730 results about "Optical communication networks" patented technology

An optical communications network having at least one optical switch connected to a network access device. The optical switch includes a first line card disposed along a first communications path over which a first optical signal is transmitted. The first line card is connected to the network access device. A second line card is disposed along a second communications path over which a second optical signal is transmitted. An inter-card communication channel is provided for bridging the second path to the first line card. The system enables the rapid switching of traffic from the first optical path to the second optical path.

A method of carrier recovery from a high speed optical signal received through an optical communications network. A stream of multi-bit digital samples of the optical signal is processed to generate a multi-bit estimate X′(n) of each one of a plurality of transmitted symbols. A phase of each symbol estimate X′(n) is rotated, and a respective symbol phase error Δφ(n) of the rotated symbol estimate determined.

Protection techniques within optical communication networks are extremely important. An alternative to a line protection scheme, as most current optical communication networks use, is to utilize a path protection technique in which working and protection paths that are desired are assigned during network setup. During normal operations, only the working path is configured within the network elements' switch fabric with protection paths being left unconfigured. If a failure indication is detected in the working path by a network element, a protection entry within a routing table of the network element is looked up to determine protection switching data that is required to switch the data traffic to the pre-assigned protection path. This protection switching data is inserted within the path overhead for the data traffic so that it can be communicated to all of the network elements that require their switch fabrics reconfigured to establish the protection path of communications. This protection technique allows for similar switching speed to that of line switching protection such as BLSR designs, but with an increase in efficiency in terms of protection bandwidth.

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.

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.

A routing method for a network including a first type of nodes and a second type of nodes, in particular an optical telecommunication network including transparent codes and regenerating nodes, includes: constructing a simplified network topology including the given node, the second nodes, first paths between the given node and the second nodes and second paths between each couple of second nodes, wherein the first and second paths pass only through first nodes and have an acceptable run-through cost, and, if the given node receives a routing request specifying a destination node that is reachable only through a second node, constructing an enhanced network topology by adding to the simplified network topology the destination node and third paths between the destination node and the second nodes that pass only through first nodes and have an acceptable run-through cost; and searching for a path having the lowest run-through cost from the given node to the destination node in the enhanced network topology.

The invention pertains to wavelength-agile optical filters suitable for wavelength-division-multiplexed (WDM) optical communications networks. More particularly, the invention pertains to optical filters with a wavelength reference that can be remotely switched to arbitrarily selectable channels on a standard grid, and to re-configurable optical communications networks employing same. The present invention provides a communication apparatus with a tunable filter which may be used in a wide range of applications including tuning an external cavity laser (ECL), selecting a wavelength for an add / drop multiplexer and providing channel selection and feedback for a wavelength locker. The filter may be utilized as a discrete component or in combination with circulators, wavelength lockers and gain medium. The filter may be implemented in whole or in part as part of a gain medium. The tunable filter exhibits a compact form factor and precise tuning to any selected wavelength of a predetermined set of wavelengths comprising a wavelength grid. The tunable filter may thus be utilized in telecom applications to generate the center wavelengths for any channel on the ITU or other optical grid.

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.

Bit-transparent muxing of an input signal for transport through an optical communications network. A fixed length container of the optical communications network is defined, which includes an overhead and a payload. A stuffing ratio (α) is based based on a line rate of the input signal and a data rate of the container. A number (NFS) of fixed stuffs is computed based on the stuffing ratio (α). The input signal and NFS fixed stuffs are inserted into the payload of the container, and the computed number NFS stored in the container's overhead. In some embodiments, the container is an overclocked OTU-3 (OTU3+) frame having a line rate of 44.6 Gb / s. This enables bit-transparent mux / demux of four nominal 10-Gig signals having line rates within a range of between 7.6 Gb / s and 10.4 Gb / s, or a single nominal 40-Gig signal having a line rate within a range of between 38.8 Gb / s and 41.6 Gb / s.

A system, device, and method for managing service level agreements in an optical communication system uses an optical service agent to manage a service level agreement (SLA) for a user. The optical service agent can perform both real-time and off-line analysis for the user, and can interact with various network elements (including the core optical communication network) to handle billing, penalty, and other issues associated with a SLA breach. Among other things, the optical service agent may monitor and analyze a connection in real-time for determining SLA compliance, gather and maintain statistical information relating to a connection, analyze the statistical information off-line for determining SLA compliance, patterns, and trends, interact with a service provider to enforce penalty provisions in the SLA, interact with a service provider to negotiate a credit for services not provided by the service provider in accordance with the SLA, interact with a service provider to negotiate “replacement” services for a breach of the SLA, interact with various network elements to rectify a breach of the SLA, interact with the service provider to dynamically modify the SLA based upon changing user requirements, and interface with a billing / accounting system to provide SLA-related information.

A signal equalizer for compensating impairments of an optical signal received through a link of a high speed optical communications network. At least one set of compensation vectors are computed for compensating at least two distinct types of impairments. A frequency domain processor is coupled to receive respective raw multi-bit in-phase (I) and quadrature (Q) sample streams of each received polarization of the optical signal. The frequency domain processor operates to digitally process the multi-bit sample streams, using the compensation vectors, to generate multi-bit estimates of symbols modulated onto each transmitted polarization of the optical signal. The frequency domain processor exhibits respective different responses to each one of the at least two distinct types of impairments.

An optical fiber amplifier utilizing a phosphate glass optical fiber highly doped with rare-earth ions such as erbium to exhibit high gain per unit length, enabling the use of short fiber strands to achieve the needed gain in practical fiber optical communication networks. The high-gain phosphate optical glass fiber amplifiers are integrated onto substrates to form an integrated optics amplifier module. An optical pump such as a semiconductor laser of suitable wavelength is used to promote gain inversion of erbium ions and ultimately provide power amplification of a given input signal. Gain inversion is enhanced in the erbium doped phosphate glass fiber by co-doping with ytterbium. A phosphate fiber amplifier or an integrated optics amplifier module utilizing this power amplification can be combined with other components such as splitters, combiners, modulators, or arrayed waveguide gratings to form lossless or amplified components that do not suffer from insertion loss when added to an optical network. The fiber amplifier can be a single fiber or an array of fibers. Further, the phosphate glass fibers can be designed with a temperature coefficient of refractive index close to zero enabling proper mode performance as ambient temperatures or induced heating changes the temperature of the phosphate glass fiber. Large core 50-100 .mu.m fibers can be used for fiber amplifiers. The phosphate glass composition includes erbium concentrations of at least 1.5 weight percentage, preferably further including ytterbium at 1.5 weight percentage, or greater.

To provide a graphic user interface, supported by HTML or Java script, to a personal computer (102) for the control of SONET / SDH network elements (106), an RS-232 port of a PC is used to establish a PPP session to a remote access server, RAS (122). The network element (106) is therefore configured to imitate a modem, and to route PPP packets into its related management system across an optical ring (12). The management system may include an intermediate network manager (120) and a DHCP server (124). Once legitimacy of the PC is established through the IP session, the PC is provided with an IP address to invoke the PC's IP stack. Subsequently, IP is communicated across the PPP session, with the RAS (120) configured to terminate the PPP session and forward IP packets into an IP network (128). IP packets (131), received at a web server (140), are converted into command line interface (CLI) messages 135 and are sent directly to the network manager (120) within an IP packet. The network manager (120) terminated the IP packet and re-packages the CLI messages into an optical carrier format (140) for relay to an addressed network element (106). The addressed network element (106), which is responsive to the CLI messages from a management perspective, then alters its set-up or functionality accordingly. Complex text-based CLI instructions are thus avoided by a field-based engineer through the use of a GUI supported by a PC having web-browser capabilities, with an typical architecture shown in FIG. 2.

The invention pertains to wavelength-agile optical filters suitable for wavelength-division-multiplexed (WDM) optical communications networks. More particularly, the invention pertains to optical filters with a wavelength reference that can be remotely switched to arbitrarily selectable channels on a standard grid, and to re-configurable optical communications networks employing same. The present invention provides a communication apparatus with a tunable filter which may be used in a wide range of applications including tuning an external cavity laser (ECL), selecting a wavelength for an add / drop multiplexer and providing channel selection and feedback for a wavelength locker. The filter may be utilized as a discrete component or in combination with circulators, wavelength lockers and gain medium. The filter may be implemented in whole or in part as part of a gain medium. The tunable filter exhibits a compact form factor and precise tuning to any selected wavelength of a predetermined set of wavelengths comprising a wavelength grid. The tunable filter may thus be utilized in telecom applications to generate the center wavelengths for any channel on the ITU or other optical grid.

An optical communications system including a submarine optical communications system, a landing station associated with the submarine optical communications system, a terrestrial optical communications system, a point of presence associated with the terrestrial optical communications system, a first wavelength division multiplexed optical connection between the point of presence and the landing station, and a second wavelength division multiplexed optical connection between the point of presence and the landing station and routed diversely from the first wavelength division multiplexed optical connection.