Showing papers on "Photonic-crystal fiber published in 1971"

Weakly guiding fibers.

Abstract: Thin glass fibers imbedded into a glass cladding of slightly lower refractive index represent a promising medium for optical communication. This article presents simple formulas and functions for the fiber parameters as a help for practical design work. It considers the propagation constant, mode delay, the cladding field depth, and the power distribution in the fiber cross section. Plots vs frequency of these parameters are given for 70 modes

Measured attenuation and depolarization of light transmitted along glass fibers

Abstract: Loss measurements have been made on glass fibers immersed in index matching oil. The measurements include state of polarization analyses of the light leaving fiber ends. The character of the beam was determined by using α λ/4 plate in conjunction with a polaroid analyser to measure the components of unpolarized and polarized light. The data indicates that unclad fibers attenuate light much more than similar glass clad fiber waveguides. Mode purity within a multimode glass fiber was estimated from measurements of the admixture of modes leaving its end. Light guided along unclad fibers was considerably less distorted than light propagating along similar clad waveguides.

Holographic Fiber Optics

Abstract: Image-guiding structures analogous to fiber-optics plates have been prepared in a cast sheet of sensitized poly(methyl methacrylate) (PMMA) 1 by recording a pair of thick refractive index gratings at right angles to each other and to the surfaces of the sheet. The resulting structure is a periodic array of high index columns surrounded by lower-index regions and extending from one surface of the sheet to the other. When an image is introduced at one face of the array, the image is transmitted in discrete form to the opposite face, with the result illustrated by Fig. 1. The pictures in the figure were made by placing a piece of microfilm on a microscope slide, laying the P M M A bearing a circular guiding region atop the microfilm and photographing two different focal planes in transmitted light at 55 × magnification (N.A. = 0.15). For the upper picture, the microscope was focused through the 1-mm thick sheet of P M M A onto the microfilm. The guiding region lies below the rough curved boundary. For the lower picture, the microscope was focused on the upper surface of the P M M A sheet. Image transfer has occurred only where the index structure exists. Elsewhere the image is badly out of focus. The gratings that form the guiding structure have periods of 8.5 jum and at the magnification of Fig. 1 are visible as a fine mesh

Light Interface Technology Improvement Investigation.

Abstract: : The report establishes a baseline model for an optical data link utilizing a single fiber bundle. This model is solely concerned with light interface technology (LIT) for digital signal transmission. Data link performance is characterized by the pulse amplitude, pulse rise and fall times, pulse delay, and signal-to-noise ratio of the photodiode output. The LIT link has been analyzed as an entirety considering four major areas; light emitting diodes, fiber optic light guide, fiber optic/diode interface, and photodiode. Fiber optic/diode interface has been investigated with regard to loss mechanisms of coupling light into and out of fiber bundles. Fiber optic light guides have been surveyed and evaluated. The three major types that have been given consideration are total internal reflection fibers, total internal refraction fibers and waveguide mode fibers. Space division multiplexing investigations considering Lambertian sources were completed for the TIR and SELFOC fiber types. Number of channels possible, optical cross coupling of fibers, and sampling effect are the main topics discussed. Analog properties of a typical link were investigated with respect to distortion. Experiments were completed using various wavelength LEDs and at various temperatures. (Author)