Engineering topics

Egalon, Claudio O.

Publications and source records attributed to Egalon, Claudio O..

23 records · Page 2

NASA NTRS1992

Phase shift of TE and TM modes in an optical fiber due to axial strain (exact solution)

Axial strain may be determined by monitoring the phase shift of modes of a variety of optical fiber sensors. In this paper, the exact solution of a circular optical fiber is used to calculate the phase shift of the TE and TM modes. Whenever an optical fiber is stressed, the optical path length, the index of refraction, and the propagation constants of each fiber mode change. In consequence, the modal phase term, beta(ln)z, of the fields is shifted by an amount Delta phi. In certain cases, it is desirable to control the phase shift term in order to make the fiber either more or less sensitive to certain kinds of strain. It is shown that it can be accomplished by choosing appropriate fiber parameters.

Egalon, Claudio O.↗

NASA NTRS1991

Efficiency of core light injection from sources in the cladding - Bulk distribution

The behavior of the power efficiency of an optical fiber with bulk distribution of sources in its cladding is analyzed. Marcuse's (1988) results for weakly guiding cylindrical fibers with fluorescent sources uniformly distributed in the cladding are confirmed for the bulk distribution case. It is found that power efficiency increases with wavelength and with difference in refractive indices. A new independent variable for the bulk distribution is found, and it is shown that the power efficiency does not always increase with the V number.

Egalon, Claudio O.↗

NASA NTRS1991

Model of a thin film optical fiber fluorosensor

The efficiency of core-light injection from sources in the cladding of an optical fiber is modeled analytically by means of the exact field solution of a step-profile fiber. The analysis is based on the techniques by Marcuse (1988) in which the sources are treated as infinitesimal electric currents with random phase and orientation that excite radiation fields and bound modes. Expressions are developed based on an infinite cladding approximation which yield the power efficiency for a fiber coated with fluorescent sources in the core/cladding interface. Marcuse's results are confirmed for the case of a weakly guiding cylindrical fiber with fluorescent sources uniformly distributed in the cladding, and the power efficiency is shown to be practically constant for variable wavelengths and core radii. The most efficient fibers have the thin film located at the core/cladding boundary, and fibers with larger differences in the indices of refraction are shown to be the most efficient.

Egalon, Claudio O.↗

NASA NTRS1991

Behaviour of a few mode fiber modal pattern under stress

A numerical model was developed to calculate the interference pattern at the end of a multimode weakly guiding optical fiber under stress. Whenever an optical fiber is under stress, the modal phase in the interference term of the intensity formula changes. Plots of the simulated output of a stressed fiber are presented. For multimode fibers, very complicated patterns result. Under stress, lobes in the pattern are generated, displaced and power is exchanged among them.

Egalon, Claudio O.↗

NASA NTRS1991

Model of an axially strained weakly guiding optical fiber modal pattern

Axial strain may be determined by monitoring the modal pattern variation of an optical fiber. In this paper we present the results of a numerical model that has been developed to calculate the modal pattern variation at the end of a weakly guiding optical fiber under axial strain. Whenever an optical fiber is under stress, the optical path length, the index of refraction and the propagation constants of each fiber mode change. In consequence, the modal phase term of the fields and the fiber output pattern are also modified. For multimode fibers, very complicated patterns result. The predicted patterns are presented, and an expression for the phase variation with strain is derived.

Egalon, Claudio O.↗