title: All-fiber Mach-Zehnder interferometers for sensing applications.
abstract: We propose and demonstrate a thinned fiber based Mach-Zehnder interferometer for multi-purpose sensing applications. The sensor head is formed by all-fiber in-line singlemode-multimode-thinned-singlemode (SMTS) fiber structure, only using the splicing method. The principle of operation relies on the effect that the thinned fiber cladding modes interference with the core mode by employing a multimode fiber as a mode coupler. Experimental results showed that the liquid refractive index information can be simultaneously provided from measuring the sensitivity of the liquid level. A 9.00 mm long thinned fiber sensor at a wavelength of 1538.7228 nm exhibits a water level sensitivity of -175.8 pm/mm, and refractive index sensitivity as high as -1868.42 (pm/mm)/RIU, respectively. The measuring method is novel, for the first time to our knowledge. In addition, it also demonstrates that by monitoring the wavelength shift, the sensor at a wavelength of 1566.4785 nm exhibits a refractive index sensitivity of -25.2935 nm/RIU, temperature sensitivity of 0.0615 nm/°C, and axial strain sensitivity of -2.99 pm/με, respectively. Moreover, the sensor fabrication process is very simple and cost effective.
authors.affiliation: Wuhan National Laboratory for Optoelectronics, College of Optoelectronic Science and Engineering, Huazhong University of Science and Technology, Wuhan, Hubei, China.
authors.forename: Lecheng
authors.initials: L
authors.lastname: Li
authors.forename: Li
authors.initials: L
authors.lastname: Xia
authors.forename: Zhenhai
authors.initials: Z
authors.lastname: Xie
authors.forename: Deming
authors.initials: D
authors.lastname: Liu
mesh_terms: D004867:Equipment Design; D005336:Fiber Optic Technology; D005583:Fourier Analysis; D007368:Interferometry / Q000379:methods*; D055100:Optical Fibers; D055095:Optics and Photonics; D012031:Refractometry / Q000379:methods*; D015203:Reproducibility of Results; D013696:Temperature; D014867:Water / Q000737:chemistry
chemical_list: D014867:Water