Devices, methods for analog-to-digital converters (ADCs) that perform high-dynamic range measurements based on optical techniques are disclosed. In one example aspect, an optical encoder includes a polarization rotator configured to receive a train of optical pulses, and an electro-optic (EO) modulator coupled to an output of the polarization rotator. The EO modulator is configured to receive a radio frequency (RF) signal and to produce a phase modulated signal in accordance with the RF signal. The optical encoder also includes a polarizing beam splitter coupled to the output of the EO modulator; and an optical hybrid configured to receive two optical signals from the polarizing beam splitter and to produce four optical outputs that are each phase shifted with respect to one another.

In one embodiment, an apparatus comprises: a coherent optical receiver front-end circuit to receive an optical signal comprising information and further to receive a local oscillator optical signal, and output an orthogonal electrical signal based on the optical signal; a processing circuit coupled to the coherent optical receiver front-end circuit to receive the orthogonal electrical signal and process the orthogonal electrical signal to generate therefrom sum of squares information; and a non-coherent receiver coupled to the processing circuit to recover the information from the sum of squares information. Other embodiments are described and claimed.

A signal processing device combines a plurality of received signals, and includes: a phase reference signal selection means for selecting a signal serving as a phase reference from among the plurality of received signals on the basis of the quality of the plurality of received signals; a relative phase calculation means for obtaining information about the relative phases of the plurality of received signals before the combining; a phase compensation means for performing relative phase compensation on each of the plurality of received signals on the basis of the relative phases; and a phase correction means for calculating a phase correction amount based on the relative phase information and performing phase correction on the received signals, wherein when switching occurs in the selected phase reference signal, the phase correction amount is changed by as much as the relative phase difference between the phase reference signals before and after the switching.

A Wireless LAN (WLAN) Li-Fi transceiver includes a Wi-Fi device and an Analog Front-End (AFE). The Wi-Fi device is configured to produce a spatial stream carrying data, and to produce from the spatial stream In-phase and Quadrature (I/Q) signals for transmission over a radio channel having a predefined Radio Frequency (RF) band. The Analog Front-End (AFE) is configured to modify the I/Q signals, or modify operation of the Wi-Fi device, for producing a real Li-Fi signal in a predefined optical band, and to transmit the data carried by the spatial stream to a remote Li-Fi receiver by driving an optical emitter with the real Li-Fi signal.

A frame synchronization apparatus (10) according to this invention includes a multiplication unit (11) configured to multiply a received signal by an inverse complex number of a predetermined synchronization pattern with respect to a predetermined signal point on a complex space diagram for each of a plurality of symbols of the received signal, an addition average unit (12) configured to perform addition averaging of outputs from the multiplication unit for the plurality of symbols of the received signal, and a synchronization determination unit (13) configured to perform coincidence determination of whether an output from the addition average unit (12) falls within a predetermined coincidence determination range of the predetermined signal point, and determine a synchronization state of the frame synchronization based on a result of the coincidence determination. According to this invention, it is possible to provide a frame synchronization apparatus that correctly determines a synchronization state even if an error rate of received symbols is high.

In a coherent optical receiver device, the dynamic range considerably decreases in the case of selectively receiving the optical multiplexed signals by means of the wavelength of the local oscillator light, therefore, a coherent optical receiver device according to an exemplary aspect of the invention includes a coherent optical receiver receiving optical multiplexed signals in a lump in which signal light is multiplexed; a variable optical attenuator; a local oscillator connected to the coherent optical receiver; and a first controller controlling the variable optical attenuator by means of a first control signal based on an output signal of the coherent optical receiver; wherein the coherent optical receiver includes a 90-degree hybrid circuit, a photoelectric converter, and an impedance conversion amplifier, and selectively detects the signal light interfering with local oscillation light output by the local oscillator out of the optical multiplexed signals; and the variable optical attenuator is disposed in the optical path of the optical multiplexed signals in a stage preceding the photoelectric converter, inputs the optical multiplexed signals, and outputs them to the coherent optical receiver controlling the intensity of the optical multiplexed signals based on the first control signal.

In some embodiments, an apparatus includes a memory and a processor operatively coupled to the memory. The processor is configured to send a stimulus signal at a frequency that corresponds to a first frequency value to a tributary channel of a coherent optical transponder. The processor is configured to adjust an amplitude of the stimulus signal and receive a first plurality of output optical power values. The processor is configured to adjust the frequency of the stimulus signal and receive a second plurality of output optical power values. The processor is configured to determine a bandwidth limitation and a modulation nonlinearity, and then send a first signal to a first filter to reduce the bandwidth limitation and a second signal to a second filter to reduce the modulation nonlinearity.

A network or system in which a hub or primary node may communicate with a plurality of leaf or secondary nodes. The hub node may operate or have a capacity greater than that of the leaf nodes. Accordingly, relatively inexpensive leaf nodes may be deployed to receive data carrying optical signals from, and supply data carrying optical signals to, the hub node. One or more connections may couple each leaf node to the hub node, whereby each connection may include one or more spans or segments of optical fibers, optical amplifiers, optical splitters/combiners, and optical add/drop multiplexer, for example. Optical subcarriers may be transmitted over such connections, each carrying a data stream. The subcarriers may be generated by a combination of a laser and a modulator, such that multiple lasers and modulators are not required, and costs may be reduced. As the bandwidth or capacity requirements of the leaf nodes change, the number of subcarriers, and thus the amount of data provided to each node, may be changed accordingly. Each subcarrier within a dedicated group of subcarriers may carry OAM or control channel information to a corresponding leaf node, and such information may be used by the leaf node to configure the leaf node to have a desired bandwidth or capacity.

A network or system in which a hub or primary node may communicate with a plurality of leaf or secondary nodes. The hub node may operate or have a capacity greater than that of the leaf nodes. Accordingly, relatively inexpensive leaf nodes may be deployed to receive data carrying optical signals from, and supply data carrying optical signals to, the hub node. One or more connections may couple each leaf node to the hub node, whereby each connection may include one or more spans or segments of optical fibers, optical amplifiers, optical splitters/combiners, and optical add/drop multiplexer, for example. Optical subcarriers may be transmitted over such connections, each carrying a data stream. The subcarriers may be generated by a combination of a laser and a modulator, such that multiple lasers and modulators are not required, and costs may be reduced. As the bandwidth or capacity requirements of the leaf nodes change, the number of subcarriers, and thus the amount of data provided to each node, may be changed accordingly. Each subcarrier within a dedicated group of subcarriers may carry OAM or control channel information to a corresponding leaf node, and such information may be used by the leaf node to configure the leaf node to have a desired bandwidth or capacity.

An apparatus includes a first modulator configured to modulate a radio frequency (RF) input signal onto a first optical signal and a second modulator configured to modulate a local oscillator (LO) signal onto a second optical signal. The apparatus also includes a photonic integrated circuit having an optical demodulator configured to generate, using the modulated optical signals, I and Q signals representing a demodulated version of the RF input signal. The optical demodulator may include an optical filter bank having multiple optical filters, where different optical filters are configured to pass different frequencies or frequency ranges. The optical filters may include at least one narrowband optical filter and/or one or more tunable optical filters. The narrowband optical filter(s) may be configured to isolate global navigation satellite system-related signals. The tunable optical filter(s) may be configured to isolate signals over a frequency range of about 900 MHz to about 12 GHz.