title: Terahertz refractive index sensors using dielectric pipe waveguides.
abstract: A dielectric pipe waveguide is successfully demonstrated as a terahertz refractive index sensor for powder and liquid-vapor sensing. Without additional engineered structures, a simple pipe waveguide can act as a terahertz resonator based on anti-resonant reflecting guidance, forming multiple resonant transmission-dips. Loading various powders in the ring-cladding or inserting different vapors into the hollow core of the pipe waveguide leads to a significant shift of resonant frequency, and the spectral shift is related to the refractive-index change. The proven detection limit of molecular density could be reduced to 1.6nano-mole/mm3and the highest sensitivity is demonstrated at around 22.2GHz/refractive-index-unit (RIU), which is comparable to the best THz molecular sensor [Appl. Phys. Lett. 95, 171113 (2009)].
authors.affiliation: Department of Photonics, National Cheng Kung University, 1 University Road, Tainan 70101, Taiwan.
authors.forename: Borwen
authors.initials: B
authors.lastname: You
authors.forename: Ja-Yu
authors.initials: JY
authors.lastname: Lu
authors.forename: Chin-Ping
authors.initials: CP
authors.lastname: Yu
authors.forename: Tze-An
authors.initials: TA
authors.lastname: Liu
authors.forename: Jin-Long
authors.initials: JL
authors.lastname: Peng
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D005740:Gases / Q000032:analysis*; D008832:Microchemistry / Q000295:instrumentation*; D010363:Pattern Recognition, Automated / Q000379:methods*; D044367:Phase Transition; D011208:Powders / Q000032:analysis*; D012031:Refractometry / Q000295:instrumentation*; D012996:Solutions / Q000032:analysis*; D020349:Surface Plasmon Resonance / Q000295:instrumentation*; D055053:Terahertz Radiation
chemical_list: D005740:Gases; D011208:Powders; D012996:Solutions