Refractive index sensitivity of nano-film coated long-period fiber gratings

Towards refractive index sensitivity of long-period gratings at level of tens of µm per refractive index unit: fiber cladding etching and nano-coating deposition.

In this work we report experimental results on optimizing the refractive index (RI) sensitivity of long-period gratings (LPGs) by fiber cladding etching and thin aluminum oxide (Al2O3) overlay deposition. The presented LPG takes advantage of work in the dispersion turning point (DTP) regime as well as the mode transition (MT) effect for higher-order cladding modes (LP...

Transmission Characteristics of Long-Period Fiber Gratings Having Arbitrary Azimuthal/Radial Refractive Index Variations

A numerical method is presented for determining the transmittance of long-period (LP) fiber-gratings having arbitrary azimuthal/radial refractive index variations. The method uses coupled-mode theory and includes both the sine and cosine character of the LP modes. The model treats interactions between the fundamental mode and high-azimuthal-order cladding modes. The method utilizes the transfer...

Refractive index sensitivity of fibre optic long period gratings with SiO2 nanoparticle based mesoporous coatings

A fibre optic long period grating (LPG) with a nano-assembled mesoporous coating of alternate layers of poly (allylamine hydrochloride) (PAH) and SiO2 nanospheres was used for the development of a fibre-optic refractometer. PAH/SiO2 films of different thickness have been deposited onto LPG in order to study the effect of the film thickness on sensor performance. The device showed a sensitivity ...

Refractive Index Sensitivity in Thinned Uv and Arc Induced Long-period Gratings: a Comparative Study

In this work, a comparative study aimed to investigate the effects of cladding stripping on the external refractive index sensitivity in tapered and UV long period gratings is presented. Here, wet chemical etching combined with microscopic analysis allow us to identify the experimental dependence of the surrounding refractive index (SRI) sensitivity on the cladding radius for both grating types...

Improved Refractive Index Sensitivity Utilizing Long-Period Gratings with Periodic Corrugations on Cladding