Abstract: This invention provides a wavelength converter and an optical cross-connect system using the same. The inventive system enables one multi-wavelength light source to provide each wavelength converter with the necessary tuned wavelength, without using individual light sources with different wavelengths for each wavelength of a multiplexer. The wavelength converter converts the input multi-channel optical signals into wavelengths used for a subsequent transmission. A wavelength division multiplexer is provided to divide all input optical signals connected to the output link into wavelength units, or collects the divided wavelength-unit optical signals. Meanwhile, a multi-wavelength light source generates a multi-wavelength optical signal, which is applied to and de-multiplexed by the wavelength division multiplexer, and then adapted as a tuned wavelength for wavelength conversion of each channel optical signal.

Abstract: Disclosed is a method for fabricating high-purity silica glass using a sol-gel processing that includes the steps of: (a) mixing a deionized water with a fluorine compound and a dispersion agent to prepare an aqueous premix solution; (b) mixing the aqueous premix solution with a fumed silica; (c) mixing the resulting mixture to form a dispersed sol; (d) aging the sol at the ambient temperature to stabilize silica particles; and, (e) removing air voids from the sol and adding a gelation agent.

Abstract: A receiver in an optical network with a bit rate detection circuit for automatically detecting input signal data bit rates to automatically adjust the frequency of a voltage controlled oscillator in the receiver is disclosed. The receiver has a data rate detection and frequency adjustment circuit which automatically detects the data rate of an input signal and automatically adjusts the frequency of the VCO in the receiver in accordance with the data rate of the input signal. The data rate detection and frequency adjustment circuit detects the data rate of the input signal by converting the input signal into a DC voltage value that varies with respect to the data rate of the input signal.

Abstract: An apparatus and method for controlling the data flow of the Ethernet hub in a half-duplex mode, wherein the hub includes a switch to control data packets flowing through a plurality of communication ports. The system includes a destination address (DA) detector for detecting the DA of the data packet received through the input-port of the communication port to determine whether the data packet is to be treated by the switch, a logic gate for generating a selection signal based on the determination of the DA detector and an overload signal supplied by the switch when the hub is overloaded with the data packets, a jamming signal generator for generating a jamming signal in response to the selection signal, a MAC for converting the data packet into a bit stream as set forth in a carrier-sense multiple access with a collision detection (CSMA/CD) protocol, and a selector for selectively transmitting the jamming signal or the packet from the MAC in response to the selection signal.

Abstract: There is provided a grating fabrication device and method to form gratings on a semiconductor substrate. The substrate is loaded into a reactor filled with an etchant solution, and an array of parallel light of interference light with different periods is projected onto the substrate to etch the portion of the substrate that is exposed to the light via an oxidation-reduction reaction. At the same time, the inclination angle of the substrate is selectively varied to obtain the different grating periods.

Abstract: Disclosed is a multimode optical fiber having a structure to reduce scattering loss which includes a core divided into a central region having the optimal refractive index according to an optimal core shape index minimizing the scattering loss of the multimode optical fiber, and a peripheral region having the refractive index lower than that of the central region; and a cladding enclosing the core and having the refractive index lower than the lowest refractive index of the core.

Abstract: An apparatus and method for measuring residual stress and photoelastic effect of an optical fiber is disclosed.

Abstract: An optical device module using an integral heat transfer module. The heat transfer module has an integrally formed heat source and a temperature sensor for reading temperature. A heat transfer path is simplified in packaging the optical device module, so that the optical device can avoid performance degradation due to nonuniform temperature distribution. The amount power consumption can be reduced and excellent workability can be ensured.

Abstract: The present invention discloses a backlight including external electrode fluorescent lamps and a method for driving the backlight. The backlight includes fluorescent lamps having external electrodes made of an electrically conductive material for wrapping the outer peripheral surfaces including edge cross-sections on both ends of a glass tube with a layer of fluorescent substance applied thereon. The backlight is constructed in a manner that a plurality of such fluorescent lamps are installed at the outer portions of a plastic light guide, and an alternating current type power source is applied from the outside to the fluorescent lamps by installing a plurality of the fluorescent lamps between a reflecting plate and a diffusing plate and electrically connecting them with one another.

Abstract: An optical amplifier with improved output power utilizing less optical fiber components and reduced noise is disclosed. A first optical fiber amplifier is pumped by a first light source prior to splitting into a number of sub-bands, and a second optical fiber amplifier is pumped by a second light source. One of the sub-bands is amplified in multiple stages using a reflector, by passing the amplified sub-band back into the second optical amplifier in a reverse direction. Thereafter, all amplified sub-band signals are recombined to produce an output signal.

Abstract: Disclosed is an apparatus and method of monitoring the queue state of a switch in the subscriber board of an asynchronous transfer mode switching system. A difference value between the present time value and a previous input time value stored in a memory per connection is inputted to a forward resource management (FRM) cell when a resource management (RM) cell is inputted from a source, and a switch load measurement value written in the FRM cell is obtained by calculating the difference value between the present time value and a previous output time value stored in the memory per connection when the FRM cell transmitted from the source passes through the switch. The obtained switch load measurement value is inputted to a backward resource management (BRM) cell transmitted from a destination to be transmitted to the switch.

Abstract: A mobile communication system for providing a home zone service and a method thereof. In the mobile communication system, a home zone signal generator generates a home zone signal, a mobile radio terminal receives the home zone signal and determines whether the mobile radio terminal is currently within or outside a home zone based on the strength of the home zone signal, and a base station communicates with the mobile radio terminal. A visitor location register temporarily stores a first and a second telephone numbers of a subscriber, wherein each telephone number represents different charge rates. A mobile exchange receives a call information, a mobile identification number, and the home zone in/out information from the base station and selects one of the first and second telephone numbers of a subscriber corresponding to the mobile identification number and the home zone in/out information.

Abstract: An avalanche photodiode capable of generating a minimal surface leakage current as well as achieving a uniform electrical field. The avalanche photodiode includes a semiconductor substrate provided with a lower electrode underneath it, an amplification layer producing pairs of electron-holes through ionized collision of carriers injected by an internal electrical field, and an absorption layer producing the carriers according to splitting of the pairs of electron-holes by the electrical field. The avalanche photodiode further includes a contact layer formed on the absorption layer, with a core section in the center of the contact layer and a guard section surrounding the core section spaced apart from each other, and at least one upper electrode with a core electrode formed on the core section and a guard electrode formed on the guard section. The upper electrode generates the internal electrical field together with the lower electrode.

Abstract: There is provided alkaloid halogen-doped sulfide glasses for an optical amplifier and a fabricating method thereof. An alkaloid halogen-doped sulfide glass is formed of silica doped with a Ge—Ga—S three-component system, Pr3+, and an alkaloid halogen. To fabricate the alkaloid halogen-doped sulfide glass for an optical amplifier, silica doped with Ge, Ga, S, Pr3+, and an alkaloid halogen as a starting material is filled into a container. The container is sealed in a vacuum and the starting material in the container is fused by heating the container. The container is cooled and the starting material is sintered by heating the container at a glass transition temperature.

Abstract: The present invention discloses a semiconductor optical amplifier module with a monitoring device. The amplifier module includes a housing having a window on both sides of the opposite walls for forming a path of a first optical fiber and a second optical fiber, respectively; a semiconductor optical amplifier mounted in the housing for amplifying input optical signals and outputting the amplified optical signals; a first supporter for supporting the first optical fiber; a second supporter for supporting the second optical fiber; and a first optical detector for detecting non-coupled light, which is generated at the end of the first optical fiber.

Abstract: Disclosed is an apparatus for measuring a residual stress and a photoelastic effect of an optical fiber, which includes: a light source; a rotary type optical diffuser distanced from the light source in a predetermined distance for suppressing the spatial coherence of a light radiated in the light source; an optical condenser for condensing the radiated light passed through the optical diffuser into a spot where the optical fiber is located; a polarizer for polarizing the light passed through the optical condenser into a 45° linear polarized light from an axis of the optical fiber; a polarization analyzer, installed at 90° angle with respect to the polariscope and attached closely with the optical fiber, to prevent the penetration by the background image of the optical fiber; an optical fiber strain unit including a strain sensor for straining the optical fiber on the polarization analyzer toward a longitudinal direction and measuring the strain on the optical fiber; an object lens for magnifying the

Abstract: The proposed amplifier structure and associated method of optical signal amplification efficiently utilizes the limited length of rare earth-doped optical amplifier. A multi-stage of amplification stages, which includes a first erbium-doped fiber amplifier stage pumped by a first pump light source and a second erbium-doped fiber amplifier stage pumped by a second pump light source, is provided and includes a split section disposed between the first and second amplification stages for splitting the amplified signal light into a C-band and a L-band; a reflector for reflecting the amplified output of the second amplifier stage back into the second amplifier stage and the first amplifier stage in a reverse direction; a combiner for combining the reflected output, in succession, from the second amplifier and first amplifier to produce an output signal; and, a circulator for redirecting the reflected output traveling in a reverse direction to the input of the combiner.

Abstract: There is provided a package for holding long-period fiber gratings formed on an optical fiber from which an outer coating is partially removed to form the gratings thereon. A recoating is then applied to the long-period fiber gratings to maintain the optical characteristics of the long-period fiber gratings, and thereafter a silica glass tube is fixed around the recoating to protect the long-period fiber gratings from an ambient environment.

Abstract: An improved electro-absorption semiconductor modulator using an external modulation, in which a multi-quantum well (MQW) structure for absorbing a light beam is provided to increase an optical absorption capability according to an electric field, thus increasing an optical power difference between ON and OFF states. Accordingly, the electro-absorption semiconductor modulator includes a semiconductor substrate; a lower cladding layer deposited over the semiconductor substrate; a multi-quantum well (MQW) layer comprised of barrier layers and undoped well layers stacked, in succession, predetermined times on the lower cladding layer, the barrier layers being doped with an impurity; an upper cladding layer deposited over the multi-quantum well layer; and, an ohmic contact layer deposited over the upper cladding layer. The impurity comprises an n-type dopant such as silicon and has a doping density of 1017/cm3.

Abstract: A method for determining a coverage area according to antenna patterns in a sector base station system provided that the antenna gain of the omni base station is identical to the antenna gain of the sector base station. The method includes the steps of calculating the ratio of the coverage area of the sector base station to the omni base station, calculating the coverage area of the omni base station considering a handover area, and multiplying the calculated ratio of coverage area of the sector base station by the calculated coverage area of the omni base station, to determine the number of base stations required in designing the wireless network by the operator.