Abstract: Provided is an athermal external cavity laser (ECL), whose output optical power and output wavelength can be kept regular irrespective of temperature changes without using additional temperature controlling components. The ECL comprises: a semiconductor amplifier; an optical fiber comprising a core in which a Bragg grating is formed and a cladding surrounding the core; and a thermosetting polymer that fixes the optical fiber to a ferrule and has a negative thermooptical coefficient, wherein the thickness of the cladding surrounding the core in which the Bragg grating is formed is smaller than the portion of the cladding surrounding the portion of the core where the Bragg grating is not formed, and the thermosetting polymer the negative thermooptical coefficient surrounds the cladding.

Abstract: An optical backhaul network for a wireless broadband service is provided. The optical backhaul network for a wireless broadband service includes: a plurality of optical network units for outputting an uplink optical signal having a multiplexed wavelength; an optical line termination for outputting a downlink optical signal of a single mode in order to transmit the downlink optical signal to the plurality of the optical network units in a broadcasting form; and a plurality of remote nodes for outputting a part of the downlink optical signal to the plurality of the optical network units and for outputting the uplink optical signal to the optical line termination. Therefore, one center and a plurality of access points can be efficiently connected.

Abstract: Provided is an Optical Line Terminal (OLT). The OLT may include a first Wavelength division multiplexer/demultiplexer (WDM MUX/DeMUX) to perform a wavelength demultiplexing on seed light received from a seed light source, and a second Wavelength division demultiplexer (WDM DeMUX) to receive, from at least one ONU/ONT, an upstream optical signal generated using the seed light having the wavelength demultiplexing performed, and to perform a wavelength multiplexing on the received upstream optical signal.

Abstract: Disclosed are an apparatus and method for detecting optical signals. The optical signal detection apparatus includes: a signal receiver to convert a received optical signal into an electrical signal; a threshold decision unit to establish a mathematical model based on the electrical signal and to decide an optimized threshold value based on the mathematical model; and a signal detector to detect the electrical signal based on the optimized threshold value. Hence, since threshold values optimized adaptively according to received signals are used, a bit error rate may be lowered and accordingly detection performance may be improved.

Abstract: In a Wavelength-Division-Multiplexed Passive Optical Network (WDM-PON) utilizing a conventional downstream optical signal reusing method, there is an inventory problem that different optical transmitter types need to be provided for the operation, management, replacement, etc. of a system. A WDM-PON system according to the present invention, includes: a seed light (SL) unit generating a seed light whose wavelength intervals and center wavelengths are adjusted using at least one seed light source; an optical line terminal (OLT) receiving the wavelength-multiplexed seed light from the seed light unit, transmitting a downstream optical signal to a subscriber of the WDM-PON, and receiving a upstream optical signal from the subscriber; and an optical network unit (ONU) receiving the downstream optical signal from the OLT, flattening and modulating the downstream optical signal with upstream data so that the downstream optical signal is reused for carrying upstream data.

Abstract: Provided are an apparatus and method for tracking a wavelength in a passive optical subscriber network in which a central base station and at least one subscriber terminal are connected via a remote node. The apparatus includes a first wavelength aligning unit multiplexing and aligning wavelengths of optical signals from a plurality of single-mode optical sources of the central base station; a second wavelength aligning unit multiplexing and aligning wavelengths of optical signals transmitted to the remote node from a plurality of single-mode optical sources of the subscriber terminal; and a third wavelength aligning unit demultiplexing and aligning wavelengths of optical signals from the second wavelength aligning unit, the third wavelength aligning unit being included in the central base station.

Abstract: Provided is a time division multiple access over wavelength division multiplexed passive optical network (TDM-over-WDM-PON) system. According to the TDM-over-WDM-PON system, a downstream optical signal is separated according to a wavelength in a remote node, transmitted to an optical amplifying device located in subscriber equipment, amplified in the optical amplifying device, transmitted back to the remote node, and then transmitted to the subscriber equipment. Also, an upstream optical signal is transmitted to a wavelength converting device located in the subscriber equipment from the remote node, wavelength-converted in the wavelength converting device, returned back to the remote node, and then transmitted to a central office.

Abstract: The present invention relates to a mobile terminal and a control method thereof. The method of controlling a mobile terminal in accordance with the present invention includes, when a specific message is received, separating text information and voice characteristic information included in the received message, converting the text information into a specific voice signal based on the separated voice characteristic information, and outputting the converted voice signal. In accordance with the present invention, text information to which voice characteristic information, indicating a sender's voice characteristic, is added is transmitted. Accordingly, text information received from a sender-side terminal can be heard as a sender's voice.

Abstract: Provided are a wavelength division multiplexing-passive optical network (WDM-PON) in which a reflective semi-conductor optical amplifier (RSOA) is used as each optical transmitter of an optical line termination (OLT) and an optical network unit (ONU) and additional spectrum-sliced light is injected into RSOAs of each of the OLT and the ONU, and a WDM-PON that is combined with time division multiple access (TDMA) technology, by which the number of included ONUs increases and conventional TDMA ONUs can be used.

Abstract: Provided is a wavelength tunable external cavity laser comprising: a semiconductor laser diode that outputs multi-wavelength optical signals and is mounted on a first substrate; and a wavelength tunable reflection filter that is mounted on a second substrate, outputs single wavelength optical signals among the multi-wavelength optical signals using resonance of external cavity formed between a semiconductor laser diode and a Bragg-grating having a predetermined period, and tunes the wavelength of the output single wavelength optical signal by varying the refractive index of the Bragg-grating. The wavelength tunable Bragg-grating reflection filter and the semiconductor laser diode are mounted on separate substrates, and the optical coupling efficiency between the semiconductor laser diode and the waveguide type Bragg-grating reflection filter is increased using an active alignment method to increase the optical output power and enable a stable oscillation mode.

Abstract: Provided are extendable loop-back passive optical network (PON) and scheduling method and apparatus for the same. The loop-back type PON includes an OLT (optical line terminal) including a wavelength-tunable optical transmitter and a wavelength-locked optical receiver, and an RN (remote node) including an optical coupler/splitter, the optical coupler/splitter receiving optical signals from the wavelength-tunable optical transmitter and splitting the optical signals by wavelength so as to transmit the optical signals to corresponding ONTs (optical network terminals). Each of the ONTs transmits upstream data to the OLT using the same wavelength as the wavelength of the optical signal received from the OLT through the RN. Since the optical network makes use of the TDM and WDM communication schemes, the optical network can be maintained and upgraded at lower cost.

Abstract: A Reflective Semiconductor Optical Amplifier (RSOA) for compensating for light loss in an optical link, an RSOA module for improving polarization dependency using the RSOA, and a Passive Optical Network (PON) for increasing economical efficiency and practical use of a bandwidth using the RSOA are provided. The PON includes a central office comprising a plurality of optic sources transmitting a downstream signal and a plurality of first receivers receiving an upstream signal; at least one optical network terminal (ONT) including a second receiver receiving the downstream signal and an RSOA which receives the downstream signal, remodulates the downstream signal into the upstream signal, and transmits the upstream signal in loopback mode; and a remote node interfacing the central office with the ONT. The upstream signal and the downstream signal are transmitted between the remote node and the ONT via a single optical fiber. The remote node includes an optical power splitter at its port connected to the ONT.

Abstract: A Reflective Semiconductor Optical Amplifier (RSOA) for compensating for light loss in an optical link, an RSOA module for improving polarization dependency using the RSOA, and a Passive Optical Network (PON) for increasing economical efficiency and practical use of a bandwidth using the RSOA are provided. The PON includes a central office comprising a plurality of optic sources transmitting a downstream signal and a plurality of first receivers receiving an upstream signal; at least one optical network terminal (ONT) including a second receiver receiving the downstream signal and an RSOA which receives the downstream signal, remodulates the downstream signal into the upstream signal, and transmits the upstream signal in loopback mode; and a remote node interfacing the central office with the ONT. The upstream signal and the downstream signal are transmitted between the remote node and the ONT via a single optical fiber. The remote node includes an optical power splitter at its port connected to the ONT.

Abstract: Provided are an apparatus and method for measuring signal performance and an apparatus for selecting a signal. The apparatus includes a wavelength selector selecting a signal having a specific wavelength from an input signal, a time selector selecting a signal input at a specific time from the selected signal having the specific wavelength, and a performance measurer measuring signal performance for the signal of the specific wavelength that is input at the specific time and selected by the time selector. Thus, it is possible to measure signal quality of each wavelength-division multiplexing (WDM)-time-division multiplexing (TDM) channel in a WDM-TDM hybrid environment.

Abstract: Provided is an apparatus for connecting a wavelength division multiplexing passive optical network (WDM-PON) to a time division multiplexing passive optical network (TDM-PON). In a hybrid, passive optical network which is a combination of the WDM-PON and the TDM-PON, the apparatus is formed at a subscriber side for matching the WDM-PPN and the TDM-PON. Accordingly, a passive remote mode can be implemented as a passive node not an active node. Therefore, the entire optical network can be efficiently operated. In addition, since the apparatus located on the subscriber side uses a wavelength-tunable light source, any dependency on the wavelength of a WDM-PON optical signal is removed.

Abstract: A seed light module based on a single longitudinal mode oscillation light source is provided.

Abstract: A spectrum-sliced seed light module for a wavelength division multiplexing passive optical network (WDM PON) is provided. The seed light module includes an optical amplifier to amplify seed light, an optical wavelength filter to transmit broadband light, which is output in opposite direction to an output direction of the seed light, at periodic frequency intervals, and a reflective mirror to reflect light which is spectrum-sliced through the optical wavelength filter to the optical wavelength filter.

Abstract: A method of restoring a target network to which users having different recovery requirements are connected is provided. The method includes analyzing network components including availability information of each user and parameters reflecting characteristics of the target network; and determining optimized restoration architecture for the target network based on the result of the analysis. Accordingly, when failure occurs in a network to which various subscribers having different recovery requirements are connected, the network can be promptly recovered from the failure.

Abstract: Disclosed are an optical transmission apparatus and method in a wavelength division multiplexing passive optical network (WDM-PON). The optical transmission apparatus outputs an optical signal by applying a DC bias current and an RF signal to a laser diode at a threshold current level of the laser diode, thereby broadening an optical spectrum of the laser diode. Accordingly, an optical link becomes less vulnerable to reflection induced noise, which contributes to improve stability and reliability of the optical link.

Abstract: A Reflective Semiconductor Optical Amplifier (RSOA) for compensating for light loss in an optical link, an RSOA module for improving polarization dependency using the RSOA, and a Passive Optical Network (PON) for increasing economical efficiency and practical use of a bandwidth using the RSOA are provided. The PON includes a central office comprising a plurality of optic sources transmitting a downstream signal and a plurality of first receivers receiving an upstream signal; at least one optical network terminal (ONT) including a second receiver receiving the downstream signal and an RSOA which receives the downstream signal, remodulates the downstream signal into the upstream signal, and transmits the upstream signal in loopback mode; and a remote node interfacing the central office with the ONT. The upstream signal and the downstream signal are transmitted between the remote node and the ONT via a single optical fiber. The remote node includes an optical power splitter at its port connected to the ONT.