Abstract: An optical receiver circuit includes a light receiving element to convert an optical signal into a current signal, a submount substrate on which the light receiving element is mounted, a wiring connected to an anode pad of the light receiving element and a wire connected to a preamplifier on the submount substrate, a wiring to which a bias voltage is applied on the submount substrate; a wiring connected to a cathode pad of the light receiving element on the submount substrate; and a resistor connected to the wiring to serve as a path when the bias voltage is applied to the light receiving element via the wiring on the submount substrate. A resistance value of the resistor is determined such that a resonance peak between the preamplifier and ground is suppressed and that oscillation in the preamplifier is suppressed.

Abstract: An O-band optical communication system includes a transmitter, a receiver, and an optical fiber system coupled between the transmitter and the receiver. The optical fiber system includes at least a first fiber segment, with a positive dispersion-wavelength gradient and a first zero dispersion wavelength, coupled in series to a second fiber segment, with a negative dispersion-wavelength gradient and a second zero dispersion wavelength. When an optical signal propagating along the first fiber segment has a wavelength shorter than the first zero dispersion wavelength and experiences negative dispersion, at least partial positive dispersion compensation is provided by propagation along the second fiber segment. When light of the optical signal propagating along the first fiber segment has a wavelength longer than the first zero dispersion wavelength and experiences positive dispersion, at least partial negative dispersion compensation is provided by propagation along the second fiber segment.

Abstract: An optical transmission device includes a first detector, a generator, a second detector, and a controller. The first detector detects optical output power of an optical signal for each channel for input to a Mach-Zehnder unit that has asymmetric optical waveguides. The generator superimposes, based on the detected optical output power for each of the channels, a dither signal onto an optical signal in a specific channel from among the plurality of channels for input to the Mach-Zehnder unit. The second detector detects an amplitude value of the dither signal superimposed onto the optical signal in the specific channel output from the Mach-Zehnder unit. The controller adjusts a phase difference in the Mach-Zehnder unit such that the amplitude value of the dither signal superimposed onto the detected optical signal in the specific channel is less than a predetermined threshold.

Abstract: Method and apparatus to maintain a resonant condition of an optical cavity such that the optical path length through the optical cavity is independent or minimally dependent on the angle of incidence of a received optical signal are disclosed. A material within the optical cavity has an index of refraction that varies as a function of an angle of propagation of light within the material, thereby achieving the independence of the optical path length and the angle of incidence. The resonant condition is maintained over a range of angles of incidence of the received optical signal.

Abstract: Embodiments relate to a free space optical (FSO) communications system with a feed-forward control path. A data-encoded FSO beam is transmitted from a local terminal to a remote terminal. The local terminal directs a propagation direction of the FSO beam by a beam steering unit. To reduce pointing errors between the terminals, the FSO communications system includes a feed-forward control path. The control path includes an inertial measurement unit (IMU) that outputs motion data indicative of motion of the local terminal, for example if the local terminal is mounted to a tower that sways. The control path also includes a controller that receives the motion data from the IMU and generates feed-forward control signals for the beam steering unit. The control signals compensate for an effect of the motion of the local terminal on the propagation direction of the FSO beam.

Abstract: A system may include a first module at a far end, and an optical fiber coupled to the first module. The system may also include a second module at a near end that is configured to generate and transmit instructions to the first module to control operation of the first module.

Abstract: An optical signal control device (70) is configured to include: a leakage amount calculating unit (83) calculating, from a light intensity measured by a first light intensity measuring unit (77) and a light intensity measured by a second light intensity measuring unit (78), a leakage amount of light leaking from other optical signals to each of optical signals included in a combined signal; and an attenuation amount calculating unit (84) calculating, from the light intensity measured by the second light intensity measuring unit (78) and the leakage mount of light, an attenuation amount of each of the optical signals included in the combined signal, and a wavelength selective switch (71) attenuates each of the optical signals included in the combined signal depending on the attenuation amount calculated by the attenuation amount calculating unit (84).

Abstract: The present invention relates to the field of network communications. An Optical Line Terminal (OLT) allocates a Pseudo Wire (PW) label of an access segment PW for a port, and establishes a corresponding relationship between the port information and the PW label; and carries the corresponding relationship between the port information and the PW label in a label management message, and sends the label management message to an Optical Network Unit (ONU) so that the ONU updates a forwarding table, in which the label management message adopts an access network management protocol. As a consequence, a problem of supporting Pseudo Wire Emulation Edge-to-Edge (PWE3) on a data plane of an access segment of an access network is solved under the conditions that device complexity of the ONU is not increased and a configuration of the ONU is slightly changed.

Abstract: A system for powering a network element of a fiber optic wide area network is disclosed. When communication data is transferred between a central office (CO) and a subscriber terminal using a network element to convert optical to electrical (O-E) and electrical to optical (E-O) signals between a fiber from the central office and twisted wire pair, coaxial cable or Ethernet cable transmission lines from the subscriber terminal, techniques related to local powering of a network element or drop site by the subscriber terminal or subscriber premise remote powering device are provided. Certain advantages and/or benefits are achieved using the present invention, such as freedom from any requirement for additional meter installations or meter connection charges and does not require a separate power network.

Abstract: An optical communication device includes a conversion unit that receives an optical signal transmitted from a first optical communication device and converts the optical signal into a digital electric signal based on a clock signal, a clock switching unit that switches an oscillator generating the clock signal, and an operation mode control unit that detects an operation mode of the first optical communication device in the digital electric signal and commands the clock switching unit to perform switching from the oscillator generating the clock signal to an oscillator generating a clock signal at a frequency based on the operation mode of the first optical communication device.

Abstract: An optical communications network comprises optical data links comprising data channels. A time-domain sampled waveform of a selected data channel is obtained. The Fourier transform is applied to the time-domain sampled waveform of the selected data channel to generate a frequency-domain waveform of the selected data channel. Time-domain sampled waveforms of the selected data channel's neighboring data channels are obtained. The Fourier transform is applied to the time-domain sampled waveforms of the neighboring data channels to generate frequency-domain waveforms of the neighboring data channels. The noise-to-signal ratio is calculated based on the frequency-domain waveforms. Based on the calculated noise-to-signal ratio, an optical signal to noise ratio (OSNR) penalty is estimated. A notification is generated when the OSNR penalty exceeds a predetermined threshold.

Abstract: An optical circuit device includes a first to fourth optical couplers, wherein the first optical coupler splits a first input light into a first output beam and a second output beam with a 90-degree phase difference therebetween, and the second optical coupler splits a second input light into a third output beam and a fourth output beam with a 180-degree phase difference therebetween. The third optical coupler combines one of the first and second output beams and one of the third and fourth output beams, and outputs a first optical signal and a second optical signal having a 180-degree phase shift from each other. The fourth optical coupler combines the other of the first and second output beams and the other of the third and fourth output beams, and outputs a third optical signal and a fourth optical signal having a 180-degree phase shift from each other.

Abstract: An optical reception terminal includes a plurality of matrix filters (40, 41) respectively provided for a plurality of modes and configured to perform polarization separation and equalization on a coherently received signal in a corresponding mode, and two combining filters (50, 51) respectively provided for two polarizations and configured to combine signals in corresponding polarization among signals output from the plurality of matrix filters (40, 41) after weighting the signals. Filter coefficients of the plurality of matrix filters (40, 41) and weighting coefficients of the two combining filters (50, 51) are controlled based on a deviation from a desired state of both signals in two polarizations after combining by the two combining filters (50, 51), so as to minimize a sum of deviations.

Abstract: A fiber loop includes a plurality of processors coupled to each other and a controller coupled to each of the plurality of processors. The controller is configured to: assign to each of the plurality of processors a number of wavelengths for interconnect communications between the plurality of processors; receive, from a first processor of the plurality of processors, a request for one or more additional wavelengths; determine whether an interconnect bandwidth utilization on the fiber loop is less than a threshold; and in response to determining that the interconnect bandwidth utilization on the fiber loop is less than the threshold, reassign, to the first processor, one or more wavelengths that are assigned to a second processor of the plurality of processors.

Abstract: Designs, methods, and applications for fault localization and fiber security in optical transponders is described. In one embodiment a two-way time transfer protocol or other suitable method for synchronizing clocks between distant transponders is used. The clock synchronized transponders have digital signal processing to continually detect high precision time-histories of physical layer attributes in the transmission between the two transponders. Physical layer attributes can include: state-of-polarization changes, changes in polarization-mode-dispersion, change in propagation delay, changes or loss-of-light, changes in OSNR, changes in BER between the two nodes. By recording these physical layer changes and time-stamping them information on the magnitude and estimated location of the changes can be inferred by from the time records. In one aspect the method may be used in a distributed optical sensor for monitoring trespassing events that are a risk to fiber security of an optical transmission link.

Abstract: Embodiments of the disclosure relate to managing a communications system based on software defined networking (SDN) architecture. An SDN controller is provided in the communications system to manage a wireless distribution system (WDS) and a local area network (LAN) based on SDN architecture. The SDN controller is communicatively coupled to a WDS control system in the WDS and a LAN control system in the LAN via respective SDN control data plane interfaces (CDPIs). The SDN controller analyzes a WDS performance report and a LAN performance report and provides a WDS configuration instruction(s) and/or a LAN configuration instruction(s) to the WDS control system and/or the LAN control system to reconfigure a WDS element(s) and/or a LAN element(s) to improve quality-of-experiences (QoEs) of the communications system. Monitoring and optimizing the WDS and the LAN based on a unified software-based network management platform can improve performance at reduced operational costs and complexity.

Abstract: A first signal is generated having a first frequency spectrum comprising one or more stopbands in which components of the first signal exhibit attenuated energy relative to an average energy of the first signal. A second signal is generated having a second frequency spectrum comprising non-zero energy at frequencies within the one or more stopbands. A third signal is generated by a crosstalk-inducing subsystem from a combination of the first signal and the second signal. The third signal is detected at a receiver device and an estimate of crosstalk induced by the crosstalk-inducing subsystem is calculated using a measurement of the third signal at the frequencies within the one or more stopbands. According to some examples, the second frequency spectrum comprises a tone within at least one of the stopbands.

Abstract: A signal detection circuit includes: a first DC voltage remover that removes a DC voltage from an input differential signal; a limiting amplifier that adjusts an amplitude of the input differential signal; a reset signal generator that generates an internal reset signal on the basis of the input differential signal obtained after the amplitude is adjusted; a first bias voltage applying unit that generates a differential signal for detection by applying a bias voltage to the signal from which the DC voltage is removed; and a flip-flop circuit that generates a packet detection signal by holding a state indicating input of a packet signal on the basis of the differential signal for detection and releasing the holding on the basis of the internal reset signal. The reset signal generator includes: a differential single-phase conversion circuit; a voltage holding circuit; and a voltage comparison circuit.

Abstract: A framework for virtual network element of optical access networking has been designed to provide a cloud-residing core system (i.e. Mobile core controller or SDN controller) for running higher layers without requiring dedicated hardware at the edge of the network. In this framework, a service operator can create multiple optical access network connections for serving a single or multiple types of wired or wireless subscriber by programming (via software) optical ports of a Virtual Optical Edge Device to perform the desired MAC and/or PHY layer of a selected optical protocol. The Virtual Optical Edge Device in turn performs the desired PHY function or MAC and PHY function of selected protocol per each southbound port. The Virtual Optical Edge Device performs data abstraction function on all data associated with southbound ports and presents the core network a unified API via its northbound ports.

Abstract: A method and apparatus for controlling an optical switch. The switch includes a switching fabric and optical amplifiers for amplifying optical signals. A configuration for the switching fabric is generated and implemented. The configuration indicates a set of optical paths between switching fabric input ports and the output ports. Optical path losses through the switching fabric vary based on the configuration. An amplifier control signal for controlling gains of the optical amplifiers, is also provided. The configuration for the switching fabric is generated based on the gains of the optical amplifiers, the amplifier control signal is generated based on the configuration for the switching fabric, or both.