Embedded progressive-three-layered fiber long-period gratings for respiratory monitoring

A long-period grating (LPG) was written into a progressive three-layered single-mode fiber that was embedded into a flexible platform as a curvature sensor. The spectral location and profile of the LPGs were unaltered after implantation in the platform. The curvature sensitivity was 3.747 nm m with a resolution of ± 1.1 × 10-2 m-1. The bend sensor is intended to be part of a respiratory monitoring system and was tested on a resuscitation training manikin. © 2003 society of Photo-Optical Instrumentation Engineers.

Bend and index insensitive long period grating in progressive three layered optical fibre

A long period fibre grating written in a progressive three-layered optical fibre is shown to exhibit an attenuation band that has a very low bending sensitivity (5.1×10 –2 nm m) compared to normal step-index fibre, and is also insensitive to changes in the refractive index of the surrounding medium. Applications to sensing and telecommunications are discussed.

Embedded progressive-three-layered fiber long-period gratings for respiratory monitoring

A long-period grating (LPG) was written into a progressive three-layered single-mode fiber that was embedded into a flexible platform as a curvature sensor. The spectral location and profile of the LPGs were unaltered after implantation in the platform. The curvature sensitivity was 3.747 nm m with a resolution of ±1.1×10–2 m–1. The bend sensor is intended to be part of a respiratory monitoring system and was tested on a resuscitation training manikin.

Investigations of the spectral sensitivity of long period gratings fabricated in three-layered optical fiber

Long period gratings (LPGs) were written into a progressive three-layered (PTL) monomode optical fiber. The spectral sensitivity was experimentally measured with respect to temperature and the surrounding refractive index, and compared with theoretical predictions. The behavior of the devices suggests that this type of fiber may be useful as a means of reducing the sensitivity of LPGs to the surrounding medium and for simultaneous temperature and refractive index sensing.

Formation and characterization of ultra-sensitive surface plasmon resonance sensor based upon a nano-scale corrugated multi-layered coated D-shaped optical fiber

We present experimental results on the performance of a series of coated, D-shaped optical fiber sensors that display high spectral sensitivities to external refractive index. Sensitivity to the chosen index regime and coupling of the fiber core mode to the surface plasmon resonance (SPR) is enhanced by using specific materials as part of a multi-layered coating. We present strong evidence that this effect is enhanced by post ultraviolet radiation of the lamellar coating that results in the formation of a nano-scale surface relief corrugation structure, which generates an index perturbation within the fiber core that in turn enhances the coupling. We have found reasonable agreement when we modeling the fiber device. It was found that the SPR devices operate in air with high coupling efficiency in excess of 40 dB with spectral sensitivities that outperform a typical long period grating, with one device yielding a wavelength spectral sensitivity of 12000 nm/RIU in the important aqueous index regime. The devices generate SPRs over a very large wavelength range, (visible to 2 mu m) by alternating the polarization state of the illuminating light.

A method of fundamental solutions for transient heat conduction in layered materials

In this paper we investigate an application of the method of fundamental solutions (MFS) to transient heat conduction in layered materials, where the thermal diffusivity is piecewise constant. Recently, in Johansson and Lesnic [A method of fundamental solutions for transient heat conduction. Eng Anal Boundary Elem 2008;32:697–703], a MFS was proposed with the sources placed outside the space domain of interest, and we extend that technique to numerically approximate the heat flow in layered materials. Theoretical properties of the method, as well as numerical investigations are included.

On an indirect integral equation approach for stationary heat transfer in semi-infinite layered domains in R3 with cavities

Regions containing internal boundaries such as composite materials arise in many applications.We consider a situation of a layered domain in IR3 containing a nite number of bounded cavities. The model is stationary heat transfer given by the Laplace equation with piecewise constant conductivity. The heat ux (a Neumann condition) is imposed on the bottom of the layered region and various boundary conditions are imposed on the cavities. The usual transmission (interface) conditions are satised at the interface layer, that is continuity of the solution and its normal derivative. To eciently calculate the stationary temperature eld in the semi-innite region, we employ a Green's matrix technique and reduce the problem to boundary integral equations (weakly singular) over the bounded surfaces of the cavities. For the numerical solution of these integral equations, we use Wienert's approach [20]. Assuming that each cavity is homeomorphic with the unit sphere, a fully discrete projection method with super-algebraic convergence order is proposed. A proof of an error estimate for the approximation is given as well. Numerical examples are presented that further highlights the eciency and accuracy of the proposed method.

Investigations of the spectral sensitivity of long period gratings fabricated in three-layered optical fiber

Long period gratings (LPGs) were written into a progressive three-layered (PTL) monomode optical fiber. The spectral sensitivity was experimentally measured with respect to temperature and the surrounding refractive index, and compared with theoretical predictions. The behavior of the devices suggests that this type of fiber may be useful as a means of reducing the sensitivity of LPGs to the surrounding medium and for simultaneous temperature and refractive index sensing.