725 results about "Optical communication networks" patented technology

An optical communications network includes a terminal which can simultaneously receive and modulate an optical signal. The terminal includes an optical modulator which is controlled by varying the bias voltage applied to it.

The preferred embodiments of the present invention include an optical splitter module having connectorized pigtails that are stored on the bulkhead faceplate of the module. The module includes an optical splitter output harness, for example, a ribbon cable assembly attached to the bulkhead with rugged strain relief mechanism. The ribbon harness is converted to individual pigtails with connectors which are stored on adapter receptacles on the faceplate. Adapter receptacles used may optionally be half receptacles when storage is the only desired function or may be full receptacles when access to the pigtail ferrule tip is required. Access to the ferrule tip may be required for attaching fiber optic terminators to eliminate undesirable reflections caused by unterminated connectors. The module provides an administrative location for splitter outputs prior to being connected individually into service. The module also provides an administrative storage location for splitter outputs taken out of service as a temporary staging area before being reassigned and connected individually into service again.

A label switching routing protocol for establishing a datapath as a sequence of locally unique labels in an optical communications network, is provided. A wavelength on an optical cross-connect is considered as a label, or one portion of a label. Timeslots may be assigned to designated wavelengths so as to form the second portion of a composite label. An optical/time cross-connect (OTXC) capable of wavelength conversion from an input to an output interface creates the datapath based on wavelength to wavelength substitution, under the control of a multi-protocol label switching (MPLS) protocol.

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.

A system (100) to enable the transfer of Internet protocol (IP) format data (12, 14) over a point-to-multipoint passive optical network (PON, 16) is illustrated in FIG. 2. An exchange (102) is connected to a plurality of outstations (104-108) via an optical communication resource (24, 26-38) including a passive optical splitter (22) providing isolation to individual outstations. Media access control of the plurality of outstations is administered by the exchange (102), with collision detection logic (112) in the exchange determining collision (158) of Internet protocol (IP) encoded data communicated thereto through the PON (16). The IP encoded data realises a transport mechanism through the PON. Each of the plurality of outstations (104-108) and the exchange (102) is adapted to pass data in an IP format to and from the optical communication resource such that IP encoded data is transported, in use, directly between the outstation and the exchange.

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 injection locked transmitter for an optical communication network includes a master seed laser source input substantially confined to a single longitudinal mode, an input data stream, and a laser injected modulator including at least one slave laser having a resonator frequency that is injection locked to a frequency of the single longitudinal mode of the master seed laser source. The laser injected modulator is configured to receive the master seed laser source input and the input data stream, and output a laser modulated data stream.

Disclosed is a multi-wavelength locking method for a wavelength division multiplexing (WDM) optical communication network, and in particular, a multi-wavelength locking method and apparatus for a WDM optical communication system that can lock wavelengths of optical signals by producing pilot tones by applying a sine-wave current to a plurality of transmission lasers having different wavelengths, passing the optical signal through a Fabry-Perot etalon filter, and then Fourier-transforming the filtered optical signal. The multi-wavelength locking method includes frequency-modulating an optical signal by applying a small and specified sine-wave current to a bias current for driving WDM lasers, detecting pilot tones produced after filtering the optical signal through a filtering section and converting the detected signal into a digital signal by performing a sampling of the detected signal, detecting a magnitude and phase of the pilot tones by performing a fast Fourier transform, providing Fourier-transformed data as a first derivative signal of the filtering section, and locking an operation wavelength of WDM channels by controlling the temperature or current if resonance frequencies of the filtering section coincide with respective standard frequency.

Optical signals are received from a free-space link by directing received light onto a plurality of microlenses and then directing light received through each of the microlenses into a respective single mode optical fiber (SMF). Light beams from the SMFs are combined into a single light beam in one SMF. The single light beam is amplified with a multi-wavelength fiber amplifier and attenuated with a variable optical attenuator. The power gain of the multi-wavelength fiber amplifier and the attenuation of the variable optical attenuator are controlled. The single light beam is directed into a fiber optic communication system that is optically coupled to the variable optical attenuator.

A method and system for providing tandem protection in a communication system. Path protection is provided using at least two redundant communication paths and selecting the communication path having a higher signal quality. Interface protection is provided through a protection transceiver. The interface protection may be delayed while the path protection attempts to restore communication.

An exemplary embodiment of the invention is a method of detecting network elements in an optical communications network. The method includes an initiating network element generating a neighbor discovery message including a requested hierarchy level at which neighbor discovery is requested and transmitting the neighbor discovery message downstream along the optical communications network. A downstream network element receives the neighbor discovery message, determines if the downstream network element operates at the requested hierarchy level. The downstream network element generates a responding neighbor discovery message if the downstream network element operates at the requested hierarchy level and transmits the responding neighbor discovery message to the initiating network element. Alternate embodiments include a system and storage medium for implementing the method.

A bi-directional wavelength division multiplexed (WDM) optical communications network that includes components for automatically detecting a fault along a primary optical waveguide in a link forming part of a bi-directional WDM communication network and switching the transmission path of the optical signals propagated along that link from that waveguide to a second standby waveguide whenever a fault is detected in the first waveguide using 1×2 optical switches, optical filters, photodetectors and electronics in a configuration designed to avoid silent event failures. Replacing the 1×2 optical switches with 2×2 optical switches in conjunction with other equipment can allow either the constant monitoring of the standby waveguide, provide back up for optical transmitters, receivers and couplers on the path containing the primary waveguide and/or allow carriage of low priority traffic on the standby waveguide as long as it is in standby mode. No handshaking mechanism is required between the opposite ends of the waveguides for the switchover protection.

A method and system of determining a new path through an optical network from a source node to a destination node when a link in an original path fails are disclosed. When a fault on a link is detected, adjoint weights are assigned to each operational link for each node on the original path. A connection cost is determined for each node based on the adjoint weights of the links connected to the node. A new path through the optical network is determined based at least in part on the adjoint weights and the connection costs.

Systems and methods that allow for transmitting qubits and classical signal over the same channel of an optical telecommunications network that includes an optical fiber. The method includes sending the qubits of wavelength λ_S over a quantum optical path that includes the optical fiber during a time interval ΔT₀ when there are no classical optical signals of wavelength λ_S traveling over the optical fiber. The method also includes sending the classical signals over a classical optical path that includes the optical fiber, wherein the classical signals are sent outside of the time interval ΔT₀ to avoid interfering with the qubit transmission. Systems and methods for using the present invention to form quantum key banks for encrypting classical signals sent over the optical telecommunications network are also disclosed.