Showing papers on "Fiber Bragg grating published in 1975"

Polarization-selective laser mirror

Abstract: An optical substrate has an electrically conductive grating on one surface. Over the grating is a multilayered dielectric coating.

Formation of a Spherical Lens at Optical Fiber Ends with a CO(2) Laser.

Abstract: A study was made of the use of a CO(2) laser for producing a hemispherical lens at the end of a fiber. When the fiber end is heated to the softening points of the material, it tends to become spherical in shape due to surface tension. A one-dimensional heat conduction model for the fiber can reasonably predict the required laser power for a given pulse length to produce lenses on fibers made of various kinds of materials. A He-Ne laser beam was coupled into a fiber to investigate the properties of the spherical lens. We also observed that such lens can couple light from a source into the fiber, can be used for imaging, and can focus enough laser intensity for machining various materials.

Directing optical beam

Abstract: Methods and apparatus for directing a beam of optical radiation toward a selected location and modulating the intensity thereof at the location by directing the beam over a path that includes a Bragg grating, and selectively modifying the angle between the direction at which the beam enters the Bragg grating and a direction of Bragg incidence of the grating by applying an electric or acoustic field to change the index of refraction in a portion of the path. An electric field may be applied either by interdigital electrodes at the grating, to change the Bragg angle thereof, or by electrodes at different angles across an earlier portion of the path, to change the direction at which the beam enters the grating. An acoustic field may be applied in an analogous manner. Useful for modulating and switching in planar wave guides and bulk material.

Double optical fiber waveguide ring laser gyroscope

Abstract: A laser gyroscope for determining rotation of an area circumscribed by two closely adjacent optical fiber waveguides which serve as double laser cavities. Laser oscillation is restricted to one direction only in each optical fiber waveguide with the direction of oscillation in each waveguide being opposite to that in the adjacent optical fiber waveguide. Fractional parts of the laser radiation from the laser oscillation in each optical fiber waveguide are superimposed to develop a beat frequency therebetween which is proportional to the angular rotation of the area circumscribed by the two optical fiber waveguides.

Fiber-optic laser illumination

Abstract: Multiple-wavelength light from an ion laser was transmitted through a 85-µm optical fiber to provide illumination for viewing and color photography. Also adequate black-and-white TV display and photography were obtained using red light from an He-Ne laser transmitted through the same optical fiber.

Electro-optic diffraction grating tuned laser

Abstract: An electro-optic diffraction grating tuned laser comprising a laser medium, utput mirror, retro-reflective grating and an electro-optic diffraction grating beam deflector positioned between the laser medium and the reflective diffraction grating. An optional angle multiplier may be used between the electro-optic diffraction grating and the reflective grating.

Woven fiber optics.

Abstract: In this paper we describe how the art of weaving can be applied to fiber optics in order to produce precisely controlled reproducible image guides and image dissectors. As examples of the types of device for which woven fiber optics are applicable, we describe a 3:1 interleaver for use with a cathode-ray tube to produce color images, and a high speed alpha numeric output device. The techniques of weaving fiber optics are discussed in sufficient detail in order to allow for further work. Although, in principle, one might be able to weave glass optical fibers, all the work described here made use of plastic optical fibers 0.25 mm in diameter.

Coherence of laser radiation traveling along an optical fiber

Abstract: The degree of coherence of the laser radiation transmitted by a single optical fiber was determined by the Young interference method. It was found that the modulus of the complex degree of coherence decreased with increasing fiber length and also with decreasing diameter (in the case of large diameters). However, for fibers up to 10 cm long this modulus did not fall below ~0.7. The results obtained were explained by a difference between the paths of different rays of the laser beam which appeared during the passage through the fiber; the imperfections in the fiber also played an important role. The main factors responsible for the path difference were considered and their relative importance was estimated.

Semiconductor laser with a distributed feedback

Abstract: Stimulated emission was obtained from an optically pumped gallium arsenide laser with a distributed feedback The feedback was produced by a diffraction grating formed on the surface of a p –type GaAs layer prepared by the diffusion of zinc into an n –type substrate The grating was in optical contact with the active layer and its period satisfied the Bragg condition for a guided mode within the gain band of the laser For the selected Bragg scattering order, the radiation was extracted at right angles to the grating surface The far-field distribution consisted of a single lobe with a divergence of 5–20', which corresponded to the emission from one to five randomly distributed modes whose frequencies depended on the position of the excited region in the laser

Use of gradient light guides in semiconductor lasers

Abstract: A gradient light guide (glass fiber) with a parabolic distribution of the refractive index was used in a semiconductor laser resonator and as a collimator. A fiber 19 mm long of 0.8 mm radius and with a refractive index fall of 3×10−10 was brought into direct contact with a laser and produced a light beam of 10–14 mrad divergence. It was found that a fiber with a silvered end influenced the spectrum and the intensity of the laser radiation.