Abstract: Components, systems, and methods for reducing location-dependent destructive interference in distributed antenna systems operating in multiple-input, multiple-output (MIMO) configuration are disclosed. Interference is defined as issues with received MIMO communications signals that can cause a MIMO algorithm to not be able to solve a channel matrix for MIMO communications signals received by MIMO receivers in client devices. These issues may be caused by lack of separation (i.e., phase, amplitude) in the received MIMO communications signals. Thus, to provide amplitude separation of received MIMO communications signals, multiple MIMO transmitters are each configured to employ multiple transmitter antennas, which are each configured to transmit in different polarization states. In certain embodiments, one of the MIMO communications signals is amplitude adjusted in one of the polarization states to provide amplitude separation between received MIMO communications signals.

Abstract: A burst-mode receiver for receiving burst optical signals having different intensities by a reversely connected APD, including: a current detection circuit outputting a photocurrent that is generated by APD and is output from a current mirror circuit (CMC) as a voltage proportional to the photocurrent, the CMC being connected in series between a power supply and APD; a peak detector circuit detecting and holding a peak value of the output voltage of the current detection circuit; a resistor connection switching circuit, which is inserted between the CMC and APD, for connecting a series resistor to APD in series by switching; and a comparator outputting a switching signal for switching the resistor connection switching circuit so that the series resistor is connected to APD in series in a case where a voltage detected by the peak detector circuit is equal to or more than a predetermined threshold.

Abstract: In a receiver, a reception front end receives a polarization-scrambled polarization multiplexed optical signal, polarization-separates the received polarization multiplexed optical signal, and converts each signal into quantized signals. A digital signal processor samples the quantized signals, demodulates the signals by using a polarization separation digital signal processing algorithm, and outputs demodulated signals. When phase and amplitude variations of the demodulated signals are greater than a predetermined value, a control circuit causes the digital signal processor to interrupt processing using the polarization separation digital signal processing algorithm, changes an initial value of a filter coefficient, and then causes the digital signal processor to start the processing using the polarization separation digital signal processing algorithm.

Abstract: An optical transmitter may include one or more lasers configured to provide a primary optical signal having a primary wavelength and a secondary optical signal having a secondary wavelength to a modulator via corresponding first and second modulator inputs. The modulator may combine the primary and secondary optical signals into a combined optical signal and modulate, with an electrical signal, the combined optical signal to provide a modulated optical signal to an optical filter. The optical filter may be configured to separate, from the modulated optical signal, a modulated primary optical signal having the primary wavelength and a modulated secondary optical signal having the secondary wavelength and provide the modulated primary optical signal to a primary optical link and the modulated secondary optical signal to a secondary optical link.

Abstract: An apparatus comprising a digital signal processor (DSP) configured to code a plurality of data sub-streams using a plurality of modulation formats to generate a plurality of coded data symbols, wherein each modulation format leads to a unique bit rate for coded data symbols associated with a modulation format, transform the coded data symbols into a frequency domain by applying Fourier transform on each coded data symbol, map the frequency-transformed data symbols onto a plurality of subcarrier signals associated with a plurality of frequency tones, wherein at least two of the subcarrier signals correspond to different modulation formats, and generate an electrical signal in a time domain based on the subcarrier signals.

Abstract: An optical transmission system includes an optical transmitter and an optical receiver. The optical transmitter includes: a first digital signal processor configured to generate an electric-field information signal corresponding to a transmission signal; and a transmitter front-end configured to generate an optical signal from the electric-field information signal. The optical receiver includes: a receiver front-end configured to generate an electric signal corresponding to the optical signal; and a second digital signal processor configured to detect polarization dependent effects on the optical signal based on the electric signal. The first digital signal processor corrects the electric-field information signal based on the polarization dependent effects detected by the second digital signal processor in the optical receiver.

Abstract: An information communication method of transmitting a signal using a change in luminance is provided. The information communication method includes: determining a pattern of the change in luminance, by modulating the signal to be transmitted; and transmitting the signal, by at least one light emitter changing in luminance according to the determined pattern of the change in luminance. In the determining, a first luminance change pattern corresponding to a body which is a part of the signal and a second luminance change pattern indicating a header for specifying the body are determined. In the transmitting, the header and the body are transmitted by the at least one light emitter changing in luminance according to the first luminance change pattern, the second luminance change pattern, and the first luminance change pattern in the stated order.

Abstract: An optical switch includes an input port, output ports, and a spatial light modulating section that receives an optical signal from the input port to deflect the optical signal to a selected one of the output ports. A phase distribution with the same radius of curvature as that of a wavefront of the optical signal and a phase distribution that allows the deflected optical signal to be coupled to the output port are set for the spatial light modulating section.

Abstract: Embodiments of the present invention provide a method and an apparatus for detecting a fiber jumper connection. The method includes: receiving first configuration information delivered by a management system, where the first configuration information includes port identities of at least one pair of ports that are supposed to be connected on a fiber distribution device; receiving second configuration information reported by the fiber distribution device; and matching the ports that are supposed to be connected indicated by the first configuration information and the connected ports indicated by the second configuration information to obtain a matching result, where the matching result includes port identities of connected ports and unconnected ports that do not match the ports that are supposed to be connected, thereby improving efficiency of detecting a fiber jumper connection.

Abstract: An optical receiver circuit includes a polarization beam splitter configured to split input signal light into two different polarized wave components; two variable optical attenuators configured to respectively adjust attenuation of and output the signal light split by the polarization beam splitter according to polarization state; and a single planar optical waveguide on which the polarization beam splitter and the two variable optical attenuators are disposed.

Abstract: In one embodiment, optical node includes an input port configured to receive an input optical frame and a first optical switch coupled to the input port, where the first optical switch is configured to remove the input optical frame to produce a removed input optical frame when an address of the input optical frame is a node address of the optical node and to pass the input optical frame to a second optical switch when an address of the input optical frame differs from the address of the optical node. The optical node also includes the second optical switch coupled to the first optical switch, where the second optical switch is configured to output the input optical frame to an output port when the address of the input optical frame is not the node address of the optical node and the address of the input optical frame is not an empty address.

Abstract: An optical network is configured to provide an optical reroute over a backup path (2139) during a failure in a signal path (2133). The network comprises a first node (B). A second node (C) is coupled to receive a signal from the first node (B) via the signal path (2133), and a backup signal via the backup path (2139). The network is adapted to transmit a signal and a corresponding backup signal from the first node to the second node even when there is no failure in the signal path (2133), wherein the backup signal is blocked at the second node (C) when there is no failure in the signal path (2133). Embodiments of the invention utilize the broadcast and blocking functionalities of a wavelength selective switch (WSS) device. Such WSS devices enable, in the case of a failure of a link, the fast switchover of optical traffic onto local detours within a reduced time.

Abstract: A free-space optical transceiver includes a repositionable mirror for receiving and sending light beams with another transceiver. To properly align the light beams, the position of the mirror is determined in using a position sensor. The position sensor is mounted within a base substructure that is coupled to a steerable mirror substructure containing the mirror. The position sensor reflects sensor light off of the mirror to determine the position of the mirror along two different axes. The position sensor includes an optical element for shaping the sensor light. The components of the position sensor are mounted to the base substructure such that alignment of the position sensor is not required. Further, by coupling the position sensor to the base substructure and not the steerable mirror substructure, the moment of inertia and center of gravity of the steerable mirror substructure is improved, thereby improving the steering responsiveness of the mirror.

Abstract: In some embodiments, an apparatus includes an optical transmitter module that can be electrically coupled to an electrical serializer/deserializer and a controller. The optical transmitter module can include an electrical detector that can receive an in-band signal. The electrical detector can send to the controller a first power error signal and a second power error signal based on the in-band signal. The controller can send a correction control signal to the electrical serializer/deserializer based on the first power error signal and the second power error signal such that the electrical serializer/deserializer sends a pre-emphasized signal to the optical transmitter module based on the correction control signal. In such embodiments, the first power error signal, the second power signal and the correction control signal are out-of-band signals.

Abstract: A light-receiving circuit includes an optical-to-electrical transduction element, a TIA processing section to output a voltage in proportion to a current input from the optical-to-electrical transduction element, and a control section to control the TIA processing section. The TIA processing section includes a TIA, which generates the voltage output signal in proportion to the current input from the optical-to-electrical transduction element, an amplifier, which amplifies the output signal of the TIA, a monitoring portion, which monitors the current to be input to the TIA, and an offset-adjusting portion provided between the TIA and the amplifier to adjust and output an offset level of the output signal of the TIA to the amplifier. The control section acquires a value of the current to be input from the monitoring portion to the TIA, and controls the offset-adjusting portion so as to adjust the offset level in proportion to that acquired current value.

Abstract: An optical switch is configured in a “dual-ganged” switch geometry to provide for the simultaneous switching of a selected transmit/receive pair of optical signal paths between a specific optical communication device and an optical communication network. A biaxially-symmetric signal redirection component may be used to direct the signals between the selected channel and the optical communication device. A specific waveguide (e.g., fiber) array topology within the dual-ganged switch (DGS) breaks the symmetry between the network transmit/receive arrays and a pair of transmit and receive signal paths associated with the communication device to improve isolation and minimize the possibility of cross-talk between non-selected waveguides in the transmit and receive arrays. The possibility of “hits” during switching between channels can be eliminated, and is controlled by dictating the process or switching steps used to rotate the biaxially-symmetric signal redirection element.

Abstract: A device for pre-emption in passive optical networks may include a first media access control (MAC) module configured to receive a first type of data traffic and transmit the first type of data traffic to a MAC merge module. The device may further include a second media access control (MAC) module configured to receive a second type of data traffic and transmit the second type of data traffic to the MAC merge module. The device may further include the MAC merge module configured to receive the first and second types of data traffic from the first and second MAC modules, respectively, and provide the first and second types of data traffic for transmission over a port. The MAC merge module may be configured to pre-empt the transmission of the first type of data traffic over the port in favor of the second type of data traffic.

Abstract: In some embodiments, an apparatus includes a switch device that can be operatively coupled to a network having a set of links. The switch device can receive at a first time, a message having a set of physical coding sublayer (PCS) lanes. The message can include an error notification within a first subset of PCS lanes from the set of PCS lanes and not within a second subset of PCS lanes from the set of PCS lanes. The error notification is associated with signal degradation of a link from the set of links, where the switch device can send a first signal in response to receiving the message at the first time. The switch device can also receive at a second time a message without the error notification, and the switch device can send a second signal in response to receiving the message at the second time.

Abstract: An optical assembly package is provided for the optical receive components of an optical transceiver. The optical assembly package includes a receptacle subassembly configured to receive an end of an optical fiber. A housing is provided having an opening at one end configured to receive the receptacle assembly. Optical routing and wavelength demultiplexing elements are mounted to a bottom wall of the housing. An electrical subassembly comprising a support plate, a circuit board mounted on the support plate, an integrated circuit mounted to the circuit board, and a plurality of photodetectors mounted to the support plate proximate an edge of the circuit board. The electrical subassembly is positioned a stacked arrangement beneath the housing to minimize an overall length of the optical assembly package.

Abstract: A transmitter of a binary data stream comprises: a serial/parallel converter to split the binary data stream into m different parallel bit streams, each bit stream having a rate D/m which is m times lower than the initial rate D; m first encoding modules to error-correcting encode each bit stream individually; a time-interleaver to intermix the information bits originating from different encoded bit streams; an encoder to error-correcting encode the m interleaved bit streams into p bit streams; p electro-optical modulators to modulate each of the p bit streams delivered by the interleaver by means of p optical carriers of different wavelengths; and a wavelength-division multiplexer to combine the less p optical carriers into a single optical signal.