| Class / Patent application number | Description | Number of patent applications / Date published |
|---|
| 398187000 | Frequency modulation | 24 |
| 20080247765 | POWER SOURCE FOR A DISPERSION COMPENSATION FIBER OPTIC SYSTEM - This invention generally relates to an optical filter for a fiber optic communication system. An optical filter may be used, following a directly modulated laser source, and converts a partially frequency modulated signal into a substantially amplitude modulated signal. The optical filter may compensate for the dispersion in the fiber optic transmission medium and may also lock the wavelength of the laser source. | 10-09-2008 |
| 20090003842 | CHIRPED LASER WITH PASSIVE FILTER ELEMENT FOR DIFFERENTIAL PHASE SHIFT KEYING GENERATION - Apparatus and methods for driving a transmitter to generate DNPSK signals is disclosed including generating N data streams comprising data symbols and for each of a plurality of sets of N simultaneous data symbols of the N data streams, imposing signals are on L of a plurality of signal lines, with the value of L corresponding to values of the N simultaneous data symbols. Signals on the plurality of signal lines are ANDed with a clock signal synchronized with the N data streams to produce RZ signals. The RZ signals are summed and the summed signal is input to a laser that produces an output having frequency modulation corresponding to the magnitude of the summed signal. The output of the laser is passed through an optical discriminator. | 01-01-2009 |
| 20090041472 | AUTOMATIC ADJUSTING SYSTEM OF FREQUENCY SHIFT KEYING MODULATOR - An optical modulator achieving high extinction ratio and an optical modulator system. By a control system performing an adjustment method comprising predetermined steps by applying a bias voltage daringly to a modulation electrode for switching the USB signal and LSB signal of an established optical SSB modulator or optical FSK modulator, a means for adjusting bias voltage applied to each bias electrode preferably automatically is provided and a bias point where the extinction ratio of an optical modulator is maximized can be obtained. | 02-12-2009 |
| 20090080905 | HIGH POWER, LOW DISTORTION DIRECTLY MODULATED LASER TRANSMITTER - An optical transmitter is disclosed wherein a directly modulated laser outputs a frequency modulated signal through a semiconductor optical amplifier. Both the optical transmitter and semiconductor amplifier are modulated according to an output of a digital data source. An optical filter is positioned to receive an output of the semiconductor optical amplifier and has a frequency dependent transmission function effective to convert the amplified signal into a filtered signal having enhanced amplitude modulation. In some embodiments, the semiconductor optical amplifier is coupled to the digital data source by means of a compensation circuit configured to high-pass filter the output of the digital signal source. In other embodiments, the semiconductor optical amplifier is coupled to the digital data source by means of a compensation circuit configured to produce an output including a first-order time derivative of the output of the digital signal source. | 03-26-2009 |
| 20090245812 | OPTICAL TRANSMISSION CIRCUIT - Provided is an optical transmission circuit capable of realizing a high-quality optical signal waveform with low power consumption. An optical transmission circuit ( | 10-01-2009 |
| 20090304393 | SUPER HIGH SPEED OPTICAL FREQUENCY SWEEPING TECHNOLOGY - 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 ( | 12-10-2009 |
| 20100014874 | PHASE CONTROL OPTICAL FSK MODULATOR - There is provided an optical modulator capable of controlling the phase of a USB signal and the phase of an LSB signal of an optical FSK modulated signal. A modulation signal is applied to a main Mach-Zehnder electrode (or an electrode C) ( | 01-21-2010 |
| 20100040382 | DISPERSION TOLERANT OPTICAL SYSTEM AND METHOD - 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 Δν comprising a first instantaneous frequency (ν | 02-18-2010 |
| 20100150575 | Method and Optical Transmitter for Optimizing DC Bias Voltage Input to Optical Modulator with Duo-Binary Modulation - An optical transmitter is provided which optimizes DC bias voltage input to an optical modulator employing a duo-binary modulation scheme. The optical transmitter including a signal combiner which converts an electrical signal for optical transmission into a high-speed electrical signal, and an optical modulator which receives and modulates the high-speed electrical signal from the signal combiner further includes a frequency divider to divide frequency of a sinusoidal watchdog clock signal from the signal combiner and to output the divided signal to be added to direct current (DC) bias voltage input to the optical modulator; and a bias voltage modifier to adjust the DC bias voltage by analyzing the modulated electrical signal from the optical modulator. Accordingly, it is possible to conveniently optimize the DC bias voltage with a simple design. | 06-17-2010 |
| 20100172655 | NON-FEEDBACK PRE-ENCODER FOR OPTICAL DQPSK MODULATION - A non-feedback pre-encoder for optical DQPSK modulation includes four differential encoders, two power splitters, two delay lines, one exclusive OR gate and a cross switch. Each of two data streams input to the pre-encoder is divided into two identical streams by one of the power splitter, called an upper stream and a lower stream, respectively. Every upper stream is differentially encoded by one of the differential encoders, and outputs of the differential encoders are fed into the XOR gate. An output of the XOR gate drives the cross switch as a control signal. Two lower input data stream are delayed in the delay lines, and fed into the cross switch. The outputs of the cross switch are differentially encoded, separately, where outputs of the pre-encoder are provided. The invention eliminates the speed limitation due to the electrical propagation by constructing an all-forward control signal. | 07-08-2010 |
| 20110206383 | SYSTEMS AND METHODS FOR PROVIDING AN OPTICAL INFORMATION TRANSMISSION SYSTEM - The present invention describes systems and methods of providing optical information transmission systems. An exemplary embodiment of the present invention includes a precoder configured to differentially encode a binary data signal, a duobinary encoder configured to encode the differentially encoded binary data signal as a three-level duobinary signal, an electrical-to-optical conversion unit configured to convert the three-level duobinary signal into a two-level optical signal, and an optical upconversion unit configured to modulate the two-level optical signal onto a higher frequency optical carrier signal and transmit the modulated higher frequency optical carrier signal onto an optical transmission medium. | 08-25-2011 |
| 20120243880 | MULTI-WAVELENGTH LIGHT SOURCE - 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. | 09-27-2012 |
| 20130028614 | OPTICAL MODULATION DEVICE AND BIAS VOLTAGE CONTROL METHOD - An optical modulation device includes a generating circuit that generates a low-frequency signal, an average value of amplitude as an alternating-current component of the low-frequency signal being different from a center value of the amplitude of the low-frequency signal, a superimposing unit that superimposes the low-frequency signal on a data signal, an optical modulator that modulates, using the superimposition of the low-frequency signal by the superimposing unit, light from a light source and outputs a light signal, a calculating circuit that calculates an amplitude average value and an amplitude center value of a low-frequency component obtained from the light signal output by the optical modulator, and a controller that controls a bias voltage of the optical modulator such that the amplitude average value is brought closer to the amplitude center value of the frequency component calculated by the calculating circuit. | 01-31-2013 |
| 20130121706 | SIGNAL TRANSMISSION AND RECEPTION DEVICE AND METHOD - A signal transmission and reception device and method are provided. The transmission method comprises generating multiple optical carriers from a basic optical carrier; modulating optical carriers, except for a predetermined optical carrier, in the optical carriers by using multiple data signals respectively, to generate multiple optical modulated signals; and synthesizing the multiple optical modulated signals and the predetermined optical carrier into a single optical signal, and transmitting the signal. The reception method comprises separating an optical signal into multiple optical carriers, the optical carriers having different frequencies and including a predetermined optical carrier; generating from the predetermined optical carrier multiple optical waves, frequencies of which correspond to frequencies of optical carriers, except for the predetermined optical carrier, in the multiple optical carriers; and demodulating the optical carriers, except for the predetermined optical carrier, in the multiple optical carriers by using the multiple optical waves respectively. | 05-16-2013 |
| 20130148983 | MODULATOR FOR FREQUENCY-SHIFT KEYING OF OPTICAL SIGNALS - 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. | 06-13-2013 |
| 20140003823 | METHODS AND ARRANGEMENTS FOR GENERATING A WAVEFORM FOR FREQUENCY SHIFT KEYING COMMUNICATIONS | 01-02-2014 |
| 20140219664 | DISPERSION TOLERANT OPTICAL SYSTEM AND METHOD - 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 Δν comprising a first instantaneous frequency (ν | 08-07-2014 |
| 20140308048 | METHODS AND ARRANGEMENTS FOR FREQUENCY SHIFT COMMUNICATIONS BY UNDERSAMPLING - 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. | 10-16-2014 |
| 20140334830 | System and Method for Generating A Frequency Modulated Linear Laser Waveform - 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. | 11-13-2014 |
| 20140369699 | SYSTEMS AND METHODS SIDEBAND HETERODYNING DETECTION - 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. | 12-18-2014 |
| 20150104193 | System and Method for Generating A Frequency Modulated Linear Laser Waveform - 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. | 04-16-2015 |
| 20150326321 | OPTICAL TRANSMISSION AND RECEPTION APPARATUS AND METHOD FOR UPLINK TRANSMISSION IN ORTHOGONAL FREQUENCY DIVISION MULTIPLE ACCESS-PASSIVE OPTICAL NETWORK (OFDMA-PON) - Provided is an optical transmission apparatus and method for uplink transmission in an orthogonal frequency division multiple access-passive optical network (OFDMA-PON), wherein the optical transmission apparatus includes a digital signal processor to output a baseband orthogonal frequency division multiplexing (OFDM) signal, a tone generator to generate a dithering tone, a synthesizer to synthesize the dithering tone and the baseband OFDM signal, and an optical source to output an output light in which a spectrum width is increased to be greater than a spectrum width of a carrier light based on the baseband OFMD signal synthesized with the dithering tone. | 11-12-2015 |
| 20160036531 | WAVELENGTH-REUSE FIBER-OPTIC TRANSMITTERS - A fiber-optic transmitter comprises a transmitter optical port, an optical circulator, a semiconductor optical amplifier, and a two-port modulation-averaging structure. The optical circulator has at least three ports, a first one of the three circulator ports being optically coupled to the transmitter optical port. The semiconductor optical amplifier has an input optical port, an output optical port, and an electrical input port. The two-port modulation-averaging structure is optically coupled between the input optical port and a third one of the three circulator ports. | 02-04-2016 |
| 20160036533 | OPTICAL TRANSMITTER AND METHOD FOR CONTROLLING BIAS OF OPTICAL MODULATOR - An optical transmitter includes: a mapper that generates an electric field information signal from transmission data; a phase rotation circuit that adds a phase rotation to the electric field information signal; a driver that generates a driving signal from the electric field information signal to which the phase rotation is added; a modulator that generates a modulated optical signal according to the driving signal; and a controller that controls a bias of the modulator according to a change in a carrier frequency of the modulated optical signal corresponding to the phase rotation that is added to the electric field information signal by the phase rotation circuit. | 02-04-2016 |
