Abstract: A wavelength division multiplexing-passive optical network (WDM-PON) system includes a light source provider configured to wavelength-division-multiplex a laser light source of a wavelength allotted to each subscriber and optical-power-divide the multiplexed light source, a plurality of optical line terminals each configured to transmit a light source for upward signal with the power-divided light source and convert an upward optical signal into an electric signal, a plurality of optical network units each configured to convert the light source for upward signal into the upward optical signal, and a multiplexer/demultiplexer configured to separate the signal source for upward signal transmitted from the optical line termination in each subscriber or to multiplex the upward optical signal for each subscriber transmitted from the optical network unit so as to transmit the multiplexed signal into the optical line terminal.

Abstract: A passive optical network communication system transmits an optical time-division multiplexed signal from a central office through a passive optical coupler to a number of subscribers, and transmits optical encoded signals from the subscribers through the passive optical coupler to the central office. Optical encoded signals from different subscribers are separated by a decoding process performed at the central office. All operations can be synchronized with a clock signal which is generated at the central office and recovered from the optical time-division multiplexed signal by the subscribers' equipment. The communication range can be extended inexpensively by using a single high-power light source at the central office while using relatively low-power light sources at the subscribers' equipment.

Abstract: A passive optical network system (PON) has a plurality of OLTs and ONUs with different transmission rates. OLTs with different transmission rates share information of priority frames and destinations, and determine timing for frame transmission to ONUs so that the signal from each of the OLTs does not collide when multiplied in a splitter. OLTs transmit the data to the ONU as a burst signal to prevent the signals with different rates from colliding. ONU acquires the information of the following burst frames. ONU receives only the signal addressed to the own ONU or with the transmission rate of own ONU, therefore errors in ONUs can be avoided. OLT receives only the signal with the transmission rate of own OLT from ONUs based on the transmission timing from the ONUs shared by the line terminators, errors in OLTs can be avoided.

Abstract: The present invention provides a method for detecting a security module for link protection in an EPON, wherein an OLT and an ONU in the EPON can check whether or not an encryption module is present in each other and check the configuration of each other in order to avoid loss of a message when the message is encrypted for link protection between the OLT and the ONU in the EPON.

Abstract: A Session Initiation Protocol (SIP) network can malfunction or be incorrectly provisioned in such a way that an Optical Network Terminal (ONT) cannot perform SIP operations and complete SIP voice path calls between the ONT voice port and the SIP network. Accordingly, a technique for validating SIP operations is provided which (i) verifies locally stored SIP operation parameters are currently valid, (ii) initiates an SIP session with a known SIP validation endpoint in an event the locally stored SIP operation parameters are verified to be currently valid, and (iii) reports results of the verifying of the locally stored SIP operation parameters or the initiating of the SIP session. By validating SIP operation parameters, the ONT maintains its state of readiness to support SIP sessions, such as in-coming or outgoing normal or emergency 9-1-1 voice calls.

Abstract: In a light reception element such as an APD (Avalanche Photo Diode) used for receiving a high-speed and weak optical signal, it is possible to prevent the phenomenon of distortion of a signal inputted after a large-level light is received. A PON (Passive Optical Network) system includes an OLT (Optical Line Terminal) which can impartially and effectively transmit light reception data to each ONU (Optical Network Unit). According to a light reception amplitude received by each ONU, an inter-frame gap of an appropriate length is assigned for each ONU. The OLT includes a unit for measuring and accumulating the reception light amplitude and data on the inter-frame gap of an appropriate length decided in advance according to the characteristic of the light reception device and generates a grant value for assuring an inter-frame gap of an appropriate length by using the both information.

Abstract: In accordance with the teachings of the present invention, a hybrid passive optical network using shared wavelengths is provided. In a particular embodiment, a system for communicating optical signals over a network includes an upstream terminal. The upstream terminal includes a signal source operable to transmit a downstream signal comprising at least traffic in a first wavelength and traffic in a second wavelength. The upstream terminal is operable to receive upstream traffic in a third wavelength, wherein the third wavelength is shared by a first plurality of downstream terminals and a second plurality of downstream terminals. The system also includes a distribution node comprising a wavelength router. The wavelength router is operable to receive the downstream signal, route the traffic in the first wavelength to the first plurality of downstream terminals, and route the traffic in the second wavelength to the second plurality of downstream terminals.

Abstract: A mesh optical network node has switch cards which carry active components, such as wavelength routers to switch the paths of optical signals through the node and a fiber organizer handles the numerous optical fiber interconnections among the switch cards. The fiber organizer has no active components and can include optical paths to verify not only that a switch card connection to the fiber organizer has been made but that the connection is properly made.

Abstract: The present invention relates to an electrical point-to-multipoint repeater for Passive Optical Networks (PONs). A multiport passive optical network extender (1) comprises an optical input/output port for connection via an optical fiber (4) to the feeder side of the PON; a plurality of optical input/output ports for connection via respective optical fibers (5) to the distribution side of the PON; and an electrical distribution network (6) for connecting the feeder-sided input/output port to the plurality of distribution-sided input/output ports in the electrical domain.

Abstract: An optical communication system is constructed which enables highly reliable and flexible connection to communication nodes connected to a path establishment circuit, by utilizing wavelength-routing characteristics of a path establishment circuit such as an arrayed waveguide grating. The optical communication system has multiple communication nodes having a signal output port and signal input port pair, and a path establishment circuit having multiple optical input ports and multiple optical output ports which are set so that optical signals input from the respective optical input ports are output to predetermined optical output ports corresponding to the wavelengths of the optical signals.

Abstract: An optical-inclusive, dWDM local area network and the accompanying signaling protocol necessary to facilitate communication between nodes in a network. This network architecture provides for a packet-oriented network, independent of the number of nodes and the number of supported wavelengths, and provides for scheduled access to the medium, which guarantees higher utilization.

Abstract: The present invention relates to a method, a device and a system for user authentication on a PON. The method includes the following steps: an OLT receives a user authentication request initiated by an ONU, which carries a password ID; the OLT authenticates according to the user password ID reported by the ONU, and opens or closes a channel from the ONU to the network side according to the authentication result. The invention further discloses a PON and an OLT. According to the method for user authentication in the invention, user management and maintenance of PON may be easier and simpler, and terminal interchangeability and user security may be improved; moreover, after a user changes the ONU, the new ONU may also access the network using the password ID.

Abstract: An apparatus and method for supporting quality of services (QoS) for respective subscriber classes for an Ethernet passive optical network (E-PON) are provided. The method for supporting QoS includes specifying bandwidths and subscriber classes for respective ports for a plurality of subscriber termination systems connected to a service provider termination system; based on the bandwidth information, allocating bandwidths for respective subscriber ports of the subscriber termination systems; based on the subscriber class information, assigning IP addresses to respective subscriber of the subscriber termination systems according to subscriber class; and by using the bandwidths and IP addresses, supporting QoS according to subscriber class in transmitting and receiving data between the service provider termination system and the subscriber termination systems.

Abstract: The present invention relates to an optical network terminal (ONT), a method for configuring rate limiting attributes of ports, and a method for processing packets. The ONT includes a passive optical network (PON) protocol processing module, and a user network interface (UNI) module, which are connected through an internal interface. The ONT also includes a port rate limiting module connected to a UNI. The port rate limiting module stores rate limiting attributes, and the ONT uses these attributes to control the traffic of the UNI. The port rate limiting attributes are configured for the ONT through an ONT management and control interface (OMCI) message of an optical line terminal (OLT). In this way, when the ONT receives data from the UNI, it can control the traffic of the UNI according to the port rate limiting attributes.

Abstract: A problem detection device at an optical network unit (ONU) end in a passive optical network (PON) system and a method thereof are provided, which aim at solving the problem that the user cannot check out photo-physical data on the physical architecture, logical signal information on the logical architecture, and parameter information on the network communication protocol of the PON system economically, quickly, and accurately, once a connection error occurs at the ONU end. The technical lies in using an optical network signal to pass through the integrated optical path analysis module, the ONU module, and the network communication protocol message analysis module included in the problem detection device to achieve the detection and analysis of the problem of the ONU connection error at one time once the problem detection device is connected to the PON system.

Abstract: Provided is a WDM-PON system based on a wavelength-tunable ECL. A method of controlling an upstream optical wavelength of an ONT in WDM-PON system, the method comprises: determining upstream optical wavelength information of the ONT corresponding to a downstream optical wavelength predetermined to the ONT newly installed by being connected to a network; in an OLT, loading the determined upstream optical wavelength information onto the downstream optical wavelength assigned to the ONT and transmitting the loaded upstream optical wavelength information to the ONT; in the ONT, generating an upstream optical wavelength based on the upstream optical wavelength information transmitted by being loaded on the downstream optical wavelength from the OLT; and in the ONT, loading upstream data onto the generated upstream optical wavelength and transmitting the loaded upstream data to the OLT.

Abstract: The present invention relates to a long-reach wavelength division multiplexing passive optical network(WDM-PON), and especially to the long-reach WDM-PON capable of ensuring economic and stable QoS (Quality of Service). The Long-reach WDM-PON in accordance with the present invention includes an optical transmitter/receiver located at central office and each optical network termination; wavelength division multiplexer/demultiplexer located at said central office and remote node; and broadband incoherent light source which is connected with a long-reach single-mode fiber to said wavelength division multiplexer/demultiplexer and spectrum-sliced and injected into the transmitters located at said central office and each optical network termination.

Abstract: Disclosed is a passive optical network comprising a central office including a plurality of first reflective semiconductor optical amplifiers of a quantum-dot type, each of which generates a wavelength-seeded downstream optical signal on a downstream channel of a corresponding wavelength, a plurality of optical network units each of which includes a second reflective semiconductor optical amplifier of a multi-quantum-well type, the second reflective semiconductor optical amplifier generating a wavelength-seeded upstream optical signal on an upstream channel of a corresponding wavelength and a remote node for outputting the downstream optical signals to corresponding optical network units, and multiplexing and outputting the upstream optical signals to the central office.

Abstract: An apparatus has a cross connection circuit, first switching sections located on the input side of the cross connection circuit to switch a presently-used transmission path and a reserve transmission path, and second switching sections located on the output side of the cross connection circuit to switch the presently-used transmission path and the reserve transmission path and comprises slot sections, first selecting section selectively connecting any one of the slot sections to the input side of the first switching section, second selecting section connecting the output side of the first switching section to the input side of the cross connection circuit, third selecting section selectively connecting the output side of the cross connection circuit to the input side of any of the second switching sections, and fourth selecting section connecting the output side of the second switching section to any one of the slot sections.

Abstract: An optical wavelength division multiplexing network has a multi-level structure where a plurality of optical network units (ONUs) are connected to a lowest-level network. A node apparatus connected to networks other than the lowest-level network includes (a) passive optical components to branch optical signals from a higher-level network to a lower-level network, and couple optical signals from the lower-level network to the higher-level network, and (b) optical amplifiers for the optical signals. A node apparatus connected to the lowest-level network includes (a) an optical multiplexer/de-multiplexer to de-multiplex optical signals from the higher-level network, selectively output an optical signal to each ONU, and multiplex wave-length specific optical signals from the ONUs into a multiplexed optical signal, and (b) optical amplifiers for the optical signals.

Abstract: Regarding the passive optical network (PON) system of the present invention, in an OLT, data of different bit rates is framed, and framed data rows are subjected to FEC encoding processing without changing the line up of the data, and a check bit is added to the end of the frame, and an optical signal that has been modulated in accordance with the data row to which the check bit has been added is transmitted to the optical transmission line. Then in an ONU that corresponds to a high speed bit rate to which an optical signal from the OLT has been applied via a power splitter, forward error correction of the reception data is performed. As a result in a PON system in which data of different bit rates coexist, the minimum reception rate of a high speed ONU can be improved without having an influence on a low speed ONU.

Abstract: A Passive Optical Network system implementing a parent station capable of receiving high-speed burst signals transmitted from a plurality of subsidiary stations to a parent station, with excellent bandwidth utilization efficiency in the link from the stations to the parent. The system is provided with a configuration in which, when launched or an addition of a new subsidiary station, the parent stores threshold values appropriate for the received signals on the basis of the strength of the received signal for each subsidiary station, from among a plurality of preset threshold value candidates, and in response to the parent station's sending of a transmission grant with respect to each subsidiary station each time the subsidiary station transmitting optical signals changes, the stored threshold value corresponding to the subsidiary station is set in the receiver circuit.

Abstract: A passive optical network includes an optical line termination for generating multiple downward optical signals and multiple optical network units for receiving the downward optical signals. Each optical network unit includes a receiver for converting a corresponding downward optical signal inputted from the optical line termination into a first voltage signal and outputting the first voltage signal. Additionally, each optical network unit includes a transmitter for calculating a distance to the optical line termination from an intensity of the first voltage signal outputted from the receiver and generating an upward optical signal having an intensity adjusted according to the calculated distance to the optical line termination.

Abstract: A MAC (Medium Access Control) control block for controlling transmission of data between a plurality of MAC clients and a plurality of MACs in an Ethernet passive optical network (EPON) is provided. The MAC control block includes the plurality of MAC clients and the plurality of MACs associated with the MAC clients for forming a frame for data transmission; a plurality of optical multipoint (OMP) blocks connected between the MAC clients and the MACs for implementing a multipoint control protocol (MPCP); and a multipoint gating control block for controlling the OMP blocks so that when any one of the OMP blocks is transmitting the data, the other OMP blocks are prevented from transmitting data.

Abstract: Processing a received optical signal in an optical communication network includes equalizing a received optical signal to provide an equalized signal, demodulating the equalized signal according to an m-ary modulation format to provide a demodulated signal, decoding the demodulated signal according to an inner code to provide an inner-decoded signal, and decoding the inner-decoded signal according to an outer code. Other aspects include other features such as equalizing an optical channel including storing channel characteristics for the optical channel associated with a client, loading the stored channel characteristics during a waiting period between bursts on the channel, and equalizing a received burst from the client using the loaded channel characteristics.

Abstract: A MAC (Medium Access Control) control block for controlling transmission of data between a plurality of MAC clients and a plurality of MACs in an Ethernet passive optical network (EPON) is provided. The MAC control block includes the plurality of MAC clients and the plurality of MACs associated with the MAC clients for forming a frame for data transmission; a plurality of optical multipoint (OMP) blocks connected between the MAC clients and the MACs for implementing a multipoint control protocol (MPCP); and a multipoint gating control block for controlling the OMP blocks so that when any one of the OMP blocks is transmitting the data, the other OMP blocks are prevented from transmitting data.

Abstract: An ultra wideband adapter and a system including the ultra wideband adapter are disclosed. The ultra wideband adapter includes a first input to receive video from a passive optical network element, a second input to receive data from the passive optical network element, an ultra wideband modulator to modulate the received data, a diplexer to diplex the received video with the modulated ultra wideband data to provide a diplexed video, and an output to transmit the diplexed video.

Abstract: A method of controlling behavior of an element in a passive optical network (PON) is provided. The method includes (i) issuing a message from a first PON element to a second PON element to cause the second PON element to enter or maintain a state of upstream communications, the state of upstream communications having an enabled state or a disabled state, (ii) ranging the second PON element by the first PON element if the state of upstream communications of the second PON element is in the enabled state, and (iii) bypassing the ranging of the second PON element if the state of upstream communications of the second PON element is in the disabled state.

Abstract: In accordance with the teachings of the present invention, a system and method for transmitting optical markers in a passive optical network (PON) system is provided. In a particular embodiment, a method for transmitting optical markers in a PON system includes transmitting a first optical marker signal, the first optical marker signal used to identify at least one of the first optical marker signal, an upstream wavelength corresponding to the first optical marker signal, and an optical network unit (ONU) type transmitting at the upstream wavelength corresponding to the first optical marker signal. The method also includes transmitting a second optical marker signal, the second optical marker signal used to identify at least one of the second optical marker signal, an upstream wavelength corresponding to the second optical marker signal, and an ONU type transmitting at the upstream wavelength corresponding to the second optical marker signal.

Abstract: A device capable of equalizing optical powers of optical signals in a passive optical network, the device comprising a first optical coupler for receiving optical signals having different optical power levels, an optical circulator capable of directing the optical signals from the first optical circulator, a laser diode capable of generating equalized optical signals having a predetermined range of optical power levels in response to the optical signals directed from the optical circulator, and a second optical coupler for receiving the equalized optical signals.

Abstract: A bandwidth allocation device and a dynamic bandwidth allocation method are provided for differentiated classes of service in an Ethernet Passive Optical Network (EPON), which includes an optical line termination (OLT), an optical distribution network (ODN), and a plurality of optical network units (ONUs). The OLT includes a Multi-Point Control Protocol (MPCP) allocator, which includes a class-based queue state counter and a grant generator. The ONU includes an MPCP requester, which includes a class-based buffer counter and a request generator. The device and the method enable efficient utilization of network resources using class-based grant allocation.

Abstract: An optical communication system comprises a base station, a plurality of trunk optical fibers connected to the base station, a plurality of star couplers connected to the trunk optical fibers, a plurality of remote stations, and a plurality of branch optical fibers. The branch optical fibers have first branch cut ends at positions adjacent to each of the star couplers and second branch cut ends at positions adjacent to the remote station groups. The first branch cut ends are connected to the second ports of the star couplers and the second branch cut ends to the remote stations of a remote station group.

Abstract: Raman interference (also known as Raman scattering) during an idle frame transmission state in a passive optical network (PON) having radio frequency video overlay is reduced by generating and transmitting data packets having both random data and random length. Randomly varying both the packet data content and the packet length can achieve significant improvement in Raman interference reduction. The random packet data and length in effect spreads the interference across a spectrum wide enough that there is no interference effect perceptible to a television viewer.

Abstract: A fiber optic communication system includes a device of switching and setting wavelength of optical signals used in communication by network-node equipments, which sets the mapping of the wavelength of the optical signal used in communication by the network node equipments, and the input/output ports of an array waveguide grating (AWG), so as to construct a predetermined logical network topology by a plurality of network node equipments which are connected via optical fibers to the array waveguide grating that outputs optical signals inputted to optical input ports, to predetermined optical output ports in accordance with the wavelength thereof. As well as enabling a simple construction, it is easy to realize flexible network design, construction, and operation, and different network groups can also be easily connected to each other. Moreover, a fiber optic communication system having robust security and which can be stably operated even at the time of failure is realized at low cost.

Abstract: Disclosed is a wavelength division multiplexed passive optical network (WDM PON) system including a central office, a remote Node, and an optical fiber coupled between the central office and the remote node, wherein the central office includes an optical power splitter coupled to the optical fiber, wherein the optical power splitter (1) divides an upstream optical signal from the optical fiber into a plurality of upstream optical signals having substantially similar power and (2) outputs downstream optical signals to the optical fiber, and a plurality of optical transceiver modules to (1) receive the plurality of upstream optical signals, and (2) output the downstream optical signals to the optical power splitter, and wherein at least one of the optical transceiver modules having an optical transmitter including a semiconductor optical amplifier and a reflection-type optical fiber grating located at a predetermined distance from the semiconductor optical amplifier, the optical transmitter transmitting light o

Abstract: An apparatus and system are provided for delivering communication services such as video, data and telephony services to individual residential units. According to one embodiment, an optical network terminal (ONT) for providing communication services to a single residential unit comprises a passive optical network interface (PI) circuit, a residential service interface (RSI) circuit, and a power unit. The PI circuit receives optical signals from an optical fiber and transmits optical signals onto the optical fiber. The PI circuit is adapted to convert received optical signals containing voice information to electrical voice ATM cells, received optical signals containing data information to electrical data ATM cells, and received optical signals containing video signals to electrical video signals.

Abstract: A technique for transferring information in a passive optical network is disclosed. The technique may be realized as a method for transferring information in a passive optical network having a plurality of network nodes. The method comprises transmitting a downstream signal during a control/management time slot of a periodic frame having N control/management time slots and M data time slots, wherein the downstream signal includes an identifier of a service node in the network, wherein each of the N control/management time slots corresponds to a respective one of N possible service nodes in the network. The method also comprises responding to the downstream signal with an upstream signal during the control/management time slot of the periodic frame. The method further comprises allocating at least one of the M data time slots of the periodic frame to the service node based at least in part upon the upstream signal.

Abstract: A passive optical network suitable for use as a telecommunications access network, having a head-end transmitting in a first optical frequency and one or more subscriber stations transmitting on a second common optical frequency. A carrier sense, multiple access protocol, with collision detection, is used, the collision detection being performed in the subscriber and head-end stations.

Abstract: An optical communications system includes a receiver subsystem with at least two heterodyne receivers. The receiver subsystem receives a composite optical signal having two or more subbands of information and corresponding tones. An optical splitter splits the composite optical signal into optical signals. Each optical signal includes a subband(s) and corresponding tone. Each heterodyne receiver receives an optical signal. The receiver includes a heterodyne detector coupled to a signal extractor. The heterodyne detector mixes the optical signal with an optical local oscillator to produce an electrical signal which includes a frequency down-shifted version of the subband and the tone of the optical signal. The signal extractor mixes the frequency down-shifted subband with the frequency down-shifted tone to produce a frequency component containing the information.

Abstract: A single free-beam region for coupling electromagnetic radiation in and out is provided in order in the case of an AWG coupler for spectrally separating electromagnetic radiation to achieve a more stable thermal characteristic and a space-saving layout.

Abstract: Methods and apparatus for providing enhanced optical networking service and performance which are particularly advantageous in terms of low cost and use of existing infrastructure, access control techniques, and components. In the exemplary embodiment, current widespread deployment and associated low cost of Ethernet-based systems are leveraged through use of an Ethernet CSMA/CD MAC in the optical domain on a passive optical network (PON) system. Additionally, local networking services are optionally provided to the network units on the PON since each local receiver can receive signals from all other users. An improved symmetric coupler arrangement provides the foregoing functionality at low cost. The improved system architecture also allows for fiber failure protection which is readily implemented at low cost and with minimal modification.

Abstract: An optical wavelength division multiplexing network which can carry out large-capacity access service with a simple constitution is provided. In an optical network comprising a plurality of layers, a highest level network comprises a ring network having a center node and remote nodes; an intermediate level network comprises a ring centered around a node belonging to the higher level network, and a lowest level network comprises a star network centered around an access node which multiplexes traffic from a plurality of ONU, the ONU and the access node being directly joined together by optical fibers; the center node belonging to the highest level network and the ONU establish a direct communication path by using lights of different wavelengths; at nodes provided therebetween, the optical signals are not electrically processed but are amplified, branched, and routed.

Abstract: In a ring network comprising a plurality of nodes and a 16 channel coarse wavelength-division multiplexing (CWDM) plan, a technique is disclosed for adding and dropping channels that reduces the maximum attenuation loss that any channel encounters—thereby enabling longer rings to be constructed without using optical amplifiers in the ring. The 16 channels are typically distributed between the wavelengths 1310–1610 nm with 20 nm separation between channels. It is obscured that glass fibers have gradually decreasing loss at longer wavelengths in this band. The network includes a hub and several nodes that are interconnected by optical fibers in a ring configuration, where distance from the hub is the minimum value measure in either the clockwise or counterclockwise direction. Channels are assigned to the various nodes based on their wavelength. The channels whose wavelengths are near 1310 nm are assigned to nodes that are progressively closer to the hub.

Abstract: A wavelength-selective routing capability is provided in a single network element by configuring the network element using a combination of add/drop network elements to route individual optical channels of WDM signals among a plurality of optical transmission paths coupled to the network element. Any optical channel of any WDM signal received at the network element can be selectively added, dropped, or routed among the multiple optical transmission paths within and external to the node.

Abstract: Networks and networks for performance monitoring (PM) in a passive optical network, which contain at least one optical line terminator (OLT) and at least one optical network terminal (ONT), provide increased PM flexibility over traditional ONT management and control interface functionality. These networks and networks include setting a PM initialization time at the ONT, maintaining a base PM time at the ONT, zeroing an interval end time counter at the ONT and collecting a first set of PM data in PM bins for a specified PM time interval. The interval end time counter can sequentially increment after completing collection the first set of PM data. Once collection of the first set of PM data is complete and the interval end time counter has been incremented, these networks and networks can collect more sets of PM data in other PM bins for the PM time interval. Once PM data are collected, the OLT can retrieve the PM initialization time and the base PM time from the ONT, as well as the PM data from the PM bins.

Abstract: An autoprotected optical communication ring network includes a first and a second optical carrier having opposite transmission directions and a plurality of optically reconfigurable nodes optically connected along the first and the second optical carrier and adapted to communicate in pairs on links susceptible to failure, the ring network having a normal operative condition in which the nodes of each pair are optically configured so as to exchange optical signals on a working arc path at a respective first wavelength (?x) on the first carrier and at a respective second wavelength (?y) different from the first wavelength (?x) on the second carrier, the working path having a complementary arc path defining a protection arc path in which the first wavelength (?x) on the first carrier and the second wavelength (?y) on the second carrier can be used for further links.

Abstract: An optical communication system comprises a base station, a plurality of trunk optical fibers connected to the base station, a plurality of star couplers connected to the trunk optical fibers, a plurality of remote stations, and a plurality of branch optical fibers. The branch optical fibers have first branch cut ends at positions adjacent to each of the star couplers and second branch cut ends at positions adjacent to the remote station groups. The first branch cut ends are connected to the second ports of the star couplers and the second branch cut ends to the remote stations of a remote station group.

Abstract: A passive optical star coupler, and associated method of operation arranged to transmit signals received at any input port to all output ports other than an output port associated with the input port. In this way all received signals are broadcast to all connected network equipment with the exception of the transmitting equipment.

Abstract: Disclosed herein is a terminal device including a photodetector, amplitude detecting circuit, light source, drive circuit, and control circuit. The photodetector receives a first optical signal. The amplitude detecting circuit detects the amplitude of an output from the photodetector. The drive circuit supplies a drive current to the light source so that the light source outputs a second optical signal. The control circuit decreases and increases the drive current according to an increase and decrease in the amplitude detected by the amplitude detecting circuit, respectively. In the case that this terminal device is used with another terminal device to construct a network, the dynamic range of the other terminal device can be reduced. Accordingly, the use of this terminal device can improve the extensibility of the network.

Abstract: A wavelength division multiplex optical star coupler comprises an input port which inputs a first optical signal, a first optical coupler which divides the first optical signal input from the input port into a plurality of first optical signals, a plurality of input/output ports, each of which outputs one of the plurality of first optical signals divided by the first optical coupler and inputs a second optical signal, an output port which outputs the second optical signal, and a second optical coupler, provided between the input port and the first optical coupler or between the first optical coupler and the input/output ports, which provides the first optical signal to the input/output ports and the second optical signal to the output port.