Showing papers on "Radiation mode published in 1971"

Bending losses of the asymmetric slab waveguide

Abstract: The bending losses of the asymmetric slab waveguide are computed. The computation is based on the knowledge of the exact form of the solution of Maxwell's equations of the bent structure and the additional assumption that the field near the bent waveguide can be approximated by the field of the straight waveguide. The result of this theory is in good agreement with an existing theory. It appears that the bending loss formula can be used to estimate the bending losses of the round optical fiber if the mode parameters entering the formula are replaced by the corresponding mode parameters of the round fiber. We present curves that allow the numerical evaluation of the bending loss of the lowest order even TE mode of the symmetric slab waveguide.

Mode Reflectivity and Waveguide Properties of Double-Heterostructure Injection Lasers

Abstract: It is shown that the mirror reflectivity for tightly confined planar waveguide modes becomes a function of both the waveguide and mode parameters. This dependence of the mirror reflectivity plays the dominant role in the selection of the oscillating transverse modes and explains why room‐temperature cs‐type double‐heterostructure lasers tend to lase in higher‐order TE modes. Experimental investigations show that the waveguide and mode parameters are qualitatively consistent with a dielectric step waveguide which is mainly perturbed by small gradients of the optical dielectric constant arising from impurity segregation.

Pulse transmission through a dielectric optical waveguide.

Abstract: Waveguide propagation of a pulse-modulated carrier wave is formulated to include distortion due to dispersion in both attentuation and phase velocity. An optimum input gaussian pulse width exists for maximum information carrying capacity. Results are applied to a numerical study of several singlemode glass optical waveguides in which mode and dielectric dispersion may total zero at some wavelength. For our low-loss (20 dB/km) guides in kilometer lengths, information rates of at least 3 x 10(10) bits/sec should be attainable.

Propagating modes of a metal-clad dielectric-slab waveguide for integrated optics

Abstract: Propagating modes of a dielectric-slab waveguide consisting of a dielectric core and metal clads are analyzed numerically by using a simplified model The behavior of modes is graphically shown and their peculiarities due to dielectric properties of metal are described It is shown that the TE 0 mode has the smallest attenuation constant when the wavelength is sufficiently short and that the TM 0 mode changes continuously to the TEM mode of a parallel-plate waveguide in the submillimeter region, but it has generally a very high attenuation at an optical wavelength

Voltage‐Induced Optical Waveguide

Abstract: An optical waveguide based on electro‐optic index changes in LiNbO3 has been constructed. Voltage and polarization dependence of the waveguide mode structure has been observed and is described qualitatively with a simple theory.

Waveguide gas laser devices

Abstract: There are disclosed gas lasers in which the light is guided by a hollow dielectric waveguide which also serves to confine the discharge. These lasers are typically designed to have resonators with Fresnel numbers small enough (less than DIFFERENCE 0.5) to suppress the dominant free space mode and having sufficient gain for a waveguide mode of oscillation to exist. Each laser has an internal resonator structure and is designed in such a way that the electrical excitation of the gas discharge can be accomplished without interfering with the light guiding properties of the waveguide. Several novel techniques for forming waveguide laser tubes of the required small dimensions are also disclosed. The embodiments include a capillary ring-type configuration that is r.f.-excited, a distributed feedback configuration using periodic changes in waveguide bore cross section, or wall index of refraction, and various rectangular waveguide configurations, for example, two flat glass plates spaced at the edges by two thin-film strips.

Method of making waveguide mode filter

Abstract: A waveguide mode filter comprising a dielectric-lined waveguide having a series of electrically lossy vanes in the lining parallel to the waveguide axis dissipates longitudinal and radial current components produced by unwanted modes and thereby suppresses such modes. A method of forming the vanes includes the steps of flooding the dielectric-lined waveguide interior with a solution containing lossy particles, drawing a cutting head through the waveguide to slice the dielectric lining so that the solution flows into the incisions and is trapped therein, and drawing a wiper through the waveguide to remove the excess solution.

Waveguide mode transducer

Abstract: A transducer for converting the TE20 rectangular wave mode into the TM11 circular wave mode utilizes a circular waveguide capable of supporting the TM11 mode which is mounted to a broad side of a rectangular waveguide transmitting the TE20 wave mode. Two antiphase coupling ports formed at prescribed distances from the center of the circular waveguide and along a diameter thereof which is perpendicular to the longitudinal axis of the rectangular waveguide transfer energy from the TE20 wave mode into a substantially pure TM11 mode in the circular guide when the proper electrical and magnetic field patterns are obtained at the ports by adjusting a movable plunger within the rectangular waveguide.

Multi-mode, monopulse feed system

Abstract: A wide band multi-mode feed device, capable of propagating a TE10 and a hybrid shaping mode is provided. A narrow ridge hybrid mode generator, disposed between a mode cavity and a mode phasor, controls a sum pattern E-plane shaping mode. The narrow ridge provides only a negligible coupling to the TE20 mode since the narrow ridges are placed only in the null regions of the TE20 mode. The mode cavity and an inverse mode launcher control unwanted cross polarization resulting from the TE11 and TM11 modes. This device is most useful for high efficiency monopulse antenna systems and especially for systems where the accurate gathering and analysis of tracking data is a prime requisite.

Electronically tunable optical filter using acoustic waves

Abstract: A tunable optical filter suitable for use in integrated optical circuits including the combination of a substrate having an optical waveguide such as a thin film thereon. Means such as an optical fiber or grating is provided for introducing light waves in a first mode into the waveguide. An acoustic transducer driven by a tunable electronic signal source is used to propagate acoustic waves on the surface of the waveguide. The optical and acoustic waves interact to produce another optical wave having a mode different than the original optical wave when phase matching conditions are satisfied. A mode filter is located in the waveguide to block the original optical wave and pass the second optical wave.

Field configuration of the TMc01 mode in an elliptical waveguide

Abstract: A new field configuration for the TMc01 mode in an elliptical waveguide is proposed. The theoretical computations are verified by practical measurements.

Stable resonators with increased fundamental mode volume for CO2 laser oscillators

Abstract: A method is described for designing a single mode CO2 laser cavity of high Fresnel number which oscillates in the fundamental transverse mode and a single longitudinal mode. A short, large bore cavity was constructed which oscillates in the TEM00 mode without the use of intracavity irises. The radii of curvature of the reflectors were designed using the Gaussian beam equations of Kogelnik and Li and an experimentally determined mode selection parameter.

A Laser Resonator with a Selector for a Higher Transverse Mode (Correspondence)

Abstract: A new laser resonator is proposed in which a specified higher order Hermite-Gaussian mode becomes the lowest loss mode. The two reflectors in the resonator are blocked in the vicinity of the characteristic zeros of the mode and the edge (i.e., |x|, |y| /spl rlarr2/ /spl infin/). In such a configuration the mode volume is enhanced, and mode selection is improved as compared with a conventional resonator in which a Gaussian mode is the dominant one. We have specialized to TEM/sub 22/ mode. The solutions to the integral equation for the eigenmodes and eigenvalues of the resonator are obtained on a digital computer. The computed eigenfunctions and mode selection show several interesting characteristics, and the loss mechanism for a few low-loss modes are elucidated. The computational results show that the location and the width of the blocking structure are closely related to the mode competition phenomenon and therefore mode selection.