title: Optical fiber Fabry-Perot interferometer cavity fabricated by femtosecond laser micromachining and fusion splicing for refractive index sensing.
abstract: We demonstrate a fiber in-line Fabry-Perot interferometer cavity sensor for refractive index measurement. The interferometer cavity is formed by drilling a micro-hole at the cleaved fiber end facet, followed by fusion splicing. A micro-channel is inscribed by femtosecond laser micromachining to vertically cross the cavity to allow liquid to flow in. The refractive index sensitivity obtained is ~994 nm/RIU (refractive index unit). Such a device is simple in configuration, easy for fabrication and reliable in operation due to extremely low temperature cross sensitivity of ~4.8 × 10(-6) RIU/°C.
authors.affiliation: The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.
authors.forename: C R
authors.initials: CR
authors.lastname: Liao
authors.forename: T Y
authors.initials: TY
authors.lastname: Hu
authors.forename: D N
authors.initials: DN
authors.lastname: Wang
mesh_terms: D004867:Equipment Design; D019544:Equipment Failure Analysis; D005336:Fiber Optic Technology / Q000295:instrumentation*; D007368:Interferometry / Q000295:instrumentation*; D007834:Lasers; D012031:Refractometry / Q000295:instrumentation* / Q000379:methods*