Reducing processing complexity and cost associated with a soft forward error correction (FEC) operation
Granted: August 12, 2014
Patent Number:
8806304
A system is configured to receive a word on which to perform forward error correction; identify least reliable positions that correspond to encoded bits, within the word, associated with a lowest level of reliability; generate candidate words based on different combinations of inverted encoded bits; identify a pair of candidate words that includes a candidate word and another candidate word, the candidate word includes an inverted most reliable bit of the encoded bits within the…
Channel de-skewing for a coherent optical receiver
Granted: July 22, 2014
Patent Number:
8787777
A system may receive a group of electrical signals from an optical receiver and via a group of channels; identify a first signal, as a reference signal, that is received via a first channel; and identify a second signal, as an orthogonal signal, that is received via a second channel, where the second signal may be orthogonal to the first signal. The system may further measure a group of skew values based on a difference in arrival times between one or more other signals, of the group of…
Optical receiver integrated on a substrate
Granted: July 15, 2014
Patent Number:
8781324
A coherent optical receiver circuit is disclosed in which various components of the optical receiver may be provided or integrated, in one example, on a common substrate. Further integration is achieved by incorporating various optical demultiplexer designs that are relatively compact and conserve space on the surface of the substrate. The optical receiver circuit may be used to demultiplex quadrature phase shift keying (QPSK) optical signals.
PMD and chromatic dispersion tolerant clock recovery
Granted: July 8, 2014
Patent Number:
8774644
Consistent with the present disclosure, a method and system for detecting a clock phase of an optical signal in a coherent receiver is provided that is insensitive to polarization mode dispersion (PMD) and other polarization effects in the optical communication system. The clock phase of the received signal is estimated by first calculating a phase shift between a pair of related frequency domain data outputs of a Fourier transform circuit. The calculated phase shift includes a phase…
Carrier phase estimation filter length optimization
Granted: July 8, 2014
Patent Number:
8774322
The present disclosure provides a system, apparatus and method to reduce phase noise associated with a received data signal, while optimizing system performance. An optimal length of a digital filter, employed in a carrier phase recovery process, is determined such that phase noise is reduced in the received data signal. Reduction of the phase noise present in the received data signal leads to improved receiver performance. The optimal length of the digital filter may be continuously…
Wavelength division multiplexed optical communication system having variable channel spacings
Granted: July 1, 2014
Patent Number:
8768177
Consistent with the present disclosure, data, in digital form, is received by a transmit nodes of an optical communication, and converted to analog signal by a digital-to-analog converter (DAC) to drive a modulator. The modulator, in turn, modulates light at one of a plurality of wavelengths in accordance with the received data. The modulated light is then transmitted over an optical communication path to a receive node. At the receive node, the modulated optical signal, as well as other…
Interconnection system and method
Granted: June 24, 2014
Patent Number:
8762920
The present disclosure provides a system, apparatus and method to transport data across a network node, as part of a network infrastructure of an optical transmission system. According to the various embodiments of the disclosure, a base architecture is provided which includes interconnectivity providing high throughput, while mitigating factors which may lead to signal loss or signal degradation. The base architecture is easily expandable to accommodate additional traffic.
Upgradable WDM system
Granted: June 10, 2014
Patent Number:
8750722
Consistent with the present disclosure, a wavelength division multiplexed (WDM) optical communication system including on-off-keying (OOK) transmitters, for example, may be upgraded to include advanced modulation format transmitters, such as quadrature phase shift keying (QPSK) transmitters. Rather than replace all the OOK transmitters with QPSK transmitters at once, each OOK transmitter is replaced with a lower rate modulation format transmitter, such as a binary phase shift keying…
Photonic integrated circuits having chirped elements
Granted: April 22, 2014
Patent Number:
8705904
Consistent with the present disclosure, optical devices are provided along different optical paths in a photonic integrated circuit (PIC). The optical components have different optical losses associated therewith so that optical signals propagating in the optical paths have desired power levels, which may be uniform, for example.
PMD-insensitive method of chromatic dispersion estimation for a coherent receiver
Granted: April 22, 2014
Patent Number:
8705986
Consistent with the present disclosure, a method and system for estimating chromatic dispersion of an optical signal in a coherent receiver is provided that is insensitive to polarization mode dispersion (PMD) and other polarization effects in the optical communication system. The effects of chromatic dispersion in the optical system are estimated by first calculating a phase shift between a pair of related frequency domain data outputs of a Fourier transform circuit. The calculated…
Clocking of client signals output from an egress node in a network
Granted: April 22, 2014
Patent Number:
8705402
Consistent with the present disclosure, client data, which may include multiplexed data sub-streams, is supplied to an ingress node of a network. Each sub-stream typically has a corresponding data rate, i.e., an original data rate, prior to multiplexing. The client data is encapsulated in a plurality of successive frames that are output from the ingress node and propagate, typically through one or more intermediate nodes, to an egress node. At the egress node, data rates associated with…
Coherent detection for an integrated circuit having a multiplexer or a demultiplexer with a shared propagation region
Granted: March 25, 2014
Patent Number:
8682114
An optical device may include a slab, a first waveguide extending from a first portion of the slab to supply multiple first optical signals to the first portion of the slab, multiple second waveguides coupled to a second portion and to a third portion of the slab. The optical device may include multiple third waveguides provided extending from a fourth portion of the slab to direct a corresponding one of the multiple first optical signals away from the slab, a fourth waveguide extending…
Activation signaling in transport networks
Granted: March 11, 2014
Patent Number:
8670302
A method comprising the steps of receiving a signal indicative of a failure of a working connection in a mesh network having a headend node, a tailend node and an intermediate node, and having a protecting connection, and transmitting an activation message via the protecting connection from at least one of the headend node and the tailend node to the intermediate node for activating the protecting connection.
Variable channel spacing in a coherent transmission system
Granted: February 25, 2014
Patent Number:
8660428
The present disclosure provides a transmission system, apparatus and method to provide for variable channel spacing in multiplexed or combined optical signals for transmission over a network infrastructure. The channel spacing may be monitored and maintained at desired values in order to maximize the channel density under various conditions related to the network infrastructure. The individual carrier frequencies associated with each signal channel of the transmission system may be…
Communication network with skew compensation
Granted: February 25, 2014
Patent Number:
8660020
Embodiments of the present invention compensate for skew across a wavelength division multiplexed network. The network is a wavelength division multiplexed optical transport network. The skew compensation can be performed electrically or optically. It can be performed on the transmission side of the network, the receiver side of the network or at any intermediary node on the network.
Wavelength division multiplexed optical communication system architectures
Granted: February 18, 2014
Patent Number:
8655190
Consistent with the present disclosure, data, in digital form, is received by a transmit nodes of an optical communication, and converted to analog signal by a digital-to-analog converter (DAC) to drive a modulator. The modulator, in turn, modulates light at one of a plurality of wavelengths in accordance with the received data. The modulated light is then transmitted over an optical communication path to a receive node. At the receive node, the modulated optical signal, as well as other…
Degradation adaptation network
Granted: February 18, 2014
Patent Number:
8655169
Consistent with the present disclosure, based on system requirements or in response to an increase in optical signal-to-noise level of an optical channel, such as a WDM channel, additional FEC bits are inserted into and replace selected data payload bits in each frame carried by the channel. The replaced data payload bits may then be transmitted in subsequent frames on the same channel. As a result, the transmitted frames have a reduced data payload rate, but a higher coding gain.…
Mach-Zehnder having segmented drive signal electrodes
Granted: February 4, 2014
Patent Number:
8644650
Consistent with the present disclosure, MZ drive signal electrodes may be provided relatively close to and parallel to one another, such that the underlying waveguide arms may also be provided close to and parallel to one another. As a result, common mode performance of an MZ modulator may be obtained. In one example, an electrode wiring configuration consistent with the present disclosure may permit a waveguide arm separation of 40 microns or less.
Forward error correction (FEC) convergence by controlling reliability levels of decoded words in a soft FEC decoder
Granted: February 4, 2014
Patent Number:
8645788
A system receives a first word on which to perform error correction; identifies combinations in which encoded bits, within the first word, can be inverted; generates candidate words based on the first word and the combinations; decodes the candidate words; determines distances between the decoded words and the first word; selects, as a second word, one of the decoded words associated with a shortest distance; compares the second word to the first word to identify errors within the first…
Compact multimode interference element
Granted: February 4, 2014
Patent Number:
8644653
The present disclosure provides a system, apparatus and method to for providing highly manufacturable compact optical structures in optical circuits, increasing overall yield and lowering manufacturing costs. According to one aspect, an optical circuit is provided which includes an multimode interference element and first and second waveguides. The first waveguide may be provided adjacent a first side of the optical device and extending along at least the length of the multimode…
