%0 Journal Article
%T Pressure Sensing in High-Refractive-Index Liquids Using Long-Period Gratings Nanocoated with Silicon Nitride
%A Mateusz Smietana
%A Wojtek J. Bock
%A Predrag Mikulic
%A Jiahua Chen
%J Sensors
%D 2010
%I MDPI AG
%R 10.3390/s101211301
%X 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 ¦Ë = 1,550 nm), but is also the thinnest (
%K optical fiber sensors
%K pressure sensor
%K long-period gratings
%K plasma deposition
%K thin films
%K silicon nitride
%U http://www.mdpi.com/1424-8220/10/12/11301