Propagation Characteristics Of Optical Fibers Research Articles

The influence of concentration of Nd-Fe-B powder in composite coating of optical fiber to the sensibility to external magnetic field

Multi-mode optical fiber with magnetic composite coating was investigated as an optical fiber sensor element (OFMSE) for magnetic field sensing The composite coating was formed with dispersions of permanent magnet powder of Nd-Fe-B in poly (ethylene-co-vinyl acetate)-EVA solutions in toluene. The influence of the applied external magnetic field on the change of intensity of the light signal propagate trough developed optical fibers sensor element was investigated. In this paper the influence of the content of magnetic powder in the composite coating on the optical propagation characteristics of optical fiber were particularly investigated.

RF fiber-optic link performance

Applications that involve point-to-point routing of analog signals have benefited from the excellent propagation characteristics of optical fiber. Fiber-optic links that remote RF signals to and from phased-array radar antennas must meet especially stringent performance requirements. The past decade has seen significant progress in the performance of the fiber-optic links that distribute RF signals in antenna-remoting applications, as well as in cellular communications and cable television signal distribution networks. This article reviews the present state of the art in RF fiber-optic links.

Fiber Optic Sensors and Smart Fabrics

This paper presents novel work on developing fiber optic micro-sensors and integrating them into soldiers’ uniforms. These fiber optic sensors can be used to sense various battlefield hazards in real-time, such as chemical and biological warfare threats, above-normal field temperatures, and other hazards. The developed fiber optic sensors use multifunctional materials as modified cladding materials, which can sense various environmental conditions. Appropriate materials can be chromogenic materials, chemical or biological agent, conducting polymer and others. The sensing function is based on their ability to change the light propagation characteristics of optical fibers. Two types of materials, (1) thermochromic material, segmented polyurethane-diacetylene copolymer (SPU) [synthesized at the University of Akron (UA)], and (2) conducting polymer, polyaniline [synthesized at the University of Pennsylvania (U of P)], have been successfully used in this feasibility study to prove the concept of the design and development of the optical fiber sensors. Segmented polyurethane-diacetylene copolymer was selected as the thermochromic material for temperature sensor application. Polyaniline was chosen as the photo-chemical polymer for chemical sensor application. The developed methodology for building these sensors includes modifying the regular optical fibers, by replacing the fiber passive cladding with those sensitive materials. The integration of the sensory system into textile structures, done in collaboration with the North Carolina State University (NCSU), also showed good progress. An overview on the developed methodology and technical achievement is presented.

High-Accuracy WKB Analyses of alpha-Power Graded-Core Fibers

The WKB method is an effective approach to the analyses of propagation characteristics of optical fibers. However, conventional WKB anaIyses can not be applied to close-to-cutoff modes because the effect of core-cladding boundary is not considered exactly. This paper proposes two improved WKB analyses which consider the above effect more exactly. Both of these methods are applicable to the close-to-cutoff modes. The first one is superior in accuracy (for example, relative error in cutoff frequencies /spl lsim/10/sup -5/), but applicable only to quadratic profiles. The second one is applicable to general/spl alpha/ -power profiles; the accuracy is poorer but tolerable for most practical purposes.