Abstract: Disclosed is a bidirectional optical add/drop multiplexer that includes a first filter for reflecting a first optical signal pre-selected among input forward optical signals and transmitting the remaining forward optical signals, a second filter for reflecting a second optical signal pre-selected among input reverse optical signals and transmitting the remaining reverse optical signals, a first optical splitter for combining the first optical signal and the forward optical signals by reflection from the first filter, wherein the reflected second optical signal having passed through the first filter is outputted to a connected second drop terminal and the first optical signal input from a connected first add terminal is outputted to the first filter, and a second optical splitter for adding the second optical signal and the reverse optical signals by reflection from the second filter, wherein the reflected first optical signal having passed through the second filter is outputted to a connected first drop termi

Abstract: Disclosed is a wavelength division multiplexing optical switching system, which is connected with a plurality of nodes of an optical network and supports communication between the nodes. The optical switching system includes a wavelength division demultiplexing unit which demultiplexes optical signals received from each of the plurality of nodes and outputs them as channels with different wavelengths. A routing unit which classifies the channels in accordance with destinations thereof. A fixed wavelength converting unit which converts the classified channels into channels of a single wavelength, the single wavelength being allocated in accordance with corresponding starting places. A wavelength division multiplexing unit which collects the wavelength-converted channels in accordance with destinations and then outputs them as multiplexed optical signals.

Abstract: A single side band modulation device includes a first Mach Zehnder interferometer and a second Mach Zehnder interferometer. The first Mach Zehnder interferometer includes at least two output arms, and the second Mach Zehnder interferometer includes at least two output arms. Terminals of the output arms are connected with one another.

Abstract: A latching mechanism, which is configured to enable a pluggable optical transceiver module assembly to be plugged in or unplugged from a cage, is disclosed. The pluggable optical transceiver module assembly includes a bail clip for providing a latching portion locked in a locking member and an optical transceiver module having a connector portion including receptacle portions for accommodating external connectors.

Abstract: An athermal arrayed-waveguide grating is disclosed and includes an input waveguide for inputting two or more optical signals from one exterior side, a grating array for separating the optical signals into different wavelengths of light, a first slab, formed with two layers and having different refractive indices from each other, for connecting the input waveguide with the grating array, a second slab for causing the different light wavelengths separated at the grating array to be imaged on an egress surface thereof, and an output waveguide array for outputting each light wavelength imaged on the egress surface of the second slab to the other exterior side in the form of a separated channel.

Abstract: A burst-mode optical receiver of a differential-output structure is disclosed.

Abstract: An optical transmission system for optimizing the bias of a laser diode during an SCM analog optical transmission includes an optical transmitter for converting a baseband electric signal into an optical signal using a laser diode according to the set bias and outputting the optical signal through an optical line, an optical receiver for converting the optical signal transmitted from the optical transmitter into the baseband electric signal, a recovery unit for detecting an error generated according to the bias of the laser diode on the basis of the electric signal converted by the optical receiver, and a bias adjuster for optimally adjusting the bias of the laser diode on the basis of a value of the error detected by the reproducer.

Abstract: An optical demultiplexer having at least one Bragg diffraction grating for minimizing crosstalk on the sides of transmitting and receiving optical signals, as well as an optical communication module using the optical demultiplexer. The optical demultiplexer has first and second waveguides arranged adjacent each other in a predetermined section in order to perform mode coupling, so that the optical signals input through one end of the first waveguide are transmitted to a light receiving element through the second waveguide, and in which output light waves inputted through the other end of the first waveguide are output through the one end of the first waveguide. A first Bragg diffraction grating is formed on the second waveguide and haa wavelength selectivity, for minimizing crosstalk by transmitting a reception wavelength of the optical signals at about 100% and by reflecting a wavelength of the output light waves at about 100%.

Abstract: Disclosed is a latching apparatus for a pluggable optical transceiver module, which is configured to enable the pluggable optical transceiver module to be plugged or unplugged by pulling the pluggable optical transceiver module. The latching apparatus of the pluggable optical transceiver module connected to an optical connector and electrically connected to a cage assembly includes: a module housing, which is extended in a length direction and used to latch and fix the pluggable optical transceiver module to the cage assembly; and a clip-type latch, which is assembled through the outer circumference of the module housing and used to release the module housing from the cage assembly by horizontally and vertically moving with respect to the length direction in response to pulling of the clip-type latch when the module housing is unplugged from the cage assembly.

Abstract: Disclosed is a duobinary optical transmitter, which includes a laser source for outputting light with a predetermined wavelength; a Mach-Zehnder interferometer-type optical intensity modulator for modulating the intensity of the light according to a three-level data signal inputted through a modulation terminal; a low-pass filter for converting an inputted two-level binary data signal into a three-level data signal through an interference among codes; and, a modulator driver/amplifier for amplifying the three-level data signal and then outputting it to the modulation terminal, wherein the overall bandwidth of the low-pass filter, the modulator driver/amplifier, and the optical intensity modulator corresponds to approximately ¼ of the clock frequency of the two-level binary data signal.

Abstract: A multi-channel light source includes a semiconductor optical amplifier for generating light of a wide wavelength band and outputting the generated light through a first end and a second end. The source further includes a Fabry-Perot (FP) resonator for resonating the light inputted from the semiconductor optical amplifier to generate an FP fringe and outputting the FP fringe to the semiconductor optical amplifier. The semiconductor optical amplifier amplifies the FP fringe inputted from the FP resonator and outputs the amplified FP fringe through the first end.

Abstract: Disclosed is a land grid array module comprising: a substrate; a plurality of active and passive components mounted on both sides of the substrate; and a molding compound for encapsulating the both sides of the substrate with the active and passive components mounted thereon. The land grid array module mounts the passive and active components on both sides of the substrate, thereby improving the integration of the circuit device. Also, the use of a thin film printed circuit board or a flexible printed circuit board with high rigidity as the substrate reduces the overall thickness of the land grid array module.

Abstract: Disclosed is a duobinary optical transmission apparatus. The duobinary optical transmission apparatusenhances nonlinear and dispersion characteristics for an intermediate-long distance transmission at a high-speed transfer rate without the use an electric LPF. The duobinary optical transmission apparatus includes a light source for generating a carrier wave, a duobinary optical signal generator for receiving a Non Return to Zero (NRZ) signal and generating a modulated optical signal generated by modulating the carrier wave according to the NRZ signal, and a Return to Zero (RZ) signal generator for converting the NRZ signal into a RZ (Return to Zero) signal. Therefore, optical intensity and a phase are modulated using only a single interferometer-type optical modulator.

Abstract: A photonic crystal fiber (PCF) preform, from which a photonic crystal fiber is manufactured, includes a rod-shaped substrate with holes longitudinally formed therethrough in a photonic lattice structure, and material layers having at least two different indices of refraction. The material layers are disposed in the holes, respectively. Distribution of index of refraction of the photonic crystal fiber preform is controlled by arrangement of the material layers. Consequently, an optical fiber with very low optical loss, very low optical nonlinearity and excellent transmission characteristics can be easily manufactured, and an optical fiber with various characteristics, differing depending upon the lattice structure, can be realized.

Abstract: A circuit for shifting a level between two bi-directional signals having different voltage levels. The circuit includes a first analog switch including a first switching control terminal connected to first directional signal stage, a first input terminal connected to a first level of operating voltage, and a first output terminal connected to a second directional signal stage, for performing a switching operation for the first input terminal and the first output terminal based on a state of logic level of a signal from the second directional signal stage.

Abstract: A clock recovery method for a TDM digital video signal and a transmitting/receiving apparatus for the clock recovery method are disclosed. A transmitter inserts a user clock code containing a predetermined number of points into the digital video signal during TDM processing and transmits the digital video signal. A receiver receives the TDM digital video signal and detects the user clock code from the TDM digital video signal. It counts a reference clock signal and recovers a transmission clock signal in an LMS algorithm using the user clock code and the count value.

Abstract: An apparatus and method used in a home-zone location registering process in a portable telephone which allows a different charging rate to be applied to a subscriber based on whether the call connection is made within the home-zone area. According to the method, the portable radio telephone stores the home-zone list therein and determines whether the portable telephone deviates from the home zone area, then the portable radio telephone automatically performs the location registration process when the deviation is detected.

Abstract: Disclosed is a method for maintaining wavelength-locking of a Fabry-Perot laser regardless of a change of external temperature even though a temperature controller is not used, and a wavelength division multiplexing (WDM) light source using the method, as an economical light source used in a WDM optical communication field. The WDM light source comprises a Fabry-Perot laser for injecting spectrum-spliced incoherent light to amplify and output only an oscillation mode matching with a wavelength of the injected light, and a bias controlling unit for adjusting a bias current supplied to the Fabry-Perot laser to a value adjacent to a threshold current of the Fabry-Perot laser, whose threshold current is changed according to a temperature and a relationship between the injected light changed depending to a temperature and a wavelength of the oscillation mode.

Abstract: A keypad assembly for a portable terminal is disclosed. The keypad assembly for the portable terminal includes a light guide plate which has reflection patterns locally formed on a lower surface of the light guide plate for reflecting a part of light transmitted in the light guide plate toward an upper surface of the light guide plate. The keypad assembly also includes at least one key button seated on the light guide plate, for outputting the light reflected by the reflection patterns out of the keypad assembly, upper and lower cases for containing the light guide plate, a switch substrate seated on a bottom surface of the lower case and having at least one switch, and an extension member which extends from an upper case of the portable terminal toward the switch substrate. The extension member has a reflection filter for reflecting the light exiting from the light guide plate toward the light guide plate back.

Abstract: An optical fiber having improved compression strength is disclosed. The optical fiber includes a central tension member positioned in the center of the optical fiber and having at least one groove, at least one metal tube seated in the groove and containing at least one optical fiber, a strength member positioned around the central tension member and the tube, and a sheath positioned around the strength member.