Abstract: A method of transporting traffic on an optical ring includes, at one or more nodes coupled to the optical ring, splitting an incoming signal (including traffic in a plurality of sub-bands) into a first signal and a second signal. The first signal includes the traffic in a first sub-band of traffic channels and the second signal includes the traffic in the remaining sub-bands of traffic channels of the incoming signal. The method also includes receiving the traffic in the first sub-band at a bypass element, rejecting the traffic in a first portion of the first sub-band at the bypass element, and forwarding the traffic in a second portion of the first sub-band at the bypass element. In addition the method includes, combining the traffic in the second signal with the traffic in the second portion of the first sub-band for transport on the network.

Abstract: The present invention provides a wavelength division multiplexing transmission system for separating wavelength division multiplexing signals, where signal lights with different bit rates are wavelength division multiplexed, according to the bit rate, and processing the separated signals individually. The wavelength division multiplexed signals, where a low-speed bit rate signal is disposed in an odd channel group and a high-speed bit rate signal is disposed in an even channel group, are demultiplexed into a low-speed signal group and a high-speed signal group by an unequal bandwidth interleaver. The low-speed signal group is processed (e.g. demultiplexing, dispersion compensation) by an optical device appropriate for the low-speed signals, and the high-speed signal group is processed by an optical device appropriate for the high-speed signals.

Abstract: Techniques for providing ADM functionality to an optical (OTN/DWDM) ring are provided. A pair of muxponder components are utilized to form a transparent ADM. In one muxponder, transmit signals are sent in a first direction and receive signals are received from a second direction. In the other muxponder, transmit signals are sent in the second direction and received from the first direction.

Abstract: Wavelength assignment schemes that provide full-connectivity in RANs with fixed-tuned OADMs. In the first scheme, wavelengths are assigned to nodes according to Hadamard code, and in the second scheme, bands of contiguous wavelengths are assigned to nodes. Simulation results show that on the average, the Hadamard wavelength assignment schemes approach the performance of RANs with OADMs that add-drop all wavelengths, while saving 50% of the TDM terminals. The saving of TDM terminals by using wavelength tunable OADMs vary in different cases. Tunable OADMs are advantageous for lower traffic granularity and more interactions of a RAN with the outside network.

Abstract: Disclosed is a drop-and-continue device (84), provided between a signal converter (85) which supplies a signal to an end user and a wavelength-division multiplexing device (83) which comprises an optical demultiplexer (831) for separating an optical signal of a desired wavelength from an optical signal supplied from a head end station (82) and an optical multiplexer (832) for supplying an optical signal to a wavelength-division multiplexing device at a subsequent stage, comprising: an optical receiver (841) which converts the optical signal separated by the optical demultiplexer into an electrical signal; a transmitter (844) which transmits the electrical signal to the end user via the signal converter (85); an optical transmitter (845) which supplies an optical signal to the optical multiplexer (832); and a loopback processor (842) which loops the electrical signal output from the optical receiver back to the optical transmitter, thereby providing a drop-and-continue device that can easily add capabilities b

Abstract: An optical switch includes an optical source; a plurality of tunable optical resonators or tunable waveguides in optical communication with the optical source; and a tuning device configured to selectively route an optical beam from the optical source to at least one optical destination by tuning at least one of the optical resonators or tunable waveguides, in optical communication with at least one optical destination, to a wavelength characteristic of the optical beam.

Abstract: An optical channel monitor is provided that sequentially or selectively filters an optical channel(s) 11 of light from a (WDM) optical input signal 12 and senses predetermined parameters of the each filtered optical signal (e.g., channel power, channel presence, signal-noise-ratio). The OCM 10 is a free-space optical device that includes a collimator assembly 15, a diffraction grating 20 and a mirror 22. A launch pigtail emits into free space the input signal through the collimator assembly 15 and onto the diffraction grating 20, which separates spatially each of the optical channels 11 of the collimated light, and reflects the separated channels of light onto the mirror 22. A ?/4 plate 26 is disposed between the mirror 22 and the diffraction grating 20. The mirror reflects the separated light back through the ?/4 plate 26 to the diffraction grating 20, which reflects the channels of light back through the collimating lens 18.

Abstract: A group delay compensation equalizer is disclosed that employs a single channel four-port WDM device for compensating the group delay experienced by a plurality of wavelengths transmitted over different paths. The transmission differential between two wavelengths is compensated by transmitting the two wavelengths through two different paths where the fiber length in reflecting the second wavelength is equal to the transmission time difference between the two wavelengths. The single channel four-port group delay equalizer effectively provides a unidirectional signal flow, as compared to the conventional equalizer that transmits optical signals bi-directionally. The present invention reduces the cost of a group delay equalizer by simplifying the use of multiple three-port WDM devices into a single channel four-port WDM device.

Abstract: Systems and methods use single-fiber optical add/drop multiplexers (OADMs) to enable bi-directional data transmission in WDM systems over a single fiber. By reducing the required capacity for an optical network from dual fibers to a single fiber, significant cost and bandwidth efficiencies are achieved. The systems and methods also provide redundancy protection in single-fiber bidirectional line ring systems. In the event of a downstream fiber or device failure, the OADM module receives a signal on a first wavelength from a first direction, shifts the signal from the first wavelength to a second wavelength, and sends the signal back down the fiber it originated from on the second wavelength, thus maintaining the propagation of the signal in the ring system.

Abstract: There is provided a shutdown controller that monitors the temperature of an optical multiplexer and maximizes the loss of an optical attenuator when a temperature monitor result is abnormal. An optical level change detection circuit section is disposed with respect to an optical level monitor of individual monitors in an optical add/drop multiplexer. An optical level monitor of a total main signal is disposed downstream of the optical multiplexer. The inconsistency of the wavelength number is detected by comparing the total of the optical level monitors of the individual channels with the optical level value of the optical level monitor, upon which shutdown control is performed in which the loss of the optical attenuator is maximized in only the channel whose optical level change is detected by the optical level change detection circuit section.

Abstract: A packet-switched WDMA ring network has an architecture utilizing packet stacking and unstacking for enabling nodes to access the entire link capacity by transmitting and receiving packets on available wavelengths. Packets are added and dropped from the ring by optical switches. A flexible credit-based MAC protocol along with an admission algorithm enhance the network throughput capacity.

Abstract: This invention provides a new architecture for a communication system between head-ends and end-users which expands bandwidth and reliability of the communication system. A mux-node receives communication signals from a head-end and forwards the received communication signals to one or more mini-fiber nodes. The connection to the head-end is via a small number of optical fibers and the connections to each of the mini-fiber nodes may be via one or more optical fibers that may provide full duplex communication. The head-end may communicate with the mux-node using digital or digital and analog signals. The mini-fiber nodes may combine the signals received from the head-end with loop-back signals used for local media access control prior to forwarding the signals to the end-users. Upstream data are received by the mini-fiber nodes and transmitted to the mux-node.

Abstract: A system and method for modularly scalable architecture for optical networks are provided. In one embodiment, a node for an optical network comprises a plurality of in-line switches connected to an optical ring and operable in a first state to both pass an optical signal received from the optical ring to an associated coupler and pass an optical signal received from the associated coupler to the optical ring. The optical signal carries traffic in a plurality of channels. A drop coupler is coupled to a first in-line switch and is operable to receive an optical signal from the in-line switch where the switch is in the first state, pass a first copy of the optical signal back to the in-line switch for passing to the optical ring, and drop a second copy of the optical signal to a distributing element. The distributing element is operable to receive the second copy and pass traffic in one or more channels of the second copy.

Abstract: There is provided a method of, and apparatus for, regulating radiation component (wavelength channel) power in a wavelength division multiplexed (WDM) optical communications system (10). The system (10) comprises a plurality of nodes (20) interconnected through optical waveguides (30, 40) (optical fibers). The method is characterised by: passing one or more tokens (300) around the system from node to node; adjusting nodal settings (150, 170), such as optical attenuation, applied at each node to regulate the power of WDM radiation components at the node in response to receiving one or more tokens; and repeating the method until WDM radiation component power within the system is substantially regulated.

Abstract: An optically amplified wavelength division multiplexing network has the functionality to add/drop channels at the optical add/drop multiplexing (OADM) nodes. The OADM node includes a receiver amplifier, an OADM module, and a transmitter amplifier. Once the OADM node detects a loss of signal (LOS) due to a fiber cut or network element failure upstream, the receiver amplifier is kept in operation as a noise source. The output of the receiver amplifier is immediately raised by increasing pump power to compensate for the LOS. The noise power received at the transmitter amplifier from the receiver amplifier is substantially equal to the signal power expected before LOS. The transient effect of downstream optical amplifiers is therefore completely suppressed and the inter-channel stimulated Raman scattering (SRS) induced spectrum tilt does not change. After the noise power is raised, the receiver amplifier may be shut down at a speed much slower than the speed of downstream amplifier control circuitry.

Abstract: An optical control monitor and a method for adjusting for changes in optical signals transmitted through an optical network. The method comprises the steps of transmitting a set of optical signals through a network, each of the optical signals having a respective wavelength; and tracking changes to said set of signals by passing each of the signals through a filter having a bandpass function, and dithering the filter bandpass about the wavelengths of each of said set of signals to generate filter output signals. The filter output signals are used to adjust the network or the set of optical signals to compensate for said changes.

Abstract: The invention describes an integrated-photonics arrangement, implementable in a multi-guide vertical integration structure composed from III-V semiconductors and grown in one epitaxial growth run, that allows for vertical and lateral splitting of optical signals co- or bi-directionally propagating in the common passive waveguide into plurality of the vertically integrated passive or active wavelength-designated waveguides, therefore, enabling the wavelength-designated waveguides operating in different wavelengths to be monolithically integrated onto the same substrate and connected to the shared passive waveguide.

Abstract: A reconfigurable optical add drop multiplexer core device includes a light distributor, a light combiner, and first and second sets of add and drop ports. The light distributor is configured to receive an optical signal along a primary input of the reconfigurable optical add drop multiplexer core device and to distribute the received optical signal along a plurality of subtending outputs. The light combiner is configured to receive optical signals along a plurality of subtending inputs, to combine the received optical signals into a combined signal, and to output the combined signal. The add and drop ports in the first set function as add and drop ports, respectively, and the add and drop ports in the second set function as both add and drop ports, respectively, and as express ports connectable to another reconfigurable optical add drop multiplexer core device.

Abstract: The present invention extends the concept of a standard array waveguide grating (AWG), which focuses each wavelength component launched via an input AWG to a Rowland circle inside a planar lightwave chip (PLC) where discrete waveguides are located, to one which focuses each wavelength component outside of the PLC chip along a straight line. An array of MEMS mirrors or other redirecting elements is positioned at the focus location for independently redirecting each of the wavelength channels back to any number of selected output AWGs formed on the same PLC chip as the input AWG.

Abstract: An integrated reconfigurable planar lightwave add-drop (RPLAD) multiplexer for use in a WDM optical communication system is arranged such that each drop port can receive any wavelength channel and each add port can transmit on any wavelength channel. Drop port reconfigurability is achieved by integrating a cross-connect functionality into the RPLAD, illustratively using optical 1×2 switches to perform “space” switching. The switches are controlled from a remotely located node controller. Add port reconfigurability is achieved by having tunable lasers and a wavelength independent optical power combiner, which may be a star coupler that is integrated with the other above-mentioned elements.

Abstract: An optimum optical node processor is provided to a metropolitan network in which the distance of a transmission line between each optical node processor is short. The optical node processor according to the invention is provided with an optical add/drop multiplexer (OADM), variable optical control means connected to the OADM for collectively attenuating the intensity level of WDM optical signals, a controller for controlling the variable optical control means and monitoring control means for controlling the controller according to information from an external device, and enables the automatic power reduction (APR) control and the output control of an optical network system.

Abstract: Systems and methods to reduce passband side-lobes associated with WSS-based ROADMs by applying a filter on each channel are provided. In an exemplary embodiment, a comb filter, such as a thin film filter or an interleaver, is utilized. Additionally, the present invention provides systems and methods to adaptively control amplifier target power and per wavelength target power to maintain signal launching power as per design in networks with WSS-based ROADMs. Accordingly, signal OSNR does not collapse faster than other similar configured system without WSS-based ROADM. In order to correct amplifier target power, the present invention utilizes system information about side-lobe size and OSNR at each amplifier.

Abstract: An apparatus for shared optical performance monitoring (OPM) is provided. A wavelength sensitive device receives light at an input port and routes it wavelength selectively to a set of output ports. To perform optical performance monitoring on the output ports, a monitoring component of each output signal is extracted, and these monitoring components are then combined. A single OPM function is then performed on the combined signal. However, with knowledge of the wavelengths that were included in each output signal, a virtual OPM function can be realized for each output port. The per port functionality can include total power per port, power per wavelength per port, variable optical attentuation, dynamic gain equalization, the latter two examples requiring feedback.

Abstract: A reconfigurable optical add-drop mulitplexer comprises a first waveguide layer having formed therein a first multiplexer-demultiplexer, a second multiplexer-demultiplexer, and a plurality of optical switches. The reconfigurable optical add-drop multiplexer further comprises a second waveguide layer optically coupled to the first waveguide and having a second effective index of refraction, said second waveguide layer having an optical amplifier formed therein. An input signal is amplified by the optical amplifier and communicated to the first optical multiplexer-demultiplexer where the signal is demultiplexed into a plurality individual wavelength signals. The second optical multiplexer-demultiplexer is adapted to receive a multiplexed add signal and to demultiplex the add signal into component wavelength signals. The individual wavelength signals are received at the optical switches and selectively routed to either an optical detector or toward the first multiplexer-demultiplexer.

Abstract: An optical transceiver for transmitting light source control information, which is applied to a Subcarrier Multiplexing optical network, is disclosed. The optical transceiver includes a controller, an SCM frame generation/restoring unit, a modulator/demodulator, and an EO/OE converter. The controller controls transmission of light source control information or collects received light source control information. The SCM frame generation/restoring unit generates an SCM frame containing light source control information received from the controller. The modulator/demodulator modulates an SCM frame generated by the SCM frame generation/restoring unit into a signal suitable for transmission. The EO/OE converter converts a transmission signal modulated by the modulator/demodulator into an optical signal and transmits the optical signal through an optical fiber. An optical network having a telephone office OLT and subscriber ONTs, each having the optical transceiver, is also disclosed.

Abstract: A method for transmitting a packet in a wireless access network based on a wavelength identification code scheme. The method comprises the steps of connecting n number of RNCs (Radio Network Controllers) to one sub-ring where the “n” is a positive integer, and assigning a unique wavelength to each RNC; identifying a packet to be transmitted between the RNCs located within a same sub-ring using the assigned unique wavelength, and transmitting the packet through an SRC (Sub-Ring Controller); connecting m number of SRCs to one main-ring where the “m” is a positive integer, and assigning a unique wavelength to each SRC; and detaching a wavelength identification code from the packet to be transmitted between the RNCs located within different sub-rings, and transmitting the packet having the encapsulated wavelength identification code through an MRC (Main-Ring Controller).

Abstract: The optical signal multiplexer/demultiplexer of the invention is characterized by incorporating a bidirectional optical transceiver which is capable of using individual channels working in a transmitting and receiving modes simultaneously. The device consists of a number of optical prisms combined into a single module and provided with appropriate dichroic mirrors and interferrometric filters located on the outer surfaces of the prisms. According to one embodiment of the invention, the module consists of two sequentially arranged parallelogram prisms, a single-channel signal input/output unit with an optical collimator/focusator on one side of the prism module and a two-channel signal output/input unit with a respective optical collimator/focusator on the other side of the prism module.

Abstract: A system and methods are disclosed for a hybrid silicon-organic scalable reconfigurable optical add-drop multiplexer. An embodiment of a scalable reconfigurable optical add-drop multiplexer (ROADM) includes an optical bus for optical signals of different wavelengths, a plurality of add/drop optical waveguides, and a plurality of ring resonators, each being optically coupled to the optical bus and to one of the add/drop optical waveguides. The ring resonators are coated with an organic electro-optic cladding layer and are configured to switch wavelength selected optical signals between the optical bus and the add/drop optical waveguides in response to control voltages applied to the organic electro-optic cladding layer. The individual ring resonators of the ROADM can be independently modulated and tuned to filter specific wavelengths.

Abstract: An optical ring network architecture including a number (N) of multi-add/drop filters, such as filters formed using symmetrical pairs of frequency routers. Each multi-add/drop filter is coupled to two other multi-add/drop filters using N?2 transmission media, such as optical fibers, to form a ring. The network also includes a number (N) of terminal stations associated with the multi-add/drop filters. A terminal station (p) is coupled with, and receives information from, its associated multi-add/drop filter (p) through a single optical fiber. In addition, the terminal station p is coupled with, and transmits information in a first direction around the ring to, a multi-add/drop filter p+1 through a single optical fiber. Communications from terminal station p to each other terminal station in the first direction are assigned one of N?1 wavelengths such that no two wavelengths on a given optical fiber are associated with communications between terminal stations in the same direction.

Abstract: A selective WDM add-channel system and method for adding channels to a WDM (wavelength division multiplexed) signal input to produce a WDM signal output while protecting against signal collisions are provided. The method protects against signal collisions by determining channel wavelengths of add-channel signals and at least one of the WDM signal input and the WDM signal output to ensure that channels that are added to the WDM signal input have different channel wavelength than each other and the channels that are already part of the WDM signal input. The selective WDM add-channel system comprises a selective combiner and a controller and is operable to selectively combine a plurality of add-channel inputs with a WDM input signal to produce a WDM output signal based on the channel wavelengths of the add-channel input signals and at least one of the WDM input signal and the WDM output signal.

Abstract: An optical transmission device improved in quality and reliability of OADM function and permitting configuration of highly-flexible, economical OADM networks. A wavelength tunable filter variably selects a wavelength according to a control frequency. A filter controller applies the control frequency to the filter while scanning wavelength over an entire signal bandwidth, to detect, from a reference wavelength monitor signal supplied thereto, a reference control frequency which permits the filter to select a reference wavelength and according to which wavelength is matched. On receiving a wavelength selection request, the controller obtains a target control frequency from the reference control frequency and the position of a target wavelength relative to the reference wavelength, and applies the obtained frequency to the filter. A reference wavelength filter transmits the reference wavelength therethrough. A light-receiving element monitors the transmitted reference wavelength to generate the monitor signal.

Abstract: Embodiments of present system encompass: a plurality of laser sources that produce a plurality of respectively different optical wavelengths; a matrix switch having a plurality of inputs operatively coupled to the plurality of laser sources, each of the plurality of inputs receiving a respective optical wavelength; and the matrix switch having an output that produces a series of interleaved pulses of the different optical wavelengths.

Abstract: The invention relates to wavelength-selective optical filters for allowing light of a narrow optical spectral band, centered around a wavelength (?c) to pass through them, while reflecting the wavelengths lying outside this band. According to the invention, the transfer function (T1,2(?)) of the component is defined by multiplying two transfer functions of spectrally offset Fabry-Perot filters.

Abstract: The network comprises an optical ring link (F) and a concentrator (HUB) that sends via one end of the link “downlink” optical signals carried by respective wavelengths and receives “uplink” optical signals via the other end of the link. The link is divided into a plurality of segments (FS1-FS4) separated by access nodes (AN1-AN3) for receivers (RX) of downlink optical signals and for senders (TX) of uplink optical signals. Each access node comprises coupling means that are not wavelength-selective for coupling the segment on the upstream side of the node to the segment on the downstream side and to the receivers and to couple the senders (TX) to the segment on the downstream side. The downlink optical signals are carried by wavelengths belonging to a set of predefined wavelengths. To optimize the use of spectral resources, a rejection filter (NF) is inserted into a segment to reject a portion of the wavelengths of said set of wavelengths.

Abstract: Provided is an optical network node device. According to the optical network node device, a planar lightwave circuit (PLC) based or a blocker based 4-terminals ROADM can be used in a node of at least degree 3, a proceeding direction of a wavelength channel can be changed in an electrical cross connect switch, and transmission in a unit smaller than a wavelength channel can be cross connected, dropped, and added, or transmission capacity can be redistributed in the electrical cross connect switch. Accordingly, efficient transmission in a small capacity and large capacity transmission of a wavelength channel can be performed simultaneously, and thus an optical network can be effectively managed. Also, since the node of at least degree 3 uses the PLC based or a blocker based reconfigurable optical add drop multiplexer (ROADM), the node of at least degree 3 can use the same ROADM module as a node of degree 2. Accordingly, the optical network node device has an advantage in manufacturing and managing a node.

Abstract: An optical transmission apparatus includes a return line for connecting a first transmission line and a second transmission line opposed to the first transmission line in order to make it possible to commonly use a transmitter-receiver or a repeater, for example, between a trunk line and a branch line and prevent a situation that the power of branched signal lights increases excessively. The optical transmission apparatus is configured so that dummy lights inputted together with signal lights to be added to signal lights transmitted through the first transmission line are sent to the second transmission line through the return line and are outputted together with signal lights to be dropped from the second transmission line.

Abstract: A wavelength division multiplexed optical communication system including a first optical line interface optically coupled to a first transponder and an optical demultiplexer through which the first optical line interface is not optically coupled to the first transponder. The system also includes a second optical line interface and at least one switch. The switch is operable to optically couple the second optical line interface to (a) the first optical line interface through at least the optical demultiplexer, and alternatively (b) the second transponder. A method for an optical add/drop multiplexing system also is provided.

Abstract: A method for communicating optical traffic in a network comprising a plurality of network nodes includes receiving traffic to be added to the network at a network node. The network is operable to communicate received traffic in an optical signal comprising one or more channels. The method also includes determining a data rate and one or more destination nodes of the received traffic and assigning the received traffic to one or more of the channels of the optical signal based on the determined data rate and the destination nodes. The method further includes configuring one or more of the network nodes to process the traffic contained in the assigned channels based on the data rate and the destination nodes of the optical traffic and communicating the traffic through network in the assigned channels of the optical signal based on the determined data rate and the one or more destination nodes.

Abstract: An Ethernet passive optical network (EPON) ring for providing protection against fiber failures. The optical network unit (ONU) is coupled to the ring fiber by a three-port passive optical splitting module that has three two-way optical passages. By the three two-way optical passages, the OUN receives/transmits data from/to the two ends of the optical line termination (OLT) to provide protection while the fiber failure. Moreover, it provides better authorization of users and simpler collision detection by the two-way transmission of the three-port passive optical splitting module to prevent hackers from invading and to reduce collisions.

Abstract: A high-speed WPAN (Wireless Personal Area Network) system for extending a service area includes an optical fiber serving as a medium for transmitting data; a plurality of pico-nets each including a plurality of devices and a PNC (Pico-Net Coordinator) device for managing the devices; a plurality of two-way signal converters corresponding to the pico-nets, each of the signal converters adapted for converting an optical signal received from the optical fiber into an electrical signal to transmit the electrical signal to the pico-nets, and for converting an electrical signal received from each of the pico-nets into an optical signal to transmit the optical signal to the optical fiber. A plurality of connectors are attached to the optical fiber and the signal converters for transmitting signals input from the optical fiber and the signal converters bidirectionally.

Abstract: A modular cross connect system for optical telecommunication networks has the optical unit divided in at least two main bodies with one section for connection comprising the collimators and a main commutation section with MEMS devices. The first section is a fixed part while the second section is a readily removable section. The two sections face each other through a window and, in the first section, optics are provided for steering all or part of the optical signals from and to the main MEMS unit to a MEMS standby or protection plane to allow replacement of the main MEMS unit without interrupting service.

Abstract: A hub for use in a passive optical network (PON) includes a transmission fiber on which an information-bearing optical signal is received, a double-cladded, rare-earth doped fiber located along the transmission fiber for imparting gain to the information-bearing optical signal, and a combiner having an output coupled to the transmission fiber and a plurality of inputs. The output is coupled to the transmission fiber such that optical energy at pump energy wavelengths but not signal wavelengths are communicated therebetween. At least one pump source is optically coupled to one of the inputs of the combiner for providing optical pump energy to the double-cladded, rare-earth doped fiber. An optical splitter is also provided. The optical splitter has an input coupled to the transmission fiber for receiving an amplified, information-bearing optical signal and a plurality of outputs for directing portions of the amplified, information-bearing optical signal to remote nodes in the PON.

Abstract: A technique for photonic switching is disclosed. In one particular exemplary embodiment, the technique may be realized as a method for photonic switching. The method may comprise receiving at least one optical signal at a photonic line card, wherein the at least one optical signal comprises one or more wavelength channels and the photonic line card comprises at least one integrated optical switch. The method may also comprise routing at least one of the one or more wavelength channels through the at least one integrated optical switch to a photonic bus, wherein the photonic bus comprises a plurality of optical paths and each of the plurality of optical paths is capable of carrying multiple wavelength channels.

Abstract: A method and a system in which selected wavelengths of a wavelength division multiplexed (WDM) signal are modulated with multicast data for multicasting data services on an optical network. The WDM signal is received from a hub node of the optical network, such as a unidirectional ring network or a bi-directional ring network. A four-port wavelength crossbar switch (4WCS) selectably switches selected wavelengths from the optical network to a modulator loop. The modulator loop includes a multicast modulator that modulates the selected plurality of wavelengths with the multicast data. Each modulated wavelength is then switched back to the optical network by the 4WCS switch, and sent to a plurality of subscriber nodes of the optical network. This architecture allows a facility provider to be physically separated from a content provider, and affords the flexibility of selectively delivering multicast content to individual subscribers.

Abstract: An optical transmission device capable of preventing deterioration in the transmission quality of a signal beam. A wavelength-multiplexed signal beam from a transmission path is split by a splitter, and the split signal beams are input to first and second optical paths, respectively. An add/drop unit for adding/dropping a wavelength-multiplexed signal beam is removably insertable in the second optical path. A switch outputs the wavelength-multiplexed signal beam, received from one of the first and second optical paths, to an optical amplifier. The optical amplifier amplifies the wavelength-multiplexed signal beam output from the switch and outputs the amplified signal beam to a subsequent circuit.

Abstract: Apparatus for diversely routing optical wavelengths across a point-to-point subnetwork. An optical network includes a first optical ring having at least first, second, and third nodes adjacently positioned; a second optical ring having at least fourth, fifth, and sixth nodes adjacently positioned, pairs of optical fibers link the adjacent nodes; a point-to-point subnetwork having at least first, second, third, and fourth optical fibers optically coupling the first and second optical rings. The first node is configured to route working bands across the first optical fiber to the fifth node and to route a copy of the working bands to the second node. The second node is configured to route either the copy of the working bands or a select subset of the copy of the working bands across the third optical fiber to the fourth node.

Abstract: Optical bypass node upgrade configurations are disclosed: (1) a configuration where optical taps are pre-positioned in wavelength division multiplex (WDM) line systems terminating at optical-electrical-optical (OEO) core switching nodes to allow for future upgrade of the nodes to degree-two or higher optical bypass; (2) a configuration where the taps are pre-positioned in a degree-two optical bypass node to allow for future upgrade to a degree-N optical bypass node; and (3) a configuration and procedure for upgrading OEO core switching nodes to optical bypass when the taps have not been pre-positioned in the WDM line systems. These configurations do not introduce bit errors for non-upgraded optical paths.

Abstract: The present invention relates to an optical transmission apparatus capable of suppressing a transitional gain variation when a number of signal wavelengths changes, and maintaining communication quality in optical signals. The optical transmission apparatus is provided with an optical power control device that varies light power of light for each wavelength component corresponding to a wavelength channel, the light including signal light and spontaneous emission light; a wavelength arrangement information obtaining unit that obtains arrangement information of the wavelength channel of the signal light; and a control unit that controls the power control device based on the arrangement information obtained at the wavelength arrangement information obtaining unit so that light power of a wavelength component of the signal light and light power of a wavelength component other than the wavelength component of the signal light become substantially equal.

Abstract: A method and system provide capacity-efficient restoration within an optical fiber communication system. The system includes a plurality of nodes each interconnected by optical fibers. Each optical fiber connection between nodes includes at least three channel groups with different priority levels for restoration switching in response to a connection failure. The system maintains and restores full-capacity communication services by switching at least a portion of the channel groups from a first optical fiber connection to a second optical fiber connection system based on the priority levels assigned to the channel groups. Service reliability is effectively maintained without incurring additional costs for dedicated spare optical fiber equipment by improving idle capacity utilization.

Abstract: The tunable add/drop multiplexer including a tiltable mirror, a fixed thin film filter, and first and second retro-reflector elements for redirecting express channels back out an input/output port and for redirecting drop channels back out an add/drop port, respectively.