Silica based fibre-optic refractive index sensors are gaining acceptance over conventional refractometers and finding applications in chemical/biological sensing due to many of their desirable properties. Here we present an optical fibre-based refractive index sensor that uses the power transmission through etched D-shaped fibres. The sensor's operating point and resolution can be tailored for a specific application by selecting the correct combination of the operating wavelength and the cladding thickness of the etched fibre. The sensor's power transmission depends on the surrounding refractive index in which the sensor head is immersed. The sensor presented has a maximum resolution on the order of 10^-6 in its "high resolution" region and on the order of 10^-4 in its "low resolution" region. The refractive index at which the maximum resolution occurs in the high resolution region can be shifted by ~0.012 and by ~0.027 in the low resolution region. To date, such high resolutions have been reported over narrow ranges and/or for fibre Bragg grating based sensors, which require optical spectral analysis which typically, is costly.

Date Published: 12 August 2008
PDF: 12 pages
Proc. SPIE 7099, Photonics North 2008, 709924 (12 August 2008); doi: 10.1117/12.806231

Published in SPIE Proceedings Vol. 7099:
Photonics North 2008
Réal Vallée; Michel Piché; Peter Mascher; Pavel Cheben; Daniel Côté; Sophie LaRochelle; Henry P. Schriemer; Jacques Albert; Tsuneyuki Ozaki, Editor(s)