Polarization dependent properties of graphene oxide-coated tilted fiber Bragg gratings for refractometry

Graphene oxide (GO) thin films fabricated by the vacuum filtration method were deposited on bare tilted fiber Bragg grating for refractometry measurements. Two different layer thicknesses (100 nm and 200nm) were used to prepare the samples. The amplitude spectra of the GO-coated TFBGs (GO-TFBGs) were measured with linearly polarized light for different refractive index values of LiCl solutions (1.3333-1.3342). We show that when polarized light is used, the 200 nm GO-TFBGs achieve similar behavior as plasmonic gold-coated TFBGs (Au-TFBGs). This latter exhibits a characteristic attenuation in the amplitude spectrum when P-polarized light excites a surface plasmon resonance (SPR). This behavior suggests that GO is present as a mix of discontinuous and stratified flakes favorable for plasmon-plasmon hybridization, which can be generated for both P and/or S-polarization of the light.