200 results about "Propagation constant" patented technology

Optical plasmon-wave attenuator and modulator structures for controlling the amount of coupling between an guided optical signal and a surface plasmon wave. Optical power coupled to the plasmon wave mode is dissipated in varying amounts producing an intensity modulation effect on the optical signal. For electrical modulation, an additional dielectric (or polymer) layer with variable refractive index in optical contact with a metal layer supporting at least one plasmon wave mode is used to perturb or vary the propagation constant of plasmon wave. Propagation constant variation results in the power coupling variation between the surface plasmon wave and the optical wave. The refractive index variation of the dielectric (or polymer) layer can be accomplished via an electro-optic traveling-wave, a lump-element, or any other integrated optics modulator configuration situated to affect the layer, thereby permitting data rates into tens of GHz. Because of the extremely small interaction lengths needed, the optical plasmon-wave modulator is a very compact device which can be implemented on the top of a fiber or as an integrated optical planar structure.

High-speed optoetectronic devices having a waveguide densely integrated with and efficiently coupled to a photodetector are fabricated utilizing methods generally compatible with CMOS processing techniques. In various implementations, the waveguide consists essentially of single-crystal silicon and the photodetector contains, or consists essentially of, epitaxially grown germanium or a silicon-germanium alloy having a germanium concentration exceeding about 90%.

A transmission line microwave apparatus includes at least one nonreciprocal transmission line part, which includes a series branch circuit equivalently including a capacitive element and a shunt branch circuit equivalently including an inductive element. The nonreciprocal transmission line part has gyrotropic characteristic by being magnetized in a magnetization direction different from the propagation direction of a microwave, and has an asymmetric structure to a plane formed by the propagation direction and the magnetization direction. The nonreciprocal transmission line part has a propagation constant and an operating frequency set in a dispersion curve that represents a relation between the propagation constant and the operating frequency so that the propagation constant in the forward direction and the propagation constant in the backward direction have nonreciprocal phase characteristics different from each other. A microwave transmission line is constituted by cascade-connecting at least one non-reciprocal transmission line part between first and second ports.

For the cost effective implementation of negative-index refraction, an anisotropic hyperbolic planar metamaterial comprising a first set of substantially parallel, unloaded and coplanar transmission lines, said first set being spaced with a periodicity dy a second set of substantially parallel, unloaded and coplanar transmission lines, said second set being spaced with a periodicity dx, further being coplanar and substantially orthogonal with said first set of transmission lines, wherein the periodicities of said first set and second set of transmission lines being governed by the relationship βx(fr)dx+βy(fr)dy=2π, where: βx and βy are the intrinsic propagation constants of electromagnetic waves of frequency fr propagating along the first and second set of transmission lines, respectively.

A photonic crystal directional coupler composed of at least two linear defect waveguides introduced into a photonic crystal. The medium constant and the lattice constant of the photonic crystal at the photonic crystal directional coupling part, the sizes and shapes of the elements constituting the periodical structure of the photonic crystal are varied. Thereby the difference in propagation constant between the even and odd modes of the photonic crystal directional coupling part is increased, thus shortening the coupling length of the photonic crystal directional coupler.

Disclosed is an electromagnetic wave transmission device with regulative and controllable magnetic field based on sub-monolayer wavelength metal grating; the device comprises a sub-monolayer wavelength metal grating and magnetoactive medium filled in the slit of the sub-monolayer metal grating; the metal part of the device and the magnetoactive medium have the same thickness, the thickness at least meets and supports the lowest-level Fabry-Perot cavity resonance demand of the designed work wavelength in the grating slit; the period and slit of the grating are shorter than the wavelength of the electromagnetic wave. By changing the size of the additional magnetic field, the propagation constant of the waveguide mode in the metal grating slit can be regulated to change the electromagnetic transmission characteristic of the device and realize the purpose of initial regulation of polarization-independent electromagnetic wave transmission spectrum and the electromagnetic wave transmission spectrum magnetic field.

Optical switches based on the balanced bridge interferometer design require precisely made (or half a coupling length) directional couplers to achieve minimum crosstalk for the two switch outputs. Precision 3 dB-directional couplers require the waveguide dimensions and fabrication parameters of the evanescent region to be tightly controlled making a low crosstalk switch difficult to manufacture and expensive. A new type of balanced bridge interferometer type switch is disclosed where the input and output directional couplers are asymmetrically biased to induce a certain difference in the propagation constants between the two waveguide in the directional couplers. By using the asymmetrically biased directional couplers with a certain tuning a bias voltage for the directional couplers. Low crosstalk switches can be achieved for a very wide range of directional coupler strengths, relaxing the precise half-coupling length directional couplers required in conventional design. This relaxation of the precise directional coupler waveguide regions allows a relaxation in the manufacturing tolerance of the devices and therefore make the switch much easier to make. Because low crosstalk switches can be a device with an extended operating range and broader directional coupler parameters, switches can be used for a much broader wavelength bandwidth. In one of the embodiments, this new design allows a device to switch both TE and TM mode optical signals simultaneously at low crosstalk levels to result in a polarization-independent optical switch.

The invention discloses a radio frequency noise de-embedding method, which comprises the following steps of: forming a device under test, an open de-embedding test structure and a thru de-embedding test structure on a silicon chip; performing tests to obtain scattering parameters of the device under test, the open de-embedding test structure and the thru de-embedding test structure and a noise parameter of the device under test; and performing de-embedding calculation by utilizing each scattering parameter and the noise parameter of the device under test to obtain a noise parameter of a radio frequency device, wherein the normalized characteristic impedance and propagation constant of a pure metal wire are calculated by utilizing the scattering parameters of inter-signal metal wires of the thru de-embedding test structure, and then an ABCD parameter of an input end metal wire or an output end metal wire of the device under test is calculated. By the method, the number of the thru de-embedding test structures on the silicon chip can be greatly decreased, the area of the silicon chip can be saved, test time can be shortened, and cost can be greatly decreased.

An apparatus and associated method for controlling the propagation constant of a region of focusing propagation constant in an optical waveguide. The method comprising positioning an electrode of a prescribed electrode shape proximate the waveguide. A region of focusing propagation constant is projected into the waveguides that corresponds, in shape, to the prescribed electrode shape by applying a voltage to the shaped electrode. The propagation constant of the region of focusing propagation constant is controlled by varying the voltage. Light of certain wavelengths passing through the region of focusing propagation constant has a variable focal length.

Methods are provided for reducing interference from stray currents in buried pipelines/metal structures during MEIS testing or other current-sensing applications in the pipeline. Methods are also provided for measuring bulk complex electrical impedance between a buried pipe and the soil, thereby rendering an indication of the quality of the anti-corrosive coating. Methods are also provided for measuring the complex propagation constant of AC voltages propagating along an attenuative pipeline. This information is useful for assessing the general condition of the anti-corrosive coating involved, or to enhance MEIS inspection of the pipeline. Methods are also provided for enhancements to MEIS testing, including (a) canceling magnetometer offset effects associated with the Earth's magnetic field after the magnetometer is positioned for measurement, (b) implementing a separate sensing connection to the pipe so as to avoid interference from voltage loss in the pipe feed-line connection, (c) providing a power amplifier to excite the pipe with large-amplitude signals.

There is disclosed an optical fiber wherein an absolute value of the fourth order dispersion β₄ of fourth derivative β₄ of propagation constant β with respect to angular frequency ω at a mean zero dispersion wavelength λ₀ in an overall length is not more than 5×10⁻⁵⁶ s⁴/m and wherein a fluctuation of a zero dispersion wavelength along a longitudinal direction is not more than ±0.6 nm.

A system and method for using loop topology identification to investigate a transmission line having a plurality of cable segments. At a measurement plane for each segment, a probing signal is transmitted into the cable. A reflected signal is detected, and an equivalent total input impedance is calculated. The system iteratively calculates the distance between the measurement planes as well as the length, characteristic impedance, and the propagation constant of each segment. A model is used to calculate the respective equivalent input impedance of each segment using the calculated characteristic impedance, propagation constant, and length of the preceding segment. The equivalent total input impedance is then calculated from the iteratively calculated segment values.

An apparatus and method for transmitting a plurality of light signals is disclosed. The apparatus includes a splitter configured to split an incoming light signal into a plurality of light signals. Phase control units are included which modify the phase of the light signals. Waveguides are coupled to the phase control units. Each waveguide has a different propagation constant, that is different from adjacent waveguides and the difference between the propagation constants of any two adjacent waveguides is substantially larger than an effective coupling constant between said two adjacent waveguides. Coupling members couple the light signal in one of the plurality of waveguides to free space. The splitter may include output and/or input waveguides and a dispersion element splitting and/or combining: light.

The invention provides a novel over-mode circular waveguide broadband directional coupler and a design method thereof. According to the over-mode circular waveguide broadband directional coupler and the design method thereof, a standard rectangular waveguide in the traditional over-mode circular waveguide directional coupler is replaced with a non-standard over-mode rectangular waveguide; the cutoff wave number of a basic mode TE10 of the non-standard over-mode rectangular waveguide is changed through adjusting the size of the non-standard over-mode rectangular waveguide, and the cutoff wave number of the basic mode TE10 of the non-standard over-mode rectangular waveguide is enabled to be the same as that of a working mode TEmn in an over-mode circular waveguide, so that the propagation constant of the TE10 at any frequency point is the same as that of the TEmn, then, forward waves of the coupler can meet equidirectional superposing conditions at any frequency point, and the aims of expanding the working bandwidth of the over-mode circular waveguide directional coupler and reducing in-band coupling degree fluctuation are achieved.

Techniques for implementing series-fed antenna arrays with a variable dielectric waveguide. In one implementation, coupling elements with optional controlled phase shifters are placed adjacent each radiating element of the array. To avoid frequency sensitivity of the resulting array, one or more waveguides have a variable propagation constant. The variable waveguide may use certain materials exhibiting this phenomenon, or may have configurable gaps between layers. Plated-through holes and pins can control the gaps; and/or a 2-D circular or a rectangular travelling wave array of scattering elements can be used as well.

The invention relates to a metal film lens with nano-suture, and is characterized in that: an incident wave is firstly determined, and then proper substrate material is chosen, a layer of metal film is vapor deposited on a substrate, the incidence of the incident wave is vertical to the surface of a metal film, and then the skin depth of the incident wave in the chosen metal film is computed; the direction of X axis is chosen along the metal film, and sampling is implemented along the forward direction of X axis; then the width of the metal suture of each sample point is computed by computing the phase offset and the propagation constant of each sample point; a suture distribution along the negative direction of the X axis which is symmetrical to the suture distribution along the forward direction is chosen; finally the suture width of each sample point is obtained according to the design; then a metal film lens with nano-suture is produced by using the existing processing technology. The invention can change the suture distribution of the metal film lens according to the position of any given objective image to achieve the near field imaging or the distant field imaging, simultaneously the designed lens of the invention has simple structure, and can be used for the optical system integration extremely conveniently, the lens has extensive application prospect.

A duplexer includes: a first filter of which first and second ends connect to a common terminal and a first terminal respectively; and a second filter having a passband higher than that of the first filter, a first end and second end thereof connecting to the common terminal and a second terminal respectively, wherein a phase shifter is located neither between the first filter and the common terminal nor between the second filter and the common terminal, the second filter is a ladder-type filter including piezoelectric thin film resonators connected in a ladder shape, a propagation constant in a direction perpendicular to a thickness direction of a piezoelectric thin film in the piezoelectric thin film resonator is a real number at frequencies lower than a resonance frequency of the piezoelectric thin film resonator, and a resonator at a first stage is a parallel resonator in the second filter.

The invention relates to an electro-optic directional coupler suitable for use as a variable optical attenuator at reduced voltages compared to those known in the prior art. The present invention has found that by careful selection of an asymmetric directional coupler geometry, the transfer function of the device can be shifted so that it has an operating point between maximum and minimum transmission. Signal electrodes driven in push pull configuration advantageously use this operating point to achieve significant reduction in operating voltages for switching to maximum or minimum transmission. Asymmetry is created in the directional coupler by forming the waveguides to have different propagation constants by a difference in waveguide width, depth, index of refraction or index profile. Asymmetry can alternatively be created by causing mechanical stress in the waveguides through the placement, number, or dimensions of the electrodes, or through asymmetric dielectric structures between the waveguides and the electrodes.