Refractive index sensor based on a microhole in single-mode fiber created by the use of femtosecond laser micromachining
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Updated: Jun 19, 2026

Implementation of a Reference Interferometer for Nanodetection
Published on: April 26, 2014
Ying Wang1, D N Wang, Minwei Yang
1Department of Electrical Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China.
Abstract:
A compact in-fiber refractive index (RI) sensor is presented that is based on a microhole created in a conventional single-mode fiber by the use of femtosecond laser micromachining. The transmission properties of such a device with a microhole of different diameters have been investigated in the wavelength region of 1500-1600 nm and in the RI range of 1.30-1.45. It is found that the relationship between the transmission and the RI is critically dependent on the size of the microhole in the fiber core region. The highest resolution obtained is 6.70x10(-5), in the RI range of 1.37-1.42, when the microhole diameter is approximately 8 microm, close to the fiber core size. The in-fiber RI sensor developed in this work is easy to fabricate and can be used to implement temperature-independent measurements.

