Abstract: Methods and systems for encoding multi-level pulse amplitude modulated signals using integrated optoelectronics are disclosed and may include generating a multi-level, amplitude-modulated optical signal utilizing an optical modulator driven by first and second electrical input signals, where the optical modulator may configure levels in the multi-level amplitude modulated optical signal, drivers are coupled to the optical modulator; and the first and second electrical input signals may be synchronized before being communicated to the drivers. The optical modulator may include optical modulator elements coupled in series and configured into groups. The number of optical modular elements and groups may configure the number of levels in the multi-level amplitude modulated optical signal. Unit drivers may be coupled to each of the groups. The electrical input signals may be synchronized before communicating them to the unit drivers utilizing flip-flops.

Abstract: An information processing apparatus includes a memory, and a processor coupled to the memory and configured to receive a designation of a progression degree in which a circuit pattern displayed on a two-dimensional model of a printed circuit board is traced from a start point to an end point of the circuit pattern, display, on the two-dimensional model, the circuit pattern from the start point to a point corresponding to the progression degree on a three-dimensional model of the printed circuit board based on a setting of the start point and the end point of the circuit pattern, and display the circuit pattern of the two-dimensional model to distinguish a first pattern to form a part of the circuit pattern and a second pattern to form a part of the circuit pattern, the first pattern and the second pattern having portions overlapping each other.

Abstract: It is impossible to compensate non-linearity in an optical transmitter during operations, therefore, an optical transmitter according to an exemplary aspect of the invention includes a selective addition means for adding a coefficient to digital data to be transmitted if the digital data being included in one of data intervals of predetermined number, the predetermined number being integer more than one, and for changing the coefficient with a period longer than the symbol period of the data transmitted by the optical transmitter; a data processing means for processing the digital data by using a parameter; a driving signal means for generating a driving signal from the digital data adjusted by the selective addition means and the data processing means; a modulating means for modulating light into lightwave signal by the driving signal; and a control means for receiving a monitor signal obtained by monitoring the lightwave signal having a frequency component determined by the period of changing the added coef

Abstract: Disclosed are a frame error concealment method and apparatus and an audio decoding method and apparatus. The frame error concealment (FEC) method includes: selecting an FEC mode based on at least one of a state of at least one frame and a phase matching flag, with regard to a time domain signal generated after time-frequency inverse transform processing; and performing corresponding time domain error concealment processing on the current frame based on the selected FEC mode, wherein the current frame is an error frame or the current frame is a normal frame when the previous frame is an error frame.

Abstract: In an adaptation module relating generally to adaptive optical channel compensation, an analysis module is coupled to receive a first data signal and a second data signal and coupled to provide first information and second information. A comparison module is coupled to compare the first information and the second information to provide third information. An adjustment module is coupled to receive the third information to provide fourth information to compensate for distortion in the second data signal with reference to the first data signal. The second data signal is associated with a conversion of the first data signal to an optical signal for communication via an optical channel.

Abstract: Systems and methods for measuring the in-phase/quadrature (I/Q) skew of optical signals. The method may be used to characterize the I/Q skew of optical signals transmitted by optical coherent transponders in complex modulation formats. The method may include providing an input signal to a transponder to produce a periodic (and generally sinusoidal) output signal, providing the output signal to a test system including an optical spectrum analyzer, measuring the optical power of a first harmonic of the signal, and comparing the measured optical power to calibration data to determine the I/Q skew. The optical power may be analyzed in a portion of the spectrum where sensitivity of the power to changes in skew is highest. The calibration data may map previously-obtained optical power measurements to corresponding known skew amounts. The system may provide more accurate skew measurements using less expensive equipment than existing skew measurement methods.

Abstract: Disclosed are a frame error concealment method and apparatus and an audio decoding method and apparatus. The frame error concealment (FEC) method includes: selecting an FEC mode based on at least one of a state of at least one frame and a phase matching flag, with regard to a time domain signal generated after time-frequency inverse transform processing; and performing corresponding time domain error concealment processing on the current frame based on the selected FEC mode, wherein the current frame is an error frame or the current frame is a normal frame when the previous frame is an error frame.

Abstract: The present invention is directed to communication systems and techniques thereof. More specifically, embodiments of the present invention provide a calibration system for optical transmitter. The calibration system provides a predetermined set of operating parameters to the optical transmitter and measures the second harmonic value of the transmitter output. A calibrated set of parameters is determined by selecting operating parameters associated with the minimum second harmonic value. There are other embodiments as well.

Abstract: This disclosure provides systems, methods, and apparatus for improving spectral efficiency of a communication system. The communication system can include a transmitter, a receiver and a communication link for communicating data between the transmitter and the receiver. The transmitter can employ a multi-carrier technique to transmit data to the receiver. The transmitter can generate a plurality of carrier signals using a receiver-side comb generator, one of which is sent to the transmitter as a pilot carrier signal combined with modulated carrier signals over an optical link. At the receiver the receiver-side comb generator uses the pilot carrier signal to generate a plurality of receiver-side carrier signals, which are used for detecting the modulated carrier signals. As the phase noise in the modulated carrier signals and the phase noise in the receiver-side carrier signals have the same characteristics, the phase noise is cancelled at the receiver, resulting in improved detection.

Abstract: An optical transmission device includes: a drive signal generate unit that generates a drive signal; a modulation unit that modulates an optical signal in accordance with the drive signal; a detect unit that detects a fluctuation of a signal component of the drive signal with respect to an optical signal output by the modulation unit; and a correct unit that corrects a parameter of the drive signal generate unit in accordance with a detect result of the detect unit so that a non-linear characteristic of the modulation unit gets closer to a linear characteristic.

Abstract: A monitoring system for a multi-laser module includes detectors corresponding to each laser and situated to receive a portion of the associated laser beam uncombined with other beams. Laser characteristics are measured and stored, and in operation are used to identify device failures. A comparator receives a reference value and compares the reference value with a current operational value. If the current value is less that the reference value, a possible failure is indicated. Signal cross-coupling among the detectors is also used to identify undesirable scattering that can be associated with surface contamination or device failure.

Abstract: A system for suppressing even-order distortion in a photonic link includes a laser for providing laser light to a first input of a Mach-Zehnder modulator (MZM), where the MZM has a second input for receiving an RF input signal, a third input for applying a DC bias voltage to the MZM, and an optical signal output. A dc-voltage-biased photodiode has an input, coupled to the MZM optical signal output, and a modulated RF signal output. The MZM DC bias voltage is set at a value to generate an even-order distortion amplitude substantially equal to an even-order distortion amplitude from the photodiode and 180 degrees out of phase so as to substantially cancel the photodiode even-order distortion. The invention provides the cancellation of photodiode even-order distortion via predisortion linearization with a MZM biased slightly away from quadrature, employing a single fiber run and a single photodiode. The invention provides an improvement in carrier-to-intermodulation ratio (CIR) upwards of 40 dB.

Abstract: A hybrid wavelength division multiplexing system wherein one or more intensity modulated signals generated by optical amplitude modulators are co-propagated with one or more phase modulated signals generated by optical phase modulators, wherein a drive voltage of said optical amplitude modulator is adapted to reduce an extinction ratio of the intensity modulated signal to minimize a cross-phase modulation impact on the co-propagating phase modulated signals.

Abstract: An optical transmission apparatus includes transmitters configured to correspond to the polarization multiplexing optical signals, each of at least two of the transmitters including a first computing unit that computes, based on information regarding an optical transmission line including a plurality of spans and a polarization multiplexing optical signal, data waveform information regarding the transmitter and transmits the data waveform information to at least one another transmitter provided for at least one another polarization multiplexing optical signal, and a second computing unit that receives data waveform information from the at least one another transmitter provided for the at least one another polarization multiplexing optical signal and pre-equalizes or reduces cross phase modulation occurring in the optical transmission line of a transmission signal based on the data waveform information received from the at least one another transmitter provided for the at least one another polarization multipl

Abstract: An optical modulator including an information-containing radio frequency signal input; a semiconductor device having an optical input optically for receiving the coherent light beam, and a electrode connected to said radio frequency signal input and having a modulated bias potential so that current is generated in the second semiconductor device and extracted therefrom, while the coherent light beam is optically modulated by the signal changing the carrier density in the semiconductor device.

Abstract: An Ethernet adapter system may include a transmitter to insert a payload type identifier sequence in a generic frame procedure header to indicate that a network is a converged enhanced Ethernet network. The transmitter may insert idle sequences in a stream of data frames transmitted along a link. The system may include a receiver to recognize a condition and to force a loss of synchronization condition on the link that will be converted by the receiver into a loss of light condition. The receiver may scan the transmitted stream of data frames for invalid data frames and introduce a code into the stream of data frames whenever an invalid data frame is detected.

Abstract: A transceiver architecture for wireless base stations wherein a broadband radio frequency signal is carried between at least one tower-mounted unit and a ground-based unit via optical fibers, or other non-distortive media, in either digital or analog format. Each tower-mounted unit (for both reception and transmission) has an antenna, analog amplifier and an electro-optical converter. The ground unit has ultrafast data converters and digital frequency translators, as well as signal linearizers, to compensate for nonlinear distortion in the amplifiers and optical links in both directions. In one embodiment of the invention, at least one of the digital data converters, frequency translators, and linearizers includes superconducting elements mounted on a cryocooler.

Abstract: The present invention relates to an improved installation for conveying electrical signals carried by a first triaxial cable (2) to a second triaxial cable (6) and vice versa. It comprises: a first interface (3) between the first triaxial cable (2) and a fiber optic cable (4) and a second interface (5) between the fiber optic cable (4) and the second triaxial cable (6). A television camera (7) is connected to a remote camera control unit (1) via this installation. The first triaxial cable (2) connects the camera control unit (1) with the first interface (3). The first interface (3) comprises a first adapter converting electrical signals, conveyed by the first triaxial cable (2), to optical signals. The fiber optic cable (4) transmits optical signals to the second interface (5). The second interface (5) comprises a second adapter converting optical signals to electrical signals. The second triaxial cable (6) transmits the electrical signals to the television camera (7).

Abstract: A driving element which performs driving according to a level of a voltage signal to be transmitted optically, a modulation current driving circuit configured to supply a modulation current modulated by the driving element to a light source for optical communication configured to convert a current signal into light and to output the light, and a constant current supply circuit configured to supply a constant current to the light source for optical communication are included. Then, when the voltage signal is at a first level, the driving element is turned on and the modulation current driving circuit supplies the modulation current to the light source for optical communication. When the voltage signal is at a second level, the driving element is turned off and the modulation current driving circuit stops supplying the modulation current. The present technique can be applied, for example, to an optical transmission system.

Abstract: A method to process applicable to coherent optical channels with either linear or nonlinear phase noise includes: splitting a received sequence of data into clusters of points according to a cumulative log-likelihood function from constellation obtained in a previous iteration; generating new constellation points by calculating a center of mass of the clusters of points; repeating until convergence or until a predetermined number of iterations has been reached to determine a signal constellation; and transmitting signals over the coherent optical channels with nonlinear phase noise using the disclosed signal constellation and LDPC-coded modulation concepts.

Abstract: According to a first aspect of the present invention there is provided an apparatus for performing power equalization and phase correction of two signals (400). The apparatus comprises a first hybrid coupler (401) configured to operate as a power combiner, and a second hybrid coupler (402) configured to operate as a power divider, wherein the apparatus is configured to provide an output (406) of the first hybrid coupler as an input (407) to the second hybrid coupler.

Abstract: A WDM-PON system configured to perform an asymmetric wavelength division multiplexing and demultiplexing is proposed. A receiving end of WDM-PON system configured to receive a light transmitted from a transmission end including a first wavelength division multiplexer/demultiplexer includes a second wavelength division multiplexer/demultiplexer configured to demultiplex the light received rom the transmission end, where the second bandwidth of wavelength division multiplexer/demultiplexer is substantially greater than that of the first wavelength division multiplexer/demultiplexer.

Abstract: An optical homodyne communication system and method in which a side carrier is transmitted along with data bands in an optical data signal, and upon reception, the side carrier is boosted, shifted to the center of the data bands, and its polarization state is matched to the polarization state of the respective data bands to compensate for polarization mode dispersion during transmission. By shifting a boosted side carrier to the center of the data bands, and by simultaneously compensating for the effects of polarization mode dispersion, the provided system and method simulate the advantages of homodyne reception using a local oscillator. The deleterious effects of chromatic dispersion on the data signals within the data bands are also compensated for by applying a corrective function to the data signals which precisely counteracts the effects of chromatic dispersion.

Abstract: An optical transceiver includes an optical IC coupled to a processor IC. For transmit, the optical IC can be understood as a transmitter IC including a laser device or array. For receive, the optical IC can be understood as a receiver IC including a photodetector/photodiode device or array. For a transmitter IC, the processor IC includes a driver for a laser of the transmitter IC. The driver includes an equalizer that applies high frequency gain to a signal transmitted with the laser device. For a receiver IC, the processor IC includes a front end circuit to interface with a photodetector of the receiver IC. The front end circuit includes an equalizer that applies high frequency gain to a signal received by the receiver IC. The driver can be configurable to receive a laser having either orientation: ground termination or supply termination.

Abstract: A non-linear distortion compensator includes: a first signal generator configured to generate a signal with a second multivalued level lower than a first multivalued level from an input signal; a non-linear distortion calculator configured to calculate non-linear distortion of the signal with the first multivalued level based on the signal with the second multivalued level generated by the first signal generator; and a non-linear compensator configured to compensate the non-linear distortion of the signal with the first multivalued level based on the non-linear distortion calculated by the non-linear distortion calculator.

Abstract: An optical system has an optical emitter that transmits an optical signal through an optical fiber. An optical detector detects light from the fiber and provides an analog signal indicative of such light. A crosstalk cancellation element is configured to receive an electrical signal from the optical emitter and to adjust such signal in order to form a cancellation signal that models the optical and/or electrical crosstalk affecting the analog signal. The cancellation signal is subtracted from the analog signal thereby removing optical and/or electrical crosstalk from the analog signal.

Abstract: A lighting system includes light fixtures not in communications with and not synchronized with one another, and one or more light sensors. Each light fixture separately emits data encoded visible light including light fixture information encoded therein in a manner that avoids visually perceptible flicker and enables light fixture information emitted by one light fixture to be distinguished from light fixture information emitted by other light fixtures. The light fixture information is encoded into data encoded visible light such that a difference between different levels of the data encoded visible light is indicative of an illumination capability of the light fixture and such that visually perceptible flicker is avoided. Each light sensor separately receives portions of data encoded light visible light emitted by multiple light fixtures and separately determines the identity of and the maximum and present illumination contributions for each light fixture.

Abstract: An Ethernet adapter system may include a transmitter to insert a payload type identifier sequence in a generic frame procedure header to indicate that a network is a converged enhanced Ethernet network. The transmitter may insert idle sequences in a stream of data frames transmitted along a link. The system may include a receiver to recognize a condition and to force a loss of synchronization condition on the link that will be converted by the receiver into a loss of light condition. The receiver may scan the transmitted stream of data frames for invalid data frames and introduce a code into the stream of data frames whenever an invalid data frame is detected.

Abstract: A transmitter reduces or minimizes pulse narrowing. In one approach, an optical transmitter is designed to transmit data over an optical fiber at a specified data rate using on-off keying. The transmitter includes a pre-converter electrical channel and a limiting E/O converter. The pre-converter electrical channel produces a pre-converter signal that drives the limiting E/O converter. The pre-converter electrical channel is designed to reduce pulse narrowing in the pre-converter signal. In one implementation, the pre-converter electrical channel includes a pre-emphasis filter that is designed to minimize pulse width shrinkage.

Abstract: Disclosed are an apparatus and method configured to process video data signals operating on a passive optical network (PON). One example method of operation may include receiving a data signal at an optical distribution network node (ODN) and identifying signal interference in the data signal. The method may also include modifying a shape of the data signal in the electrical domain and transmitting the modified data signal to at least one optical termination unit (ONT).

Abstract: An optical transmitter configured to perform digital signal equalization directed at mitigating the detrimental effects of a frequency roll-off in the transmitter's optical I-Q modulator. In various embodiments, a frequency-dependent spectral-correction function used for the digital signal equalization can be constructed to cause the spectrum of the modulated optical signal generated by the transmitter to have a desired degree of flatness in the vicinity of an optical carrier frequency and/or to at least partially mirror the frequency roll-off in the optical I-Q modulator.

Abstract: Aspects of the invention provide transmitters and receivers for managing multiple optical signals. High order modulation, such as phase and/or amplitude modulation, is used to achieve multiple bits per symbol by transporting multiple asynchronous data streams in an optical transport system. One or more supplemental multiplexing techniques such as time division multiplexing, polarization multiplexing and sub-carrier multiplexing may be used in conjunction with the high order modulation processing. This may be done in various combinations to realize a highly spectrally efficient multi-data stream transport mechanism. The system receives a number of asynchronous signals which are unframed and synchronized, and then reframed and tagged prior to the high order modulation. Differential encoding may also be performed. Upon reception of the multiplexed optical signal, the receiver circuitry may employ either direct detection without a local oscillator or coherent detection with a local oscillator.

Abstract: A system and method for improving receiver sensitivity of an DD-OFDM system without using frequency guard band. The method having: interleaving input data to the DD-OFDM system to generate interleaved data; encoding the input data with a first recursive systematic convolutional code to generate a first recursive systematic convolutional encoded data; encoding the interleaved data with a second recursive systematic convolutional code to generate a second recursive systematic convolutional encoded data; puncturing the first recursive systematic convolutional encoded data and the second recursive systematic convolutional encoded data to generate a parity sequence; and combining the input data with the parity sequence to generate coded DD-OFDM data; wherein the parity sequence is generated by using different puncturing rates for different OFDM subcarriers, so as to obtain higher spectral efficiency.

Abstract: A distortion compensation circuit compensates for distortion generated by one or more non-linear elements such as a laser device and/or an optical fiber and may include a primary signal path for carrying an input signal and a secondary signal paths for generating distortion. The distortion compensation circuit may also include a controllable phase inverters and a tunable filter. For example, the secondary signal path may include a distortion generator to produce distortion products from the input signal and a signal controlled phase inverter that inverts the phase of the distortion products and a tunable filter that adjusts the phase of the frequency dependent distortion. The phase inversion and tunable filter may be controlled in response to control signals generated based on one or more parameters such as, for example, laser power, input RF channel loading, temperature, and fiber length.

Abstract: The present invention provides a wavelength division multiplexing system and a method and device for its residual dispersion compensation, wherein the device for residual dispersion compensation of wavelength division multiplexing system comprises: a performance parameter detecting device for receiving and detecting performance parameter of receiving terminal optical signal and sending detecting result of the performance parameter to a central control device; the central control device for deciding a dispersion regulating mode of a tunable dispersion compensator according to the detecting result of the performance parameter and sending the dispersion regulating mode to a tunable dispersion compensator control device through control signaling; and the tunable dispersion compensator control device for receiving the control signaling sent by the central control device and adjusting dispersion compensation amount of the tunable dispersion compensator according to the control signaling in order to make residual di

Abstract: An optical network and method of protection switching between first and second transceivers where dispersion compensation is effected electrically in the transmitters. The method includes detecting, at the second transceiver, a signal failure of a signal transmitted from the first transceiver and, upon detecting the signal failure, signaling the first transceiver to change its compensation function. The signaling can be done by encoding overhead bits in a signal transmitted from the second to the first transceiver. Another method of protection switching includes both transceivers toggling alternate reception paths upon detecting a signal failure and changing their dispersion compensation function to that of their respective alternate path.

Abstract: A signal processing apparatus configured to correct a distortion introduced by a signal processing path into a processed signal comprising a transformer that transforms the processed signal into a transformed signal in frequency domain, a processor that determines a first correction function and a second correction function upon the basis of a transfer function of the signal processing path, a first multiplier that multiplies values of the transformed signal with coefficients of the first correction function to obtain a first corrected signal, a signal reverser that reverses an order of values in a copy of the transformed signal to obtain a reversed transformed signal, a second multiplier that multiplies values of the reversed transformed signal with coefficients of the second correction function to obtain a second corrected signal, and an adder that adds the first corrected signal and the second corrected signal to obtain a corrected output signal.

Abstract: An optical transmission apparatus receives an optical signal of an optical wavelength. The optical transmission apparatus has a variable wavelength filter, a neighboring frequency detection unit, and an ADC/DSP. The variable wavelength filter detects a neighboring of another optical transmission apparatus that receives an optical signal of a wavelength different from the wavelength. The neighboring frequency detection unit determines whether or not a second frequency supported by the another optical transmission apparatus where a neighboring has been detected by the variable wavelength filter is different from a first frequency supported by the optical transmission apparatus. The ADC/DSP changes a parameter for removing a phase noise from the optical signal of the wavelength according to a difference between the first frequency and the second frequency when it is determined that the second frequency is different from the first frequency.

Abstract: Linearized optical transmitter units are described for a hybrid optical fiber coaxial cable network. The linearized optical transmitter unit can comprise a directly-modulated or externally-modulated laser optically coupled to an optical conduit directed to an optical fiber communications link and electrically coupled to an electrical RF source line that provides an RF source to drive the laser or an external modulator for a light beam from the laser. A linearization information electrical component comprising memory and/or a processor, and a data output configured to transmit linearization enabling data for input into a direct digital synthesis engine that enables the direct digital synthesis engine to generate an RF signal wherein nonlinear responses of the transmitter and/or the optical fiber communications link are pre-compensated, in which the data is specific for the optical transmitter and/or the optical fiber communications link.

Abstract: The embodiments of the present invention describe a method for optimizing the capacity of an optical communication network that uses wavelength division multiplexing, wherein the spectral distribution of the signals intended to be transmitted over a plurality of channels is done dynamically through the use of a variable spectrum grid whose spectral spacings between two successive channels are determined based on the spectral width of said signals and in which dynamic filtering of said signals is carried out before their transmission in order to adjust their spectral width based on the available spectral space, and thereby reduce crosstalk between adjacent channels when the signals are transmitted.

Abstract: An optical homodyne communication system and method in which a side carrier is transmitted along with data bands in an optical data signal, and upon reception, the side carrier is boosted, shifted to the center of the data bands, and its polarization state is matched to the polarization state of the respective data bands to compensate for polarization mode dispersion during transmission. By shifting a boosted side carrier to the center of the data bands, and by simultaneously compensating for the effects of polarization mode dispersion, the provided system and method simulate the advantages of homodyne reception using a local oscillator. The deleterious effects of chromatic dispersion on the data signals within the data bands are also compensated for by applying a corrective function to the data signals which precisely counteracts the effects of chromatic dispersion.

Abstract: For providing circuit arrangement and method for transmitting signals from a data source to a data sink, the signals being TMDS encoded, the driver circuit is supplied by a connection interface, connected upstream, assigned to data source, with supply voltage, electrical TMDS encoded signals are electro-optically converted by an LED connected downstream of the driver circuit and coupled into an optical fiber as light supplied with TMDS encoded signals, the direct current portion supplied from TMDS transmitter to connection interface, to data source, is converted by driver circuit to a modulated signal current for controlling LED.

Abstract: A modulation method, especially an optical modulation method, using the principle of discrete IQ modulation. The modulation method includes generating a carrier signal (Sc) and splitting the carrier signal at a splitting position in an I branch signal and a Q branch signal; modulating the amplitude of the I branch signal according to a first modulation signal and modulating the amplitude of the Q branch signal according to a second modulation signal, each of the first and second modulation signals being arranged to adopt a given number of values according to a given number of constellation points of a given modulation scheme; phase shifting the signal in the Q branch versus the signal in the I branch; and combining the signals in the I branch and Q branch at a combining position. The combined modulated signal (Stx,mod) is arranged to be transmitted over a transmission path.

Abstract: The present disclosure provides electrical domain suppression of linear crosstalk in optical communication systems using single-carrier implementations. This electrical domain suppression applies spectral shaping in the electronic radio frequency (RF) domain. Advantageously, spectral shaping in the electronic RF domain transfers system complexity from the bulk optical domain into the highly integrated CMOS (or equivalent) domain. The spectral shaping can include electronic circuitry including an electrical filtering block and a signal linearization block prior to optical modulation. The electrical filtering block suppresses coherent interference terms and can include an RF-domain low pass filter. The signal linearization block linearizes modulator response to compensate spectral regrowth due to nonlinear mixing in the modulator.

Abstract: An optical transmission and reception system in which a plurality of tributary signals are converted into multilevel modulated light for transmission and reception. An apparatus for transmitting multilevel modulated light includes: FECs which perform error correction processing including addition of a tributary identifier; and a GEAR BOX which performs rate conversion on the processed signals.

Abstract: In accordance with embodiments of the present disclosure, a method for compensation of noise in an optical device is provided. The method may include calculating noise present in an optical carrier signal. The method may also include generating quadrature amplitude modulation input signals, the quadrature amplitude modulation input signals each including a term for compensation of the noise based on the calculated noise. The method may further include modulating the optical carrier signal to generate a modulated optical signal based on quadrature amplitude modulation input signals.

Abstract: [PROBLEM] Providing an optical source that outputs optical frequency modulated light having a constant output optical intensity. [MEANS FOR SOLVING THE PROBLEM] Provided is a light source apparatus that outputs an optical signal having an optical frequency corresponding to a frequency control signal, the light source apparatus including a laser light source section that outputs laser light having an optical frequency corresponding to the frequency control signal; and an optical intensity adjusting section that compensates for intensity change of the laser light to output laser light in which the intensity change caused by a change in the optical frequency is restricted.

Abstract: A dispersion correction circuit is provided for use with an input driving signal. The dispersion correction circuit includes an input portion an output portion and a filter portion. The input portion is arranged to receive the input driving signal. The output portion can output an output signal based on the input driving signal. The filter portion is disposed between the input portion and the output portion. The filter portion includes a first varactor, a DC bias portion, and a second varactor. The DC bias portion provides a DC bias to the first varactor. The first varactor is arranged in a first polarity direction, and the second varactor is arranged in a second polarity direction that is the same as the first direction.

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: 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.