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Pressure Sensing in High-Refractive-Index Liquids Using Long-Period Gratings Nanocoated with Silicon Nitride
Centre de Recherche en Photonique, Université du Québec en Outaouais, 101 rue Saint-Jean-Bosco, Gatineau, QC, J8X 3X7, Canada
Institute of Microelectronics and Optoelectronics, Warsaw University of Technology, Koszykowa 75, 00-662 Warsaw, Poland
* Author to whom correspondence should be addressed.
Received: 8 November 2010; in revised form: 6 December 2010 / Accepted: 9 December 2010 / Published: 10 December 2010
Abstract: The paper presents a novel pressure sensor based on a silicon nitride (SiNx) nanocoated long-period grating (LPG). The high-temperature, radio-frequency plasma-enhanced chemical-vapor-deposited (RF PECVD) SiNx nanocoating was applied to tune the sensitivity of the LPG to the external refractive index. The technique allows for deposition of good quality, hard and wear-resistant nanofilms as required for optical sensors. Thanks to the SiNx nanocoating it is possible to overcome a limitation of working in the external-refractive-index range, which for a bare fiber cannot be close to that of the cladding. The nanocoated LPG-based sensing structure we developed is functional in high-refractive-index liquids (nD > 1.46) such as oil or gasoline, with pressure sensitivity as high as when water is used as a working liquid. The nanocoating developed for this experiment not only has the highest refractive index ever achieved in LPGs (n > 2.2 at λ = 1,550 nm), but is also the thinnest (
Keywords: optical fiber sensors; pressure sensor; long-period gratings; plasma deposition; thin films; silicon nitride
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Smietana, M.; Bock, W.J.; Mikulic, P.; Chen, J. Pressure Sensing in High-Refractive-Index Liquids Using Long-Period Gratings Nanocoated with Silicon Nitride. Sensors 2010, 10, 11301-11310.
Smietana M, Bock WJ, Mikulic P, Chen J. Pressure Sensing in High-Refractive-Index Liquids Using Long-Period Gratings Nanocoated with Silicon Nitride. Sensors. 2010; 10(12):11301-11310.
Smietana, Mateusz; Bock, Wojtek J.; Mikulic, Predrag; Chen, Jiahua. 2010. "Pressure Sensing in High-Refractive-Index Liquids Using Long-Period Gratings Nanocoated with Silicon Nitride." Sensors 10, no. 12: 11301-11310.