Abstract: Systems and methods are described for transmitting information optically. For instance, a system may include an optical source configured to generate a beam of light. The system may include at least one modulator configured to encode data on the beam of light to produce an encoded beam of light/encoded plurality of pulses. The system may include a spectrally-equalizing amplifier configured to receive the encoded beam of light/encoded plurality of pulses from the at least one modulator and both amplify and filter the encoded beam of light/encoded plurality of pulses to produce a filtered beam of light/filtered plurality of pulses, thereby spectrally equalizing a gain applied to the encoded beam of light. In some cases, the system may slice the beam of slight, to ensure a detector has impulsive detection. In some cases, the system may include a temperature controller to shift a distribution curve of wavelengths of the optical source.

Abstract: In some embodiments, an optical communication system may include an optical source, a modulator, and a photoreceiver. The optical source may be configured to generate a beam comprising a series of light pulses each having a duration of less than 100 picoseconds. The photoreceiver may have a detection window duration of less than 1 nanosecond. When a first pulse travels through a variably refractive medium, photons in the first pulse may be refracted to travel along different ray paths to arrive at the photoreceiver according to a temporal distribution curve. A full width at half maximum (FWHM) value of the temporal distribution curve may be at least three times as large as a coherence time value of the first pulse, and the detection window of the photoreceiver may be at least six times as large as the FWHM value of the temporal distribution curve.

Abstract: Systems and methods are described for transmitting information optically. For instance, a system may include an optical source configured to generate a beam of light. The system may include at least one modulator configured to encode data on the beam of light to produce an encoded beam of light/encoded plurality of pulses. The system may include a spectrally-equalizing amplifier configured to receive the encoded beam of light/encoded plurality of pulses from the at least one modulator and both amplify and filter the encoded beam of light/encoded plurality of pulses to produce a filtered beam of light/filtered plurality of pulses, thereby spectrally equalizing a gain applied to the encoded beam of light. In some cases, the system may slice the beam of slight, to ensure a detector has impulsive detection. In some cases, the system may include a temperature controller to shift a distribution curve of wavelengths of the optical source.

Abstract: In some embodiments, an optical communication system may include an optical source, a modulator, and a photoreceiver. The optical source may be configured to generate a beam comprising a series of light pulses. The photoreceiver may have a detection window duration of 1 nanosecond or less. When a first pulse travels through a variably refractive medium, photons in the first pulse may be refracted to travel along different ray paths to arrive at the photoreceiver according to a temporal distribution curve. A full width at half maximum (FWHM) value of the temporal distribution curve may be greater than a coherence time value of the first pulse, and the detection window of the photoreceiver may be greater than the FWHM value of the temporal distribution curve.

Abstract: An injection locking laser source is provided for an optical communications system. The injection locking laser source includes a laser cavity configured to receive an externally injected low linewidth primary light source. The laser cavity includes a cavity length, a cavity facet reflectivity, and a cavity quality factor. The injection locking laser source further includes an emitting region configured to output a secondary light source injection locked to the externally injected low linewidth primary light source at a stable detuning frequency based on a photon number, a steady-state phase, and a carrier number of the primary light source injected into the cavity.

Abstract: In some embodiments, an optical communication system may include an optical source, a modulator, and a photoreceiver. The optical source may be configured to generate a beam comprising a series of light pulses each having a duration of less than 100 picoseconds. The photoreceiver may have a detection window duration of less than 1 nanosecond. When a first pulse travels through a variably refractive medium, photons in the first pulse may be refracted to travel along different ray paths to arrive at the photoreceiver according to a temporal distribution curve. A full width at half maximum (FWHM) value of the temporal distribution curve may be at least three times as large as a coherence time value of the first pulse, and the detection window of the photoreceiver may be at least six times as large as the FWHM value of the temporal distribution curve.

Abstract: A vehicle behavior of a monitored vehicle is learned. A vehicle illumination of the monitored vehicle is detected and monitored. If a light-pattern occurs in the detected vehicle illumination, wherein the light-pattern corresponds to a frequency, intensity and/or color dependent glowing of the vehicle illumination, and further wherein the light-pattern starts with a flashing up of the detected vehicle illumination and ends after a certain time without glowing of the respective part of the detected vehicle illumination, then the method further monitors the light-pattern; monitors a vehicle movement of the monitored vehicle during the occurrence of the light-pattern; and compares the monitored light-pattern with a known light-pattern from a light-pattern data entry stored in an light-pattern database. If the comparison results in the monitored light-pattern being unknown, the method stores the light-pattern and the vehicle movement together as a new light-pattern data entry in the light-pattern database.

Abstract: A waveguide illuminator includes an input waveguide, a waveguide splitter coupled to the input waveguide, and a waveguide array coupled to the waveguide splitter. The waveguide array includes an array of out-coupling gratings that out-couple portions of the split light beam to form an array of out-coupled beam portions for illuminating a display panel. The out-coupling gratings may be apodized to reduce light scattering by the gratings. Additionally, gaps between the out-coupling gratings along the waveguides may be filled by gap gratings and/or etched grooves running parallel to the waveguides.

Abstract: In one embodiment, a wide-band laser beam is split into a plurality of sub-laser beams, with each sub-laser beam at a discrete wavelength. Each of the sub-laser beams is transmitted simultaneously through an antenna, with each sub-laser beam transmitted at a different angle due to properties of the antenna. Sub-laser beams that reflect off an object are received back at the same, or a different, antenna and passed to a demultiplexor. The demultiplexor passes each sub-laser to a different waveguide based on the discrete wavelength associated with each sub-laser beam. A detector receives the sub-lasers beam through the waveguides, and calculates the positions of various points on the object based in-part on which waveguide each sub-laser beam is received from and the frequency of each sub-laser beam.

Abstract: A backscattered signal can be received from a sensing fiber that extends into a wellbore. The backscattered signal can have been generated based on an optical signal launched into the sensing fiber. A first delayed signal, a second delayed signal, a first non-delayed signal, and a second non-delayed signal can be generated from the backscattered signal. A polarization control device can shift a polarization of the first delayed signal or the first non-delayed signal. A first demodulated signal can be determined based on the first delayed signal and the first non-delayed signal. A second demodulated signal can be determined based on the second delayed signal and the second non-delayed signal. Data about an environment of the wellbore can be determined by processing the first demodulated signal and the second demodulated signal to compensate for noise in the first demodulated signal or the second demodulated signal.

Abstract: A sampling gate comprising a first frequency input coupled to a first frequency path from a broadband photodiode. The sampling gate also includes a positive bias input coupled to a positive offset portion of a second frequency path from the broadband photodiode. The sampling gate also includes a negative bias input coupled to a negative offset portion of the second frequency path from the broadband photodiode. The sampling gate combines a first frequency signal from the first frequency path and a second frequency signal from the second frequency path to create a combined broadband frequency signal from the broadband photodiode.

Abstract: The present invention relates to a method and an apparatus for quantum key distribution according to a continuous-variable quantum key distribution protocol, which distributes the quantum key in a reverse post-processing manner and, after photon sub traction at a receiver (Bob), detects bit information from a received quantum state to calculate and share the quantum key, such that security can be further enhanced and a cryptographic key generation rate can be increased since the cryptographic key is not exposed to an attacker (Eve).

Abstract: An optical transmission system includes a laser module generating a modulated optical waveform, including both amplitude and frequency modulation, at center frequencies corresponding to different operating temperatures; and an optical shaping filter, with passbands corresponding to the different center frequencies, that converts at least part of the frequency modulation to additional amplitude modulation.

Abstract: A superposition circuitry superposes a dither signal on a reference DC bias voltage and outputs a resultant voltage as a bias voltage to an MZ modulator, during control of a driving voltage amplitude. During the control of the driving voltage amplitude to the MZ modulator, an amplitude setter determines, by varying the amplitude of an output voltage from an amplifier, a plurality of amplitudes of output curves from a synchronous detector, each of which is obtained by varying the reference DC bias voltage output from a bias controller, and the amplitude setter sets the amplification factor of the amplifier, based on an amplitude of the output voltage from the amplifier that corresponds to an amplitude satisfying a predetermined condition, out of the plurality of the amplitudes of the output curves from the synchronous detector.

Abstract: A lamp for use in a lighting assembly comprising a two-wire light string, wherein the lamp is adapted for fitting in a socket of the two-wire light string, and receiving a voltage signal and a superimposed control signal via the two-wire light string and the socket. The lamp includes control electronics provided for the purpose, when the lamp has been fitted in a socket, of receiving voltage via the voltage signal and receiving instructions via the control signal superimposed on the voltage signal; and at least one LED source, of which at least one of an intensity and a colour is adjustable on the basis of the instructions via the control electronics. The control electronics are further provided for receiving an address for the lamp via the control signal superimposed on the voltage signal and for subsequently confirming receipt of the address.

Abstract: The present disclosure relates to a method, an apparatus and a system for monitoring performance of optical network equipment. The method comprises receiving an optical channel signal comprising a first pilot tone in a first spectral sub-band of the optical channel signal and a second pilot tone in a second spectral sub-band of the optical channel signal, the first and the second spectral sub-bands being on opposite sides of a reference frequency of the optical channel signal. The performance of the optical network equipment is monitored based on a power mismatch between the first and second pilot tones of the received optical channel signal. An apparatus and a system for monitoring performance of the optical network equipment are also described.

Abstract: A system monitors optical performance of an optical link within an optical network. The system includes an optical transmitter having an expanded-spectrum pilot-tone modulator for modulating an expanded-spectrum pilot tone onto a high-speed data signal to generate an expanded-spectrum optical signal and an optical receiver for receiving the expanded-spectrum optical signal and for detecting and decoding the expanded-spectrum pilot tone to enable monitoring of the optical performance of the optical link.

Abstract: An apparatus has a pixel array arrangement having a number of photosensitive detectors. Processing circuitry is configured to process data captured by at least one pixel of the array to provide image information and detect data on an encoded pulsed light signal. In a specific embodiment, data is captured at a vehicle. Information for the vehicle is determined based on the encoded pulsed light signal.

Abstract: A laser includes first through fourth gain media, first through fifth wavelength selective filters, and first through fourth wavelength selective mirrors. The first through fourth gain media emit laser beams of different wavelengths. Each of the first through fifth wavelength selective filters includes first through fourth input/output ports. The fifth wavelength selective filter selects light of periodic wavelengths. The first through fourth wavelength selective filters have their respective first input/output ports connected to the first through fourth gain media, respectively, have their respective fourth input/output ports connected to the first through fourth wavelength selective mirrors, respectively, and have their respective second input/output ports connected to the first through fourth input/output ports, respectively, of the fifth wavelength selective filter.

Abstract: A relay device includes: a first port, a plurality of second ports, a splitter configured to branch first optical signals input from the first port into the plurality of second ports; and a plurality of optical modulators configured to modulate shared carrier light by multiplexing the carrier light with a plurality of second optical signals with different frequencies input from the plurality of second ports and by inputting the multiplexed carrier light into a plurality of nonlinear optical mediums, and to transmit the carrier light to the first port.

Abstract: Exemplary methods and systems may generally be implemented to allow a macro-network base station without access to a GPS reference signal to provide some or all of the functionality for which existing macro-network base stations typically rely on GPS. In a first aspect, an exemplary macro-network base station may determine its location using a location-determination technique that is based upon the angles of arrival of FM radio signals from nearby FM stations. In a second aspect, an exemplary macro-network base station may stabilize its local oscillator by phase-locking its local oscillator to an FM radio signal, and periodically adjusting its local oscillator to account for phase drift of the FM radio signal. And in a third aspect, an exemplary macro-network base station may synchronize its frame-start timing with a nearby base station using a frame-start timing signal that the base station has synchronized to frame transmissions from the nearby base station during a setup routine.

Abstract: An emergency manager for a lighting device (1), which lighting device is configured to transmit information by coding its output light. The emergency manager has a light coding unit (5), configured to code light emitted by a light emitter (3), thereby enabling the light emitter to emit a coded light signal including an individual identifier identifying the lighting device; an emergency indicator (7); and a control unit (9). The control unit is configured to control the light coding unit to adjust the coded light signal to increase a robustness of a transmission of the coded light signal upon receiving an emergency indication from the emergency indicator.

Abstract: An optical transmitter, comprising: a master laser device for generating a master signal; one or more slave laser devices, injected with the master signal such that signals generated by the one or more slave laser devices are phase-locked with the master signal; an input for receiving one or more data streams to be transmitted, the one or more data streams being used to modulate respectively the one or more slave laser devices, such that each signal generated by the one or more slave laser devices respectively comprises a modulated part and a carrier part; and an interfering arrangement, for destructively interfering the signals generated by the one or more slave laser devices with a signal derived from the master signal, so as to generate an output signal in which the carrier part is at least partially cancelled. In embodiments, the transmitter comprises multiple slave laser devices, whose outputs can be coherently multiplexed together to generate multiple-bit output signals.

Abstract: Aspects of the disclosure relate generally to a circuit for sustaining an radio frequency (RF) modulated optical signal. The circuit may comprise a self injection locking component having a fiber optic delay line over which a portion of the optical signal propagates. The circuit may also comprise a self phase locked loop component having at least two fiber optic cables having different lengths and over which another portion of the optical signal propagates and a phase detector coupled to the at least two fiber optic cables and configured to determine a phase difference between the signals propagating over one of the respective fiber optic cables. The circuit may further comprise a voltage controlled oscillator configured to generate a stable oscillating signal in response to signals generated by each of the self injection locking and self phase locked loop components, the stable oscillating signal being configured to sustain the optical signal.

Abstract: A system for generating a frequency modulated linear laser waveform includes a single frequency laser generator to produce a laser output signal. An electro-optical modulator modulates the frequency of the laser output signal to define a linear triangular waveform. An optical circulator passes the linear triangular waveform to a band-pass optical filter to filter out harmonic frequencies created in the waveform during modulation of the laser output signal, to define a pure filtered modulated waveform having a very narrow bandwidth. The optical circulator receives the pure filtered modulated laser waveform and transmits the modulated laser waveform to a target.

Abstract: In some examples, a transmit assembly is described that may include a first optical transmitter, a second optical transmitter, and a polarizing beam combiner. The first optical transmitter may be configured to emit a first optical data signal centered at a first frequency. The second optical transmitter may be configured to emit a second optical data signal centered at a second frequency offset from the first frequency by a nominal offset n. The polarizing beam combiner may be configured to generate a dual carrier optical data signal by polarization interleaving the first optical data signal with the second optical data signal. An output of the polarizing beam combiner may be configured to be communicatively coupled via an optical transmission medium to a polarization-insensitive receive assembly.

Abstract: Systems and methods for sideband heterodyning detection are provided. In certain embodiments a system includes an optical resonator configured to allow light to resonate therein; at least one light source that is controlled to form multiple optical fields, wherein each field is phase or frequency modulated at a common modulation frequency and is at a different frequency. The system also comprises multiple heterodyne modulators that phase or frequency modulate a respective field in the multiple fields at a respective heterodyne frequency to form multiple sidebands, wherein the corresponding heterodyne frequency is different for each heterodyne modulator; at least one coupler that couples the multiple sidebands into the optical resonator; and a feedback control that is configured to detect the multiple sidebands transmitted out of the resonator to create multiple detected sideband signals and adjust frequencies of the plurality of fields based on the multiple detected sideband signals.

Abstract: A system for generating a frequency modulated linear laser waveform includes a single frequency laser generator to produce a laser output signal. An electro-optical modulator modulates the frequency of the laser output signal to define a linear triangular waveform. An optical circulator passes the linear triangular waveform to a band-pass optical filter to filter out harmonic frequencies created in the waveform during modulation of the laser output signal, to define a pure filtered modulated waveform having a very narrow bandwidth. The optical circulator receives the pure filtered modulated laser waveform and transmits the modulated laser waveform to a target.

Abstract: An apparatus receives data encoded in a format where information bits for transmission are mapped into symbols each carrying a plurality of bits, some of which are encoded through a frequency-shift keyed (FSK) format and the rest of which are encoded through an additional modulation format on at least one FSK carrier. The receiver detects the signal through a dual-polarization coherent receiver front-end, and recovers polarization components of the signal by decoding a first non-zero portion of a plurality of bits carried by a symbol based on frequency slot position of at least one FSK carrier in the polarization components and a second non-zero portion of the plurality of bits carried by the symbol based on the additional modulation carried by at least one FSK carrier in the polarization components. Pilot-assisted orthogonal frequency-division de-multiplexing (PA-OFDM) may be used for spectrally-efficient signal reception, even in the presence of severe FSK errors.

Abstract: The present invention is directed to a method including determining an appropriate power level for a phase modulator for an optimum number of subcarriers; and applying the determined appropriate power level via a controller to produce the optimum number of subcarriers, wherein the optimum number of subcarriers enables an optical-orthogonal frequency division multiplex O-OFDM based variable rate transmitter with automatic control by a controller to produce an optimum setting based on a required rate.

Abstract: Embodiments may provide a way of communicating via an electromagnetic radiator, or light source, that can be amplitude modulated such as light emitting diode (LED) lighting and receivers or detectors that can determine data from light received from the amplitude modulated electromagnetic radiator. Some embodiments may provide a method of transmitting/encoding data via modulated LED lighting and other embodiments may provide receiving/decoding data from the modulated LED lighting by means of a device with a low sampling frequency such as a relatively inexpensive camera (as might be found in a smart phone). Some embodiments are intended for indoor navigation via photogrammetry (i.e., image processing) using self-identifying LED light anchors. In many embodiments, the data signal may be communicated via the light source at amplitude modulating frequencies such that the resulting flicker is not perceivable to the human eye.

Abstract: Light output from a seed light source generation unit that outputs continuous light having a single frequency or a plurality of frequencies is input by a multi-wavelength light source to an optical circulation unit, and light having a plurality of frequencies that is frequency-synchronized with seed light output from the seed light source generation unit is generated. The optical circulation unit is provided with an optical frequency shifter to shift light frequencies, and includes a circulation circuit to return output from the optical frequency shifter to the input side. On a circulation path, an optical spectral shaper capable of adjusting an optical amount of attenuation for each frequency unit is provided so that optical amount of attenuations are adjusted, and thereby the number and the like of optical frequencies output from the optical circulation unit are changed.

Abstract: Disclosed is an apparatus and a method for transmitting data by using visible light. The transmission apparatus includes: a Serial-to-Parallel (S/P) converter for performing a Serial-to-Parallel conversion on transmission data, and generating multiple parallel data; a modulation means for modulating the multiple parallel data generated by the S/P converter, and generating multiple modulation signals; an Inverse Fast Fourier Transform (IFFT) means for performing an IFFT on the multiple modulation signals so that the multiple modulation signals are orthogonal to one another, and generating an IFFT signal; and a light-emitting means for causing a light source to emit light based on the IFFT signal generated by the IFFT means.

Abstract: Return To Zero (RZ) shaping is performed for a first I/Q modulator whose output corresponds to a first polarization component using a first two digital-to-analog convertors (DACs), each of which is sampled at approximately twice a modulation symbol rate or more and has an output with a first interleaving order that interleaves one of a first pair of intended drive signal patterns and zeros. RZ shaping is also performed for a second I/Q modulator whose output corresponds to a second polarization component using a second two DACs, each sampled at approximately twice the modulation symbol rate or more and having a second interleaving order that interleaves zeros and one of a second pair of intended drive signal patterns, the second interleaving order opposite the first interleaving order. The first polarization and the second polarization may be combined, thereby forming an Interleaved Return To Zero (IRZ) Polarization Division Multiplexed (PDM) signal.

Abstract: An electronic device comprising an optical gate, an electrical input an electrical output and a wide bandgap material positioned between the electrical input and the electrical output to control an amount of current flowing between the electrical input and the electrical output in response to a stimulus received at the optical gate can be used in wideband telecommunication applications in transmission of multi-channel signals.

Abstract: Consistent with the present disclosure, data, in digital form, is received by a transmit nodes of an optical communication, and converted to analog signal by a digital-to-analog converter (DAC) to drive a modulator. The modulator, in turn, modulates light at one of a plurality of wavelengths in accordance with the received data. The modulated light is then transmitted over an optical communication path to a receive node. At the receive node, the modulated optical signal, as well as other modulated optical signals are supplied to a photodetector circuit, which receives additional light at one of the optical signal wavelengths from a local oscillator laser. An analog-to-digital converter (ADC) is provided in the receive node to convert the electrical signals output from the photodetector into digital form. The output from the ADC is then filtered in the electrical domain, such that optical demultiplexing of individual channels is unnecessary.

Abstract: In an FSK receiver according to the present invention, a correction operation for a DC offset component is performed based on a maximum value and a minimum value of a demodulation signal. If a difference between the maximum and minimum values is less than a predetermined threshold value TH1, the correction operation is halted. Thus, the FSK receiver can rapidly perform an appropriate offset removal from a multi-level FSK signal.

Abstract: An optical modulator includes a light input/output unit receiving an incident optical signal which has not been modulated, splitting the incident optical signal into a first optical signal and a second optical signal, and transmitting the first and second optical signals to a first path and a second path, respectively, of an optical waveguide. A phase shifter is positioned in at least one of the first and second paths and modulates a phase of at least one of the first and second optical signals, which have been received through the first and second paths, respectively, in response to an electrical signal. A phase-modulated signal is output. A reflective grating coupler reflects signals respectively received through the first and second paths back along the first and second paths respectively.

Abstract: An optical communication system and method of use are described. The system comprises an optical source adapted to receive a digitally encoded data signal comprising sequences of data at a data rate (B) and comprising two signal levels representing a first state and a second state of the data signal, the optical source being adapted to produce an optical signal substantially frequency modulated with frequency excursion ?? comprising a first instantaneous frequency (?0) associated to the first state and a second instantaneous frequency (?1) associated to the second state; an optical converter adapted to receive the substantially frequency modulated optical signal, the optical converter having an optical transfer function varying with frequency and including at least one pass band, the at least one pass band having a peak transmittance and at least a low-transmittance region.

Abstract: In an embodiment, an optical communication system includes an optical transmitter and an optical discriminator. The optical transmitter is configured to emit a frequency modulated signal having a bit rate frequency and a frequency excursion between 20% and 80% of the bit rate frequency. The optical discriminator is configured to convert the frequency modulated signal to a substantially amplitude modulated signal and includes a delay line interferometer (DLI). The DLI includes an input, an output, a first optical path coupling optical signals from the input to the output and a second optical path coupling optical signals from the input to the output. The first and second optical paths have different lengths.

Abstract: An information transmission system includes: an information sending device including a light emitting section that emits light in a plurality of colors, a modulating section that modulates information to be transmitted into signals composed of changes in color, and a light emission control section that controls the light emitting section to emit light while changing color temporally based on the signals generated by the modulating section; and a receiving device including a camera that captures an image having color, and a control and communication section that detects a temporal color change of the light emitting section emitting light by light emission control by the information transmitting device, from images consecutively captured by the camera, decodes the detected color change into information, and outputs the generated information to a display section.

Abstract: Provided is an optical module. The optical module includes: an optical bench having a first trench of a first depth and a second trench of a second depth that is less than the first depth; a lens in the first trench of the optical bench; at least one semiconductor chip in the second trench of the optical bench; and a flexible printed circuit board covering an upper surface of the optical bench except for the first and second trenches, wherein the optical bench is a metal optical bench or a silicon optical bench.

Abstract: An optical transmitter device includes a laser source, a driving circuit, and an optical modulator. The driving circuit is connected to the laser source. The driving circuit includes a thermistor configured for compensating the temperature variation of the laser source to stabilize the frequency of a laser beam output from the laser source. The optical modulator is configured for modulating the laser beam to form a plurality of second laser beams which have different frequencies.

Abstract: An optical signal processing apparatus includes a mixer and a first optical modulator. The mixer modulates a carrier signal of a first specific frequency received from a first oscillator with an information signal to generate a subcarrier modulated signal. The first optical modulator optically modulates, with the subcarrier modulated signal received from the mixer, carrier light optically modulated by a second optical modulator at a second specific frequency received from a second oscillator to generate and output modulated carrier light.

Abstract: The present invention has an object to provide an optical modulation device and an optical modulation method that achieve an excellent spectral efficiency with a simple and compact configuration and low power consumption. An optical modulation device according to an exemplary aspect of the present invention includes a CW light source (11), a coupler (12), optical modulators (14a) and (14b), an optical frequency shifter (15b), a serial-to-parallel converter (21), and a delay circuit (24a). The serial-to-parallel converter (21) divides a data signal having a bit rate B into two data strings having a bit rate B/2, and extracts a clock signal (CLK). The delay circuit (24a) temporally synchronizes the two data strings. CW light emitted from the CW light source is split into two beams by the coupler (12). The optical modulators (14a) and (14b) generate optical signals by modulating the two split light beams according to the data strings.

Abstract: A method for processing received electromagnetic radiation includes receiving electromagnetic radiation having a plurality of carrier waves in the frequency range between 0.1 and 10 terahertz and having modulated onto the carrier waves information with a signal frequency of less than 50 GHz. The received radiation is filtered with a filter that is tunable in the frequency range from 0.1 to 10 terahertz so as to obtain at least one carrier wave as a terahertz signal. The terahertz signal is provided to a detection circuit that is sensitive to the terahertz signal frequency.

Abstract: It is an object to provide an optical frequency control device or the like which can quickly carry out control over a wide frequency range. The object is achieved by an optical frequency control device or the like comprised of an optical SSB modulator (2), a bias voltage source (3) for applying a bias voltage to the optical SSB modulator (2), and a modulating signal source (4) for applying a modulating signal to the optical SSB modulator (2), wherein the modulating signal source (4) is provided with an arbitrary waveform generator (5) for generating an electrical signal with an arbitrary waveform, and an electrical signal multiplier (6) for multiplying a frequency of the electrical signal generated by the arbitrary waveform generator (5).

Abstract: In one embodiment, a system includes at least one tone generator, a first transmitter, and a second transmitter. The at least one tone generator is operable to generate a plurality of modulation tones comprising at least a first modulation tone having a first tone frequency and a second modulation tone having a second tone frequency that is different from the first tone frequency. The first transmitter is operable to apply the first modulation tone to a first optical signal such that at least a portion of the first optical signal is divided into one or more sidebands. The second transmitter is operable to apply the second modulation tone to a second optical signal such that at least a portion of the second optical signal is divided into one or more sidebands.

Abstract: Techniques and configurations are provided to generate multiple coherent optical subcarriers. A laser source generates as output a light beam at a carrier frequency. A multicarrier generator is provided that is coupled to the laser source and comprises one or more dual carrier generators each configured to modulate the light beam at the same modulation frequency or different modulation frequencies so as to output a plurality of light beams each at a different subcarrier frequency that is offset from the carrier frequency. The multicarrier generator generates the plurality of light beams on individual outputs, e.g., fibers, without the need for an optical demultiplexing filter.

Abstract: Described are an FSK modulator and a method for large-alphabet FSK modulation. The FSK modulator and the method are based on filtering of a multi-tone optical source such as a mode-locked laser which provides a comb distribution of tones. A frequency-selective component selects for transmission a subset of the tones. In various embodiments the frequency-selective component is a Mach-Zehnder interferometer filter or a microring resonator filter. A second frequency-selective component selects a subset of the tones from the comb distribution provided by the first frequency-selective component. Still more frequency-selective components can be used according to the number of tones supplied by the multi-tone optical source to the FSK modulator. The optical signal exiting the last frequency-selective component includes only a single tone which corresponds to the symbol to be transmitted.