187 results about "Add-drop multiplexer" patented technology

A tunable optical filter is provided that includes an array of independently tunable filter elements. Each of the elements is located along a different optical path that extends between an input and an output port. Optical assemblies for receiving an incident optical signal for providing a filtered optical signal are also provided. In one embodiment, polarization independent spectral filtering can be achieved. Wavelength selectable add / drop multiplexers and demultiplexers, dynamic gain equalizers and attenuators, optical channel blockers and branch filters, switches, and modulators are also provided. Furthermore, methods for constructing and operating filters consistent with this invention are also provided.

Optical networks are increasingly employing optical network nodes having multiple interfaces to allow a node to direct optical signals received at any interface to any other interface connected to the node. Constructing a larger wavelength selective switching (WSS) module used in such a node can be complex and expensive. A method an apparatus for constructing a large WSS using parallelism is provided. In example embodiments, a larger WSS may include multiple parallel non-cascaded smaller WSSs and an optical coupler configured to optically couple the multiple parallel, non-cascaded smaller WSSs. This technique may be used to construct both N×1 and 1×N WSSs. Because the technique employs multiple parallel, non-cascaded WSSs, all inputs of a larger N×1 WSS and all outputs of a larger 1×N WSS are available receive or transmit external signals rather than being rather than being unavailable due to, for example, cascading smaller WSS devices together.

It was difficult to detect a wavelength error. Further, a wavelength error of an optical add signal is accompanied by a calculation error of the number of wavelengths of a wavelength division multiplexing signal, which causes a set value of an optical signal level to become abnormal, resulting in the degradation of the optical signal. According to the present invention, part of an inputted optical add signal 118 is reflected by a mirror 117, and is thereby inputted into an optical wavelength multiplexer 105 in the reverse direction so that the optical add signal is returned to paths 115-1 through 115-16 corresponding to wavelengths λ1 through λ16. If the returned optical add signal is an optical add signal having a correct wavelength (in FIG. 1, λ16), the optical signal enters its corresponding backward direction optical detector 113-16. Accordingly, it is possible to check whether or not a wavelength of the optical add signal is correct.

A reconfigurable optical add / drop multiplexer (ROADM) includes a first optical dynamic gain equalization filter (DGEF) having a first input for receiving an initial wavelength division multiplexed (WDM) signal, a first output for sending a phase shifted WDM signal, and a second output connected to a demultiplexer for demultiplexing a WDM drop signal thereby producing a plurality of drop channels. A second DGEF having a first input for receiving the phase shifted WDM signal, a second input connected to a multiplexer, for multiplexing a plurality of add channels to produce thereby a wavelength division multiplexed (WDM) add signal, and an output for sending a second adjusted WDM signal. The ROADM allows for the channels from the initial WDM signal to be dropped, added and equalized.

In an Optical Add-Drop Multiplexer, a drop section comprises a Wavelength Selective Switch (WSS) having at least one drop-port, the WSS being operative to couple a respective set of w (where w>1) wavelength channels from a received Wavelength Division Multiplexed (WDM) signal to each drop port. A respective 1:s power splitter is associated with each drop port. Each power splitter supplies the respective set of channels received from its drop port to each one of a corresponding set of coherent receivers. Each coherent receiver operates to receive a selected one of the respective set of channels.

This invention relates to provisioning wavelength-selective switches and reconfigurable optical add-drop multiplexers to minimize the bandwidth narrowing effect from the optical filters. Novel architectures and methods are disclosed that can significantly reduce bandwidth-narrowing on channels in a reconfigurable WDM network where a large number of optical filter elements are cascaded. Instead of blocking unused channels as in the prior art, unused channels are selectively provisioned depending on the state of their adjacent channels. Unused adjacent channels of an active channel are provisioned to follow the same path as the active channels. As each channels is deployed, the channel frequency is selected so as to minimize bandwidth narrowing.

Architecture for a SONET network element. The architecture includes an interconnection system for a network element, including a line unit slot, a switch fabric slot, and service unit slots. The line unit slot is connected as a hub to the switch fabric slot and the service unit slots in a first star interconnection configuration. The switch fabric slot is connected as a hub to the line unit slot and the service unit slots in a second star interconnection configuration. The star interconnection configurations provide fault isolation between different units, and allow for replacement of failed units without interfering with the links of other units to the hub. A service unit is provided including a first backplane interface for connecting with an ATM star interconnect configuration within the network element, and a second backplane interface for connecting to an STM star interconnect configuration within the network element.

A Resilient Packet Ring (RPR) add / drop device to connect multiple rings, e.g. SDH / SONET rings, wavelength or fibers, to a single switch or router device is disclosed. The add / drop device according to the invention comprises two multiplexing framer devices and an Add / Drop Multiplexor-Media Access Control (ADM-MAC) device. Each of the multiplexing framer devices combine at least two RPR data signals having an input data rate into a single data stream having an output data rate being higher than the input data rate for transmission on a shared medium or vice versa. The ADM-MAC device interfaces the two multiplexing framer devices and the switch or router device.

An optical interleaver for receiving an incident beam carrying a wavelength-division-multiplexed (WDM) signal comprising a plurality of channels at center wavelengths .lambda..sub.1, .lambda..sub.2, .lambda..sub.3, .lambda..sub.4, .lambda..sub.5, .lambda..sub.6, . . . and generating therefrom at least one de-interleaved output signal comprising the odd channels .lambda..sub.1, .lambda..sub.3, .lambda..sub.5, . . . or the even channels .lambda..sub.2, .lambda..sub.4, .lambda..sub.6, . . . is described. The optical interleaver comprises a splitting element for splitting an incident beam into a first optical signal directed along a first path and a second optical signal directed along a second path, a first resonant element positioned along the first path, a second resonant element positioned along the second path, and a combining element positioned to receive and to interferometrically combine the outputs of the first and second resonant to produce the output signal. The optical interleaver may be implemented using a free-space configuration using a beamsplitter and a plurality of resonant cavities such as asymmetric Fabry-Perot resonators or Michelson-Gires-Tournois resonators. In an alternative preferred embodiment, the optical interleaver may be implemented in a Mach-Zender-style configuration using couplers and fiber ring resonators. According to a preferred embodiment in which the optical interleaver is in a free-space configuration, the splitting element that receives the incident beam comprises a partially reflective surface positioned such that a normal to the reflective surface is at a less-than-30 degree angle with respect to the incoming beam for increased stability against polarizations in the incoming beam. According to another preferred embodiment, thermal stability of the optical interleaver is enhanced by configuring and dimensioning the optical interleaver such that the amount of glass or other optical material in the first and second split-beam paths is equalized. In accordance with reciprocity principles, the optical interleaver is readily adapted to operate as an interleaver, de-interleaver, or add / drop multiplexer.

The present invention discloses a concept of natural index contrast (NIC) for producing photonic waveguides and methods of fabrication thereof. Such waveguide forms the basis of a class of chip-scale micro- and nano-photonic integrated circuits (PICs). The NIC method utilizes the built-in refractive index difference between two layers of dielectric thin films of two different materials, one laid on top of another. This new class of waveguides simplifies the PIC fabrication process significantly. Based on the NIC based waveguides, PICs can be fabricated for a number of photonic applications such as arrayed waveguide grating (AWG), reflective arrayed waveguide grating (RAWG), interleaver, interferometer, and optical sensor. Additionally, several other PICs can also be fabricated via tiers of integration, such as triple-phase integration. Examples of such devices include optical amplifier, wavelength router, sensor, optical modulator, transmitter, receiver, transponder, fully built dense wavelength division multiplexer and demultiplxer, optical power splitter, multicahnnel tunable optical attenuator, and multicahnnel tunable optical add-drop multiplexer. Unlike hybrid integration, triple-phase integration monolithically integrates multiple optical functionalities on a single chip.

A reconfigurable WDM add / drop multiplexer and its method of operation at an add / drop node on an optical fiber carrying a plurality of WDM signals is described. The WDM add / drop multiplexer has a coupler and a demultiplexer element dropping WDM signals from the optical fiber to a plurality of drop terminals, and a wavelength-selective switch adding WDM signals from a plurality of add terminals onto the optical fiber. The coupler splits the WDM signals received from the optical fiber and passes the split WDM signals to the first and second output terminals. The demultiplexer element separates the split WDM signals at the plurality of drop terminals. The wavelength-selective switch, which has an input terminal for connection to the second coupler output terminal and an output terminal for connection to the optical fiber, selectively adds WDM signals on the plurality of add terminals to the optical fiber responsive to control signals.

A method and apparatus for adapting a network topology including at least one hybrid digital cross-connect system (DCS) / SONET ring structure such that DCS network elements are managed by a DCS element management system, while SONET network elements such as ring structures are managed by a SONET element management system. A digital link is created to separate pure DCS equipment from SONET equipment within the hybrid DCS. Based on this separation, the hybrid DCS is logically decomposed into separate DCS and SONET equipment such that a SONET ring structure including an add-drop multiplexer (ADM) included within the DCS may be managed as a homogeneous SONET ring by a SONET network element manager, while the DCS equipment is managed by a DCS element manager.

The invention discloses an optical isolator, an optical add / drop multiplexer and an optical combiner, wherein the optical isolator comprises an input wave guide, a waveguide grating containing magneto-optic material and an output wave guide which are connected sequentially in series; the optical add / drop multiplexer comprises the optical isolator, a main input end, a first circulator, a second circulator, a main output end, a downloading end and an uploading end, wherein the main input end, the first circulator, the optical isolator, the second circulator and the main output end are connectedsequentially in series, the downloading end is connected with the first circulator, and the uploading end is connected with the second circulator; and the optical combiner comprises the optical isolator, a first input end, a second input end, an optical circulator containing the magneto-optic material and an output end, wherein the first input end, the optical isolator and the output end are connected in series, and the second input end is connected with the optical circulator containing the magneto-optic material. The optical isolator, the optical add / drop multiplexer and the optical combiner have small volumes and good mechanical stability.

In today's reconfigurable optical add / drop multiplexer (ROADM) based optical node, ROADMs multiplex (and demultiplex) colored optical signals to form wavelength-division multiplexed (WDM) signals. Transponders connected to the ROADMs' add / drop ports convert noncolored optical signals to colored optical signals (and vice versa). Dedicating transponders to given ports degrades the node's ability to route around network failures. Example embodiments of the invention include an optical node and corresponding method for routing optical signals within an optical node that compensate for this inflexibility. The optical node may include two ROADMs to transmit respective WDM signals onto at least two internode network paths and a routing module that can direct channels of the same wavelength along different internode network paths. Advantageously, a transponder may transmit (receive) different signals at the same wavelength to (from) different network node interfaces within the optical node, thereby improving the optical node's ability to route around network failures.

A reconfigurable optical device including input and output ports, and add or drop ports, has a high degree of flexibility such that any wavelength channel from any optical signal introduced through the add ports may be added to any of the optical signals transmitted through the output ports. In addition, any wavelength channel from any optical signal received through the inputs ports may be dropped through any of the drop ports. Furthermore, the optical device is configurable to allow the same wavelength channel from two different optical signals supplied respectively through any two inputs ports to be simultaneously directed to two different drop ports.

Techniques are disclosed for generating a hitless migration plan to optimal state, given an optimal routing and wavelength assignment for demands. For example, a technique for use in performing a circuit transition in accordance with an optical ring-based network comprises obtaining a first (e.g., initial) circuit layout and a second (e.g., final) circuit layout for a given set of demands to be routed on the optical ring-based network. The technique then comprises calculating a transition sequence plan useable to transition the network from the first circuit layout to the second circuit layout such that substantially no network service disruption occurs due to the circuit transition. The transition sequence plan is calculated by determining a minimum set of circuits that when moved from first positions in the first circuit layout result in a feasible transition sequence for remaining circuits in the first circuit layout. Wavelength equivalence and demand equivalence properties may be applied individually or jointly.

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.

At a WDM add / drop node of an optical fiber, an add / drop multiplexer system with opto-electric components in the through channel path has an optical switch connected in parallel with an add / drop multiplexer. Upon a power loss to the add / drop multiplexer, the optical switch bypasses the add / drop multiplexer so that WDM channel signals pass through the WDM add / drop node without interference from the unpowered add / drop multiplexer. Loss of through channels at the node is prevented. Upon a return of power, the optical switch reroutes the WDM signals on the optical fiber to the add / drop multiplexer but after the add / drop multiplexer is fully operational.

A miniature WDM add / drop multiplexer and its manufacture is described. The device has a plurality of wavelength-dependent filters in the form of thin-film filters mounted to a core frame with the end sections of the input / output optical fiber and other optical fibers associated with each of the filters. The stresses associated with the filters are accounted for. The core frame is sealed, together with the overall package assembly, to provide for long-term reliability of the device. The described device and method of manufacture is also generally applicable to WDM multiplexers and demultiplexers.

A tunable (reconfigurable) OADM provides multiple drop ports and multiple add ports by which desired channels can be removed from, or added to, a composite optical signal. In one embodiment, a programmable demultiplexer is arranged to receive an input signal containing components at x different wavelengths from an optical input port, and distribute the input signal components among K output ports. K−1 of the output ports are the “drop” ports of the OADM, and cumulatively contain w different wavelengths. The remaining port, which is the “through port” that carries the z wavelengths not dropped from the original input signal, is connected to the first port of an M port programmable multiplexer having M−1 other input ports. The remaining M−1 ports are the “add” ports of the OADM, which cumulatively receive v different wavelengths to be added by the OADM.

The embodiment of the invention relates to a pocket add-drop multiplexer and a data transmission method thereof. The pocket add-drop multiplexer comprises a line interface unit including a first line interface and a second line interface, a dispatching unit used for dispatching data frames of an input and transmission side and sending the data frames of the input and transmission side through the second line interface, and a tributary unit used for capsulating received data into a third transmission container data pocket and sending the third transmission container data pocket to the dispatching unit or used for encapsulating a first transmission container data pocket sent by the dispatching unit to restore data. The pocket add-drop multiplexer and the data transmission method thereof take the transmission container data pockets of the transmission side as a pocket add-drop multiplexing structure of a pocket dispatching entity; and the data pocket has the advantages of simple structure, self-synchronizing capability and simple logic when processed.

A method and system for using optical phase conjugation in an optical communications network including an add-drop multiplexer. The method includes determining a position for an optical phase conjugator such that channel quality for a channel in improved above a threshold. Transmission characteristics such as amplifier launch power or dispersion features may be adjusted to compliment the optical phase conjugation. An alternate method includes positioning the optical phase conjugator to improve a weighted average channel quality for the network.

The present invention relates to a 4-port wavelength selective router and the add / drop multiplexer using the above router. More particularly, it relates to a 4-port wavelength selective router that can effectively routes counter-propagating signals while suppressing multiple reflections generated in the bidirectional transmission systems and networks.

A communication system (10) employs switching circuits, such as an add / drop multiplexer (70) and another add / drop multiplexer (110). The bandwidth of a circuit switched connection between the switching circuits is altered without taking down the connection.

The invention provides a reconfigurable optical add-drop multiplexer and a reconfigurable optical add-drop multiplexing method. The reconfigurable optical add-drop multiplexer comprises an optical processing unit and a first output port, wherein the optical processing unit is used for receiving a first optical signal including multiple optical channels and processing the first optical signal to generate a second optical signal; the second optical signal at least comprises a part of one optical channel in the multiple optical channels of the first optical signal; and the second optical signal generated by the optical processing unit is externally output by the first output port. According to the reconfigurable optical add-drop multiplexer and the reconfigurable optical add-drop multiplexing method, any number of dimensionalities can be supported, the adding / dropping and the going to / coming from an optical channel of any broadband and any wavelength in any direction can be realized, and any part of wavelength and any part of the broadband of the optical channel can be output to other external reconfigurable optical add-drop multiplexer nodes so as to meet the demands on colorless, directionless, contentionless and gridless.

The present invention provides a colorless multiplexing system and method for detecting new optical channels at power levels below that which would cause data errors in existing traffic, and on top of background light, thus, overcoming a known risk inherent in colorless multiplexing—that a channel of the same wavelength as an existing channel is incorrectly added to the original working, traffic-carrying, channel's path.

The present invention discloses a bidirectional add / drop multiplexer (BADM) and a bidirectional add / drop amplifier (BADA) module which add / drop wavelength-interleaved counter-propagating signals. The mid-stage device in the BADM and the BADA module is shared by the counter-propagating signals. The BADM according to the present invention comprises (1) two wavelength selective couplers (WSC1, WSC2) with an input port (d1 or d2), an output port (f1 or f2), and a common port (e1 or e2). (2) Two optical isolators (Iso1, Iso2) with an input port (g1 or g2) and an output port (h1 or h2). (3) Two optical circulators (Cir1, Cir2) with an input port (a1 or a2), an output port (c1 or c2) and a common port (b1 or b2). (4) A bidirectional multiplexing / demultiplexing means with N input / output ports at its both sides. And (5) a mid-stage device composed of a means for compensating the chromatic dispersion of the optical fibers, a means for flattening the spectral response of the optical amplifiers, a means for suppressing the accumulation the amplified spontaneous emission noise or a combination of these means. The BADA module according to the present invention comprises an above-described BADM and two bidirectional optical amplifier (BOA1, BOA2). It can further comprises two unidirectional optical amplifiers (UOA1, UOA2).