Abstract: Photovoltaic devices with very high breakdown voltages are described herein. Typical commercial silicon photovoltaic devices have breakdown voltages below 50-100 volts (V). Even though such devices have bypass diodes to prevent photovoltaic cells from going into breakdown, the bypass diodes have high failure rates, leading to unreliable devices. A high-efficiency silicon photovoltaic cell is provided with very high breakdown voltages. By combining a device architecture with very low surface recombination and silicon wafers with high bulk resistivity (above 10 ohms centimeter (?-cm)), embodiments described herein achieve breakdown voltages close to 1000 V. These photovoltaic cells with high breakdown voltages improve the reliability of photovoltaic devices, while reducing their design complexity and cost.

Abstract: A method of entangling photons in a distributed quantum-based communication system is disclosed which includes generating sets of entangled photon pairs between a plurality of remote nodes (Nodes Ai and Nodes Bi) and a central entangling node (Node C), wherein Nodes Ai and Bi are in both quantum communication and classical communication with Node C, wherein one photon of a first entangled photon pair set is transmitted Node Ai and one photon of a second entangled photon pair set is transmitted to Node Bi, each over the associated quantum channels, and performing Bell-state measurements between the other photon of the first entangled photon pair and the other photon of the second entangled photon pair, such that if the photons arrive at about same time having about same frequency, then the photon pairs are marked as being entangled.

Abstract: A method of encoding quantum information on one or several degrees of freedom of coherent states of photons of a baseband input optical signal, a quantum transmitter, and a computer-readable medium. The quantum transmitter comprises a modulator configured to encode quantum information on one or several degrees of freedom of coherent states of photons of a baseband input optical signal using sideband modulation of the baseband optical input signal.

Abstract: Systems and methods are described for transmitting information optically in free space. For instance, a system may include an optical signal generator to generate an amplified beam of light. A telescope transmits the amplified beam through the medium and receives an inbound beam of light. A detector system may include one or more (or multiple) detectors and a routing system that transmits the inbound beam to a selected set of detectors. In some cases, the system can determine a re-configuration condition based on control parameters and perform a system re-configuration to direct the inbound beam to a different set of detectors. In some cases, the system includes a remote fiber head or wavelength division multiplexing.

Abstract: The quantum communication system conveys information by exploiting quantum properties of photon streams. A photon source producing a pair of spatially separated and polarization-entangled photon streams is used. The pair collectively exist in a quantum superposition state by virtue of their mutual entanglement. An encoder establishes a modulation control signal corresponding to the information to be conveyed. An optical quantum circuit is placed in the path of one of the pair of streams, so that the first stream passes through it. The optical quantum circuit alters the quantum polarization state of the photon passing through it based on the control signal. In this way information is encoded into quantum probability distributions of the superposition state through quantum parallelism and quantum interference, whereby information is conveyed in the photon streams.

Abstract: A system includes N-distant independent plasmonic graphene waveguides. The N-distant independent plasmonic graphene waveguides are used to generate an N-partite continuous variable entangled state.

Abstract: To provide an optical communication device including a transmitting optical output unit for transmitting information by optical communication, a receiving optical sensor for receiving information by optical communication, an optical switch that is connected to the transmitting optical output unit and the receiving optical sensor via an optical splitter, a plurality of head parts that are connected to the optical switch, and a control unit for performing control so as to transmit information by emitting a laser from each of the plurality of head parts by switching and guiding a light output by the transmitting optical output unit to the plurality of head parts with the optical switch, and receive information by switching a light received by the plurality of head parts with the optical switch and guiding the light to the receiving optical sensor.

Abstract: A system for superadditivity for remote sensing and communication includes coupling optics to direct several input pulses received over a communication channel to an interaction medium. A probe beam entering the interaction medium at an angle performs state preparation and manipulation. A detector reads the output light of the interaction medium. Orthogonality states of symbols represented by the plurality of input pulses are affected by the communication channel, and the interaction medium provides the output light via local entanglement of the plurality of input pulses and the probe beam.

Abstract: A free-space optical communication system includes a transmitter and a receiver, the transmitter being configured to transmit an encrypted message to the receiver at the mid-infrared domain, the transmitter comprising a master mid-infrared optical source configured to generate a mid-infrared signal and a chaos generator configured to generate a chaotic signal by applying external optical feedback to the master mid-infrared optical source, the transmitter being configured to determine an encrypted message from an original message by applying a message encryption technique to the original message and to send the encrypted message to the receiver through an optical isolator, the receiver comprising a slave mid-infrared optical source similar to the master mid-infrared optical source the slave mid-infrared optical source being configured to recover the chaotic signal from the encrypted message by applying chaos synchronization, the receiver further comprising a first detector configured to detect the encrypted me

Abstract: Disclosed herein is a pulse repetition rate multiplier including a photonic integrated circuit (PIC) including cascading Mach-Zehnder interferometers (MZIs). An input may be connected to one end of the PIC and an output may be connected to the other end of the PIC such that a signal from the input runs through the cascading MZIs and out the output. The input may be configured to receive an input pulsed signal and the output may be configured to output a repetition rate multiplied signal. Advantageously, using a PIC as opposed to an optical fiber-based pulse rate multiplier allows for accurate fabrication of a pulse repetition rate multiplier configured to accept higher frequency pulsed signals.

Abstract: Quantum information system with metadata management includes an entangled quantum state source that generates quantum information in quantum form comprising two entangled states. A metadata collector generates metadata in classical form associated with the generated quantum information. A first receiver measures one of the two entangled states to generate quantum state information in classical form comprising a first state value and first TOA. A second receiver is configured to measure the other entangled states to generate quantum state information in classical form comprising a second state value and second TOA. A first processor generates a comb using the first TOA and the metadata to tag the generated quantum state information in classical form comprising the first state value. A second processor coupled to the first processor and to the second receiver is configured to process the comb and metadata to determine correlated data associated with the two entangled states.

Abstract: An apparatus includes a plurality of processing layers coupled in series. Each processing layer in the plurality of processing layers includes a Gaussian unit configured to perform a linear transformation on an input signal including a plurality of optical modes. The Gaussian unit includes a network of interconnected beamsplitters and phase shifters and a plurality of squeezers operatively coupled to the network of interconnected beamsplitters and phase shifters. Each processing layer also includes a plurality of nonlinear gates operatively coupled to the Gaussian unit and configured to perform a nonlinear transformation on the plurality of optical modes. The apparatus also includes a controller operatively coupled to the plurality of processing layers and configured to control a setting of the plurality of processing layers.

Abstract: In an HDMI (High Definition Multimedia Interface) video signal transmission system in which a fiber optic cable connects the HDMI transmitter and receiver, the HDMI receiver supplies a DC power to the receiver-side connector of the fiber optic cable on a designated pin of the HDMI interface, such as pin 14 of the Type A interface. The DC power does not affect the AC signal (e.g. ARC) transmitted on this pin under the HDMI specification. The receiver-side connector uses this power to power its internal components such as optical transceiver and signal processing chips. This eliminates the need to supply power to the receiver-side connector via a separate USB cable. One example of the HDMI receiver is a video matrix switch, which acts as a receiver for devices plugged into its input HDMI ports. A fiber optic cable incorporating Bluetooth wireless chips in its two connectors is also disclosed.

Abstract: A system and method for safe use of an optics assembly with an external light source and an optically coupled optics module is disclosed. The system includes an external light module emitting a continuous wave laser through an output port. An optics module has an input port and a memory. The optics module generates a modulated optical signal. The memory stores the power level of the continuous wave laser signal received by the optics module. An optical jumper is provided for coupling the output port with the input port. A communication bus is coupled between a controller and the external light source module. The controller sets the external light source at a low power level and transitions the external light source to a high power level when the stored power level of the continuous wave laser signal received by the optics module exceeds a predetermined level.

Abstract: Improving the signal to noise ratio in an optical link involves either reducing the noise or increasing the RF power coupled into the optical link by lowing the voltage, V?, required to induce a phase change of ? of the optical beam passing through the optical modulator. The present disclosure relates to methods and architectures for increasing the optical power through a link through providing one or more laser sources, additional modulators or photodiode receivers and dividing the optical power through these components so that none are overloaded.

Abstract: A multi-wavelength light source includes a laser, an optical modulator, an optical mixer, an optical demultiplexer, and an optical power adjuster that are sequentially coupled. The laser is configured to generate a first optical signal. The optical modulator modulates the first optical signal, to generate a second optical signal, where the second optical signal includes at least two wavelength components. The optical mixer mixes frequencies based on the at least two wavelength components to generate a third optical signal, where the third optical signal includes at least four wavelength components. The demultiplexer separates the at least four wavelength components. The optical power adjuster adjusts, based on a specified power threshold, a power of each of the wavelength components obtained by separation by the demultiplexer.

Abstract: Quantum satellite-based global networks are provided. A system as provided herein includes a processor and a memory that stores first executable instructions that, when executed by the processor, facilitate performance of operations, the operations comprising receiving qubits from a quantum sensor device via a quantum communication channel established between the system and the quantum sensor device; providing quantum input data, derived from the qubits, to a quantum machine learning model; and adjusting a property of a communication network based on an output of the quantum machine learning model, produced in response to the providing of the quantum input data, resulting in an increased performance of a mobile application utilizing resources enabled via the communication network.

Abstract: An optical line terminal (OLT) operating within a multi-rate PON is configured to perform downstream timeslot scheduling among an associated number of ONUs so as to minimize the change in information rate from one scheduled ONU timeslot to the next. In this manner, the clock recovery component at each ONU is best able to follow the change in information rates, remaining locked on the system clock regardless of the specific implementation of the clock and data recovery (CDR) functionality at a given ONU. The OLT may schedule timeslot assignments that span a pair of adjacent parts (referred to as a two-part cycle), with the first part having timeslots assigned from the lowest information rate (e.g., NRZ) to the highest (e.g., PAM4) and the second part's timeslots assigned in the reverse order; that is, from the highest to the lowest information rate.

Abstract: Systems and methods include detecting a fast fiber transient on a span based on analyzing power data, wherein the power data is for any of optical wavelengths of traffic channels, optical service channel (OSC) wavelengths, and telemetry from a network element; and responsive to detecting the fast fiber transient, causing an optical time domain reflectometer (OTDR) trace on the span with a specific configuration based on the fast fiber transient.

Abstract: A system and method for transmitting data ultrasonically through biological tissue employs a network of a plurality of nodes, at least a portion of the nodes implantable within the biological tissue. At least one implanted node includes a transmitter having an orthogonal frequency division multiplex signal generator to encode an ultrasonic signal for transmission through the biological tissue to an ultrasonic receiver at another node.

Abstract: A mobile system (1,11) comprises a camera (3) and at least one processor (5). The at least one processor is configured to capture an image with the camera, e.g. of a light beacon (15), to determine whether a certain object is recognized in the captured image, e.g. by querying a database (19), and to start detecting and/or decoding data being communicated via visible light in dependence on the certain object being recognized.

Abstract: Quantum mechanics provides several features useful for datacenter networking. The no cloning theorem, which states that it is impossible to mate a duplicate of an arbitrary, unknown quantum state, can be used to detect eavesdroppers. Entanglement allows two parties to have common knowledge of a shared state. These properties are being used today for quantum key exchange and quantum computing, but they are currently too expensive for general use. Fortunately, we can use classical mechanisms to get a close enough approximation of these quantum properties to solve some important problems in distributed computing. Nothing we describe here is quantum mechanical. Rather, we show that it is possible to use classical mechanisms to emulate some properties of quantum mechanics, which enable us to address interesting problems in distributed computing. The engineering insight, is that we can get closer to achieving these properties than might be expected through conventional thinking.

Abstract: An optical Digital Signal Processor (DSP) circuit includes a digital core configured to implement digital signal processing functionality and configured to operate at a plurality of baud rates including a full baud rate and a half-baud rate; and an analog interface including a Digital-to-Analog Converter (DAC) section and an Analog-to-Digital Converter (ADC) section, wherein the analog interface is connected to the digital core and is configured to operate at the full baud rate when the digital core is configured to operate at any of the plurality of baud rates.

Abstract: The disclosure describes aspects of using multiple species in trapped-ion nodes for quantum networking. In an aspect, a quantum networking node is described that includes multiple memory qubits, each memory qubit being based on a 171Yb+ atomic ion, and one or more communication qubits, each communication qubit being based on a 138Ba+ atomic ion. The memory and communication qubits are part of a lattice in an atomic ion trap. In another aspect, a quantum computing system having a modular optical architecture is described that includes multiple quantum networking nodes, each quantum networking node including multiple memory qubits (e.g., based on a 171Yb+ atomic ion) and one or more communication qubits (e.g., based on a 138Ba+ atomic ion). The memory and communication qubits are part of a lattice in an atomic ion trap. The system further includes a photonic entangler coupled to each of the multiple quantum networking nodes.

Abstract: A system and method for radio frequency (RF) signal processing via photonic local oscillator (LO) phase control generates a set of N optical carriers and M sets of control inputs, each control input including an amplitude and/or phase control for the nth carrier. Each nth optical carrier is split into an RF path and M LO paths, the RF path including N electro-optical (EO) modulators for amplitude/phase modulation of each nth carrier per a set of N RF input signals and each mth LO path including a set of N EO modulators for amplitude/phase modulation of each nth carrier per the mth control input. Demodulators generate M in-phase and quadrature (I/Q) balanced optical outputs based on the multiplexed N combined RF optical outputs and each mth set of N combined LO optical outputs. The M I/Q balanced optical outputs are converted to the electrical and then to the digital domain.

Abstract: An asymmetric bidirectional optical wireless communication system based on orbital angular momentum comprises a system end device and a client end device. The system can split light into P-polarization beam and S-polarization beam, and utilize the orbital angular momentum multiplexing technology to increase the system capacity for uplink transmission in the client end device. In addition, the system also uses the combination of a beam homogenizer and a spatial light modulator to design an orbital angular momentum multiplexer with low energy loss, which can increase the number of orbital angular momentum channels by increasing the effective area of the components.

Abstract: A computer-implemented event statistic generation method for intrusion detection comprises processing a plurality of return signals from a coherent optical time domain reflectometer into time domain signals for each of a plurality of sensor bins, the plurality of return signals corresponding to a plurality of stimulation pulses injected into an optical sensor fiber during a time period.

Abstract: A digital receiver is configured to process a polarization multiplexed carrier from a communication network. The polarization multiplexed carrier includes a first polarization and a second polarization. The receiver includes a first lane for transporting a first input signal of the first polarization, a second lane for transporting a second input signal of the second polarization, a dynamic phase noise estimation unit disposed within the first lane and configured to determine a phase noise estimate of the first input signal, a first carrier phase recovery portion configured to remove carrier phase noise from the first polarization based on a combination of the first input signal and a function of the determined phase noise estimate, and a second carrier phase recovery portion configured to remove carrier phase noise from the second polarization based on a combination of the second input signal and the function of the determined phase noise estimate.

Abstract: Systems and methods for operating a communication device. The methods comprise: receiving a carrier signal modulated with a modulation signal comprising a symbol conveyed in a symbol timing window; determining an energy value for each timeslot in the symbol timing window; combining the energy values to determine a combined energy value for each bit of the symbol in a manner in which the combined energy value is penalized if more than one timeslot of the symbol timing window comprises energy contained in the carrier signal; and generating a soft value for each bit of the sequence of bits by combining the combined energy value with a weight value, where the weight value is selected from a plurality of weight values based on a number of timeslots in the symbol timing window which comprises energy contained in the carrier signal.

Abstract: An apparatus includes a plurality of processing layers coupled in series. Each processing layer in the plurality of processing layers includes a Gaussian unit configured to perform a linear transformation on an input signal including a plurality of optical modes. The Gaussian unit includes a network of interconnected beamsplitters and phase shifters and a plurality of squeezers operatively coupled to the network of interconnected beamsplitters and phase shifters. Each processing layer also includes a plurality of nonlinear gates operatively coupled to the Gaussian unit and configured to perform a nonlinear transformation on the plurality of optical modes. The apparatus also includes a controller operatively coupled to the plurality of processing layers and configured to control a setting of the plurality of processing layers.

Abstract: A LIDAR device for scanning a scanning angle using at least one beam includes at least one beam source generating the at least one beam, a rotatable deflection unit deflecting the at least one beam, and a detector receiving the at least one beam after reflection on an object, where at least two cylindrical lenses are situated in a beam path of the at least one beam between the beam source and the deflection unit, at least one cylindrical lens is rotatable.

Abstract: A multi-level semiconductor device, the device including: a first level including integrated circuits; a second level including a structure designed to conduct electromagnetic waves, where the second level is disposed above the first level, where the first level includes crystalline silicon; and an oxide layer disposed between the first level and the second level, where the second level is bonded to the oxide layer, and where the bonded includes oxide to oxide bonds.

Abstract: A satellite receiver includes: N reception antenna elements; N demultiplexing units; a correlation detection unit configured to perform correlation processing on each of reception signals demultiplexed by the N demultiplexing units with a reception antenna element that receives the highest power being set as a reference element so as to calculate a relative phase difference, and calculate an excitation coefficient for cancelling a phase difference between the N reception antenna elements for each of sub-channels based on the calculated relative phase difference; N phase compensation units configured to multiply the reception signals demultiplexed by the N demultiplexing units, respectively, by the excitation coefficient for each of the sub-channels; and a combiner configured to combine multiplication results from the N phase compensation units for each of the sub-channels to generate output signals.

Abstract: A computer-implemented event statistic generation for intrusion detection comprises processing a plurality of return signals from a coherent optical time-domain reflectometer into time-domain signals for each of a plurality of sensor bins, the plurality of return signals corresponding to a plurality of stimulation pulses injected into an optical sensor fiber during a time period. For each sensor bin, transforming the respective time-domain signal into a corresponding frequency-domain signal, calculating, from the respective frequency-domain signal, a first signal power area of a first frequency band expected to contain system noise and a second signal power area of a second frequency band expected to contain any energy related to at least a first event; and generating an event statistic proportional to the ratio of the second signal power area to the first signal power area at least in part by dividing the second signal power area by the first signal power area.

Abstract: The disclosure describes aspects of using multiple species in trapped-ion nodes for quantum networking. In an aspect, a quantum networking node is described that includes multiple memory qubits, each memory qubit being based on a 171Yb+ atomic ion, and one or more communication qubits, each communication qubit being based on a 138Ba+ atomic ion. The memory and communication qubits are part of a lattice in an atomic ion trap. In another aspect, a quantum computing system having a modular optical architecture is described that includes multiple quantum networking nodes, each quantum networking node including multiple memory qubits (e.g., based on a 171Yb+ atomic ion) and one or more communication qubits (e.g., based on a 138Ba+ atomic ion). The memory and communication qubits are part of a lattice in an atomic ion trap. The system further includes a photonic entangler coupled to each of the multiple quantum networking nodes.

Abstract: Embodiments of the present disclosure are directed toward a universal serial bus (USB) device and a USB host controller. The USB device and USB host controller may be configured to couple to one another via a USB link that may include a high-speed data line and a low-speed data line. The USB device may then transmit, via the high-speed data line, an indication of a digital image to the USB host controller. Other embodiments may be described and/or claimed.

Abstract: 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.

Abstract: A device including an optoelectric circuit that is configured to provide galvanic isolation between a first circuit and a second circuit is disclosed. The optoelectric circuit includes at least one non-inverting buffer and a metal semiconductor diode. The at least one non-inverting buffer is positioned between a collector of a phototransistor and an anode of a light emitting diode. The metal semiconductor diode is positioned between the collector of the phototransistor and the at least one non-inverting buffer.

Abstract: [Problem] To accommodate single-band signal processing devices in a high-density manner. [Solution] Provided is a system including: a first signal cable; a second signal cable; a third signal cable; a fourth signal cable; a first multi-band signal processing device that processes a first signal input from the first signal cable and outputs a resultant second signal to the second signal cable; a second multi-band signal processing device that processes a third signal input from the third signal cable and outputs a resultant fourth signal to the fourth signal cable; a first joint box that accommodates the first signal cable, the first multi-band signal processing device, the second signal cable, and the fourth signal cable; and a second joint box that accommodates the second signal cable, the third signal cable, the second multi-band signal processing device, and the fourth signal cable.

Abstract: A method includes sending a probe beam into a beam path that induces a lateral displacement to the probe beam. The probe beam includes a plurality of orthogonal spatial modes that are entangled with each other. The method also includes measuring a phase of each spatial mode from the plurality of orthogonal spatial modes in the probe beam at a detector disposed within a near field propagation regime of the probe beam. The method also includes estimating the lateral displacement of the probe beam based on a phase of each spatial mode from the plurality of spatial modes in the probe beam after the beam path.

Abstract: A faceplate pluggable remote laser source and system incorporating such a laser source. The system may include an enclosure having a faceplate; a first optical connector, in the faceplate; a laser module; and a loopback fiber cable, connected between the laser module and the first optical connector. The faceplate may form an exterior boundary of the enclosure. The laser module may have a first end including an electrical interface, and a second end including an optical interface. The first end of the laser module may be engaged in a receptacle in the faceplate, and the second end of the laser module may extend outside the faceplate. The laser module may be configured to receive electrical power through the electrical interface, and to produce unmodulated light at the optical interface. The loopback fiber cable and the first optical connector may be configured to route the unmodulated light back into the enclosure.

Abstract: An apparatus for calibrating a differential circuit that includes a differential integrator having an input, a gain, and an output connected to a comparator. The differential integrator output is chargeable to a threshold prior to an integration period. The differential integrator integrates the input during the integration period such that the differential integrator output goes toward zero from the threshold. The comparator detects the output of the differential integrator reaching zero. The apparatus includes a closed-loop gain trim circuit to perform a coarse calibration to adjust and set the gain of the differential integrator and a reference generator that generates the threshold to which the differential integrator output is pre-charged. The reference generator is trimmable during a fine calibration to adjust and set the threshold to correct for residual gain error in the differential circuit remaining after the coarse calibration is performed.

Abstract: A digital receiver is configured to process a polarization multiplexed carrier from a communication network. The polarization multiplexed carrier includes a first polarization and a second polarization. The receiver includes a first lane for transporting a first input signal of the first polarization, a second lane for transporting a second input signal of the second polarization, a dynamic phase noise estimation unit disposed within the first lane and configured to determine a phase noise estimate of the first input signal, a first carrier phase recovery portion configured to remove carrier phase noise from the first polarization based on a combination of the first input signal and a function of the determined phase noise estimate, and a second carrier phase recovery portion configured to remove carrier phase noise from the second polarization based on a combination of the second input signal and the function of the determined phase noise estimate.

Abstract: In an optical communications network, the supervisory control signal is duplicating at the OSI layer 2 or layer 3 level to generate a primary supervisory control signal and a secondary supervisory control signal. Access to the primary supervisory control signal is enabled at a network interface of a network device. In response to detecting a failure of the optical communications network or the device, access to the primary supervisory control signal is disabled and access to the secondary supervisory control signal is enabled.

Abstract: Photonic processors are described. The photonic processors described herein are configured to perform matrix-matrix (e.g., matrix-vector) multiplication. Some embodiments relate to photonic processors arranged according to a dual-rail architecture, in which numeric values are encoded in the difference between a pair optical signals (e.g., in the difference between the powers of the optical signals). Relative to other architectures, these photonic processors exhibit increased immunity to noise. Some embodiments relate to photonic processors including modulatable detector-based multipliers. Modulatable detectors are detectors designed so that the photocurrent can be modulated according to an electrical control signal. Photonic processors designed using modulatable detector-based multipliers are significantly more compact than other types of photonic processors.

Abstract: 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.

Abstract: An apparatus is described which uses directly modulated InGaN Light-Emitting Diodes (LEDs) or InGaN lasers as the transmitters for an underwater data-communication device. The receiver uses automatic gain control to facilitate performance of the apparatus over a wide-range of distances and water turbidities.

Abstract: To optimize the efficiency and reliability of downhole data transmissions, an optical splash communication system may be utilized. A downhole tool may include an optical splash communication system that comprises multiple electrical elements where the electrical elements communicate with each other by transmitting and receiving via free space an optical splash signal through an inner space of the downhole tool. The electrical elements may comprise or be coupled to a light source and a detector. Multiple optical splash communication systems may be deployed in multiple downhole tools such that each downhole tool may communicate with another downhole tool via an opening, for example, a transparent sealed window, between the downhole tools. The opening is sufficient to permit transmissions to occur even when the downhole tools are rotated independently of each other.

Abstract: A method of processing a visible light communication (VLC) signal using a single-photon avalanche diode (SPAD) includes detecting photons of a VLC signal at a SPAD detector, counting the photons detected by the SPAD detector to generate a combined VLC signal comprising a data signal and an ambient signal, extracting the ambient signal from the combined VLC signal, subtracting the ambient signal from the combined VLC signal to generate the data signal, and outputting the data signal as a bitstream.

Abstract: Modulated entangled photon pairs are used to transmit data between a sender and receiver subsystem. The sender subsystem comprises at least one data input, a modulator to modulate the photons, a photon combiner and a transmitter coupler to direct the modulated entangled photon pairs towards a receiver. The receiver subsystem comprises a receiver coupler, a photon de-combiner to direct the photons to polarization analyzers to transmit photons of a specified polarization to detectors, and a processor to record the information transmitted by the detectors. The sender subsystem transmits information to the receiver subsystem through the modulation of the entangled photon state. The present system and method is quantum which provides advantages over classical and optical communications. These advantages include using less power to transmit information, and allowing transmission through and around obstructions and adverse environments.