Abstract: In a digital broadcasting system comprising a server for retransmitting a digital broadcast on the basis of an Internet protocol (IP), a user terminal for receiving the digital broadcast on the basis of the IP, and a router for connecting the server with the user terminal, the server performs a method for providing the broadcasting channel information that includes the steps of dividing a broadcasting stream to be transmitted to the user terminal into the broadcasting channel information and other information excluding the broadcasting channel information by demultiplexing the broadcasting stream and extracting the broadcasting channel information from the divided broadcasting stream, converting the extracted broadcasting channel information into IP-based broadcasting channel information by inserting the Internet protocol information for each broadcasting channel into the extracted broadcasting channel information, and remultiplexing the IP-based converted broadcasting channel information and the other inform

Abstract: A self-healing WDM (Wavelength Division Multiplexing)-PON (Passive Optical Network) system is disclosed and includes a CO (Central Office), a RN (Remote Node) and a plurality of subscriber units. The system includes a trunk working fiber and a trunk protection fiber for connecting the CO with the RN, a distribution working fiber, and a distribution protection fiber for connecting the RN with the subscriber units. The CO is connected to the trunk working fiber and the trunk protection fiber, and contains an optical switching unit switched when an error or communication failure occurs, an upstream working optical receiver and an upstream protection optical receiver for receiving upstream data, and a downstream working light source and a downstream protection light source for transmitting downstream data.

Abstract: A bidirectional optical transceiver includes a wavelength-selecting filter, an optical fiber, a transmitting module, and a receiving module. The wavelength-selecting filter is placed on an optical axis, passes a first optical signal therethrough, and reflects a second optical signal perpendicularly to the traveling path of the second optical signal. The optical fiber has a face that is opposite to the wavelength-selecting filter and is inclined at an angle of ? with respect to a normal line perpendicular to the optical axis. The transmitting module is placed on the optical axis in opposition to the optical fiber with respect to the wavelength-selecting filter and has a light source for generating the first optical signal and outputting the generated first optical signal to the wavelength-selecting filter at an inclined angle with respect to the optical axis.

Abstract: Disclosed is a two-fiber optical ring network having a plurality of nodes linked by first and second fiber optic links, wherein each node comprises a first splitting section for splitting optical signals from optical signals traveling through the first fiber into the protection channels; a first add/drop section for performing adding and/or dropping optical signals passing through the first splitting section to a plurality of channels; a first switching section for combining optical signals in the protection channels to the first fiber when there is no link failure between adjacent nodes and for combining optical signals in the protection channels to the second fiber when there is a link failure between adjacent nodes; and, a controlling section for identifying whether or not the optical link failure occurs in the fibers and for generating a control signal to activate a restoration process according to the identified outcome.

Abstract: An optical multi-ring network for burst data communication is disclosed. The multi-ring network includes a plurality of optical single-ring networks having a plurality of optical add/drop routers connected with each other through fiber links, and a core optical router for supporting communication between the optical single-ring networks. The core optical router includes a wavelength division demultiplexing section for demultiplexing optical signals received from the each single-ring network and outputting the demultiplexed optical signals as channels whose wavelengths are different from each other; a branching section for branching off and outputting a portion of each channel; and a switching section for switching each channel to a path directed to the destination of each channel according to a first control signal.

Abstract: A wideband optical module includes a downward wideband light source for generating downward light, an upward wideband light source for generating upward light, a first circulator including a first to a third port for outputting multiplexed downward optical signals to the second port and for outputting multiplexed upward optical signals to the first port, a second circulator including a first to a third port for outputting multiplexed upward optical signals to the second port and for outputting multiplexed downward optical signals to the first port, a first optical coupler connected to the third port of the first circulator and the second port of the second circulator for outputting the downward light to the third port of the first circulator, and a second optical coupler connected to the second port of the first circulator and the third port of the second circulator for outputting the upward light to the third port of the second circulator.

Abstract: Disclosed is a bi-directional optical add/drop multiplexer connected to an optical fiber for transmitting optical signals multiplexed in a wavelength division multiplexing optical network and which performs adding/dropping of the optical signals. The optical add/drop multiplexer includes a first wavelength division multiplexer provided with a multiplexing port functioning as a path for forward or backward optical signals and with a plurality of demultiplexing ports, each functioning as a path of demultiplexed channels. A plurality of add/drop parts, each performing adding/dropping of preset channels, and connected with the demultiplexing ports of the first wavelength division multiplexer in one-to-one. A second wavelength division multiplexer connected with the plurality of add/drop parts in one-to-one, provided with a plurality of demultiplexing ports, each functioning as a path for demultiplexed channels and with a multiplexing port functioning as a path for forward or backward optical signals.

Abstract: An apparatus for converting pulse code modulation (PCM) signals in a telecommunication system between two different modulation standards. In the apparatus, a channel selector generates a channel select signal for identifying at least one channel of the multiple channels containing input digital signals modulated by said one of said two different modulation standards. A first codec demodulates a signal on a channel designated by the channel select signal which is modulated by the first modulation standard, into an analog signal to be supplied to a second codec, which modulates the converted analog signal input into a digital signal using the second modulation standard. The reverse process is executed in a similar manner.

Abstract: A method for assigning a predetermined wavelength between two different nodes in a wavelength division multiplexing (WDM) ring communication network that has an N number of nodes and at least one pair of optical fibers sequentially connecting the N number of nodes is disclosed. A matrix is formed by an algorithm representing optical-path configuration and wavelength assignment for nodes representing three cases: (1) when the number of nodes is an even number; (2) when the number of nodes is increased; and (3) for recovery from network-cut failures.

Abstract: A multi-wavelength light source includes an amplifier for generating light over a wide wavelength range; and, an optical fiber grating including a plurality of gratings formed on an optical fiber in in parallel with each other, thereby dividing the light inputted from the amplifier into respective channels having different wavelengths to reflect the divided channels to the amplifier. The amplifier amplifies each channel reflected in the gratings.

Abstract: A burst mode optical receiver is disclosed and includes a converter for converting a burst mode signal into a voltage signal, a bottom level detector for detecting a bottom level of an output signal from the converter, an automatic gain controller for automatically controlling the gain of the converter on the basis of the bottom level detected by the bottom level detector in order to maintain an amplitude of the output signal from the converter and generating a reset signal when the bottom level is lower than a predetermined reference value, and a power level detector for detecting a power level of the output signal from the converter and generating the reset signal and an LOS signal indicative of the presence of no input signal when the detected power level is lower than a predetermined reference value.

Abstract: A method for processing a received packet in a MAC (Medium Access Control) layer of an Ethernet which receives a packet from a physical layer and transmits the received packet to a switch. The method includes the steps of detecting an error while receiving the packet from the physical layer; upon failure to detect error, transmitting the received packet to the switch; and, upon detection of error, stopping the transmission of the received packet to the switch.

Abstract: An optical wavelength tracking apparatus and method in a wavelength division multiplexed (WDM) passive optical network (PON) in which a central office (CO) having a multi-frequency light source is connected to a plurality of optical network units (ONUs) having loop-back light sources through a WDM MUX/DEMUX in a remote node (RN). The power levels of downstream and upstream WDM optical signals are measured. The WDM wavelengths of the multi-frequency light source and the WDM MUX/DEMUX are controlled to be nearly identical in order to minimize the difference between the power levels of the downstream and upstream WDM optical signals.

Abstract: A keypad assembly for a portable terminal according to the present invention includes: a keypad having pad portions with a plurality of key buttons placed thereon, light guide plates disposed between the pad portions, and reflection units disposed on the light guide plates to direct the light toward the key buttons; light sources for providing the light toward the reflection units; a plurality of spacers disposed below the light guide plates for separating the light guide plate from a substrate and for supporting the light guide plates; switches disposed below the pad portions under the key buttons for applying signal to the substrate; and a casing for enclosing the keypad.

Abstract: A subscriber interface device and method for transmitting a communication signal and a broadcasting signal to each subscriber in a communication-broadcasting convergence FTTH system. A subscriber interface, positioned in the ONU, modulates a first predetermined number of broadcasting signals selected by a subscriber among broadcasting signals received from an OLT, combines a baseband communication signal received from the OLT with the modulated broadcasting signals, and optically transmits the combined communication-broadcasting signal. A subscriber interface receiver positioned in an ONT, splits the combined communication-broadcasting signal, filters the split signals to respective frequency bands, modulates the filtered broadcasting signals, transmits the modulated broadcasting signals to a monitor of the subscriber, and transmits the filtered communication signal as a baseband signal to a communication terminal of the subscriber instead of a passband signal.

Abstract: A packaging apparatus for optical interconnection on an optical PCB includes a first substrate with a via hole formed therethrough and in which an optical waveguide is formed, an optical interconnection block having a reflective plane on its lower end inserted into the via hole, a second substrate flip-bonded to an upper surface of the first substrate, and an optically active element flip-bonded to a lower surface of the second substrate and aligned for optical communication.

Abstract: A Fabry-Perot laser generates a mode-locked channel having the same wavelength as that of light injected into the laser. The laser includes a semiconductor substrate and a lower cladding layer formed on the substrate. An active layer is formed on the lower cladding layer and has a band gap distribution that continuously varies in a longitudinal direction of the substrate. The laser further includes an upper cladding layer formed on the active layer and the lower cladding layer.

Abstract: A connectors-integrated directional coupler is provided. The directional coupler includes a housing having a body, an input connector integrally extended from one end of the body, and an output connector integrally extended from the other end of the body. A main line connects the input connector to the output connector for delivering a signal. A coupling line induces the signal from the main line.

Abstract: A bidirectional optical add-drop multiplexer adds and drops optical signals having specific wavelengths among the WDM optical signals transmitted bidirectionally through one of the optical transmission lines connected between neighbor nodes in a bidirectional WDM ring network.

Abstract: An optical fiber having reduced residual stress discontinuity is disclosed. The optical fiber includes a core which is an optical transmission medium and a clad for surrounding the core. The residual stress discontinuity at an interface between the core and the clad is 20.0 MPa or less, which is represented by an absolute value of a difference between a minimum axial stress at (r/a)=0.8-1.1 and a maximum axial stress at (r/a)=1.0-1.2, wherein a is the radius of the core and r is a radius measured from the center of the core.