Title :
Analysis of the response of long period fiber gratings to external index of refraction
Author :
Patrick, Heather J. ; Kersey, Alan D. ; Bucholtz, Frank
Author_Institution :
US Naval Res. Lab., Washington, DC, USA
fDate :
9/1/1998 12:00:00 AM
Abstract :
This paper demonstrates that the change in wavelength of a long period fiber grating attenuation band with changes in external index of refraction can be enhanced by proper selection of the grating period. We calculate and experimentally verify that the wavelength shift caused by changing the external index from n=1 to n=1.44 of the attenuation band which appears in the 1400-1600 nm region in a 200-μm period grating is four times that in a 350-μm period grating. Changes in the spectrum over a wavelength range from 1100 to 1600 nm and 1<n<1.72 index range are also presented, and implications for grating design when enhanced or reduced index sensitivity is desired are discussed. Finally, we demonstrate the use of a highly index-sensitive long period fiber grating as a chemical concentration sensor
Keywords :
chemical sensors; chemical variables measurement; diffraction gratings; fibre optic sensors; optical fibre losses; optical fibre theory; refractive index; sensitivity; 1100 to 1600 nm; 1400 to 1600 nm; 200 mum; 350 mum; chemical concentration sensor; external index of refraction; fibre optic sensors; grating design; grating period; highly index-sensitive long period fiber grating; long period fiber grating attenuation band; long period fiber gratings; reduced index sensitivity; wavelength shift; Attenuation; Chemical sensors; Fiber gratings; Glass; Laboratories; Optical attenuators; Optical coupling; Optical fiber filters; Optical fiber sensors; Optical fibers;
Journal_Title :
Lightwave Technology, Journal of
