1209results about "Multimode transmission" patented technology

An optical signaling header technique applicable to optical networks wherein packet routing information is embedded in the same channel or wavelength as the data payload so that both the header and data payload propagate through network elements with the same path and the associated delays. The header routing information has sufficiently different characteristics from the data payload so that the signaling header can be detected without being affected by the data payload, and that the signaling header can also be removed without affecting the data payload. The signal routing technique can be overlaid onto the conventional network elements in a modular manner using two types of applique modules. The first type effects header encoding and decoding at the entry and exit points of the data payload into and out of the network; the second type effects header detection at each of the network elements.

The outage probability in an under-addressed optical MIMO system may be reduced by configuring an intra-link optical mode mixer to dynamically change the spatial-mode mixing characteristics of the link on a time scale that is faster than the channel coherence time. Provided that the MIMO system employs an FEC code that has a sufficient error-correcting capacity for correcting the amount of errors corresponding to an average state of the MIMO channel, this relatively fast dynamic change tends to reduce the frequency of events during which the number of errors per FEC-encoded block of data exceeds the error-correcting capacity of the FEC code.

An optical communication system having an optical transmitter and an optical receiver optically coupled via a multi-path fiber. The optical transmitter launches, into the multi-path fiber, an optical transverse-mode-multiplexed (TMM) signal having a plurality of independently modulated components by coupling each independently modulated component into a respective transverse mode of the multi-path fiber. The TMM signal undergoes inter-mode mixing in the multi-path fiber before being received by the optical receiver. The optical receiver processes the received TMM signal to reverse the effects of inter-mode mixing and recover the data carried by each of the independently modulated components.

One embodiment provides a system for power saving in an Ethernet Passive Optic Network (EPON). The system includes an optical line terminal (OLT), an optical network unit (ONU), a traffic-detection module configured to detect status of traffic to and from the ONU, and a power-management module configured to place the ONU in sleep mode based on the detected traffic status. The ONU includes an optical transceiver that includes an optical transmitter configured to transmit optical signals to the OLT and an optical receiver configured to receive optical signals from the OLT.

An optical data link includes first and second pluralities of transmission devices, at least one of which is configured as an array. A multichannel transmission link has a first end connected to the first plurality of transmission devices and a second end connected to the second plurality of transmission devices so as to form a plurality of parallel transmission channels therebetween. The multichannel transmission link includes a multicore fiber with a plurality of individual cores having a configuration matching the array configuration of the at least one plurality of transmission devices. The multicore fiber has an endface connected directly to the at least one plurality of transmission devices, with the individual cores of the multicore fiber aligned with respective devices in the at least one plurality of transmission devices. Further described are access networks and core networks incorporating a transmission link comprising at least one span of a multicore fiber.

A dynamic upstream bandwidth allocation scheme is disclosed, i.e., limited sharing with traffic prediction (LSTP), to improve the bandwidth efficiency of upstream transmission over PONs. LSTP adopts the PON MAC control messages, and dynamically allocates bandwidth according to the on-line traffic load. The ONU bandwidth requirement includes the already buffered data and a prediction of the incoming data, thus reducing the frame delay and alleviating the data loss. ONUs are served by the OLT in a fixed order in LSTP to facilitate the traffic prediction. Each optical network unit (ONU) classifies its local traffic into three classes with descending priorities: expedited forwarding (EF), assured forwarding (AF), and best effort (BE). Data with higher priority replace data with lower priority when the buffer is full. In order to alleviate uncontrolled delay and unfair drop of the lower priority data, the priority-based scheduling is employed to deliver the buffered data in a particular transmission timeslot. The bandwidth allocation incorporates the service level agreements (SLAs) and the on-line traffic dynamics. The basic limited sharing with traffic prediction (LSTP) scheme is extended to serve the classified network traffic.

A multimode optical fiber has an equivalent modal dispersion value (DMDinner&outer) of less than 0.11 ps / m for (Δλmax×D)>0.07 ps / m as measured on a modified DMD graph. The modified DMD graph accounts for chromatic dispersion to ensure that the multimode optical fiber has a calculated effective bandwidth EBc greater than 6000 MHz-km when used with multimode transverse sources.

The present wavelength multiplexed optical system includes a multimode optical fiber that transmits wavelength multiplexed optical signals and a plurality of multimode modal dispersion compensation optical fibers. Each modal dispersion compensation optical fiber can transmit one of the multiplex wavelengths, and each modal dispersion compensation optical fiber has an optimized index profile such that the modal dispersion for the transmitted wavelength is approximately inversely equal to the modal dispersion induced in the multimode optical fiber. The wavelength multiplexed optical system facilitates an increased bitrate without reducing bandwidth.

A time-sharing Visible Light Communication (VLC) system is provided. Two or more light sources transmit data received from one or more VLC terminals located in its service area to a communication control device, and transmits data received from the communication control device to the one or more VLC terminals. The communication control device determines and groups at least one of the two or more light sources to be included in a cell according to a generated user service, maps the grouped at least one light source to the cell, allocates a time slot used to provide the user service to the cell, transmits data associated with the user service to at least one of the one or more VLC terminals through the at least one light source mapped to the cell using the allocated time slot, detects a location of the at least one VLC terminal located in a service area of the cell on a real-time basis, and remaps the cell according to the detected location.

A multimode waveguide illuminator and imager relies on a wave front shaping system that acts to compensate for modal scrambling and light dispersion by the multimode waveguide. A first step consists of calibrating the multimode waveguide and a second step consists in projecting a specific pattern on the waveguide proximal end in order to produce the desire light pattern at its distal end. The illumination pattern can be scanned or changed dynamically only by changing the phase pattern projected at the proximal end of the waveguide. The third and last step consists in collecting the optical information, generated by the sample, through the same waveguide in order to form an image. Known free space microscopy technique can be adapted to endoscopy with multimode waveguide, such as, but not limited to, fluorescence imaging or Raman spectroscopy or imaging, 3D linear scattering imaging or two-photon imaging. Super-resolution, i.e., resolution below the diffraction limit, is achieved for example but not limited to, using the STimulated Emission Depletion microscopy (STED) technique or the Structured Illumination Microscopy (SIM) technique or a stochastic illumination based method (PALM, STORM) in combination with the multimode waveguide imaging method.

An apparatus and method providing a plurality of modulated optical beams from a single layer of semiconductor material. For one example, an apparatus includes a plurality of optical waveguides disposed in a single layer of semiconductor material. Each one of the plurality of optical waveguides includes an optical cavity defined along the optical waveguide. A single bar of gain medium material adjoining the single layer of semiconductor material across the plurality of optical waveguides is included. The gain medium-semiconductor material interface is defined along each of the plurality of optical waveguides. A plurality of optical modulators is disposed in the single layer of semiconductor material. Each one of the plurality of optical modulators is optically coupled to a respective one of the plurality of optical waveguides to modulate a respective optical beam directed from the optical cavity.

The present invention includes novel techniques, apparatus, and systems for optical WDM communications. Various wavelocker apparatus and methods are disclosed that measure the frequency offsets between signal lasers and reference lasers. The measured offsets are used to adjust the signal laser frequencies to meet their target frequencies. The absolute accuracy of the reference laser frequency is improved by measuring the absorption of the reference laser by a gas cell with known fixed absorption lines versus the reference laser frequency. Apparatus and methods are disclosed to cover scenarios in which the reference laser polarization is aligned with the signal lasers, as well as those in which the reference laser polarization is not aligned with the signal lasers. The wavelocker apparatus may or may not be located at the same network site as the signal lasers.

A multimode optical fibre communications system, and in particular to a system in which non-linearities in the propagation of the signal through a multimode optical communications channel degrade the signal presented to the receiver. The system includes an optical transmitter unit for connection to a multimode optical fibre transmission link. The transmitter unit has a data input for receiving an input data signal, a data signal processing circuit and a source of optical radiation. The data signal processing circuit is arranged to receive the input data signal from the data input and to provide a processed data signal to the source of optical radiation and the source of optical radiation is arranged to generate from this an optical signal for transmission by a multimode optical fibre. The data processing circuit is arranged to provide from the input data signal a non-inverted data signal and an inverted data signal, receive a control signal for controlling the generation of the processed data signal, apply a controllable delay in accordance with the control signal to at least one of the non-inverted and inverted data signals, and combine the non-inverted and inverted signals after the application of the controllable delay(s) and gain factor(s) to generate the processed data signal.

The present invention relates to a monitoring system that observes the power and optical frequency of a frequency-modulated optical signal, which is utilized in the communication network employing the WDM (wavelength division multiplexing) method. The monitoring system comprises demultiplex means for demultiplexing the frequency-modulated optical signal outputted from a transmitter including frequency-modulation means, photo-detection means for converting the output of demultiplex means into an electrical signal, and extraction means for extracting the power and optical frequency of an optical signal by measuring the magnitude of an amplitude-modulated tone.

Disclosed is a method for operating a wavelength-division-multiplexed passive optical network (WDM-PON) including an optical line terminal (OLT) and a plurality of optical network units (ONUs), each of which is connected to the OLT and communicates with the OLT. The method comprises the steps of transmitting a first control channel including allocation information of downstream data channels and allocation information of time slots for the downstream data channels to each of the plurality of ONUs; and transmitting downstream data to the plurality of ONUs using their associated downstream data channels, each having at least one time slot, based on the information included in the first control channel.

One embodiment provides a system for performance monitoring in a passive optic network (PON). The system includes an optical line terminal (OLT) and an optical network unit (ONU). The OLT includes an optical transceiver configured to transmit optical signals to and receive optical signals from the ONU, and a performance monitoring mechanism configured to monitor performance of the PON based on received optical signals.

A communication recovering system for a wavelength division multiplexed passive optical network (WDM PON). The communication recovering system can recover fault of optical fibers between the central office and the remote nodes without additional optical fibers by grouping two remote nodes and employing an AWG having periodic transmission characteristics, and can also simply and rapidly recover such a fault with minimal optical loss using an AWG of 2×N structure and an On-Off optical switch, although protection optical fibers are additionally installed therein. The system can rapidly recover fault of optical fibers between a local office and optical network units, 1:N manner, using 2×2 optical switches, which are installed to each of the optical network units, a reserved transmitter and receiver, and a transceiver. The communication recovering system has advantages in that it can simplify network structure, be cost-effectively implemented, reduce optical loss, and rapidly perform protection of optical fiber fault.

The present invention relates to a wavelength-division multiplexed passive optical network. In particular, it relates to a technology for minimizing the optical loss at a wavelength-division multiplexed passive optical network based on wavelength-locked light source Thereby it improves the transmission quality and increases the transmission distance. A 4-port optical path setting device of the present invention increases the amount of light injected into an optical transmitter and thereby improves the wavelength-locking characteristic of a light source. In addition, it can decrease the optical transmission loss in an optical transmission path, and by an optical amplifier being inserted therein; it can also compensate the optical loss in an optical transmission path. In the present invention, a 4-port optical path setting device having the characteristics described above and a method for fault recovery without an additional optical loss are presented.

The present invention provides a small form factor, pluggable ONU, which includes a bi-directional optical transceiver configured to transmit optical signals to and receive optical signals from an OLT. The ONU further includes an ONU chip coupled to the optical transceiver and configured to communicate with the OLT. Also included is a pluggable interface configured to electrically interface between the ONU chip and a piece of subscriber premise equipment (SPE). The ONU includes a power management module to provide power to the ONU chip and the optical transceiver, using power delivered from the SPE through the pluggable interface. The ONU is enclosed a small form factor enclosure, thereby allowing the pluggable ONU to be directly plugged into the SPE and providing an Ethernet Passive Optical Network (EPON) uplink to the SPE without requiring an separate power supply.

An optical communication link is disclosed. In one embodiment, the link includes an optical transmitter including an electrical-to-optical converter for converting electrical signals into optical signals at the system data rate and launching said signals onto an extended length of optical fiber. The link also includes an optical receiver including an optical-to-electrical converter for converting received optical signals into electrical signals. In a preferred embodiment, either of the optical transmitter or optical receiver may include at least one low speed device designed to operate at a data rate less than the system data rate, and the receiver includes an equalizer coupled to the optical-to-electrical converter for compensating for signal distortions introduced by low speed devices.

A SCM-PON using WDM includes: an OLT for transferring downstream data from an external service provider through downstream optical signals and transferring upstream data transferred through upstream optical signals to an outside; an ODN for distributing the downstream optical signals from the OLT and multiplexing the upstream optical signals to the OLT; and a plurality of ONUs for processing the downstream optical signals transferred from the OLT through the ODN and transferring upstream data of subscribers for the OLT through the upstream optical signals, wherein the optical signals between the OLT and the ONUs are divided into wavelength channels with different wavelengths and sub-carrier channels obtained by time-dividing the wavelength channels, and the upstream data and the downstream data are transferred through the sub-carrier channels.

An optical access network of wavelength division method and passive optical network using the same are disclosed. The wavelength division multiplexed optical access network includes a central office for multiplexing first optical signals for wire communication and second optical signals for wireless communication and a remote node connected to the central office through an optical fiber and for demultiplexing a multiplexed optical signal received from the central office. A plurality of subscribers may be connected to the remote node. Each subscriber receives a first optical signal having a corresponding wavelength from among the demultiplexed first optical signals. The network also includes a plurality of radio relay stations connected to the remote node, each radio relay station converting a second optical signal having a corresponding wavelength from among the demultiplexed second optical signals into a radio electric signal and wirelessly transmitting the radio electric signal.

A universal demarcation point for managing the delivery of communications services to a subscriber that provides an interface between a utility distribution network and subscriber owned equipment. The universal demarcation point includes a utility accessible portion and a subscriber accessible portion. The utility accessible portion has an input port, an output port, a plurality of modular connectors, a power supply, and a plurality of service modules. The input port provides access to the universal demarcation point for delivery of communications service from the utility distribution network. The communications services are delivered through a hybrid cable. The hybrid cable has a plurality of fiber optic cables and a plurality of copper cables. The fiber optic cables are capable of transmitting light signals and the copper cables are capable of transmitting electric power. The output port provides access for delivering the communications services from the universal demarcation point into the subscriber's dwelling. The plurality of connectors are fixedly mounted to the universal demarcation point. The power supply is removably mounted to the universal demarcation point. The power supply converts the electric power into a voltage for powering the operation of the universal demarcation point. The service modules are capable of plugging into the modular connectors and convert the light signals that are transmitted on the fiber optic cables onto cables that are suitable for use in the subscriber's dwelling. The subscriber accessible portion is adjacent to the utility accessible portion and has ports that enable the subscriber to test the integrity of the communications services delivered from the utility distribution network.

One embodiment provides an Ethernet Passive Optical Network (EPON) system for clock transport. The system includes a reference clock configured to generate a frequency-reference signal, an optical line terminal (OLT) coupled to the reference clock, and an optical network unit (ONU). The OLT includes a clock generator configured to generate an OLT clock based on at least the frequency-reference signal. The ONU includes an optical transceiver, a clock recovery module, and a clock output mechanism. The optical transceiver is configured to transmit optical signals to and receive optical signals from the OLT. The clock-recovery module is configured to recover the frequency-reference signal from the received optical signals. The clock output mechanism is configured to output the recovered frequency-reference signal, thus facilitating transport of the frequency-reference signal over the EPON.

A Passive Optical Network (PON) is provided with capability for multiple protocols and service suppliers by employing Wavelength Division Multiplexer (WDM) elements in combination with optical couplers at optical distribution nodes (ODN) intermediate a local exchange office and a customer node. The local exchange office node transmitting and receiving signals from a single optical fiber through a WDM providing M / 2 wavelength pairs for use with differing protocols and each customer node connected to one leg of an optical coupler in the ODN with a WDM associated with one of the wavelength pairs for received and transmitted signals.

Disclosed is a wavelength-division multiplexing-passive optical network having a central office including a plurality of first working and protection transmit / receive modules, working and protection optical transmitters, and a plurality of first optical switches, the first working and protection transmit / receive modules generating downstream optical signals and detecting upstream optical signals having corresponding wavelengths, the working and protection optical transmitters generating broadcasting optical signals, the first optical switches performing a switching operation when faults occur, a plurality of subscriber units for receiving broadcasting optical signals and downstream optical signals having corresponding wavelengths and generating upstream optical signals, the subscriber units including second optical switches, a remote node including working and protection optical splitters for dividing intensity of the broadcasting optical signals, the remote node being positioned between the subscriber units and the central office, working and protection main optical fibers for linking the central office with the remote node; and a plurality of working and protection branch optical fibers for linking the remote node with the subscriber units, respectively.

An optical transmitter for an optical fiber transmission system is described. The optical transmitter includes an optical source that generates an optical signal having a wavelength at an output. An optical intensity modulator modulates the optical signal with an electrical modulation signal to generate a modulated optical signal at an output. At least one parameter of the optical intensity modulator is chosen to suppress at least one of phase and sideband information in the modulated optical signal. An optical fiber is coupled to the output of the optical intensity modulator. The suppression of the at least one of the phase and the sideband information in the modulated optical signal increases an effective modal bandwidth of the optical fiber.