Abstract: It is an object of the present invention to provide an FSK demodulator which can be used in the optical information and telecommunications and the like, and which can appropriately demodulate an FSK signal by compensating a delay of an optical FSK modulated signal due to dispersion and the like of an optical fiber. The above-mentioned problem is solved by a frequency shift keying (FSK) demodulator (1) composed of a branching filter (2) for branching an optical signal according to wavelengths thereof; a delay adjusting apparatus (3) for adjusting a delay time of two lights branched by the branching filter; a first photodetector (4) for detecting one optical signal branched by the branching filter; a second photodetector (5) for detecting a remaining optical signal branched by the branching filter; and a means (6) for calculating a difference between an output signal of the first photodetector and an output signal of the second photodetector.

Abstract: An apparatus includes an oscillator circuit configured to generate a certain oscillation signal, an adder configured to add the oscillation signal to the tap coefficient of any of one or more taps of the transversal filter, a signal-quality measurer configured to measure a signal quality of a signal output from the transversal filter, and a tap-coefficient adjuster configured to control the value of the tap coefficient so that an optimal amount of shift in the signal quality of the output signal is achieved when the oscillation signal is added to the tap coefficient.

Abstract: In a quantum cryptography communication apparatus, a light pulse is generated by a light source and split into a signal light pulse and a reference light pulse on a receiving side. The signal light pulse and the reference light pulse are transmitted to a sending side via a communication channel. On the sending side, the received reference light is passed through a first optical path and phase-modulated by a randomly selected amount. Communication information is acquired on the basis of the reference light passed through the first optical path and the signal light passed via a second optical path. Frequencies of the signal light pulse and the reference light pulse are shifted. The intensity of the signal light pulses is attenuated and phase-modulated by an amount corresponding to the communication information. The resultant signal light pulse and the reference light pulse are returned back to the receiving side.

Abstract: An optical interconnect device includes a first substrate, a second substrate, an optical waveguide, an electrical wiring and a switching device. The first substrate has an electrical wiring circuit, an electrical-optical converter for converting an electrical signal to an optical signal, and a light emitting device for emitting a light. The second substrate has an electrical wiring circuit, an optical-electrical converter for converting the optical signal to the electrical signal, and a light receiving device for receiving the light from the light emitted device. The optical waveguide optically connects the light emitting and light receiving devices. The electrical wiring electrically connects the electrical wiring circuits of the first and second substrates. The switching device determines a fast signal of data to be transmitted via the optical substrate and a slow signal of data to be transmitted via the electrical wiring.

Abstract: A computer including: a casing, at least a portion of which contains a potting material acting as an optical waveguide material; a transmitter for transmitting a pulse based signal at least partially through the potting material acting as the optical waveguide material; and a receiver for receiving the pulse based signal after one or more reflections of the pulse based signal from interior surfaces of the casing; the pulse based signal having a pulse rate configured such that a subsequent pulse doesn't interfere with reflections from an immediately previous pulse.

Abstract: This disclosure is directed to optical data path systems that enable unidirectional and bidirectional transmission of optical signals between nodes of a multi-node system such as a multiprocessor system. In one aspect, an optical data path system includes an optical device layer connected to nodes of a multi-node system and a controller. The optical device layer includes a waveguide network of waveguide branches optically connecting each node of the multi-node system to every other node of the multi-node system, resonators disposed adjacent to the waveguide branches, and detectors disposed adjacent to waveguide branches of the waveguide network. Each detector is electronically connected to a node of the multi-node system. The resonators are operated by the controller to control the path of optical signals sent between the nodes of the multi-node system.

Abstract: A high peak intensity laser amplification system and the method therein implemented are provided. In a first aspect of the invention, the laser system includes at least one optical member (27) operably introducing a phase function into a high peak intensity laser pulse (25). A further aspect includes introducing destructive interference in an unchirped laser pulse prior to amplification and reconstructive interference in the output laser pulse after amplification. Dynamic pulse shaping is employed in another aspect of the present invention.

Abstract: Optical amplification by combining two or more optical signals from separate optical fibers, amplifying the combined signal using an optical fiber, and separating the amplified signals into their constituent optical signals. The separated optical signals may then be sent further in the direction they had been heading before combination. This allows multiple optical signals to be amplified using a single optical amplifier, perhaps even in a single optical fiber. Although not required, the two optical signals may even be travelling in different directions.

Abstract: For readjusting a polarization drift in the transmission of a polarization-encoded optical signal from a transmitter via a light guide to a receiver, optical auxiliary signals having the same wavelength as the polarization-encoded signal as well as different polarizations as in correspondence with a first base and a second base are fed into the light guide on the side of the transmitter while the transmission of the polarization-encoded signal is interrupted, and the optical auxiliary signals are picked up from the light guide and checked for shifts of the different polarizations by a polariometer on the side of the receiver, whereupon, in the event of the detection of polarization shifts, the different polarizations shifted during the transmission are displaced in the sense of the polarization set values via a polarization controller associated with the light guide.

Abstract: A method for amplifying a burst optical signal, a burst optical amplifier and system, and a communications system are provided according to embodiments of the present invention. The method includes: combining an auxiliary light and a signal light into a mixed light and outputting the mixed light, where the auxiliary light is a non-burst light, the signal light is a burst light, and power of the auxiliary light is set to be independent from power of the signal light; generating a pump light; and combining the pump light with the mixed light and inputting the combined light into a gain medium, so as to obtain an amplified mixed light. Present invention has the following advantages: reducing the delay time of enabling the burst optical amplifier, improving the transient response speed of the burst optical amplifier, and preventing the generation of a surge phenomenon, so as to prevent the generation of signal distortion.

Abstract: A transceiver assembly is provided for use in an optical telecommunications network. The circuitry arrangement in the transceiver of the present invention generates a ranging signal that is transmitted along the fibers attached thereto and then filters the return signal in an manner that eliminates virtually all of the noise effects found on the fiber to provide a highly reliable timing signal for an accurate delay calculation. A band pass filter is supplied in line before the input signal is allowed to pass to the ranging signal detector and comparator thereby allowing only a signal at the fundamental frequency of the input signal to pass, thereby eliminating false signal detect triggers.

Abstract: Signals can be superimposed on optical phase even when low-coherency light is used, and a bit rate and a signal coding format similar to those used in ordinary optical communications can be used. A transmitter includes an asymmetric interferometer or an antisqueezed light generator to convert a train of single pulses into a train of dual pulses. A receiver also includes an asymmetric interferometer that provides the same delay time as that between the dual pulses. The receiver allows pulses originating in the same light source to interfere, so that signals can be superimposed on the phase even when a low-coherency light source is used. The delay time (optical path length difference) provided in the asymmetric interferometer is set to be longer than half the period of the pulses outputted from the optical pulse source.

Abstract: An optical bench communicates light through free space in a plurality of trenches formed in the bench, each of the trenches formed by deep ion reactive etching and defined by two opposing side walls, such that the free space is between the opposing side walls. An exemplary embodiment has a first trench operable to receive the beam of light and operable to communicate the beam of light through the free space in the first trench; an angled reflection side wall operable to receive the beam of light routed through the first trench and operable to reflect at least a portion of the beam of light; and a second trench operable to receive the portion of the beam of light reflected from the angled reflection side wall and operable to route the portion of the beam of light through the free space in the second trench.

Abstract: In one example embodiment, an optoelectronic communications assembly having an optical receiver or an optical transmitter includes an optical interface disposed at an end thereof and through which optical signals are communicated by the optical receiver or optical transmitter. The optoelectronic communications assembly also includes an electronic component and a first electrical interface disposed at the optical interface end of the optical communications assembly and communicatively coupled to the electronic component.

Abstract: An optical power divider includes a body having a first side and a second side. The first side includes at least one cylindrical input lens and the second side includes an array of output lenses. The at least one cylindrical input lens is configured to expand input light along a first axis to be directed to a plurality of the output lenses arranged along the first axis and the output lenses are configured to focus the light received from the input lenses into respective output beams of light.

Abstract: In an optical transmission module having a communication module which is freely movable in a case, when a tensile force is generated on an optical cable after connection of an optical transmission module, optical coupling surface and an optical axis center follow each other and thus stable optical transmission can be constantly performed.

Abstract: Disclosed is a secure/non-secure bypass switch, which includes a secure mode signal path, and a non-secure mode signal path, wherein signals are routed through an encryption device connected in the secure mode signal path when no power is supplied to the switch, and the signals are routed through the non-secure path when power is supplied to the switch.

Abstract: Provided is an optical interconnection system that transmits and receives a three-level signal. The optical interconnection system includes a first and a second optical interconnection device that transmits and receives a two-level signal, and a synthesizer that outputs a three-level signal by synthesizing signals from the first and second optical interconnection devices. The optical interconnection system may transmit and receive a three-level signal while using an optical interconnection device that interconnects a two-level signal.

Abstract: A method is provided for co-site interference mitigation in an RF communication system. Spectral nulls created in an optical domain may be used to mitigate interfering signals in an RF signal. The method includes: receiving an RF input signal via an antenna; generating two optical signals that are each modulated using the RF signal; creating a phase delay in one of the two optical signals that corresponds with a spectral null at a frequency of an interfering signal; converting the two optical signals into two corresponding electrical signals and combining the two electrical signals to create spectral nulls via interference between the two signals and form a mitigated output signal. In this way, the spectral null offsets the amplitude of the interfering signal, thereby reducing the signal strength of the interfering signal.

Abstract: A complementary optical wiring apparatus includes an optical transmitter, first and second optical transmission lines, and an optical receiver, the optical transmitter has a first operation mode of transmitting an optical signal synchronized with the rising of one electrical input signal via the first optical transmission line and transmitting an optical signal synchronized with the falling thereof via the second optical transmission line, and a second operation mode of transmitting an optical signal synchronized with the rising and falling of one of two electrical input signals via the first optical transmission line and transmitting an optical signal synchronized with the rising and falling of the other electrical input signal via the second optical transmission line, and is operated after one of the two operation modes is selected.

Abstract: An apparatus comprises one or more electro-optical coupling modules. An electro-optical coupling module comprises a diode, a flexible optical coupling element, a reflective surface, and an optical fiber. The diode performs an electro-optical conversion on a signal. The flexible optical coupling element communicates the signal between the diode and the reflective surface. The reflective surface reflects the signal between the flexible optical coupling element and the optical fiber.

Abstract: A bidirectional optoelectronic device comprises a photodetector and a light source on a waveguide substrate, and a drive circuit for the light source. The waveguide substrate can include light collector(s) or trap(s) for redirecting and attenuating portions of optical signals propagating in waveguide layers on the substrate but not guided by a waveguide. A protective encapsulant can be applied that includes hollow dielectric microspheres to reduce electrical cross-talk, and that can further include an optical absorber to reduce optical cross-talk.

Abstract: Disclosed herein is an optical receiver including: a light receiving element configured to have an anode and a cathode and generate a photocurrent dependent on received signal light; a current-voltage conversion circuit configured to be connected to the anode of the light receiving element and convert the photocurrent to a voltage signal; and a capacitive passive element configured to have a first electrode and a second electrode. The cathode of the light receiving element is connected to the first electrode of the capacitive passive element, and the second electrode of the capacitive passive element is connected to a reference potential of the current-voltage conversion circuit and the second electrode is not coupled to objects other than a reference potential terminal of the current-voltage conversion circuit.

Abstract: Provided is an optical multilevel transmission system, comprising at least one optical multilevel transmitter for transmitting an optical multilevel signal obtained and an optical multilevel receiver for receiving the optical multilevel signal. The received optical multilevel signal has a larger noise in an angular direction than in a radial direction. The optical multilevel receiver sets, in a symbol decision of the received optical multilevel signal demodulated on the complex plane, for positions of all or some of ideal signal points, a width in the angular direction of a decision area, to which each of the ideal signal points belongs and which is measured along a circumference of a circle centered at an origin and passing through a center of the each of the ideal signal points, larger than a width in the angular direction of a decision area defined based on a Euclidean distance.

Abstract: In various embodiments, a secure optical communication system is disclosed. Such a system may include a photon-pair generation circuit configured to generate pairs of photons with each photon pair including a first-channel photon and a second-channel photon, a transmitting circuit configured to receive first-channel photons, and modulate the first-channel photons according to a stream of data using a first optical circulator to produce first-modulated photons, and a receiving circuit configured to receive second-channel photons, pass the second-channel photons through a complementary optical circulator to produce second modulated photons, and detect relative timing between the first-modulated photons and the second modulated photons to recover the stream of data.

Abstract: A high-speed optical transmitter comprises multiple digital lanes that are provided to a bank of digital-to-analog converters. The analog signals are then used to Phase Shift Keyed (PSK) modulation using a Chirp Managed Laser (CML)-based transmitter, and potentially using dual polarization. A corresponding optical receiver receives the sequence of optical signals at a demodulator. For each polarization, the demodulator includes a corresponding demodulation channel that is configured to demodulate that polarization component of the optical signal into one or more signal components. Each of these signal components is converted into a corresponding digital signal using a corresponding analog-to-digital converter. In the case of higher-order PSK modulation (e.g., 8PSK or higher), for each polarization, the analog converter has a lower sampling rate than for QPSK modulation.

Abstract: An optical fiber communications apparatus comprises a housing provided with a motherboard and a plurality of modular cards , each of which is engageable with the motherboard via one of the card receptors. A optical card includes an optical transceiver for communication using a digital, optical communications signal over a single optical fiber link. Each modular card is provided with a plurality of circuit sub-assemblies, each circuit sub-assembly being configured for digital communication with a respective local audio, video or data electronic device via a respective connector using a respective electronic information-carrying signal. Each circuit sub-assembly is configured for communication of an audio, video or data information-carrying signal with the transceiver using the digital, optical communications signal.

Abstract: The present invention relates to optical fibers useful for the transmission of electromagnetic energy at such high levels of power that stimulated Brillouin scattering (SBS) may be of importance. One aspect of the present invention is an optical fiber for the propagation of optical radiation having an optical wavelength, the optical fiber and optical wavelength having an SBS acoustic wavelength associated therewith, the optical fiber comprising a core having a geometrical center and an outer perimeter; and a cladding surrounding the core; wherein the core is rare earth doped and substantially free of germanium, the optical fiber has a refractive index profile such that the core is guiding for optical radiation having the optical wavelength, and the optical fiber has an acoustic index profile such that the core is antiguiding for an acoustic wave having the SBS acoustic wavelength.

Abstract: A QKD system (10) having two QKD stations (Alice and Bob) optically coupled by an optical fiber link (FL), wherein Bob includes a variable timing delay arranged between Bob's controller (CB) and modulator (MB) or detector unit (40). A set-up and calibration procedure is performed wherein delay DL2 is adjusted until the timings for the modulator and detector unit (TSB and TS42, respectively) are established. Delay DL2 is then fixed so that the detector unit and modulator operate in a common timing mode that is not changed if the synchronization signal is changed. The timing TSS of the synchronization (sync) signals (SS) sent from Alice to Bob is adjusted to arrive at optimum system performance. Once the QKD system is in operation, because the sync signal can drift, the sync signal timing TSS is dithered maintain optimum QKD system performance.

Abstract: A burst-mode differential phase shift keying (DPSK) communications system according to an embodiment of the present invention enables practical, power-efficient, multi-rate communications between an optical transmitter and receiver. An embodiment of the system utilizes a single interferometer in the receiver with a relative path delay that is matched to the DPSK symbol rate of the link. DPSK symbols are transmitted in bursts, and the data rate may be varied by changing the ratio of the burst-on time to the burst-off time. This approach offers a number of advantages over conventional DPSK implementations, including near-optimum photon efficiency over a wide range of data rates, simplified multi-rate transceiver implementation, and relaxed transmit laser line-width requirements at low data rates.

Abstract: Radio frequency identification (RFID)-equipped communication components are disclosed. The communication components can include fiber optic components, such as fiber optic connectors and fiber optic adapters as examples. An RFID-equipped circuit is provided in the communication components to communicate information. In order that the electrical circuit be provided in the communication component without altering the communication component connection type, the circuit may be disposed in at least one recessed area of the communication component housing. In this manner, the communication component maintains its connection type such that it is compatible with a complementary communication component connection type for backwards compatibility while also being RFID-equipped.

Abstract: An optical engine (11) for providing a point-to-point optical communications link between devices. The optical engine (11) includes a light source (24) optically coupled to a modulation chip (6) and configured to generate an optical beam. The optical engine further comprises a modulator (21) carried on the modulation chip and configured to modulate the optical beam. The optical engine further includes a waveguide (30), formed in a plane parallel to the plane of the substrate, and configured to guide the modulated optical beam from the modulator to at least one of a plurality of out-of-plane couplers (40) grouped in a defined region (48) of the modulation chip. The out-of-plane coupler can couple the modulated optical beam to an optical device.

Abstract: Embodiments of the present invention provide a method and apparatus for producing a phase coded non-return-to-zero (PC-NRZ) optical signal. The method includes providing an input optical signal; providing first and second drive signals, the first drive signal having a first data pattern of first and second signal levels, the second drive signal having a second data pattern, the second data pattern having third and fourth signal levels that toggle at least when the first drive signal changes from the first signal level to the second signal level; and modulating amplitude of the input optical signal with the first drive signal and modulating phase of the input optical signal with the second drive signal to produce the PC-NRZ optical signal. A PC-NRZ optical transmitter and an optical transmission system applying the PC-NRZ optical transmitter are also provided.

Abstract: A system for optoelectrical communication includes a transmitter configured to transmit optical signals. It also includes a pluggable form factor module. The module includes an input port, an output port, and a receiver configured to convert optical signals received at the input port into electrical signals. The system further includes an optoelectrical connector coupled to the module and the transmitter. The connector includes an embedded fiber coupled to the transmitter and configured to transmit the optical signals from the transmitter to the output port of the module. The connector also includes electrical contacts configured to receive the electrical signals from the receiver. The system includes a cage in a pluggable form factor configured to house the module and the connector, wherein the transmitter is positioned outside the cage.

Abstract: An optical transmission system includes more optical channels than electrical channels. If an optical channel is not functioning, the signals may be diverted to another optical channel since there are more optical channels than electrical channels. Embodiments of the present invention also relate to switches for switching the electrical channels to particular optical channels on either or both of the transmission and reception side. The switches include switching elements and selector elements for routing the electrical signals between the electrical channels and optical channels. In one embodiment, the multiple optical channels are incorporated into a single cable. The single cable may have the electrical interface for a number of electrical channels exposed for mechanical and electrical coupling with an external port, whereas the optical channels may be hidden within the cable coating.

Abstract: A method for upgrading an optoelectrical system includes securing a transmitter to a line card, wherein the line card comprises an optoelectrical connector. It also includes coupling the transmitter to the connector, wherein the connector comprises an embedded fiber configured to be coupled to the transmitter. In addition, the method includes inserting a pluggable form factor module comprising a receiver, an input port, and an output port into a cage secured to the line card. Further, the method includes coupling the pluggable form factor module to the connector such that an optical signal transmitted by the transmitter propagates in an optical line of sight between the embedded fiber of the connector and the output port. The connector comprises electrical contacts that are configured to be coupled to the module such that the receiver can convert optical signals received at the input port into electrical signals and transmit the electrical signals to the line card via the connector.

Abstract: There is provided an optical receiver including a variable-ratio splitter to split an input signal light into a plurality of signal lights, based on a variable ratio, a plurality of photo detectors to receive the plurality of signal lights respectively, an operation circuit to output a reception electrical signal, based on a reception processing on one of the plurality of signal lights, a calculation circuit to calculate a total power of the plurality of signal lights received by the plurality of photo detectors, and an output unit to output a signal regarding the total power.

Abstract: A fiber optic interconnect device includes a silicon substrate having at least one groove formed therein. The groove includes a pair of sidewalls and a first end disposed at an end of the pair of sidewalls. The device also includes an optical fiber disposed in the groove, the optical fiber having a cylindrical body, an endface formed on an end of the cylindrical body, and a multi-faceted mirror formed on the endface, and a light source adapted to transmit light to the multifaceted mirror to launch light through the optical fiber to a detector.

Abstract: An optical interface device determines whether frequency deviation of a clock signal corresponding to an optical signal from a client side is abnormal based on a stuff amount when subjecting a data signal corresponding to an optical signal input from the client side to a stuffing process, inserts an alarm indication signal (AIS) indicating that the frequency deviation is abnormal into a predetermined region of a data signal when the deviation is determined to be abnormal, and outputs an optical signal generated corresponding to the data signal to a WDM line side so as to transfer the AIS to another component disposed downstream therefrom, so that locating a site where an abnormal state occurs is made easier.

Abstract: It is determined that service is to be disconnected for at least a first subscriber of a video content network employing at least one fiber optic cable. The service to the at least first subscriber is provided from a cross-connect cabinet, over the at least one fiber optic cable, to a premises of the at least first subscriber. Sufficient macro-bending loss is induced in the at least one fiber optic cable so as to cause a signal-to-noise ratio at the premises to degrade such that the service is disconnected. The macro-bending loss is induced in a portion of the at least one fiber optic cable which services only the first subscriber. The macro-bending loss can be induced, for example, by winding about a single mandrel, two mandrels in a figure eight pattern, in a tortuous groove in a tray, and so on.

Abstract: An optical interconnect includes a transmitter circuit, a receiver circuit and an optical signal transmission route. The transmitter circuit includes a control circuit and an electrical/optical converter circuit. The control circuit receives an input electrical signal and outputs a drive signal. The electrical/optical converter circuit includes a light emitting element and converts the drive signal to an optical signal. The receiver circuit includes an optical/electrical converter circuit and a data recovery circuit. The data recovery circuit includes a second trigger signal generator and a latch circuit. The optical/electrical converter circuit includes a light receiving element and a received-signal amplifying circuit. The light receiving element converts the optical signal from the light emitting element to an output current signal. The received-signal amplifying circuit converts the output current signal to a required digital voltage signal.

Abstract: A system includes a transmitter is configured to transmit an electromagnetic signal to a receiver, which is configured to receive the electromagnetic signal and another electromagnetic signal for mixing therewith. Propagation paths of the signals to the transmitter and receiver include a first propagation path of the electromagnetic signal to the transmitter, and a second propagation path of the other electromagnetic signal to the receiver. The arrangement, which is located along either or each of the propagation paths of signals to the transmitter and receiver, is configured to alter the length of a respective propagation path. And the processor configured to recover an amplitude and phase of the transmitted electromagnetic signal, including being configured to receive a sequence of samples of the received electromagnetic signal, and Discrete Fourier Transformation process the sequence of samples.

Abstract: A device can convert electrical signals into modulated light signals and conduct those modulated light signals between components within the device or between the device and another device through at least a portion of the housing of the device that is transparent to the light wavelength of the modulate light signals.

Abstract: Various embodiments of the present invention are directed to optical broadcast buses configured with shared optical interfaces for fan-in and fan-out of optical signals. In one aspect, an optical broadcast bus (100,200,300) comprises a number of optical interfaces (121-123,210,212,216,218,301-303), a fan-in bus (102,202) optically coupled to the number of optical interfaces, and a fan-out bus (104,204) optically coupled to the number of optical interfaces. Each optical interface is configured to convert an electrical signal produced by the at least one node into an optical signal that is received and directed by the fan-in bus to the fan-out bus and broadcast by the fan-out bus to the number of optical interfaces. Each optical interface also converts the optical signal into an electrical signal that is sent to the electronically coupled at least one node for processing.

Abstract: A receiver (e.g., for a 10G fiber communications link) includes an interleaved ADC coupled to a multi-channel equalizer that can provide different equalization for different ADC channels within the interleaved ADC. That is, the multi-channel equalizer can compensate for channel-dependent impairments. In one approach, the multi-channel equalizer is a feedforward equalizer (FFE) coupled to a Viterbi decoder, for example a sliding block Viterbi decoder (SBVD); and the FFE and/or the channel estimator for the Viterbi decoder are adapted using the LMS algorithm.

Abstract: A hybrid balanced code is formed from a low rate (narrow bandwidth) balanced code and a high rate (wide bandwidth) low density code. Data encoded using the hybrid balanced code is transmitted between a first communication network entity and a second communication network entity. The hybrid code enables a system having a hybrid transmitter to transmit either a low rate stream detectable by a low rate receiver or a hybrid stream, from which the low rate data may be detected by a low rate receiver while both the high rate data and the low rate data may be detected by a high rate receiver.

Abstract: A method and apparatus for receiving a digital signal having a plurality of significant bits of resolution. The apparatus includes a mode locked laser comprising a single output. The apparatus also includes a beam divider operable to receive the single output. The apparatus also includes a plurality of optical modulators operable to communicate with said beam divider and operable to receive a respective plurality of signals corresponding to a plurality of significant bits of resolution. Optionally, the apparatus also includes a source operable to output a digital waveform with the plurality of signals corresponding to the plurality of significant bits of resolution of the digital waveform, the plurality of signals operable to drive the plurality of optical modulators.

Abstract: The present invention relates to a method for modulation, the method comprising: receiving a data stream; forming a modulated electrical signal from the data stream by using a plurality of data signals, each of the plurality of data signals representing at least one data bit of the data stream, wherein one of the plurality of data signals is a zero signal and wherein the remainder of the plurality of data signals comprises periodic, positive non-zero subcarrier signals and/or non-periodic signals with a positive DC-level; and providing the modulated electrical signal representing the data stream. The present invention also relates to a device performing the modulation method and to a system incorporating such a device.

Abstract: The present invention relates to the communication or reproduction of sound, in particular audible sound. There is provided a method of communicating a sound, including the steps of: transmitting, onto an optical link, pairs of signal copies, the signal copies of a given pair having a time offset relative to one another; applying the audible sound to the optical link, such that the audible sound causes a phase modulation to the transmitted signal copies; receiving modulated signal copies previously transmitted onto the link; and, for received pairs of signal copies, causing one signal copy of a pair to mix with the other signal copy of that pair so as to produce a signal representative of the sound. The sound is an audible sound. It has been found that a delay of at least 75 micro seconds allows for a better reproduction of audio sounds, since these have a relatively low frequency content.

Abstract: A transmitter includes a plurality of encoders configured to receive source bit streams from m information sources, each of the plurality encoders including identical (n,k) low-density parity check (LDPC) codes of code rate r=k/n, where k is a number of information bits and n is codeword length. An interleaver is configured to collect m row-wise codewords from the plurality of encoders, and a mapper is configured to receive m bits at a time column-wise from the interleaver and to determine an M-ary signal constellation point. A modulator is configured to modulate a light source in accordance with the output of the mapper at a transmission rate Rs/r (Rs—the symbol rate, r—-the code rate). A receiver and transmission and receiving methods are also disclosed.