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: Optical network systems and components 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 DACs 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 DACs, and supplies a plurality of optical subcarriers based on the outputs, such that one of the optical subcarriers has a frequency bandwidth that is wider than remaining ones of the optical subcarriers, said one of the optical subcarriers carrying information for clock recovery.

Abstract: Methods, systems, and apparatus for subcarrier modulation with radio frequency inphase-quadrature (IQ) modulators. A system includes a plurality of IQ modulators, each configured to receive an input electrical signal comprising an inphase signal and a quadrature signal, and each configured to modulate the inphase signal and quadrature signal based on one of a plurality of local oscillator signals to output a multiplexed signal. Each of the plurality of local oscillator signals is supplied by a respective one of a plurality of local oscillator circuits. A modulator circuit is configured to modulate a carrier optical signal from a laser having a frequency ?c based on the multiplexed signal to generate a modulated optical signal centered at frequency ?c and comprising a plurality of subcarriers. A center frequency of each of the plurality of subcarriers is offset from ?c by a frequency of said one of the plurality of local oscillator signals.

Abstract: Optical network systems and components 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 DACs 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 DACs, and supplies a plurality of optical subcarriers based on the outputs, such that one of the optical subcarriers has a frequency bandwidth that is wider than remaining ones of the optical subcarriers, said one of the optical subcarriers carrying information for clock recovery.

Abstract: A hub node may or have a capacity greater than that of associated leaf nodes. Accordingly, 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, each connection including one or more segments of optical fibers, optical amplifiers, optical splitters/combiners, and optical add/drop multiplexer. 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. As the capacity requirements of the leaf nodes change, the number of subcarriers associated with, and thus the amount of data provided to, each node, may be changed accordingly.

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: 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 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: Probabilistic constellation shaping (PCS) is applied to a desired probability distribution over the 2-D constellation points. Constellation points are partitioned into multiple disjoint sets in which all the constellation points within a subset have the same energy level (i.e., amplitude) or distance from the origin on the complex plane. Each of the sets may be further subdivided into smaller disjoint sets of constellation points to facilitate labeling of the constellation points. The sets may be indexed from 0 to the total number of disjoint sets to form an index set. The desired distribution may then be applied over the index set either using a distribution matcher (DM) or using a lookup table. The desired distribution may be generated before forward error correction (FEC) encoding that preserves the generated amplitude distribution through FEC encoding of data bits.

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 a further aspect of the present disclosure, previously encoded data is stored in a memory, and an encoder accesses both input data and previously encoded data to generate new encoded data or a new codeword. Each codeword is stored in a row of the memory, and with each newly generated codeword, each previously stored code word is shifted to an adjacent row of the memory. In one example, the memory is delineated as a plurality of blocks including rows and columns of bits. When generating a new code word, randomly selected columns of bits in the memory are read from randomly selected blocks of the memory and supplied to the encoder. In this manner the number of times the memory is access is reduced and power consumption is reduced.

Abstract: Optical network systems and components 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 DACs 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 DACs, and supplies a plurality of optical subcarriers based on the outputs, such that one of the optical subcarriers has a frequency bandwidth that is wider than remaining ones of the optical subcarriers, said one of the optical subcarriers carrying information for clock recovery.

Abstract: Methods, systems, and apparatus, including computer programs encoded on computer storage media, for performing asymmetric pulse-shaping filtering. In some implementations, a receiver comprises a detector circuit operable to receive optical signal data from an optical link. The receiver comprises a filter circuit, coupled to the detector circuit, operable to (i) filter the optical signal data according to an asymmetric filtering scheme and (ii) output the filtered optical signal data, wherein the asymmetric filtering scheme comprises utilizing a shaping filter with first criteria, the first criteria including one or more values greater than one or more values of second criteria utilized by a shaping filter at a transmitter, the transmitter communicating with the receiver.

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: 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: 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: 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 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: 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: 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.