Abstract: Disclosed is a Cassegrain-type antenna. The Cassegrain-type antenna may comprise a main-reflector; a sub-reflector; and a radiator radiating beams by using a plurality of emitters. Also, a reflective surface of the sub-reflector has a shape of a trace formed by rotating a first curve having a vertex and being convex toward the main-reflector around a rotation axis spaced apart from the vertex.

Abstract: Provided are a technique for providing focused Bessel beams having orbital angular momentum (OAM) to a plane to solve a problem of the related art in which Laguerre-Gaussian (LG) beams having OAM and used for multiplexing of a microwave transmission system are dispersed, and an electromagnetic wave generation apparatus and method for implementing the technique.

Abstract: The present invention relates to an image detecting method of an image detector which processes a shape of an edge of an image input aperture of a 2D image detector which is used in a terahertz band whose frequency is lower than that of infrared light to have a predetermined shape so that a diffraction pattern due to the aperture is not shown in a captured image or a contrast is weakened, thereby obtaining a clear object image with a reduced distortion.

Abstract: Provided is antenna having metamaterial and providing gain improvement and beamforming together. The antenna includes a resonator and a superstrate. A feed antenna is disposed in the resonator. The superstrate includes a conductive pattern on the resonator for improving gain and beamforming of the feed antenna.

Abstract: Disclosed are a method and an apparatus for analyzing a sample using terahertz waves. The method of analyzing a sample using terahertz waves includes: generating terahertz waves; simultaneously radiating two or more electromagnetic waves with different radiation angles, using the terahertz waves with a transmitting antenna; receiving the two or more electromagnetic waves transmitting the sample with a receiving antenna; and acquiring an analysis image of the sample by processing the received two or more electromagnetic waves In accordance with the present invention, it is possible to reduce the time taken to acquire an analysis image of a sample by simultaneously radiating terahertz waves with different radiation angels from one antenna.

Abstract: A metamaterial transmission line for transmitting an electromagnetic wave. The metamaterial transmission line may include a substrate including a substrate configured to include a an upper portion and a lower portion on which a ground plane is formed, a signal line configured to be formed on the substrate, and a defected ground structure configured to include an etched region and two metal portions, wherein the etched region is generated by etching a part of the ground plane and the metal portions extend from the signal line and are disposed on the etched region.

Abstract: Provided is a high power efficiency optical-wireless transmitter capable of solving problems of low power efficiency, signal distortion due to non-linearity of output, large number of connection terminals, and non-uniformity of optical power intensities of optical sources. The high power efficiency optical wireless transmitter includes: an amplitude-to-array coder converting an amplitude of an electric signal input from a baseband modulator into optical source control signals so as to generate an optical output power corresponding to the electric signal; optical source driver groups driving optical sources based on the optical source control signals of the amplitude-to-array coder; and MMRS (modified mixed radix system) or MMRR (modified mixed radix system with Redundancy) optical source group driven by the optical source driver groups to generate various optical power intensities.

Abstract: Disclosed are a projecting type hyper-lens and a method of manufacturing the same. The projecting type hyper-lens includes a main lens layer and a substrate layer. A front surface of the main lens layer is recessed. The substrate layer supports the main lens layer. A front central portion of the main lens layer protrudes beyond a surface of the substrate layer. The projecting type hyper-lens allows an object to move towards a front surface of the hyper-lens until a distance between the front surface of the hyper-lens and the object is smaller than a half-wavelength of light, and thus images an object smaller than a half-wavelength of used light. Evanescent waves scattered from an object is used in a manner convenient to a user.

Abstract: A metamaterial transmission line for transmitting an electromagnetic wave. The metamaterial transmission line may include a substrate including a substrate configured to include a an upper portion and a lower portion on which a ground plane is formed, a signal line configured to be formed on the substrate, and a defected ground structure configured to include an etched region and two metal portions, wherein the etched region is generated by etching a part of the ground plane and the metal portions extend from the signal line and are disposed on the etched region.

Abstract: Provided is antenna having metamaterial and providing gain improvement and beamforming together. The antenna includes a resonator and a superstrate. A feed antenna is disposed in the resonator. The superstrate includes a conductive pattern on the resonator for improving gain and beamforming of the feed antenna.

Abstract: Disclosed are a projecting type hyper-lens and a method of manufacturing the same. The projecting type hyper-lens includes a main lens layer and a substrate layer. A front surface of the main lens layer is recessed. The substrate layer supports the main lens layer. A front central portion of the main lens layer protrudes beyond a surface of the substrate layer. The projecting type hyper-lens allows an object to move towards a front surface of the hyper-lens until a distance between the front surface of the hyper-lens and the object is smaller than a half-wavelength of light, and thus images an object smaller than a half-wavelength of used light. Evanescent waves scattered from an object is used in a manner convenient to a user.

Abstract: Provided is a high power efficiency optical-wireless transmitter capable of solving problems of low power efficiency, signal distortion due to non-linearity of output, large number of connection terminals, and non-uniformity of optical power intensities of optical sources. The high power efficiency optical wireless transmitter includes: an amplitude-to-array coder converting an amplitude of an electric signal input from a baseband modulator into optical source control signals so as to generate an optical output power corresponding to the electric signal; optical source driver groups driving optical sources based on the optical source control signals of the amplitude-to-array coder; and MMRS (modified mixed radix system) or MMRR (modified mixed radix system with Redundancy) optical source group driven by the optical source driver groups to generate various optical power intensities.

Abstract: Provided are a time-division data multiplexing/demultiplexing system and method capable of preventing errors in processing data signals which occur due to a phase difference between data signals and a multiplexing reference clock in a multiplexing process or a phase difference between a multiplexed data signal and a demultiplexing reference clock in a demultiplexing process. The time-division data multiplexing system includes: a phase adjusting unit which adjusts a phase of each of a plurality of data signals having different phases from one another for enabling the data signals to be time-division multiplexed when a plurality of values of the data signals indicate a stable state; and a multiplexer time-division multiplexing the phase adjusted data signals according to a multiplexing reference clock.

Abstract: The present invention relates to an apparatus and method for extracting an optical clock using filters and an amplifier. The object of the present invention is to provide an extraction of neighboring frequency components using wavelength fixed optical filters and an amplifier. In accordance with an aspect of the present invention, there is provided an apparatus for extracting an optical clock to extract a clock from the optical signal provided with plurality of peaks on a spectrum, including a first filter for extracting a central frequency component, a second filter for extracting a frequency component adjacent to the first frequency component, the amplifier for amplifying amplitude of the second frequency component until the amplitude of the second frequency component becomes the same as that of the first frequency component and the receiver for extracting a clock to do beating the first frequency component and the second frequency component.

Abstract: Provided are a method and an apparatus for detecting the fault of an optical switch. The apparatus includes an optical monitoring signal generator, a coupler, a splitter, a plurality of optical detecting and output power transition sensing units, and a fault determiner. The optical monitoring signal generator generates optical monitoring signals having different wavelengths from optical signals including data to be transmitted. The coupler optically couples the optical monitoring signals to the optical signals including data to be transmitted and inputs the coupled optical signals to an optical switch. The splitter splits the optical monitoring signals from optical signals output from the optical switch. The plurality of optical detecting and output power transition sensing units detect output power transitions of the split optical monitoring signals.

Abstract: The present invention relates to an apparatus and method for extracting an optical clock using filters and an amplifier. The object of the present invention is to provide an extraction of neighboring frequency components using wavelength fixed optical filters and an amplifier. In accordance with an aspect of the present invention, there is provided an apparatus for extracting an optical clock to extract a clock from the optical signal provided with plurality of peaks on a spectrum, including a first filter for extracting a central frequency component, a second filter for extracting a frequency component adjacent to the first frequency component, the amplifier for amplifying amplitude of the second frequency component until the amplitude of the second frequency component becomes the same as that of the first frequency component and the receiver for extracting a clock to do beating the first frequency component and the second frequency component.

Abstract: The present invention provides a clock extraction apparatus and method for an optical signal. The clock extraction apparatus includes optical branching means, optical filtering means, and clock extraction means. The optical branching means branches an optical signal, which has been transmitted from a transmitting end to a receiving end, into a plurality of optical signals to be transmitted to a plurality of paths. The optical filtering means simultaneously reflects the center wavelength and a specific side peak wavelength of the optical signal, which has been transmitted to a first path of the plurality of paths, to the optical branching means, the specific side peak wavelength being spaced apart from the center wavelength by a clock frequency. The clock extraction means extracts a clock by detecting and bandpass filtering the beating signal from the center wavelength and the specific side peak wavelength reflected to the optical branching means.

Abstract: Provided are a method and an apparatus for detecting the fault of an optical switch. The apparatus includes an optical monitoring signal generator, a coupler, a splitter, a plurality of optical detecting and output power transition sensing units, and a fault determiner. The optical monitoring signal generator generates optical monitoring signals having different wavelengths from optical signals including data to be transmitted. The coupler optically couples the optical monitoring signals to the optical signals including data to be transmitted and inputs the coupled optical signals to an optical switch. The splitter splits the optical monitoring signals from optical signals output from the optical switch. The plurality of optical detecting and output power transition sensing units detect output power transitions of the split optical monitoring signals.

Abstract: This invention relates to optical devices such as a fiber-optic frequency shifter and an optical interferometer. This invention also relates to a method of generating optical interference signals to obtain reliable sensor signals independent of polarization fluctuations of the optical waves in the fiber. Fiber-optic interferometers have many advantages such as high sensitivity and convenient way of using even in poor surrounding environments. These interferometer, however, exhibit polarization dependent signal degradation since the polarization of a light wave passing through an optical fiber irregularly changes depending on the birefringence of the fiber. This invention is characterized in that the frequencies of two orthogonal eigen polarizations of a light wave are shifted to different frequency values at one optical path of the interferometer. They produce two beat interference signals after interfering with the light wave passed through the other optical paht of the interferometer.

Abstract: The present invention relates to a Sagnac interferometric sensor array for acoustic sensing and method of sensing acoustic signal that is able to observe acoustic signals coming from several sources simultaneously. The acoustic sensor of the present invention is a Sagnac interferometric sensor array employing a depolarizer. Unlike a single Sagnac interferometric sensor, two light signals traveling in the opposite directions from each other pass through the off-center position of the loop at different times in the Sagnac loop when they are pulses, and thus, it is possible for the light pulses to be maintained at a constant phase difference by giving arbitrarily a certain amount of phase to them. By using the fact, the interferometer is constructed in such a way that the interference light output coincides with the applied acoustic signals in waveform. This invention suggests a way of fabricating an array of fiber-optic acoustic sensors that is easy to be made and is highly sensitive at some frequency band.