Abstract: An optical communication system includes a digital signal processer coupled to the coherent receiver, said coherent receiver including a nonlinearity compensation module for compensating for nonlinear effects in fiber in the optical link for increasing capacity or transmission distance of the fiber, the nonlinearity compensation module includes a spectral slicing of the signal into bands, computing nonlinear interaction between the bands with parameters opposite to those of the fiber to reverse the non-linear effects in the fiber, and only certain nonlinear interactions between bands are considered thereby reducing complexity of the nonlinearity compensation.

Abstract: In some embodiments, an apparatus includes an optical transmitter system that defines an interferometric structure and has an in-phase portion and a quadrature portion. The optical transmitter system has a transmission configuration and a calibration configuration. The interferometric structure can produce an output associated with a skew between the in-phase portion and the quadrature portion of the optical transmitter system when in the calibration configuration. The skew is associated with a digital domain, an analog domain and an optical domain of the optical transmitter system.

Abstract: In order to reduce the circuit size for a chromatic dispersion pre-equalization operation, an optical multilevel signal pre-equalization circuit is provided with: (1) a plurality of look-up tables in which a string of middle codes utilizing a symmetry of a signal constellation of a multilevel code or a string of middle codes represented by polar coordinates is stored in association with a waveform response component; and (2) one or more operation circuits to which the waveform response component corresponding to a multilevel signal to be transmitted is inputted from the plurality of look-up tables, and which outputs a pre-equalized output waveform corresponding to the multilevel signal by operating the waveform response components outputted from different look-up tables.

Abstract: Optical devices in optical network exchange signals at a plurality of wavelengths via a plurality of pathways. Each of the optical devices is associated with a corresponding wavelength and includes multiple optical inputs/outputs (I/Os) to exchange signals at the corresponding wavelength via the plurality of pathways. During maintenance or failure of one of the optical I/Os in an optical device associated with a wavelength, communications are maintained in the optical network by switching communications at a same wavelength to another a different pathway and/or reforming the optical network using other wavelengths. For example, an optical network unit (ONU) may identify an error in a first wavelength associated with a first optical device included in an optical line terminal (OLT) and may forward data using a second wavelength associated with the other optical device included in the OLT.

Abstract: A method and a device for adjusting a laser in an optical network. At least one alive message is transmitted from a first optical component towards a second optical component. A confirmation message is transmitted from the second optical component to the first optical component determining the wavelength of the laser to be used based on the alive message received by the second optical component. Furthermore, an optical communication system is provided with an optical element.

Abstract: The present invention discloses a time/wavelength-division multiplexed passive optical network (TWPON), which has an optical splitter (21) and a waveguide grating router (WGR) (22) disposed at a remote node (RN) (20). The optical splitter (21) and the WGR (22) can be connected in a cascade or in a parallel such that the present invention can use less number of wavelengths to increase transmission capacity or increase the number of users. A channel fault monitoring (CFM) module provided at an optical line terminal (OLT) is utilized to locate fiber breaks among distribution fibers. The TWPON of the present invention can provide TDM-PON, WDM-PON, and Hybrid PON co-existing platform with less wavelengths channel fault monitoring mechanism.

Abstract: An exemplary apparatus is provided for a high capacity switching system for use in a transport network, which contains a number of input and output subsystems and a central interconnection means configurably interconnecting the input and output subsystems. The subsystems have input and output line modules for receiving and transmitting data signals to and from transmission lines of the network, one or more link modules connecting the subsystems to the interconnection means, and local switching means switching data signals in time and space domain between the input and output modules and the one or more link modules within one subsystems. The link modules are adapted to aggregate data signals from different input and output line modules of the same input and output subsystems and destined to input and output line modules of another one of the input and output subsystems into signal bursts and add a payload gap to each signal burst.

Abstract: An optical microphone for detecting an acoustic wave propagating through an environmental fluid by using a light wave, includes: an acoustic wave receiving section having a propagation medium portion through which an acoustic wave propagate and a first support portion for supporting the propagation medium portion; a light source for outputting a light wave so that the light wave passes through the propagation medium portion across the acoustic wave propagating through the propagation medium portion; a light-blocking portion having an edge line for splitting the light wave having passed through the propagation medium portion into a blocked portion and a non-blocked portion; and a photoelectric conversion section for receiving a portion of the light wave having passed through the propagation medium portion which has not been blocked by the light-blocking portion to output an electric signal.

Abstract: A system for suppressing even-order distortion in a photonic link includes a laser for providing laser light to a first input of a Mach-Zehnder modulator (MZM), where the MZM has a second input for receiving an RF input signal, a third input for applying a DC bias voltage to the MZM, and an optical signal output. A dc-voltage-biased photodiode has an input, coupled to the MZM optical signal output, and a modulated RF signal output. The MZM DC bias voltage is set at a value to generate an even-order distortion amplitude substantially equal to an even-order distortion amplitude from the photodiode and 180 degrees out of phase so as to substantially cancel the photodiode even-order distortion. The invention provides the cancellation of photodiode even-order distortion via predisortion linearization with a MZM biased slightly away from quadrature, employing a single fiber run and a single photodiode. The invention provides an improvement in carrier-to-intermodulation ratio (CIR) upwards of 40 dB.

Abstract: An optical signal terminating apparatus for an optical path network includes: a variable filter selecting an optical signal of a predetermined wavelength path making up any one of a plurality of wavebands included in one wavelength division multiplexing light selected from a plurality of wavelength division multiplexing lights respectively transmitted in parallel via a plurality of optical fibers to a relay node in the optical path network, the variable filter dropping the optical signal to an electric layer, the variable filter including a waveband separator separating the wavelength division multiplexing light into a plurality of wavebands, a waveband selector selecting one waveband from a plurality of wavebands separated by the waveband separator, a wavelength separator separating one waveband selected by the waveband selector into wavelengths, and a drop wavelength selector.

Abstract: Systems, devices and methods provide feedback about the quality of communication between a device and a remote control. A wireless signal is sent between a controlled device and the remote control. The quality of the signal can be measured and reported to a user, installer, troubleshooter, customer service agent or other person in any manner. Quality may be determined based upon the strength of the received signal as well as the amount of noise that is present. The quality measurements provide feedback that allows a user, installer, customer service representative or other person to change the positions of the device or the remote control, or to take other actions based upon the quality of the wireless signal that is received.

Abstract: In order to allow reception in which receive sensitivity does not depend upon polarization state in reception of a multi-level phase optical signal, in this optical reception method, a multi-level phase optical signal of a single polarization is separated into a first optical signal and a second optical signal of which polarizations are mutually orthogonal, the ratio of the power of the first optical signal to the power of the second signal is calculated, and the difference between the phase of the first optical signal and the phase of second optical signal is calculated as an amount of compensation, whereupon, on the basis of the ratio and the amount of compensation, the first optical signal and the second optical signal are combined using a maximal ratio combining method, and the amount of compensation is modified on the basis of the ratio.

Abstract: Disclosed herein is an optical receiver including: a light receiving element configured to have an anode and a cathode and generate a photocurrent dependent on received signal light; a current-voltage conversion circuit configured to be connected to the anode of the light receiving element and convert the photocurrent to a voltage signal; and a capacitive passive element configured to have a first electrode and a second electrode. The cathode of the light receiving element is connected to the first electrode of the capacitive passive element, and the second electrode of the capacitive passive element is connected to a reference potential of the current-voltage conversion circuit and the second electrode is not coupled to objects other than a reference potential terminal of the current-voltage conversion circuit.

Abstract: In order to provide a communication system which performs a communication while maintaining high voltage insulation, a control circuit which is operated at a low voltage, and a controlled circuit which is operated at a high voltage are connected through a propagation layer having a waveguide structure, thereby performing a communication. In particular, a displacement current (surge current) flows between a high voltage circuit and a low voltage circuit due to a potential fluctuation which occurs in the high voltage circuit A surge current protection circuit is provided, and applying an input which is out of rating to the communication module and the low voltage circuit due to such a surge current is prevented.

Abstract: There is provided an optical transmitter including: a demultiplexer configured to divide a data frame of a transmission signal into subframes with a predetermined length so as to form the subframes in a plurality of signal lanes; an index generator configured to generate an index for indicating an order of the signal lanes; a lane rearrangement unit configured to rearrange the order of the signal lanes according to the index; a carrier controller configured to generate a frequency offset of a carrier corresponding to the index; a mapping unit configured to map the transmission signal in the plurality of signal lanes with the rearranged order to the transmission signal with a phase corresponding to the frequency offset; and a transmitting unit configured to optically modulate the mapped transmission signal so as to transmit the modulated transmission signal.

Abstract: The present invention provides a nonlinear compensating apparatus and method and a transmitter. The nonlinear compensating apparatus includes: an information sequence acquiring unit, configured to acquire a symbol information sequence of the pulse signal; a perturbation quantity acquiring unit, configured to calculate, by pre-obtained weighting coefficients to which each item corresponds, the weighted sum of interaction items of pulses on one or more moments relative to the current moment; a perturbation quantity processing unit, configured to combine the items of the perturbation quantity based on the weighting coefficients; and an information compensating unit, configured to calculate a difference between the symbol information sequence and the processed perturbation quantity to obtain a compensated symbol information sequence. With the embodiments of the present invention, the complexity of calculation may be further lowered, and requirements on hardware may also be lowered.

Abstract: An emphasis signal generating circuit includes: a branch circuit configured to split a signal into a plurality of paths; a delay circuit provided in one or more of the paths into which the signal has been split by the branch circuit, the delay circuit being configured to delay one or more signals; a phase compensation circuit provided in one or more of the paths into which the signal has been split by the branch circuit, the phase compensation circuit having such characteristics that a transmission intensity of a signal is low in a low frequency band and is high in a high frequency band; and an addition/subtraction circuit configured to perform addition and/or subtraction of signals from the plurality of paths and output a result.

Abstract: A method of transmitting a data signal using an optical transmitter of an optical communications system. The optical transmitter is configured to modulate an optical carrier in successive signalling intervals to generate an optical signal. A modulation scheme is provided which comprises a multi-dimensional symbol constellation. The modulation scheme is designed such that an average degree of polarization of a modulated optical signal output from the optical transmitter has a first value when averaged across a first signaling interval, and has a second value when averaged across more than one and fewer than 100 signaling intervals. The second value is less than 10 percent of the first value. During run-time, an encoder of the optical transmitter encoding a data signal to be transmitted as symbols of the constellation, and a modulator of the optical transmitter modulating available dimensions of the optical carrier in accordance with the symbols.

Abstract: An optical signal demodulator includes: an obtaining unit configured to obtain a spectrum of an optical signal generated by a second signal being superimposed on a first signal using frequency modulation; an identifying unit configured to identify a peak wavelength which is a wavelength corresponding to a peak position of the spectrum; and a demodulating unit configured to demodulate the second signal from the optical signal using a wavelength-variable filter to which a transmitted wavelength band has been set based on the peak wavelength.

Abstract: A system and method for optical switching of networks in a multi-node computing system with programmable magneto-optical switches that enable optical signal routing on optical pathways. The system includes a network of optical links interconnecting nodes with switching elements that are controlled by electrical control signals. Data transmission is along the optical links and an optical pathway is determined by the electrical control signals which are launched ahead of optical signal. If links are available, an optical pathway is reserved, and the electrical signal sets the necessary optical switches for the particular optical pathway. There is thereby eliminated the need for optical-electrical-optical conversion at each node in order to route data packets through the network. If a link or optical pathway is not available the system tries to find an alternative path. If no alternative path is available, the system reserves buffering. After transmission, all reservations are released.