Abstract: A synchronizer/de-synchronizer maps continuous format signals of an arbitrary rate into frames of pre-selected single common rate, such as SONET frames, with no bits changed and very little jitter or wander added. In this way, the continuous format signal may be carried transparently as a tributary of a SONET network. Each frame comprises a definite number of fixed stuff bits, including transport overhead bits and reminder fixed stuff bits. A frame also comprises an adjustable number of adaptive stuff bits, resulting from the phase difference between the arbitrary rate and the common rate. A mapping function is performed in a tributary unit shelf of a SONET transport shelf, and the reverse mapping function is performed in a similar way at the far end of a SON ET connection. The stuff bits are spread uniformly within the frame.

Abstract: A concatenated signal carrying an arbitrary mix of concatenated data traffic is split and transported across a network between a start node and an end node through a hyper-concatenated connection set up through independent pointer processor state machines. At a start node, the concatenated optical signal is split into two or more hyper-concatenated data streams. If a split occurs at a frame within a concatenated signal, the start node replaces a concatenation indicator of the frame with a payload pointer from a first frame of the concatenated signal and inserts a split indicator in the SS bits of the frame overhead. At an end node, the hyper-concatenated data streams are recombined to recover the original concatenated signal. Frames containing split indicators are modified to remove the split indicator and to replace the payload pointer with a concatenation indicator.

Abstract: Multiple sub-streams are aharmonicaly interleaved into a high speed data signal by interleaving successive blocks of data from each sub-stream into the high-speed data signal using a predetermined interleaving pattern that is different for two consecutive sequences of N (an integer >2) blocks of data within the high-speed data signal. The resulting irregular distribution of bits of each sub-stream within the high speed data signal reduces the probability that error bursts due to low frequency noise will be localized in one or more of the recovered sub-stream extracted from the high speed data signal. This improved distribution of bit errors across the sub-streams reduces bit error rates in the most highly errored sub-streams, and thereby enables an increase in signal reach.

Abstract: A high capacity switch for switching communications traffic. The high capacity switch has a plurality of differing granularity switching levels, each switching level having at least one switch node capable of performing a switching operation at the granularity of the switching level and at least two primary connections, each connecting one of the switching levels to another one of the switching levels. At one of the switching levels, at least one switch node is capable of switching communications traffic along at least one switch connection path established along one of the primary connections, and is also capable of switching communications traffic along at least one secondary connection to another switch node within the same switching level, such that each of the at least one switch connection paths established is filled to a predetermined level.

Abstract: A transparent port which maps continuous format signals of an arbitrary rate into frames of a pre-selected single common rate, is provided with a programmable link termination/instigation, for example a FPGA. The port identifies the rate of the continuous signal, recognizes its protocol and the FPGA is configured accordingly. FPGA performs framing, counts errors, does code conversion, corrects parity and performs any other performance monitoring specific to the protocol. In this way, the continuous format signal may be carried transparently as a tributary of e.g. a SONET network, and the performance parameters for the previous section, such as the previous section fail, may be reported to the far end.

Abstract: An OP-N connection is mapped through a communications network between first and second end-nodes via at least one intermediate node. The integrity and validity of the OP-N connection can be determined independently of SONET/SDH lines, sections or paths mapped through the network, and potentially utilizing bandwidth of the OP-N connection. Validation of the OP-N connection can be accomplished by inserting performance monitor (PM) information into a data signal at the first end-node. The PM information is inserted into the synchronous payload envelope (SPE) of a SONET/SDH data signal. At each intermediate node between the first and second end-nodes, the PM information may be extracted, examined and/or augmented or simply pointer processed before the data signal is forwarded. At the second end-point, the PM information is extracted and examined. Multiple levels of OP-N connections are supported, with each level being provided with a respective set of PM information carried in the SPE.

Abstract: In a method and system for evaluating distributed gain in an optical transmission system, a data signal and a residual pump laser signal propagating in opposite directions within a waveguide are monitored. Modulation of the residual pump laser signal is correlated with low frequency components of the data signal. This correlation is used to determine cross-talk between the data signal pump laser signals, as a function of location within the waveguide. The distributed gain is then evaluated from the cross-talk, using a known relationship, or proportionality, between gain and cross-talk.

Abstract: A high bandwidth connection is mapped through a multi-stage switch between an ingress node and an egress node via a center stage comprising M (an integer) center stage nodes. Each center stage node is connected to the ingress and egress nodes by respective links adapted to support m (an integer) respective connections. An m×M connection matrix of connections between the ingress node and the center stage is provided. Each column of the connection matrix contains 1≦j≦m connections between the ingress node and a respective one of the center stage nodes, and each row of the connection matrix contains 1≦k≦M connections between the ingress node and the center stage nodes. The high bandwidth connection is mapped through the multi-stage switch by layering the high bandwidth connection within the connection matrix. Thus the high bandwidth connection is divided into N segments.

Abstract: A digital performance monitoring method and system for an optical communications system utilizes a channel monitor and a digital signal processor (DSP). The channel monitor is designed to monitor a respective channel signal of the optical communications system, and includes: a sample memory adapted to store sample data including a set of sequential N-bit (where N≧1) samples generated by an Analog-to-Digital (A/D) converter at a timing of a predetermined sample clock during a predetermined time interval; and a controller adapted to control storage of the sample data to the sample memory. The digital signal processor (DSP) is designed to calculate at least one performance parameter of the optical communications system based on the sample data.

Abstract: Provided is an optical apparatus and method wherein power transfer coefficients arising from SRS are measured at a designated co-location point and the power of dithers, which are impressed on the channels of a multiplexed optical signal propagating through the optical apparatus, is measured at each co-location point. Within the optical apparatus distances between co-location points are short and the power transfer coefficients are effectively constant. Consequently, the power of each channel of the multiplexed optical signal at the co-location points is obtained from the power of the dithers at a respective one of the co-location points and the power transfer coefficients measured at the designated co-location point. In some embodiments, information on the channel power at the co-location points is used to provide instructions for compensating for fluctuations in channel power and/or channel count at an input and/or channel count within the optical apparatus.

Abstract: A method and system for reducing non-linear signal degradation effects of WDM optical signals exacerbated by highly correlated bit patterns of optical waveforms in neighboring optical channels. Embodiments include offsetting the transmission times of signals in neighboring channels, and applying different scrambling patterns to the respective data streams prior to transmission on neighboring optical channels.

Abstract: A method and system is provided for compensating polarization mode dispersion (PMD) in an optical communications system includes a controller designed to control a broadband PMD compensator to differentially delay light at each one of a plurality of selected wavelengths. At least one of the selected wavelengths lies between an adjacent pair of channel wavelengths of the optical communications system. A performance parameter value indicative of PMD is measured at each channel wavelength of the optical communications system. An estimated performance parameter value is then calculated at each selected wavelength, and an error function calculated as a function of wavelength based on the estimated performance parameter values. The broadband PMD compensator is then controlled to minimize the value of the error function.

Abstract: In a coherent optical receiver, an incoming optical signal is combined with a local oscillator (LO) optical signal and the combined optical signals are detected by an optical detector and receiver arrangement. The receiver produces first and second loop control signals having respectively relatively slow and fast response speeds dependent upon frequency and phase variations between the incoming signal and the LO signal. An electrical source produces an electrical signal having a GHz frequency controlled by the second control signal. An optical source produces an optical signal with a first component having a first frequency controlled by the first control signal, and a second component having a frequency offset from the first frequency by a second frequency dependent upon the frequency of the electrical signal. The LO signal is derived from the second optical component via an optical filter and amplifier.

Abstract: Nonlinearity-induced signal distortions are compensated by processing an input communications signal, in the electrical domain prior to Electrical-to-optical conversion and transmission through an optical link of a communications system. According to the invention, a compensation operator is determined that substantially mitigates the nonlinearity-induced signal distortions imparted to an optical signal traversing the communications system. The input communications signal is then input to the compensation operator to generate a predistorted electrical signal. This predistorted electrical signal is then used to modulate an optical source to generate a corresponding predistorted optical signal for transmission through the optical communications system. With this arrangement, arbitrary nonlinearity-induced signal distortions imparted by the optical link can be compensated in such a manner that a comparatively undistorted optical signal is obtained at the receiving end of the optical link.

Abstract: A high speed D/A converter includes a phase aligner, and a vector summation block. The phase aligner operates to ensure precise phase alignment between corresponding bits of a parallel N-bit digital signal having a data rate of at least 2 GHz. The vector addition block performs a vector addition of the phase-aligned bits of the parallel N-bit digital signal. Each bit of the parallel N-bit digital signal can be weighted to ensure a correct additive contribution to the analog signal level appearing at the output of the D/A converter. Vector addition of the weighted bits can be accomplished using a microwave signal combiner network in the form of either a multistage parallel cascade of impedance matched junctions, or a linear cascade of junctions.

Abstract: The present invention discloses a high performance optical architecture for multiplexing and demultiplexing channels for use in high spectral efficiency optical systems. In general, the MUX and DeMUX architectures of the present invention will fall into two key sections or stages: a wavelength group section and a channel section. The group section makes use of characteristic associated with groups of multiplexed channels for separating said groups from an optical signal having a plurality of multiplexed groups. Advantageously, in preferred embodiments, the channel section is colorless (non-wavelength specific between groups) in order to reduce cost and complexity. With respect to the colorless channel section, components with free spectral ranges (FSRs) have been strategically added to provide repetitive optical filtering functions on group of channels (i.e., subsets of channels within each band of wavelengths) so that the colorless channel section can operate in any respective group identically.

Abstract: In a method of compensating polarization dependent loss (PDL) in a wave division multiplex (WDM) optical communications system, a performance parameter is monitored at a predetermined monitoring point. The performance parameter is indicative of respective channel PDL for each one of a plurality of channels of the optical communications system. A error function is calculated as a function of wavelength across a wavelength spectrum of interest, using the measured performance parameter values. Finally, a broadband PDL compensator is controlled based on the calculated error function.

Abstract: Polarization Dependent Effects (PDEs), including Polarization Mode Dispersion (PMD) and Polarization Dependent Loss (PDL) imposed on optical signals conveyed through an optical link are compensated by processing an input signal in the electrical domain prior to transmission. A compensation function is derived that at least partially compensates the PDEs. The communications signal is then processed in the electrical domain using the compensation function to generate an electrical predistorted signal. The electrical predistorted signal is then used to modulate an optical source to generate a corresponding predistorted optical signal for transmission through the optical link. The PDEs of the optical link operate of the predistorted optical signal such at that substantially undistorted optical signal is received at a receiving end of the link.

Abstract: A method for establishing connections along a network route, including determining a capacity and a set of concatenation constraints, and allocating selected resources along the route to allow the delivery of any combination of signals satisfying the set of concatenation constraints and having a total capacity not exceeding the determined capacity.

Abstract: A method and apparatus for using sacrificial bits in a data stream to adjust sampling parameters for the data stream is described. The sacrificial bits are a predetermined sequence of a predetermined length. The sampling parameters are perturbed during transmission or reception of the sacrificial bits in order to provide information useful in adjusting the sampling parameters of the apparatus. Adjustment is accomplished by computing a bit error rate during the perturbing of sampling parameters in order to probe edges of an eye closure of the detected signal. The advantage is faster homing on optimal sampling parameters with little sacrifice of transmission capacity.