A new method for suppression of coupling from guided optical modes into cladding modes in an optical fibre Bragg grating using a fibre with a strongly depressed cladding is proposed. Strong suppression of the coupling has been demonstrated both theoretically and experimentally. Optical fibre Bragg gratings have attracted much attention in recent years due to their numerous applications such as ...

1. The photonic-crystal fibres In conventional optical fibres, electromagnetic modes are guided by a phenomenon of total internal reflection on a core-cladding border. The core refractive index is higher than the refractive index of a cladding which is achieved by adequate doping of a central part of the based material [1]. After over 20 years of intense researches on optical fibres, including ...

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 ...

Control of dispersion in fibre optical waveguides is of critical importance to optical fibre communications systems and more recently for continuum generation from the ultraviolet to the mid-infrared. The wavelength at which the group velocity dispersion crosses zero can be set by varying fibre core diameter or index step. Moreover, sophisticated methods to manipulate higher-order dispersion so...

In this paper the physical basis for the design of an optical fibre sensor suited for aqueous medium and gas phase based on the excitation of an evanescent wave at the core/cladding interface is developed. The detection based on the refractive index changes (between 1.41 and 1.45) of the infinite dielectric medium which can be an electrolyte or a sol-gel polymer deposited on the uncladed part o...

In the last decade optical fibre tapers with micrometer diameter (often called microfibers) have been investigated for numerous applications ranging from sensing to wavelength convertors, telecom and optical manipulation. This paper reviews the various applications of microfibres. 1. Optical microfibres Although microfibers with diameters comparable to the wavelength have been manufactured for ...

for a fiber optical surface plasmon resonance (spr) sensor a short part of its cladding should be removed to coat a thin layer of a metal. usually this is problematic when an optical fiber with small core diameter is used. in this paper, a new method using µliter droplet of the hf acid for short fiber optical taper fabrication is reported. using this method in a multi-mode optical fiber with th...

We analyze an elliptical core segmented cladding fibre using the vector finite element method (FEM) and show that the segmented cladding can effectively control the birefringence of the fibre. The analysis should be useful for fibre-based polarization controlling devices and single-polarization devices.