastname: You
authors.forename: Tze-An
authors.initials: TA
authors.lastname: Liu
authors.forename: Jin-Long
authors.initials: JL
authors.lastname: Peng
authors.forename: Ci-Ling
authors.initials: CL
authors.lastname: Pan
authors.forename: Ja-Yu
authors.initials: JY
authors.lastname: Lu
mesh_terms: D000438:Alcohols / Q000737:chemistry; D003198:Computer Simulation; D004867:Equipment Design; D005336:Fiber Optic Technology; D055095:Optics and Photonics; D010969:Plastics; D055053:Terahertz Radiation; D055068:Terahertz Spectroscopy / Q000379:methods*; D014227:Triazines / Q000737:chemistry*
chemical_list: D000438:Alcohols; D010969:Plastics; D014227:Triazines; C011907:melamine