TEMPERATURE-INSENSITIVE REFRACTIVE INDEX SENSOR BASED ON TILTED FIBER BRAGG GRATING

Short-period fiber Bragg gratings with gratings planes tilted at oil angle 8 degrees corresponding to file fiber axis show core mode and a large number of cladding-mode resononces in transmission. The differences between the cladding-mode resonance and the core-mode resonance are used to detect the variation of the surrounding refractive index; this refractive index sensor is immune to temperature effects by experimental demonstrations. After the cladding of the tilted fiber, Bragg grating was etched by the hydrofluoric, TFBGs with different diameters and different-order diameters and different-order cl investigated; the sensitivity of a TFBG to the external index can be significantly improved by reducing the cladding radius. Enhanced sensitivity and accuracy are achieved when the (TM) changes between 1.333 and 1.4532. (C) 2008 Wiley Periodicals. Inc. Microwave Opt Technol Lett 51: 479-483, 2009: Published online in Wiley Inter-Science (www.interscience.wiley.com). DOI 10.1002/mop.24057