Abstract: Described is a free space optical (FSO) node capable of communicating with a remote FSO node. The FSO node includes a Tx/Rx subassembly that is capable of simultaneously receiving and transmitting light carrying data, detecting the position/orientation of the received light signals, and aligning the Tx/Rx subassembly to account for misalignments with remote node. The Tx/Rx subassembly includes a central fiber for transmitting and receiving the optical signals so that the signal data can be processed. The Tx/Rx subassembly also includes a bundle of fibers that circumscribe the central fiber and receive a portion of received light signals to detect the position/orientation of the received light signals and align the FSO node with a remote FSO node.

Abstract: Aspects of the present disclosure describe systems, methods and structures in which a hybrid neural network combining a CNN and several ANNs are shown useful for predicting G-ONSR for Ps-256QAM raw data in deployed SSMF metro networks with 0.27 dB RMSE. As demonstrated, the CNN classifier is trained with 80.96% testing accuracy to identify channel shaping factor. Several ANN regression models are trained to estimate G-OSNR with 0.2 dB for channels with various constellation shaping.

Abstract: A method includes: generating indication information, where the indication information is used to indicate a resource allocation table corresponding to a first data unit in the plurality of data units; sending the indication information in a timeslot previous to a timeslot used to send the first data unit; and sending the plurality of data units, where a resource allocation table corresponding to each data unit is selected from a plurality of resource allocation tables in a cyclic manner, and a cyclically initial resource allocation table is the resource allocation table indicated by the indication information.

Abstract: Aspects described herein include an optical apparatus comprising at least a first Bragg grating of a first stage. The first Bragg grating is configured to transmit a first two wavelengths and to reflect a second two wavelengths of a received optical signal. The optical apparatus further comprises a second Bragg grating of a second stage. The second Bragg grating is configured to transmit one of the first two wavelengths and to reflect the other of the first two wavelengths. The optical apparatus further comprises a third Bragg grating of the second stage. The third Bragg grating is configured to transmit one of the second two wavelengths and to reflect the other of the second two wavelengths.

Abstract: A mobile device comprises a plurality of transmitters and receivers, each configured for optical wireless communication, wherein the plurality of transmitters and/or receivers are arranged on at least three surfaces of the mobile device such that each of the three surfaces has a respective at least one of the transmitters and/or each of the three surfaces has a respective at least one of the receivers.

Abstract: The present invention reduces the level of optical reflections created in a photonic integrated circuit (PIC) going back into an integrated laser through Reflection Engineering; optimizing the phase/timing and position of optical reflections inherent to a PIC design while adding engineered reflections to the PIC to allow inherent reflections to be reduced or eliminated. The Wavelength Division Multiplexed (WDM) geometric optical isolator of the present invention combines an array of closely spaced WDM lasers with an array of modulators in a novel geometry in order to provide effective optical isolation of the lasers.

Abstract: A signal-to-noise ratio (SNR) estimation method includes an optical signal transmission step of inserting at least one pair of signal sequences into transmission data and transmitting the transmission data into which the at least one pair of signal sequences is inserted, a signal sequence extraction step of extracting the at least one pair of signal sequences from a received signal obtained by receiving the transmitted transmission data, an inner product calculation step of calculating an inner product value of the extracted at least one pair of signal sequences, a reception power calculation step of calculating reception power of the extracted at least one pair of signal sequences, and an SNR calculation step of calculating an SNR of the at least one pair of signal sequences on the basis of the calculated inner product value and the calculated reception power.

Abstract: Systems and methods are provided for reducing interference when optical signals are added. One embodiment includes a method for adding an optical channel for communicating data and having a bandwidth within an optical spectrum for transmission along an optical link of an optical network. The method includes creating a lower frequency holding zone having a lower frequency bandwidth adjacent to the bandwidth of the added optical channel and including at least one lower frequency sub-slice having a power spectral density that varies throughout the lower frequency sub-slice. Also, the method includes creating a higher frequency holding zone having a higher frequency bandwidth adjacent to the bandwidth of the added optical channel and including at least one higher frequency sub-slice having a power spectral density that varies throughout the higher frequency sub-slice. The lower frequency holding zone and the higher frequency holding zone are dynamically configured with respect to fiber and channel requirements.

Abstract: Aspects of the present disclosure describe systems, methods and structures for optical fiber nonlinearity compensation using neural networks that advantageously employ machine learning (ML) algorithms for nonlinearity compensation (NLC) that advantageously provide a system-agnostic model independent of link parameters, and yet still achieve a similar or better performance at a lower complexity as compared with prior-art methods. Systems, methods, and structures according to aspects of the present disclosure include a data-driven model using the neural network (NN) to predict received signal nonlinearity without prior knowledge of the link parameters. Operationally, the NN is provided with intra-channel cross-phase modulation (IXPM) and intra-channel four-wave mixing (IFWM) triplets that advantageously provide a more direct pathway to underlying nonlinear interactions.

Abstract: In the examples provided herein, a system has a plurality of arrayed waveguide gratings (AWG) having a plurality of input ports and a plurality of output ports. A signal within a given wavelength channel transmitted to one of the input ports of a given AWG is routed to one of the output ports of the given AWG based on a signal wavelength. The system also has a plurality of nodes, with each node comprising a set of components for each AWG that the node is coupled to. Each set of components comprises a plurality of optical transmitters, where each optical transmitter is tunable over multiple wavelength channels within a different wavelength band; a band multiplexer to multiplex the multiple wavelength channels within each different wavelength band; and a first output fiber to couple an output of the band multiplexer to one of the input ports of a first AWG.

Abstract: A receiver is configured to calculate a representation of a received signal conveying symbols at a frequency fS, the representation comprising non-zero components at frequencies of magnitudes exceeding fS/2. The receiver calculates a first term comprising a function of a phase difference between the representation at a first pair of frequencies separated by a gap ? and comprised within a first band of width 2? centered at fS/2, and a second term comprising a function of a phase difference between the representation at a second pair of frequencies separated by the gap ? and comprised within a second band of width 2? centered at ?fS/2, wherein ?<2?, and wherein the higher frequency of the first pair and the higher frequency of the second pair are separated by the frequency fS. An estimate of chromatic dispersion in the received signal is calculated based on the first term and the second term.

Abstract: A transimpedance amplifier converts an input current to a differential signal and outputs the differential signal. The transimpedance amplifier includes a single-ended amplifier configured to convert a current signal to a voltage signal, a first feedback circuit configured to generate a bypass current, a differential amplifier circuit configured to generate the differential signal in accordance with the difference between the voltage signal and a reference voltage signal, and a detector circuit configured to detect a start and an end of a burst optical signal. The detector circuit detects the end of the burst optical signal based on a peak value of the positive-phase component and a peak value of the negative-phase component and switches the time constant of the first feedback circuit from a first time constant to a second time constant smaller than the first time constant in response to detecting the end of the burst optical signal.

Abstract: The receiving-side system (10) includes a smaller number of optical reception front ends (12) than the number of a plurality of wavelength-multiplexed subcarrier signals. Each of the optical reception front ends (12) is configured to receive two or a plurality subcarrier signals of the plurality of subcarrier signals. A frequency offset monitoring unit (22) monitors frequency offsets of the respective subcarrier signals received by the optical reception front end (12). A light source frequency control unit (24) controls at least one of a light source frequency of the transmitting-side system (2) and a light source frequency of the receiving-side system (10) based on a result of the monitoring performed by the frequency offset monitoring unit (22).

Abstract: A self-coherent optical data receiver configured to use direct detection of optical signals that is compatible with full (amplitude/phase) electric-field reconstruction. To enable the latter, the direct-detected optical signal includes CW light whose carrier frequency is spectrally aligned with a roll-off edge of the data-modulated portion of the signal. In an example embodiment, the receiver may employ two digital filters placed upstream and downstream, respectively, of the field-reconstruction circuit. The upstream filter is configurable to at least partially cancel the effects of SSBI caused by the direct detection. The downstream filter can be configured to perform electronic dispersion compensation and/or electronic polarization demultiplexing. In different embodiments, a filter controller may operate to adaptively change the filter coefficients of the upstream filter based on different signals generated within the digital receive chain.

Abstract: Methods and systems for provisioning different services on passive optical networks or forecasting service profiles for passive optical networks. The provisioning may be based on location, guaranteed bandwidth, or the like.

Abstract: Microwave photonic vector network analyzer and a method for measuring scattering parameters of a microwave device are provided. The analyzer comprises a microwave source, wherein a signal loading module, an optical sampling module and a signal processing module are sequentially arranged along a signal output direction of the microwave source; an output end of the signal processing module is respectively connected with a control end of the microwave source and a control end of the optical sampling module; and two test ports of the signal loading module are connected with both ends of a device to be tested. The invention realizes direct sampling and frequency conversion for microwave signals, abandons a superheterodyne structure and/or direct frequency conversion structure in the traditional network analyzer, simplifies the structure of the system while improving the measurement frequency range and avoiding image interference, and reduces system complexity, cost and power consumption.

Abstract: A data center network node (28) comprises one or more switch (18,19,22,23) configured to link an optical transceiver (16,17) to an optical connection comprising a multi-core optical fiber (30) having a plurality of cores (31). For each core (31), the one or more switch (18,19,22,23) is configurable between a first configuration in which an optical signal on a said core (31) of the multi-core optical fiber bypasses the optical transceiver and a second configuration in which the optical transceiver is optically linked to the said core (31) of the multi-core optical fiber (30).

Abstract: A reception device 20 is configured to include a separation means 21 and a plurality of optical reception means 22. Each optical reception means 22 is configured to further include an optical/electrical conversion means 23 and a band restoration means 24. The separation means 21 separates a multiplexed signal into which signals of respective channels to which spectral shaping that narrows bandwidth to less than or equal to a baud rate is applied are multiplexed at spacings less than or equal to the baud rate on the transmission side into optical signals for the respective channels. Each optical/electrical conversion means 23 converts an optical signal to an electrical signal as a reception signal. Each band restoration means 24 applies processing having inverse characteristics to those of the band narrowing filter processing to the reception signal and restores the band of the reception signal.

Abstract: A skew adjustment method and a digital coherent receiver which can achieve skew adjustment without using a fixed pattern for skew detection are provided. A digital coherent receiver (100) includes: a chromatic dispersion adder (103) that adds chromatic dispersion to the optical multiplexed signal; a skew adjuster (201) that sets a quantity of skew adjustment for each of the plurality of channel signals obtained by detecting the optical multiplexed signal; and a skew controller (204) that is configured to, while monitoring signal quality of a reception signal obtained from the plurality of channel signals skew-adjusted, search for a quantity of skew adjustment at which the signal quality is made better.

Abstract: A system has a plurality of non-linear circuit stages and an intervening linear circuit stage. An input signal is provided to a first non-linear circuit stage, and from the first non-linear circuit stage, to the linear circuit stage. The first non-linear circuit stage applies a second-order distortion to the input signal and provides the resulting signal to the linear circuit stage. The resulting signal that is output from the linear circuit stage is inverted with respect to the input signal and suitably linearly processed (attenuated or amplified). This signal is then provided to a second non-linear circuit that applies a second-order distortion and outputs a signal that has an overall reduction in second-order distortion.