Transmission characteristics of long-period fiber gratings having arbitrary azimuthal/radial refractive index variations

Abstract

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 01 mode and high-azimuthal-order cladding modes. The method utilizes the transfer matrix method to model cylindrical layers both in the core and the cladding regions.

Deposition of coatings on long-period fiber gratings: tunnel effect analogy

“…In addition to this, the depth of the attenuation band could decrease to that point that, for some overlay thickness values, the attenuation bands could vanish. This phenomenon has been corroborated with another nanodeposition technique: Electrostatic-Self-Assembly (ESA) method; and the results have been explained (Del Villar et al 2005a, b) with a theoretical model based on the LP mode approximation (Anemogiannis et al 2003). On the other hand, dip-coating (DC) technique has been used to prove that a similar phenomenon is observed if an LPFG is coated with a thin overlay and the resonance wavelength shift is analyzed as a function of the ambient refractive index (Pilla et al 2005a).…”

“…This produces inexact results. However, if the modified first-order Bragg condition is applied, errors are lower than 0.1% (Anemogiannis et al 2003): where ς 11,11 and ς 1j,1j are the self-coupling coefficients of the core and the j cladding modes. However, because we are also interested in the analysis of the depth of the attenuation bands in the transmission spectrum we prefer the complete formulation (expression 1).…”

“…The variation of the effective indices of the cladding modes has an important effect in the attenuation bands of the transmission spectrum of the LPFG because there is a close relation between the wavelengths of these bands and the modified Bragg condition (Anemogiannis et al 2003).…”

Refractive Index Sensitivity In Thinned Uv And Arc Induced Long-Period Gratings: A Comparative Study

“…It is worth noting that a better accurate formulation taking into account the modal selfcoupling coefficients have been demonstrated [18], if compared with eq. (1).…”

Propagation Characteristics of Optical Long Period Fiber Gratings using Graphical Solution Methods

“…Reference [12] shows a complete method to determine the total transmission characteristics of LPG In order to evaluate the propagation characteristics of the guided core mode, optical fiber waveguide geometry is employed [13]. We assumed that the fiber geometry consists of two concentric cylinders with a step index profile that presents a uniform central core surrounded by an infinite and homogenous cladding [13][14].…”