Sensing properties of long-period fiber grating with coating InSnO by pulsed laser deposition

The influence of different film thickness on grating coupling coefficient and transmittance has been analyzed based on a four-layer structure model of grating and matrix transformation, in which the optimum thickness of coating [(In2O3)9(SnO2)1][indium tin oxide (ITO)] is found, and the influence of environmental refractive index and wavelength for the effective refractive index of cladding mode is simulated in theory, respectively. A structure of long-period fiber grating (LPFG) coated with ITO of high-index nanothin film by the pulsed laser deposition technology is reported. The difference of refractive index sensitivity of LPFG with ITO coating or not is analyzed in experiment. The refractive index sensitivity of LPFG with ITO coating or not is −298 and −150 nm / RIU, respectively.