Abstract: Provided is an optical network in which a wavelength division multiplexing-based optical transmission scheme is implemented. An apparatus for cross-connecting an optical path includes a path switch including a plurality of input terminals receiving optical signals from other nodes, and a plurality of output terminals sending the optical signals to the other nodes, the path switch switching the path of the optical signal so that the optical signal input via one of the input terminals is output to one of the output terminals; and a wavelength converter converting a wavelength of the optical signal input via the input terminal and outputting the wavelength-converted optical signal to the output terminal according to a switching result of the path switch.

Abstract: In a wavelength allocation method in a wavelength division multiplexing network, a 3R wavelength converter having a limited wavelength conversion range is disposed according to a wavelength conversion band of each node, at least one path set between transmitting/receiving nodes is selected, routing paths corresponding to the number of the selected at least one path set between the transmitting/receiving nodes having a request for a new optical path generation are extracted, it is determined whether there is a wavelength consecutive segment set that satisfies a maximum transmission distance for guaranteeing transmission quality of an optical signal and that includes one consecutive wavelength among the extracted routing paths, and a path using a first-fit wavelength is selected from paths of each wavelength consecutive segment and the wavelength is allocated when determining that there is a wavelength consecutive segment set.

Abstract: An optical sheet includes a base film in which light is incident from a lower side, a plurality of prism patterns and a diffusion member. The prism patterns are protruded to be spaced apart from each other on the base film to enhance the front luminance of light incident from the lower side of the base film. The diffusion member is disposed between prism patterns to have a diffusion surface in parallel with the base film. The diffusion member includes a plurality of diffusion dots capable of enhancing the luminance uniformity of light incident from the lower side of the base film. Thus, front luminance and luminance uniformity may be enhanced due to a juxtaposition of the prism patterns and the diffusion portion, and the viewing angle of the LCD device may be enhanced.

Abstract: Provided are an acousto-optic filter and an optical code division multiple access (CDMA) system using the acousto-optic filter. The acousto-optic filer includes: an acousto-optic mode converter (AOMC) converting an optical signal of a specific optical frequency corresponding to a frequency of an electric signal of an optical signal of a first mode having a predetermined optical frequency band; and a mode stripper (MS) stripping an optical signal of the optical signal of the first mode that has been converted to a second mode.

Abstract: A network node and method for guaranteeing the role of an optical supervisory channel (OSC) in an optical transport network (OTN) are provided. In the network node, at least two OSC units are multiplexed, one of the OSC units is set as a main unit, the other OSC unit is set as an auxiliary unit; and the auxiliary unit is activated when the main unit cannot be operated. Thereby, the network node can guarantee the stable role of the OSC.

Abstract: An apparatus and method for monitoring quality of an optical signal in an optical network based on wavelength division multiplexing optical transmission technology are provided, which are capable of monitoring the quality of an optical signal with higher accuracy. The apparatus includes: a signal extractor extracting an optical signal having a specific wavelength from input optical signals; an optical-electrical converter converting the extracted optical signal having the specific wavelength into an electrical signal; an overhead parser extracting a part of an overhead of the electrical signal to parse whether or not the quality of the signal is degraded; and a controller monitoring the quality of the optical signal according to the parsing result of the extracted overhead and restoring the optical signal whose quality is lower than a predetermined reference value.

Abstract: An apparatus and method for protection switching of an optical channel at each node in an optical network based on wavelength division multiplexing optical transmission technology are provided. The method can be applied to any node having at least two optical fiber inputs and outputs. The apparatus includes: a splitter receiving an electrical signal and splitting the received electrical signal into a plurality of electrical signals which are substantially identical to the received electrical signal; an output switching unit selecting output paths of the electrical signals split by the splitter according to an optical channel path control command of the optical network; and a plurality of optical transponders being assigned to the respective output paths of the electrical signals, converting the electrical signal input by the selection of the output switching unit to an optical signal, and transmitting the converted optical signal to another node of the optical network.

Abstract: Provided are an optical transmission apparatus and method using a light source for wavelength division multiplexing (WDM) optical communication that employs a Fabry-Perot laser diode (F-P LD) whose output wavelength is locked by an externally injected incoherent light, a multifiber, and a waveguide grating router.

Abstract: Provided is a multi-ring network operating method of cross-connecting at least two ring networks, the method including connecting an input working ring and an input protection ring of a ring network to an output working ring and an output protection ring of another ring network and then performing cross-connection between the same or different ring networks by using a multi-dimensional cross-connect apparatus. In the multi-ring operating method, a plurality of ring networks can be connected regardless of the protection method used by the ring networks, and the original protection method of each ring network can remain after they are connected.

Abstract: A photo-detecting device includes a buried doping layer of a first conductivity type and disposed at an upper portion of a silicon substrate. A first silicon epitaxial layer of first conductivity type is disposed on the buried doping layer, and a second silicon epitaxial layer of second conductivity type is disposed on the first silicon epitaxial layer. An isolation doping layer doped of first conductivity type is disposed at a predetermined region of the second silicon epitaxial layer to define a body region of second conductivity type. A silicon germanium epitaxial layer of second conductivity type is disposed on the body region.

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: A method and apparatus for controlling a wavelength tuning of an optical source in an optical communication system. An operating temperature of an optical source is controlled and monitored to shorten a wavelength tuning time of the optical source generated in an optical source generator. When the current operating temperature reaches a final target temperature, an operating current is supplied to the optical source generator, and transmission of the operating current to the optical source generator is controlled and monitored. When the operating current reaches a final operating current, the wavelength tuning of the optical source is terminated. The operating temperature is adjusted by distinguishing between a smaller amount of temperature change and a larger amount of temperature change to prevent oscillation at the point of reaching the final target temperature, thereby minimizing the time taken for the output wavelength tuning.

Abstract: Provided are an apparatus and a method for reducing a signal noise of an OCDMA receiver and an OCDMA receiver and method. The includes: a clock recovery unit extracting sine wave clock from an output signal of an OCDMA decoder including an MAI (multiple access interference) noise; a time gating unit separating an auto-correlation peak signal and the MAI noise from the output signal of the OCDMA decoder using the sine wave clock; and an optical interferometer removing an SI (signal interference) noise remaining in the auto-correlation peak signal.

Abstract: Disclosed herein is an apparatus for controlling a decision threshold voltage to an optical receiver, which is capable of automatically controlling the decision threshold voltage to the optical receiver appropriately to signal level decision on the basis of a low-frequency band signal component of an output signal from the optical receiver. The apparatus is adapted to control the level of the decision threshold voltage to the optical receiver, which converts an input optical signal into an electrical signal.

Abstract: A method for manufacturing the same, wherein the monolithic ink-jet printhead includes a manifold for supplying ink, an ink chamber having a hemispheric shape, and an ink channel formed monolithically on a substrate; a silicon oxide layer, in which a nozzle for ejecting ink is centrally formed in the ink chamber, is deposited on the substrate; a heater having a ring shape is formed on the silicon oxide layer to surround the nozzle; a MOS integrated circuit is mounted on the substrate to drive the heater and includes a MOSFET and electrodes connected to the heater. The silicon oxide layer, the heater, and the MOS integrated circuit are formed monolithically on the substrate. Additionally, a DLC coating layer having a high hydrophobic property and high durability is formed on an external surface of the printhead.

Abstract: Disclosed herein is a communication terminal which has an adequate structure for keys so as to sufficiently fulfill various communication services, to thereby make the communication terminal compact, and can control operation of the keys so as to minimize a data input error of the keys. The communication terminal includes a first housing, a second housing which is oppositely coupled to the first housing, and a control unit which interrupts operation of a data input part provided at either the first housing or the second housing according to movement of the second housing with respect to the first housing.

Abstract: The present invention relates to an apparatus and method for stabilizing a bias voltage for a pulse generating modulator, which can automatically detect an optimal bias voltage for an external modulator, which is used in RZ or CSRZ modulation of an optical transmission signal using NRZ data to generate a reference pulse optical signal, and maintain the optimal bias voltage. In the bias voltage stabilizing method of the present invention, an output signal of the external modulator, to which the bias voltage to be stabilized is applied, is detected, a drive clock signal applied to the external modulator is detected, a mean output value of the products obtained by the multiplication of the output signal and the clock signal is periodically examined, and the bias voltage is adjusted so that the mean output value becomes “0”.

Abstract: A wavelength allocation method and apparatus that is capable minimizing the number of wavelength converters is provided. In a dynamic wavelength multiplexing division network structure having a limited maximum transmission distance, an optical path is established to maximally suppress activation of a 3R wavelength converter, thereby maximizing efficiency of the 3R wavelength converter. In a dynamic wavelength multiplexing division network structure having a limited maximum transmission distance, a new optical path is established to minimize 3R wavelength conversion and suppress use of unnecessary expensive 3R wavelength converters and thereby increase network efficiency.

Abstract: In a wavelength allocation method in a wavelength division multiplexing network, a 3R wavelength converter having a limited wavelength conversion range is disposed according to a wavelength conversion band of each node, at least one path set between transmitting/receiving nodes is selected, routing paths corresponding to the number of the selected at least one path set between the transmitting/receiving nodes having a request for a new optical path generation are extracted, it is determined whether there is a wavelength consecutive segment set that satisfies a maximum transmission distance for guaranteeing transmission quality of an optical signal and that includes one consecutive wavelength among the extracted routing paths, and a path using a first-fit wavelength is selected from paths of each wavelength consecutive segment and the wavelength is allocated when determining that there is a wavelength consecutive segment set.

Abstract: A semiconductor memory device includes a switch circuit that inverts input data or output data when burn-in mode enable signals are activated or a control signal switch that inverts external control signals or internal control signals when burn-in mode enable signals are activated. A burn-in test method for the semiconductor memory device performs a pass/fail decision to determine whether the output data has passed or failed based on an inverted logical value of the input data.