Showing papers on "Radiation mode published in 1972"

Coupled-Mode Theory for Optical Fibers

Abstract: A set of coupled-mode equations is derived to describe mode propagation in uniform and slightly nonuniform cylindrical optical-fiber systems. The coupling between fibers of an array made up of n identical fibers each at the vertex of a polygon and one at the center, which is not necessarily the same as its n neighbors, is determined. Examples of this array are two fibers, three fibers in a row, and a hexagonal array with a fiber in the center. Very simple expressions for the coupling coefficients are presented. Mode coupling on a lossy fiber is investigated and a simple expression for the loss of a HE11 mode is given.

Dipole mode electromagnetic waveguides

Abstract: A new form of waveguide is described which can support propagation of electromagnetic waves in the dipole mode. The waveguide is coaxial with inner and outer members having cylindrical surfaces separated by a dielectric. The longitudinal and transverse impedances of these surfaces and the dielectric material are such that propagation in the dipole mode is possible. Structures having the necessary surface impedances are described. Apparatus for launching the dipole mode and extracting power from it are also described.

Optical waveguide light source coupler

Abstract: A light coupler for efficiently utilizing light from a source of optical wave energy in the initiation of light mode propagation in an optical waveguide. The coupler comprises a tapered core of transparent material and a layer of transparent cladding material disposed upon the surface of the tapered core. The refractive index of the core is greater than that of the cladding layer. The core has a large diameter end terminating in an optically polished surface which is adapted to receive light from the light source. The small diameter end of the core is substantially aligned with the core of the optical waveguide.

Propagation Mode and Scattering Loss of a Two-Dimensional Dielectric Waveguide with Gradual Distribution of Refractive Index

Abstract: An analytical discussion of the mode property and the scattering loss of a two-dimensional dielectric waveguide with gradual refractive-index distribution in the transverse direction is presented. To describe scattering loss, a transverse correlation as well as an axial correlation of the irregular variation of the refractive index have been used. The field distribution, the group delay, and the maximum film thickness of a single-mode waveguide scarcely depends on the shape of the distribution. The maximum value of the film thickness in the single-mode transmission region optimizes the scattering loss and the energy confinement. The scattering loss of a waveguide with a gradual index distribution is smaller than that of a three-layer waveguide when the transverse correlation is small, but it is not much altered when the transverse correlation is large.

Optical waveguide display panel

Abstract: An optical waveguide which is provided with a means such as structure or change of index of refraction of the material to deflect light out of the waveguide along a desired path.

Optical waveguide mode discriminator

Abstract: Light radiating from a multimode optical waveguide is coupled to the input ends of a plurality of optical waveguide mode discriminators, each of which has a light detector for receiving light radiating from the output thereof. The first mode discriminator propagates only the lowest order mode propagated by the multimode waveguide, the second mode discriminator propagates only the lowest and second lowest order modes, and so on. The amplitudes and phases of the lowest order mode signals provided by the detectors associated with the first and second mode discriminators are equalized and these two equalized signals are coupled to a substracter circuit which cancels the lowest order mode signals and provides a signal representative of the information propagated by the second lowest order mode. In a similar manner the information propagated by higher order modes can be obtained.

Light source coupler for optical waveguide

Abstract: A light coupler for transferring optical wave energy to or from an optical waveguide. This coupler comprises a core of transparent material surrounded by a thin layer of transparent cladding material having a thickness less than a few wavelengths. A conically shaped member which surrounds the transparent layer has its base disposed adjacent to the end of the optical waveguide. The refractive index of the transparent layer is lower than that of the core and the conical member. To couple light to the waveguide, a light beam directed at the tapered surface of the conically shaped member is refracted thereby toward the transparent layer where a portion thereof tunnels into the core and is thereafter coupled into the waveguide. When it is utilized as an output coupler, light radiates from the tapered surface at an angle dependent upon the mode of propagation in the waveguide.

Apparatus for measuring density and moisture

Abstract: A device for monitoring density of a rod of tobacco in a cigarette-making machine comprises a source of microwave radiation and a waveguide through which said radiation is propagated in the evanescent mode to a detector. The rod is passed across the path of the radiation, through apertures in the walls of the waveguide. The radiation may be split into two beams, one beam being directed through said waveguide and the other beam directed through a second, similar waveguide to a second detector providing a reference signal.

Devices for varying thin film waveguiding properties

Abstract: Operations such as modulation, switching, mode conversion and the like are performed on light propagating in a thin film waveguide by a liquid crystal member overlaying a portion of the waveguide. The material of the crystal is such that its index of refraction in the direction of wave propagation, and normal thereto, is varied by application of an electric field, thereby producing a variation in the waveguiding properties of the waveguide. Using the same principles, mode filtering is achieved by overlaying a portion of the waveguide with an anisotropic material.

Mode conversion using circumferentially corrugated cylindrical waveguide

Abstract: The principle of mode conversion using a tapered-reactance cylindrical waveguide surface is summarised. Experimental results are given for a multistage convertor which converts a TE11 mode into the HE11, TM11 and EH12 modes in successive stages.

Waveguide mode coupler for separating waves of useful mode from waves of higher mode

Abstract: A mode coupler useful in ranging systems for evaluating higher waveguide wave modes resulting from aperture deviations of an antenna exciter for determining angular deviation in the azimuth plane as well as in the elevation plane. Waves of the useful mode are separated from waves of a higher mode. A first waveguide section for propagating all evaluatable wave modes is adapted to be coupled to an antenna. A second waveguide section for propagating exclusively the useful wave mode is connected in series with the first waveguide section. A gap is provided between the first waveguide section and the second waveguide section and is provided with a plurality of apertures for the higher wave modes in the direction of propagation of the waves. New modes corresponding to the higher wave modes are substantially excited by the useful mode containing the ranging signal.

On the theory of transition radiation in a waveguide

Abstract: The transition radiation from a particle that intersects the waveguide perpendicular to its axis is considered. The expressions are derived for the radiation fields and intensities. The example of a rectangular waveguide is used to investigate the properties of the radiation, and the conditions which determine the Vavilov-Cerenkov radiation spectrum are derived.

Circular waveguide mode filter

Abstract: A circular waveguide mode filter is provided which comprises a circular waveguide consisting of an upper and lower semicircular waveguide sections and in which dielectrics or magnetic materials are disposed in either of the upper or lower waveguide sections or in both of them in a special spatial relation with them so that the desired TE01 signal mode may be propagated through the waveguide while the undesired TE0n (where n > OR = 2) modes are absorbed.

The Zoning of Radiation Mode of Finite Plate on a Wavenumber Diagram

Abstract: It is convenient to show various radiation modes of a resonant panel on a wavenumber diagram to clarify the dependence of radiation on frequency and vibration mode pattern. A correct zoning of the radiation mode on wavenumber diagram and some deductions concerning the critical frequency of a finite plate are presented.