Abstract: Systems and methods include receiving a plurality of symbols that are part of a defined Digital Signal Processing (DSP) frame for coherent optical communication, wherein the DSP frame structure has a messaging channel incorporated therein that includes a subset of the plurality of symbols; capturing multiple samples of the messaging channel; and determining a message in the messaging channel based on analysis of the multiple samples. The method can further include transmitting, in the messaging channel, a reply to the message with the reply being repeated multiple times. The analysis is performed prior to Forward Error Correction (FEC) decoding on the data path.

Abstract: A local oscillation light output unit; a phase adjustment unit; a polarization control unit; a multiplexing unit; a photoelectric conversion unit; a demodulation unit; and a control unit. The phase adjustment unit adjusts the phase of local oscillation light. The polarization control unit controls polarization rotation of an optical signal. The multiplexing unit multiplexes the local oscillation light output from the phase adjustment unit with the optical signal output from the polarization control unit. The demodulation unit performs a demodulation process based on an electric signal obtained through conversion performed by the photoelectric conversion unit. The control unit, on the basis of information about the reception status of the optical signal, controls the execution of at least one of the phase adjustment of the local oscillation light in the phase adjustment unit and the polarization rotation of the optical signal in the polarization control unit.

Abstract: Provided is a coherent detection implementing apparatus, system and method. The apparatus includes: a first transceiver unit, configured to send an optical signal in a first direction to a second device, wherein the optical signal in the first direction includes a direct current optical signal with a first wavelength and a modulated optical signal with a second wavelength; and configured to receive an optical signal in a second direction from the second device; and a first coherent receiver, connected with the first transceiver unit, and configured to take a part of the direct current optical signal with the first wavelength in the optical signal in the first direction as a Local Oscillator (LO) light for coherent reception, perform coherent frequency mixing between the LO light and the optical signal in the second direction, and demodulate the optical signal in the second direction.

Abstract: A synchronizer for synchronizing transfer over an optical link includes a frequency reference oscillator; a tracking optical timing source; a tracking comb signal; a signal processor-controller; a comb timing discriminator; a clock frequency comb; a bidirectional terminal; a time-frequency offset measurement system; and a second comb timing discriminator.

Abstract: An optical wireless transmission system 10 includes a transmission device including at least one memory storing instructions, and at least one processor configured to execute the instructions to; generate a plurality of digital outphasing signals; orthogonally modulate the digital outphasing signals at an intermediate frequency; and set an intermediate frequency for satisfying a specified signal-to-distortion power ratio based on a sampling frequency, wherein the digital outphasing signals are orthogonally modulated at the intermediate frequency; a hardware optical fiber module configured to convert orthogonally modulated digital electrical signals into optical signals, transmit the optical signals through an optical fiber, and convert the optical signals into digital electrical signals; and a remote unit configured to combine the digital electrical signals transmitted by the hardware optical fiber module, and transmit a combined signal as a radio signal.

Abstract: A device includes a photonic integrated circuit (PIC), which includes an optical phased array. The optical phased array includes multiple array elements, where each array element includes (i) an antenna element configured to transmit or receive optical signals and (ii) a phase modulator configured to modulate the optical signals transmitted or received by the antenna element. The PIC also includes at least one of (i) a source laser configured to generate optical energy, where the antenna elements are configured to transmit the optical signals based on the optical energy, and (ii) a receiver configured to receive and process the optical signals received by the antenna elements.

Abstract: A communication system in which multiple shaping codes are selectively and iteratively used to encode a data frame such that possible energy inefficiencies associated with the use of constant-probability codes and/or transmission of dummy constellation symbols can be relatively small. In an example embodiment, the used shaping codes have different respective code rates, and a code selector of the shaping encoder operates to select one of the shaping codes by adaptively matching the rate of the code to the effective rate needed to efficiently encode the unprocessed portion of the data frame. The encoding is carried out in a manner that enables the shaping decoder to unequivocally determine the shaping codes that have been used for encoding each particular data frame based on the same rate-matching criteria as those used by the shaping encoder. At least some embodiments advantageously lend themselves to being implemented using circuits of relatively low complexity.

Abstract: The present application is directed to an optical terminal including two linearly polarized optical transmit beams configured to exhibit a time-delay therebetween. The optical terminal may include a quarter-wave plate such that the linearly polarized transmit beam becomes circularly polarized. The optical terminal may also include a receiving ground terminal including a properly oriented quarter-wave plate for separating and directing the two recovered linearly polarized beams. The application is also directed to a method for reconstructing an originally transmitted data stream.

Abstract: Methods and systems for an optical connection service interface may include, in an optical data link comprising an optical fiber coupling first and second transceivers, generating a signal for the transceivers at a low frequency, and communicating, utilizing the optical fiber, an optical data signal at a high frequency and an Optical Connection Service interface (OCSi) signal at an intermediate frequency. An optical signal may be modulated at the intermediate frequencies for the OCSi, and may be modulated and communicated to the second transceiver. The communicated modulated signal and the optical data signal may be detected utilizing a photodetector in the second transceiver. The detected optical signal may be demodulated, and an optical power of the optical data signal may be configured based on the demodulated signal.

Abstract: A transmitter modulates a first polarization signal at a wavelength with a first data signal using intensity modulation. The transmitter modulates a second polarization signal at the same wavelength with a second data signal using intensity modulation. The transmitter combines the modulated, polarization signals and generates an output signal. A receiver includes a photodetector that receives the output signal and generates an electrical output signal including components of both modulated, polarization signals. A signal processing circuit implements correlation techniques or matching filters to recover the first and second data signal from the electrical output signal.

Abstract: Embodiments herein provide a self-homodyne coherent optical transmission system (Self-Homodyne system) where an optical carrier is polarization multiplexed with a modulated signal and is transmitted over the optical fiber. An Adaptive polarization control is used by the receiver for simplifying a signal processing in the receiver. Analog processing may be used for implementing LO less receiver. Transmitter uses a phase modulated carrier in place of an unmodulated carrier.

Abstract: In accordance with the present disclosure, a communication network includes a surface wave transceiver, mounted on a medium voltage power line, configured to bidirectionally communicate wireless network data via guided electromagnetic waves that propagate along a surface of the medium voltage power line. A plurality of analog surface wave repeater pairs, a plurality of digital surface wave regenerator pairs, are mounted on the medium voltage power line. A plurality of access points, supported by corresponding ones of a plurality of utility poles that also support the medium voltage power line, is configured to wirelessly transmit the wireless network data to a plurality of client devices in accordance with a wireless network protocol and to wirelessly receive client data from the plurality of client devices in accordance with the wireless network protocol. A plurality of surface wave add/drop multiplexer pairs, is also mounted on the medium voltage power line.

Abstract: In accordance with one or more embodiments, a communication network includes a surface wave transceiver, mounted on a coaxial cable of a broadband cable network, configured to bidirectionally communicate wireless network data via guided electromagnetic waves that propagate along a surface of the coaxial cable. A plurality of analog surface wave repeater pairs, and a plurality of digital surface wave regenerator pairs, are also mounted on the coaxial cable. A plurality of access points, supported by corresponding ones of a plurality of utility poles that also support the coaxial cable, is configured to wirelessly transmit the wireless network data to a plurality of client devices in accordance with a wireless network protocol and to wirelessly receive client data from the plurality of client devices in accordance with the wireless network protocol. A plurality of surface wave add/drop multiplexer pairs, is also mounted on the coaxial cable.

Abstract: Methods and systems for waveguide delay based equalization with current and optical summing in optical communication are disclosed and may include an optoelectronic receiver including a directional coupler, two or more photodetectors, and one or more current mirrors. The optoelectronic receiver may be operable to: receive an input optical signal; split the input optical signal into first and second optical signals using the directional coupler; generate a first electrical from the first optical signal using a first photodetector; generate a second electrical signal from the second optical signal using a second photodetector; mirror the second electrical signal using the current mirror; and sum the first electrical signal with the amplified second electrical signal. The optoelectronic receiver may be operable to delay the first optical signal before generating the first electrical signal, using a waveguide delay.

Abstract: An optical transmitter includes: a bit converter that processes input bits in units of four bits, and generates an output bit sequence having eight bits based on one of a first conversion table, a second conversion table, and a third conversion table; and a symbol mapper that allocates the output bit sequence to an X-polarization and to a Y-polarization of each of two consecutive time slots. The bit converter performs a process of generating the output bit sequence based on the first conversion table, the second conversion table, and the third conversion table. The bit converter performs the process such that a sequence of two most significant bits and a sequence of two least significant bits of the output bit sequence are respectively associated with values that are allocated respectively to two constellation points having phases different by 180 degrees on a complex plane.

Abstract: A system may include: an optical pulse source; fiber optic links; a first optical coupler optically coupled to the optical pulse source; a radiofrequency (RF) source; a phase modulator (PM) optically coupled to the first optical coupler and electronically coupled to the RF source; an interleaving delay optically coupled to the first optical coupler; a second optical coupler optically coupled to the PM and the interleaving delay; a laser; an optical amplifier optically coupled to the laser; a wavelength division multiplexer (WDM) optically coupled to the optical amplifier and the optical coupler; a highly nonlinear fiber (HNLF); an optical filter optically coupled to the WDM via the HNLF; an optical switch optically coupled to the optical filter; and a coherent detector optically coupled to the optical switch via a first optical path and a second optical path, the first optical path including an optical delay.

Abstract: Aspects of a symmetric coherent optical mixer are described. In one example, the coherent optical mixer includes a group of symmetric MMI couplers and a group of symmetric bend waveguides optically coupled between the MMI couplers. The group of symmetric MMI couplers can include an input for a local light reference signal, an input for a modulated light signal, and outputs for detection of data from the modulated light signal. The group of symmetric MMI couplers can include four MMI couplers, each of which comprises a 2×2 MMI coupler of symmetric dimension. The group of symmetric bend waveguides can include a symmetric layout of four 90° bend waveguides optically coupled between the four MMI couplers. The coherent optical mixer, which can be implemented as a Silicon Photonics (SiPh) device, provides better performance as a 90° degree optical hybrid than prior mixer devices due to its symmetric layout.

Abstract: An integrated coherent receiver that is configured to receive an optical signal and receive a local oscillator (LO) source from a remote location. The integrated coherent receiver is configured to extract phase and frequency information carried by the optical signal using the LO source from the remote location.

Abstract: Disclosed are a pulse radar apparatus and an operating method of the pulse radar apparatus, the pulse radar apparatus including a transmitter configured to receive a reference signal as a transmission clock signal, and transmit a transmission pulse to an object based on the transmission clock signal, a negative feedback loop configured to delay the reference signal and output the delayed reference signal as a reception clock signal, and a receiver configured to restore, based on the reception clock signal, a reflection pulse received in response to the transmission pulse being reflected from the object, wherein the negative feedback loop is configured to generate a delay control signal using the reference signal and a predetermined waveform signal generated by a waveform generator, delay the reference signal based on the delay control signal, and adjust the delay control signal by controlling the waveform generator to change the predetermined waveform signal.

Abstract: Methods and systems for waveguide delay based equalization with current and optical summing in optical communication are disclosed and may include an optoelectronic receiver including a directional coupler, two or more photodetectors, and one or more current mirrors. The optoelectronic receiver may be operable to: receive an input optical signal; split the input optical signal into first and second optical signals using the directional coupler; generate a first electrical from the first optical signal using a first photodetector; generate a second electrical signal from the second optical signal using a second photodetector; mirror the second electrical signal using the current mirror; and sum the first electrical signal with the amplified second electrical signal. The optoelectronic receiver may be operable to delay the first optical signal before generating the first electrical signal, using a waveguide delay.

Abstract: An optical circuit capable of operating as a 90° optical hybrid includes a phase-symmetric optical splitter and a 90° optical splitter, and two 2×2 optical couplers as optical combiners. The input ports of the optical combiners and the output ports of the optical splitters face a common area therebetween, with the optical splitters interposed between optical combiners as viewed along the circumference of the common area. The output ports of each optical splitter is connected to closest input ports of the optical combiners with optical waveguides of a same length. The length of the waveguides may be minimized when the optical couplers and the optical splitters are disposed in a cross-like configuration.

Abstract: An optical signal processing method and a coherent receiver, wherein an in-phase signal XI in a first polarization direction and an in-phase signal YI in a second polarization direction are added up to obtain a signal I; a quadrature signal XQ in the first polarization direction and a quadrature signal YQ in the second polarization direction are added up to obtain a signal Q; and quantization, combination, and digital signal processing are performed on the I and the Q. After summation, two signals need to be quantized. Therefore, a quantity of ADCs is reduced by half. In addition, because power consumption of a summation component is less than that of an ADS, power consumption of optical signal processing can be reduced. In addition, because there is a preset value, the summation may be performed after phase-inversion is performed on one analog signal, thereby avoiding a signal loss caused by the summation.

Abstract: Methods and systems for an optical connection service interface may include, in an optical data link comprising an optical fiber, a local control system, first and second transceivers at ends of the optical fiber, generating a signal for the local control system at a low frequency and communicating, utilizing the optical fiber, an optical data signal at a high frequency and an Optical Connection Service interface (OCSi) signal at an intermediate frequency. An optical signal may be modulated at the intermediate frequencies for the OCSi, and may be modulated and communicated to the second transceiver. The communicated modulated signal and the optical data signal may be detected utilizing a photodetector in the second transceiver. The detected optical signal may be demodulated, and an optical power of the optical data signal may be configured based on the demodulated signal.

Abstract: We disclose a lidar system that includes a modulator-based probe-light generator and a coherent optical receiver. The probe-light generator uses tunable carrier-suppressed single-sideband modulation to generate frequency-chirped optical pulses for the optical-probe beam directed at the target. The coherent optical receiver uses a homodyne detection scheme in which a split portion of the optical-probe beam is used as an optical local oscillator signal for detecting a corresponding optical beam reflected by the target. The resulting electrical RF signals generated by the receiver can be processed, e.g., using a disclosed signal-processing method, to determine one or both of the distance to the target and the velocity of the target.

Abstract: Methods and systems for waveguide delay based equalization with current and optical summing in optical communication are disclosed and may include an optoelectronic receiver including a directional coupler, two or more photodiodes, and one or more current mirrors. The optoelectronic receiver may be operable to: receive an input optical signal; split the input optical signal into first and second optical signals using the directional coupler; generate a first electrical from the first optical signal using a first photodiode; generate a second electrical signal from the second optical signal using a second photodiode; amplify the second electrical signal using the current mirror; and sum the first electrical signal with the amplified second electrical signal. The optoelectronic receiver may be operable to delay the first optical signal before generating the first electrical signal, using a waveguide delay.

Abstract: A method. The method may include transmitting an optical noise signal to a first photodetector and a second photodetector within an optical receiver circuit that includes a transimpedance amplifier circuit. The method may further include measuring, in response to transmitting the optical noise signal, a power output from the optical receiver circuit. The method may further include determining, using the power output, a difference in photodetector responsivity between the first photodetector and the second photodetector. The method may further include adjusting, using a transimpedance gain controller, an amplifier gain within the optical receiver circuit to decrease a difference in photodetector responsivity between the first photodetector and the second photodetector.

Abstract: A sensing system adapted to receive backscattered signal from a sensing fiber includes a first Faraday rotator mirror; a second Faraday rotator mirror; an optical hybrid coupled to the Faraday rotator mirrors, wherein one of the mirrors is coupled with an optical path difference; a 3-port optical circulator coupled to the sensing fiber and the optical hybrid; a first photodetector coupled to the circulator; and three photodetectors coupled to the optical hybrid.

Abstract: In a method and system for decoding a differential M-ary phase or quadrature amplitude modulated signal, the incoming signal is decoded according to a plurality of different decoding rules, wherein said plurality of decoding rules correspond to different values of a resulting frequency difference or mismatch between a signal frequency and a local oscillator reference frequency. The invention allows to increase a tolerance window for the maximal allowable frequency offset, and thus helps to speed up an initial locking process or to allow for equipment which has a lower tuning granularity.

Abstract: An optical transmission device as the first optical transmission device includes a light source to output light, an optical transmitter to transmit first information regarding a reception characteristic and power consumption of the first optical transmission device to a second transmission device, an optical receiver to receive second information regarding a reception characteristic and power consumption of the second optical transmission device, an optical branching circuit to branch the light output from the light source into transmission light for the optical transmitter and local light for coherent reception by the optical receiver, and vary power of the transmission light and power of the local light individually, and a processor to control a driving condition of the optical branching circuit, based on the first information and the second information, the power of the transmission light and the power of the local light varying in accordance with the driving condition.

Abstract: An optical receiver circuit includes: a substrate; and an optical waveguide device that is formed on the substrate. The optical waveguide device includes: a first optical splitter section branching the signal light into a first signal light propagation waveguide and a second signal light propagation waveguide and; a second optical splitter section branching the local-oscillator light into a first local-oscillator light propagation waveguide and a second local-oscillator light propagation waveguide; a first optical coupler section that combines the signal light propagating through the first signal light propagation waveguide and the local-oscillator light propagating through the first local-oscillator light propagation waveguide with each other; a second optical coupler section that combines the signal light propagating through the second signal light propagation waveguide and the local-oscillator light propagating through the second local-oscillator light propagation waveguide with each other.

Abstract: Methods and systems for an optical connection service interface may include, in an optical data link comprising an optical fiber, a local control system, first and second transceivers at ends of the optical fiber, generating a control signal for the local control system at a low frequency and communicating, utilizing the optical fiber, an optical data signal at a high frequency and an optical service signal for an Optical Connection Service interface (OCSi) at an intermediate frequency. An optical signal may be modulated at the intermediate frequencies for the OCSi, and may be modulated and communicated to the second transceiver. The communicated modulated signal and the optical data signal may be detected utilizing a photodetector in the second transceiver. The detected optical signal may be demodulated, and an optical power of the optical data signal may be configured based on the demodulated signal.

Abstract: An object of the present invention is to provide an optical 90-degree hybrid circuit which is capable of easily adjusting the optical power ratio between signal and local oscillator and suppresses an optical system of an optical receiver becoming complex and optical receivers using the same.

Abstract: Disclosed is a transparent electronic speaker device, including a transparent speaker, a touch control panel and a display panel which are sequentially stacked. The touch control panel provides a touch control function, and the display panel possesses a display function. The transparent speaker includes an upper conductive plate, a lower conductive plate and a transparent piezoelectric film sandwiched between the upper and lower conductive plates. The display panel generates and transfers a voltage driving signal through an electrical connection to the upper and lower conductive plates for actuating the transparent piezoelectric film to perform piezoelectric action, thereby generating vibration and sound. Therefore, the present invention not only integrates the functions of speaker, touch control and display, but also improves sound quality by use of the transparent piezoelectric film covering the whole electronic device without deteriorating display quality.

Abstract: An optical reception apparatus (1) of the present invention includes: a local oscillator (11) outputting local oscillation light (22); an optical mixer (12) receiving a multiplexed optical signal (21) and the local oscillation light, and selectively outputting an optical signal (23) corresponding to the wavelength of the local oscillation light from the multiplexed optical signal; a photoelectric converter (13) converting the optical signal (23) output from the optical mixer into an electric signal (24); a variable gain amplifier (15) amplifying the electric signal (24) to generate an output signal (25) whose output amplitude is amplified to a certain level; a gain control signal generating circuit (16) generating a gain control signal (26) for controlling the gain of the variable gain amplifier (15); and a monitor signal generating unit (17) generating a monitor signal (27) corresponding to the power of the optical signal (23) using the gain control signal (26).

Abstract: An optical modulator combines and inputs a signal light propagating through the optical network and a control light having information concerning the optical network to a nonlinear optical medium. The optical modulator modulates the signal light according to changes in intensity of the control light, in the nonlinear optical medium.

Abstract: The invention relates to a laser device, comprising a laser configured to generate laser light and a laser control module configured to receive at least a portion of the laser light generated by the laser, to generate a control signal and to feed the control signal back to the laser for stabilizing the frequency, wherein the laser control module comprises a tunable frequency discriminating element which is preferably continuously frequency tunable, and where the laser control module is placed outside the laser cavity.

Abstract: The present invention relates to a wavelength division multiplexing optical receiver and eliminates excess loss of one polarization component while eliminating the need for a polarization-independent operation of a light receiver. An input waveguide, made of a silicon wire waveguide, is connected to a loop waveguide equipped with a polarization rotator over a polarization beam splitter. A ring waveguide equipped with an output waveguide configuring an add-drop ring resonator array is optically connected to the loop waveguide. The output light from ports at both sides of the output waveguide is incident onto first and second light-receiving surfaces of a light receiver such that the optical distances are equal to each other.

Abstract: An optimization unit in an optical receiver divides a symbol region out of a plurality of symbol regions into which signal points that specifies symbol information included in an optical signal are classified, into a plurality of division regions from the symbol center coordinate of the symbol region. Moreover, the optimization unit accumulates the signal points of the symbol information for every division region in the symbol region. Furthermore, based on the accumulated number of signal points for every division region, the optimization unit controls the average length of a phase estimation unit when the phase noise of the optical signal is calculated.

Abstract: The invention relates to a noise compensation system, configured for compensating phase noise in coherent optical communications, and to a method for compensating phase noise.

Abstract: According to one embodiment, a system for transmitting differential optical signals can include an optical modulation device, a multi-core optical waveguide, and a balanced optical receiver. The optical modulation device can include at least one optical input port and multiple optical output ports. The optical modulation device can transform the optical input signal into multiple complimentary modulated optical signals that are transmitted from the multiple optical output ports. The multi-core optical waveguide can include multiple cores disposed within a cladding material. The multiple cores, the cladding material, or both can be configured to mitigate transmission of optical energy between the multiple cores. The balanced optical receiver can include multiple photodetectors. The balanced optical receiver can be communicatively coupled to the multiple cores of the multi-core optical waveguide.

Abstract: An optical network unit has a tunable laser. The tunable laser is tunable such that a point-to-point connection to another optical network unit is established via an optical fiber. There is also provided a method for processing data in an optical network and a corresponding communication system. The tunable laser can be adjusted based on a detected collision, and a frequency grid can be supplied from a centralized component.

Abstract: A photon detection system including a photon detector configured to detect single photons, a signal divider to divide the output signal of the photon detector into a first part and a second part, wherein the first part is substantially identical to the second part, a delay mechanism to delay the second part with respect to the first part, and a combiner to combine the first and delayed second parts of the signal such that the delayed second part is used to cancel periodic variations in the first part of the output signal.

Abstract: A reconfigurable photonic integrated circuit focal plane array (RPIC-FPA) includes detectors and photonic integrated circuit coupled to the detectors that are configured to mix a return signal beam with local oscillator (LO) beams to produce a combined beam and direct the combined beam to the detectors. The LO beams have reconfigurable optical properties enabled by the RPIC-FPA. The LO beams are individually addressed to switch the detectors between a direct detection mode and various coherent detection modes based on adjustments to the optical properties of the LO beams. In the coherent detection mode, the controller is configured to mix the return signal beam with the LO beam having adjusted optical properties to produce the combined beam, and, in the direct detection mode, the controller is configured to disable the LO beams based on adjustments to the optical properties and to direct the return signal beam to the detectors without mixing.

Abstract: An optical receiver may receive input signals carried by respective sub-carriers. The optical receiver may determine, based on the input signals, a compensation value to be used to modify an input signal. The optical receiver may use the compensation value to adjust the input signal to form a modified input signal. The compensation value may be used to modify a frequency or a phase of the input signal. The optical receiver may determine, based on the modified input signal, a phase estimate value that represents an estimated phase associated with the input signal. The optical receiver may combine the compensation value and the phase estimate value to form a phase adjustment signal, may combine the input signal and the phase adjustment signal to form an output signal, and may output the output signal.

Abstract: A communication light detecting structure includes a communication optical fiber configured to transmit communication light; a leakage optical fiber optically connected to the middle of the communication optical fiber via optical connection portions, the leakage optical fiber being different in core refractive index from the communication optical fiber; and a light detecting unit configured to detect part of the communication light leaking from the optical connection portions as leakage light. A communication light detecting optical connector includes the communication light detecting structure. A communication light detecting optical cable includes the communication light detecting structure. The communication optical fiber and the leakage optical fiber may have the same core diameter. The communication optical fiber and the leakage optical fiber may have the same cladding refractive index.

Abstract: A method of analyzing an input signal, the method including the steps of: (a) dividing a first input signal into first and second orthogonal signal polarization components; (b) dividing a second input signal into orthogonal first and second orthogonal local polarization components; (c) mixing the first orthogonal signal component with the second orthogonal local polarization component to provide a first mixed signal; (d) mixing the second orthogonal signal component with the first orthogonal local polarization component to provide a second mixed signal; (e) analyzing the first and second mixed signal to determine the polarization or phase information in the input signal.

Abstract: An integrated optical signal Synthesizer and Analyzer for optical communications, each formed on a single chip, is disclosed. The Synthesizer and Analyzer are both design to use a Dual-Polarization Quadrature Amplitude Modulation (QAM) for communication operating at high data rates. A communication system for data transmission having such synthesizer and the analyzer is also disclosed.

Abstract: A light emitting element drive circuit includes: a plurality of signal paths that respectively propagate a plurality of signals obtained by branching an input signal, a plurality of filters different in a frequency band to pass a signal; one or more amplifiers configured to amplify a signal, one or more delay circuits configured to delay a signal, and an addition circuit that adds a plurality of signals, the filter different in the frequency band being arranged in each of the plurality of signal paths, the delay circuit being arranged in one or more of the plurality of signal paths relatively low in the frequency band, the amplifier being arranged in one or more of the plurality of signal paths relatively high in the frequency band, and an output end of each of the plurality of signal paths being coupled to the addition circuit.

Abstract: An optical detector for detecting an optical signal beam (OSB) modulated in a way that it includes an in-phase and/or a quadrature component, includes: a polarization beam splitter arranged to split the OSB into two polarized OSBs; a non-polarization beam splitter arranged to further split each of the two polarized OSBs into two split polarized OSBs; at least one birefringent element providing a phase shift, the birefringent element being arranged in a path of at least one polarized OSB and/or in a path of at least one split polarized OSB so that an in-phase and quadrature phase offset between two split polarized OSBs originating from the same polarized OSB is formed in output signal beams; and at least two detection means arranged to receive at least one output signal beam that includes a in-phase and/or quadrature component of the OSB.

Abstract: A fiber optic system includes a transmitter for transmitting high-speed streaming electrical data to a receiver for receiving the high-speed data. In order to transmit multiple channels in the system at high-speeds, an electrical data signal is converted into multiple optical sub-signals. Each of the multiple optical sub-signals are transmitted at the common wavelength on multi-spatial mode media. The receiver receives the multiple optical sub-signals as a multi-spatial mode optical signal and separates the multi-spatial mode optical signal into branch signals having a common wavelength. The receiver mixes each of the branch signals with optical carrier waves having the common wavelength and converts the branch signals into electrical signals. Digital signal processing is used to recover the data sub-signals which are used to recover the original data signal.