Showing papers on "Fiber Bragg grating published in 1971"

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