Abstract: An example system includes a network switch and a plurality of server computers communicatively coupled to the first network switch. The network switch includes a first transceiver configured to transmit data according to a first maximum throughput, and each server computer includes a respective second transceiver configured to transmit data according to a second maximum throughput that is less than the first maximum throughput. The network switch is configured to transmit, using the first transceiver according to the first maximum throughput, first data including a plurality of optical subcarriers to each of the server computers. Each of the server computers is configured to receive, using a respective one of the second transceivers, the first data from the network switch, and extract, from the first data, a respective portion of the first data addressed to the server computer.

Abstract: Consistent with the present disclosure, a networking system is provided whereby flexible optical bandwidth or capacity between a primary or hub node and secondary or leaf nodes is realized to reduce overall cost and power consumption. Packets are multi-cast from a high speed transceiver in the hub node (or optical line terminal (OLT) to one or more sets of low speed transceivers in the leaf node (optical network terminal (ONT) or optical network unit (ONU)) allowing sets of low speed transceivers to pool together and share the total bandwidth allocated and received from the high speed transceiver. In one example, the hub node outputs a plurality of optical subcarriers, each of which being designated for one or more leaf nodes. Accordingly, the intended leaf node output data associated with its designated optical subcarrier or subcarriers as the case may be and supplies the data to a transceiver at the client premises.

Abstract: An example system includes a first network device having first circuitry. The first network device is configured to perform operations including receiving data to be transmitted to a second network device over an optical communications network, and transmitting first information and second information to the second device. The first information is indicative of the data, and is transmitted using a first communications link of the optical communications network and using a first subset of optical subcarriers. The second information is indicative of the data, and is transmitted using a second communications link of the optical communications network and using a second subset of optical subcarriers. The first subset of optical subcarriers is different from the second subset of optical subcarriers.

Abstract: Consistent with the present disclosure, an encoder circuit is provided at a transmit side of an optical fiber link that maps an input sequence of bits of fixed length k a sequence of symbols of a codeword of length n, such that the symbols of the codeword define a predetermined transmission probability distribution. Preferably, each symbol of the codeword is generated during a corresponding clock cycle, such that after n clock cycles, a complete codeword corresponding to the input bit sequence is output. On a receive end of the link, a decoder is provided that outputs the k-bit sequence every n clock cycles. Accordingly, buffers need not be provided at the output of the encoder and the input of the decoder, such that processing of the input sequence, codewords, and output sequence may be achieved efficiently without large buffers and complicated circuitry. Moreover, the input sequence, with any binary alphabet may be matched to a desired output distribution with any arbitrary alphabet.

Abstract: A transport network, a node, and a method are disclosed. The transport network, the node, and the method detect a failure of a super channel originating from a sliceable light source that is routed through the transport network, by detecting an optical loss of signal by an optical power monitoring device, in presence or absence of an optical loss of signal of the complete band by at least one photo detector. This information is analyzed with a fault detection algorithm using a patch cable network configuration to determine a fault indication for a failure within the first node. The fault signal indicative of the fault indication is then passed to another node on the first path.

Abstract: A transmitter can include a laser operable to output an optical signal; a digital signal processor operable to receive user data and provide electrical signals based on the data; and a modulator operable to modulate the optical signal to provide optical subcarriers based on the electrical signals. A first one of the subcarriers carriers carries first TDMA encoded information and second TDMA encoded information, such that the first TDMA encoded information is indicative of a first portion of the data and is carried by the first one of the subcarriers during a first time slot, and the second TDMA encoded information is indicative of a second portion of the data and is carried by the first one of the subcarriers during a second time slot. The first TDMA encoded information is associated with a first node remote from the transmitter and the second TDMA encoded information is associated with a second node remote from the transmitter.

Abstract: A method of executing in-session encryption verification includes receiving a plurality of client data packets for transmission through a network; receiving one or more test data packets for verifying an encryption device; merging the client data packets and the one or more test packets into a data stream; selecting security parameters for each packet in the data stream based on a corresponding packet type; encrypting each packet in the data stream using the encryption device and the corresponding security parameters; and transmitting the data stream comprising encrypted packets through the network. The method also includes decrypting the encrypted packets at a receiving system using congruent techniques.

Abstract: An apparatus comprising a control circuit providing a variable control signal, and a transmitter. The transmitter operable to provide a modulated optical signal including a plurality of optical subcarriers. One of the plurality of optical subcarriers carries a sequence of modulation symbols. The sequence of modulation symbols includes modulation symbols that are output with a variable transmission frequency in accordance with a transmission probability distribution that is variable based on the control signal.

Abstract: A network or system in which a hub or primary node may communicate with a plurality of leaf or secondary nodes. The hub node may operate or have a capacity greater than that of the leaf nodes. Accordingly, relatively inexpensive leaf nodes may be deployed to receive data carrying optical signals from, and supply data carrying optical signals to, the hub node. One or more connections may couple each leaf node to the hub node, whereby each connection may include one or more spans or segments of optical fibers, optical amplifiers, optical splitters/combiners, and optical add/drop multiplexer, for example. Optical subcarriers may be transmitted over such connections, each carrying a data stream. The subcarriers may be generated by a combination of a laser and a modulator, such that multiple lasers and modulators are not required, and costs may be reduced.

Abstract: Methods, systems, and apparatus, including computer programs encoded on computer storage media, for clock synchronizing an optical system and multiple leaf systems. In some implementations, a method includes: first data is received from an optical system. The first data is detected using a local oscillator signal provided by a local oscillator laser. The first data is processed using a first sampling rate. A frequency of a clock signal supplied by a reference clock is adjusted based on the processed first data. Second data is transmitted to the optical system at a rate based on the clock signal.

Abstract: A control circuit, comprising a processor, and a computer readable medium is described. The computer readable medium stores logic that causes the processor to analyze performance data of a link carrying data encoded in a first modulation format with a degradation prediction algorithm to determine a predicted level of degradation of the link. The processor provides first control signals to a transmitter block, and second control signals to a receiver block based upon the predicted level of degradation of the link over time. The first control signals cause the transmitter block to encode data to be transmitted over the link in a second modulation format. The second control signals cause the receiver block to decode data received from the link using the second modulation format. The first and second modulation formats conform to requirements of a same m-quadrature amplitude modulation protocol.

Abstract: Techniques are described for implementing an out-of-band communication channel used to exchange control channel information in sub-carrier-based optical communication systems. In an example implementation, an optical communication system includes a primary transceiver, a component, and secondary transceivers. The primary transceiver is operable to supply first optical subcarriers to an optical communication path, the first optical subcarriers being amplitude modulated at a first frequency to carry first control information and amplitude modulated at a second frequency to carry second control information. The component is operable to be coupled to the optical communication path and includes circuitry operable to detect the first control information. The secondary transceivers are coupled to a terminal end of the optical communication path. At least one of the secondary transceivers is operable to detect the second control information and block the first control information.

Abstract: Consistent with the present disclosure, multiple forward error correction (FEC) encoders are provided for encoding a respective one of a plurality of data streams. A mechanism is provided to mix or interleave portions of the encoded data such that each subcarrier carries information associated with each data stream, as opposed to each subcarrier carrying information associated with only a corresponding one of the data streams. As a result, both higher SNR and low SNR optical subcarriers carry such information, such that errors occurring during transmission are distributed and not concentrated or limited to information associated with a single data stream. Accordingly, at the receive end, each FEC decoder decodes information having a similar overall error rate. By balancing the error rates across each FEC encoder/decoder pair, the overall ability to correct errors improves compared to a system in which mixing or interleaving is not carried out.

Abstract: Methods, systems, and apparatus, including computer programs encoded on computer storage media, for generating, transmitting, directing, receiving, and processing optical subcarriers. In some implementations, a system includes a Tier 1 switch that supplies a plurality of data channels; a transmitter that receives the plurality of data channels, the transmitter including an optical modulator that supplies a plurality of optical subcarriers based on the plurality of data channels; an optical platform that receives the plurality of optical subcarriers, the optical platform having a plurality of outputs, each of which supplying at least one of the plurality of subcarriers; a plurality of receivers, each receiving one or more of the plurality of optical subcarriers and supplying one or more of the plurality of data channels; and a plurality of servers, each of which receiving one or more of the plurality of data channels.

Abstract: An optical network having a first terminal node, a second terminal node, and a network service system is described. The first terminal node has a plurality of ports and a signal restoration component to create a restored path. The second terminal node has a plurality of ports and a failure monitor to issue a path failure notice. A working path, a protection path, and the restored path are each fiber optic lines optically coupling the first terminal node to the second terminal node to enable a service, each path requiring a quantity of exclusive licenses. The network service system receives a path failure notice indicating a working path failure, calculates the quantity of licenses required by the restored path, releases the quantity of licenses required by the working path and applies at least a portion of the quantity of licenses to the quantity of licenses required by the restored path.

Abstract: Optical network systems are disclosed, including systems having transmitters with a digital signal processor comprising forward error correction circuitry that provides encoded first electrical signals based on input data; and power adjusting circuitry that receives second electrical signals indicative of the first electrical signals, the power adjusting circuitry supplying third electrical signals, wherein each of the third electrical signals is indicative of an optical power level of a corresponding to one of a plurality of optical subcarriers output from an optical transmitter.

Abstract: Consistent with an aspect of the present disclosure, electrical signals or digital subcarriers are generated in a DSP based on independent input data streams. Drive signals are generated based on the digital subcarriers, and such drive signals are applied to an optical modulator, including, for example, a Mach-Zehnder modulator. The optical modulator modulates light output from a laser based on the drive signals to supply optical subcarriers corresponding to the digital subcarriers. These optical subcarriers may be received by optical receivers provided at different locations in an optical communications network, where the optical subcarrier may be processed, and the input data stream associated with such optical subcarrier is output. Accordingly, instead of providing multiple lasers and modulators, for example, data is carried by individual subcarriers output from an optical source including one laser and modulator. Thus, a cost associated with the network may be reduced.

Abstract: Consistent with the present disclosure a network is provided that includes a primary node and a plurality of secondary nodes. The primary node, as well as each of the secondary nodes, includes a laser that is “shared” between the transmit and receive sections. That is, light output from the laser is used for transmission as well as for coherent detection. In the coherent receiver, the frequency of the primary node laser is detected and, based on such detected frequency, the frequency of the secondary node laser is adjusted to detect the received information or data. Such frequency detection also serves to adjust the transmitted signal frequency, because the laser is shared between the transmit and receive portions in each secondary receiver. Light output from the primary node laser, which is also shared between transmit and receive portions in the primary node, is thus also set to a frequency that permits detection of each of the incoming optical signals by way of coherent detection.

Abstract: Optical network systems are disclosed, including a transmitter comprising a digital signal processor that receives data; circuitry that generate a plurality of electrical signals based on the data; a plurality of filters, each of which receiving a corresponding one of the plurality of electrical signals, a plurality of roll-off factors being associated with a respective one of the plurality of filters; a plurality of digital-to-analog converter circuits that receive outputs from the digital signal processor, the outputs being indicative of outputs from the plurality of filters; a laser that supplies light; and a modulator that receives the light and outputs from the digital-to-analog converter circuits, the modulator supplying a plurality of optical subcarriers based on the outputs of the digital-to-analog converter circuits, such that one of the plurality of optical subcarriers carrying information for clock recovery.

Abstract: Techniques are described for implementing an out-of-band communication channel used to exchange control channel information in sub-carrier-based optical communication systems. In an example implementation, a transmitter includes a laser operable to supply an optical signal, a digital signal processor operable to supply first electrical signals based on first data input to the digital signal processor and second data input to the digital signal processor, digital-to-analog conversion circuitry operable to output second electrical signals based on the first electrical signals, modulator driver circuitry is operable to output third electrical signals based on the second electrical signals, and an optical modulator operable to supply first and second modulated optical signals based on the third electrical signals. The first modulated optical signal includes a plurality of optical subcarriers carrying user data. The plurality of optical subcarriers also being amplitude modulated to carry control information.