Abstract: A method of determining a physical layer wavelength of a tunable optical network unit (ONU) in a time wavelength division multiplexing-passive optical network (TWDM-PON) is provided. First, a receiving wavelength of a tunable receiver is tuned to a downstream wavelength of one of a plurality of operable channels in a TWDM-PON system. Then, it is checked whether the tunable receiver maintains a state of loss of signal (LOS) for a predetermined period of time or the state of LOS is cleared. In response to a determination that the state of LOS is cleared, the ONU performs subsequent link establishment procedures in the channel, and in response to a determination that the state of LOS is maintained, the receiving wavelength of the tunable receiver is changed to a downstream wavelength of another channel.

Abstract: The invention presents the channel management technology in a Time and Wavelength Division Multiplexing-Passive Optical network (TWDM-PON). According to an exemplary embodiment, the channel management technology is a wavelength management method for an Optical Network Unit (ONU) having a tunable receiver in the TWDM-PON in which a service is provided through multiple channels, the wavelength management method including: setting a wavelength of the tunable receiver as a first channel to receive a physical synchronization signal from an Optical Line Terminal (OLT); extracting either or both service utilization information and service operator information from the physical synchronization signal; and based on either or both of the service utilization information and the service operator information, determining whether to perform follow-up procedures for activation via the first channel or whether to change the wavelength of the tunable receiver into a second channel.

Abstract: Disclosed is a passive optical network system using a time division multiplexing scheme. According to one exemplary embodiment, the passive optical network system includes a plurality of optical network units (ONUs); an optical line terminal (OLT) to be connected to the plurality of ONUs for communication and to transmit and receive an optical signal to and from the plurality of ONUs using a time division multiplexing (TDM) scheme, wherein each of the plurality of ONUs includes a light source that generates an optical signal with a predetermined intensity even in burst-off state; and an optical filter disposed on a receiving path of an optical receiver of the OLT to filter out an optical noise signal received from an ONU in burst-off state among the plurality of ONUs.

Abstract: The present invention relates to an open optical access network system in which one optical access network is open to enable a plurality of service providers and a plurality of subscribers to simultaneously use the optical access network, to thereby improve the efficiency of using the optical access network, wherein each subscriber can be provided with a plurality of different services from the plurality of service providers, thereby enabling the flexible selection of services and the flexible change in services, thus improving the efficiency of using an optical infrastructure.

Abstract: Provided is a method of establishing a link between service provider equipment and subscriber equipment in a multi-wavelength passive optical network system. The method of establishing a link includes acquiring information about a wavelength plan of allocated wavelengths in the MW PON system; transmitting a first signal wavelength initialization request signal on a first upstream wavelength from physical layer to the service provider equipment; waiting for a response from the service provider equipment for a predetermined time interval after transmitting the first signal wavelength initialization request signal; and in response to failing to receive a response to the first signal-wavelength initialization request signal within the predetermined time interval, transmitting a second signal wavelength initialization request signal on a second upstream wavelength to the service provider equipment after the waiting.

Abstract: Provided is a method of selecting a wavelength of an optical network unit including selecting a pre-loaded default wavelength as an available wavelength candidate or the wavelength that has been changed when a preset wavelength changing condition is satisfied as the available wavelength candidate, acquiring frame synchronization for a downstream signal having the same wavelength as the selected available wavelength candidate, and transmitting a registration request message to an optical line terminal (OLT) from which the downstream signal has been transmitted when the frame synchronization is acquired, assigning the available wavelength candidate to an available wavelength used for communication with the OLT and registering the terminal in the OLT when a registration allowance message is received from the OLT.

Abstract: An optical network unit (ONU) having a power saving function for reducing power consumption in an optical network and a power saving method thereof are provided. The ONU includes a first signal transmitter-receiver unit configured to transmit and receive a signal to and from an optical line terminal, a second signal transmitter-receiver unit configured to transmit and receive a signal to and from customer premises equipment through multiple communication ports, a signal processing unit configured to control a signal to be transmitted and received through the first signal transmitter-receiver unit and the second signal transmitter-receiver unit, and a processor configured to control powers of the first signal transmitter-receiver unit and the signal processing unit according to whether data traffic is received through the plurality of communication ports.

Abstract: A Time Wavelength Division Multiplexing-Passive Optical Network (TWDM-PON) system and a communication link method thereof are provided. The communication link method is a method whereby an Optical Network Unit (ONU) which has established communication link to one Optical Line Terminal (OLT) establishes communication link to a different OLT. The ONU receives a wavelength change instruction to change a wavelength thereof to an operating wavelength assigned to the different OLT, and change the wavelength in response to the wavelength change instruction to synchronize to a downstream signal of the operating signal. In addition, the ONU receives an upstream discovery grant signal from the different OLT, and transmits an acknowledgement message to notify the receipt of the upstream discovery grant signal, so that the ONU establishes communication link to the different OLT.

Abstract: The TWDM-PON system includes a service provider equipment configured to comprise a plurality of Optical Line Terminals (OLTs), wherein each OLT provides a service in a TWDM scheme; a subscriber equipment configured to comprise a plurality of an Optical Network Units (ONUs), wherein each of the plurality of ONUs utilizes a service provided from one of the plurality of OLTs using an optical signal of an arbitrary wavelength; an Optical Division Network (ODN) configured to transmit multi-wavelength downstream optical signals and multi-wavelength upstream optical signals; and a Reach Extender (RE) configured to comprise at least one of a downstream optical amplifier and an upstream optical amplifier, wherein the downstream optical amplifier is configured to amplify the multi-wavelength optical signals simultaneously, and the upstream optical amplifier is configured to amplify the multi-wavelength optical signals simultaneously.

Abstract: A multi-channel transmitter optical sub-assembly (TOSA) is provided. The multi-channel TOSA includes a stem including a sub-mount, a plurality of light sources mounted on the sub-mount, a common ground pad disposed at the sub-mount and connected to ground electrodes of the light sources in common, a common lead pin installed at the stem, and connected to the common ground pad, and a thermistor mounted on the sub-mount along with the light sources.

Abstract: An APC receptacle stub and an APC TOSA having the same are provided. The APC receptacle stub includes a first APC stub and a second APC stub. The first APC stub has an optical fiber inserted thereto and is provided with one end section polished in an APC shape. The second APC stub has an optical fiber inserted thereto and is provided with one end section polished in an APC shape and an opposite end section which is coupled to an opposite end section of the first APC stub through rotation adjustment in the same axial direction as an axial direction of the opposite end section of the first APC stub. The APC receptacle stub enables easy optical alignment and is applicable to a light source that is sensitive to reflection.

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: A method and apparatus for providing passive optical networks with extended reach and/or splitting ratio are disclosed. For example, the optical network comprises a first optical line termination (OLT) device having a transceiver for sending and receiving optical signals. The optical network further comprises an optical extender box comprising at least one hybrid SOA-Raman amplifier, wherein the optical extender box is coupled to the first optical line termination device via a first standard single mode fiber section. Finally, the optical network further comprises an optical splitter coupled to the optical extender box via a second standard single mode fiber section.

Abstract: A wavelength-division multiplexing optical communication system and a method for measuring optical performance of an output signal for the system. The optical communication system includes: a service-provider device; a local node; and a plurality of subscriber devices. The service-provider device includes: a plurality of first optical transceivers; a first optical multiplexer/demultiplexer (OD/OM) connected to the plurality of first optical transceivers; and a seed-light source providing seed light. Each subscriber device includes a second optical transceiver. The local node connects the service-provider device and the plurality of subscriber devices to each other using a DWDM link comprising: a second multiplexer/demultiplexer (OD/OM); and a single-mode optical fiber for transmission. Here, the optical intensity of an output signal of the second optical transceiver is determined by compensating for the value of the loss caused when the output signal passes through the second OD/OM of the local node.

Abstract: A method and apparatus for implementing a hybrid SOA-Raman amplifier in a central office in order to enable multiple passive optical networks to share one or more enhancement service sources, e.g., to share a source for a broadcast service are disclosed.

Abstract: A method and apparatus for enabling multiple optical line termination (OLT) devices to share a feeder fiber are disclosed. For example, the optical network comprises a plurality of optical line termination (OLT) devices, where each OLT device having a transceiver for sending and receiving optical signals. The optical network further comprises a wave division multiplexer (WDM) combiner, coupled to the plurality of OLT devices, for combining optical signals received from the plurality of OLT devices. The optical network further comprises an optical extender box comprising at least one hybrid SOA-Raman amplifier, wherein the optical extender box is coupled to the WDM combiner via a first standard single mode fiber section. Finally, the optical network further comprises at least one optical splitter coupled to the optical extender box via a second standard single mode fiber section.

Abstract: A wavelength tuning time measurement apparatus and method for a multi-wavelength passive optical network (MW PON) are provided. The wavelength tuning time measurement apparatus for measuring a wavelength tuning time of a wavelength-variable light source included in the MW PON system includes an optical filter configured to pass only light of a certain wavelength bandwidth and a photo detector configured to sense light passing through the optical filter. The wavelength tuning time is a time taken from a time when a wavelength change signal is transferred to the wavelength-variable light source, to a time when light starts to be successively sensed by the photo detector.

Abstract: An optical layer monitoring apparatus and method thereof are provided. According to an embodiment of the present invention, an optical layer monitoring apparatus including an optical time domain reflectometer (OTDR) function so as to monitor an optical path of a passive optical network (PON), and a method for improving accuracy of measured monitoring results using the optical layer monitoring apparatus are provided. Therefore, it is possible to enable a user to continuously detect distortion or attenuation along the optical path, and to quickly recover from the distortion or attenuation along the optical path when distortion or attenuation is detected.

Abstract: An apparatus for driving a wavelength-independent light source is provided. The apparatus includes a seed light signal generation unit configured to generate seed light signals with one or more wavelengths based on a wavelength identification signal, a wavelength light detection unit configured to detect the wavelength identification signal from the seed light signals, an extraction unit configured to extract wavelength information corresponding to the detected wavelength identification signal and extract a driving condition of a wavelength-independent light source corresponding to the extracted wavelength information, and a driving unit configured to drive the wavelength-independent light source according to the extracted driving condition.

Abstract: A wavelength tunable light source includes: an optical gain medium generating light; a wavelength tunable filter positioned on a optical path and transmitting or reflecting only a predetermined wavelength generated from and injected into the optical gain medium; a first housing where the optical gain medium and the wavelength tunable filter are mounted; and an optical fiber block providing the optical wave having the predetermined wavelength come from the wavelength tunable filter, wherein the wavelength tunable filter comprised of a dielectric thin-film filter formed by alternately stacking a first dielectric thin film layer and a second dielectric thin film layer having different refractive index.