title: Microfiber-probe-based ultrasmall interferometric sensor.
abstract: We report an ultrasmall microfiber-probe-based reflective interferometer for highly sensitive liquid refractive index measurement. It has a 3.5 microm micronotch cavity fabricated by focused ion beam micromachining. A sensitivity of 110 nm/RIU (refractive index unit) in liquid is achieved with over 20 dB extinction ratio. Theoretical analysis shows this kind of device is a hybrid of Fabry-Perot and modal interferometers. In comparison with normal fiber interferometers, this probe sensor is very compact, stable, and cheap, offering great potentials for detecting inside sub-wavelength bubbles, droplets, or biocells.
authors.affiliation: College of Engineering and Applied Sciences and National Laboratory of Solid State Microstructures, Nanjing University, Nanjing 210093, China.
authors.forename: Jun-long
authors.initials: JL
authors.lastname: Kou
authors.forename: Jing
authors.initials: J
authors.lastname: Feng
authors.forename: Qian-jin
authors.initials: QJ
authors.lastname: Wang
authors.forename: Fei
authors.initials: F
authors.lastname: Xu
authors.forename: Yan-qing
authors.initials: YQ
authors.lastname: Lu