370 results about "Frequency comb" patented technology

A method and an arrangement are provided for scalable confocal interferometry for distance measurement, for 3-D detection of an object, for OC tomography with an object imaging interferometer and at least one light source. The interferometer has an optical path difference not equal to zero at each optically detected object element. Thus, the maxima of a sinusoidal frequency wavelet, associated with each detected object element, each have a frequency difference Δf_Objekt. At least one spectrally integrally detecting, rastered detector is arranged to record the object. The light source preferably has a frequency comb, and the frequency comb differences Δf_Quelle are changed in a predefined manner over time in a scan during measuring. In the process, the frequency differences Δf_Quelle are made equal to the frequency difference Δf_Objekt or equal to an integer multiple of the frequency differences Δf_Objekt at least once for each object element.

The invention relates to scanning pulsed laser systems for optical imaging. Coherent dual scanning laser systems (CDSL) are disclosed and some applications thereof. Various alternatives for implementation are illustrated, including highly integrated configurations. In at least one embodiment a coherent dual scanning laser system (CDSL) includes two passively modelocked fiber oscillators. The oscillators are configured to operate at slightly different repetition rates, such that a difference δfr in repetition rates is small compared to the values fr1 and fr2 of the repetition rates of the oscillators. The CDSL system also includes a non-linear frequency conversion section optically connected to each oscillator. The section includes a non-linear optical element generating a frequency converted spectral output having a spectral bandwidth and a frequency comb comprising harmonics of the oscillator repetition rates. A CDSL may be arranged in an imaging system for one or more of optical imaging, microscopy, micro-spectroscopy and / or THz imaging.

The invention discloses a method and a system for sending an SRS (survey reference signal); the method comprises the following steps: user equipment (UE) transmits the SRS to a base station on a time domain resource, a frequency domain resource and / or a code domain resource, wherein the time domain resource comprises the last time domain sign, the first time domain sign or the last but one time domain sign of a sub-frame of an SRS cycle; the frequency domain resource comprises a frequency domain location of the SRS or a sending frequency comb of the SRS, the code domain resource is obtained by the following method: a sequence group number of the SRS is generated by the UE according to a parameter which is configured for the UE by the base station through a high level signaling and is proprietary by users, and the code domain resource which is needed for sending the SRS is determined according to the generated sequence group number of the SRS. The available resource of the SRS is increased, the user multiplexing capacity of the SRS is improved, and the channel estimation quality of the base station to the SRS is improved, therefore, the application of the coordinated multi-point transmission technology to the system is supported effectively.

The invention provides a feasible Terabit transmission rate coherent light orthogonal frequency division multiplexing system which is of simpler system structure, and comprises a transmitting end and a receiving end, wherein, the transmitting end comprises a transmitting end optical carrier generation module which comprises a transmitting end laser, an optical comb generator and an optical demultiplexer. In the system, on the basis of single light source, the optical comb generator is utilized to obtain light frequency combs with multiple wavelengths, which are used as optical carriers of base band OFDM signals, and mutually orthogonal OFDM frequency bands are generated on an optical domain, thus a plurality of radio frequency (RF) oscillation sources with complex structures are not need in the prior art. By utilizing the system, an OBM-COOFDM (orthogonal-band-multiplexed-coherent optical orthogonal frequency division multiplexing) optical signal is obtained under the condition of not using the RF oscillation sources, thus greatly reducing the complexity and cost of a transmitter; and the system has better feasibility of the OBM-COOFDM hardware, thus reducing the higher sampling rate requirements of the traditional COOFDM Terabit transceiver on a digital to analog converter (DAC) and an analog to digital converter (ADC).

A waveform synthesizer comprising for synthesizing RF lightwave waveforms in the optical domain. These waveforms are constructed by generating their constituent Fourier frequency components or tones and then adjusting the amplitudes of those frequency components or tones. The apparatus includes: a RF-lightwave frequency-comb generator; and a multi-tone, frequency selective amplitude modulator coupled to the RF-lightwave frequency-comb generator for generating a continuous-wave comb comprising a set of RF tones amplitude modulated onto a lightwave carrier.

An optical data link has a transmitter and a receiver with coherent detection at the receiver and more than one optical carrier frequency. The optical carrier frequencies are generated by a frequency comb source in both the transmitter and the receiver. The frequency comb sources generate frequency combs that have frequency components and a free spectral range. The optical carrier frequencies transport more than one optical channel. Either at least one frequency component or the free spectral range of the optical comb generated at the receiver is locked to the comb generated at the transmitter by an optical phase locked loop, or an electrical phase locked loop or a feed-forward carrier recovery generates an intermediate frequency carrier reference that is routed to more than one channel to demodulate the data.

A frequency comb laser providing large comb spacing is disclosed. At least one embodiment includes a mode locked waveguide laser system. The mode locked waveguide laser includes a laser cavity having a waveguide, and a dispersion control unit (DCU) in the cavity. The DCU imparts an angular dispersion, group-velocity dispersion (GVD) and a spatial chirp to a beam propagating in the cavity. The DCU is capable of producing net GVD in a range from a positive value to a negative value. In some embodiments a tunable fiber frequency comb system configured as an optical frequency synthesizer is provided. In at least one embodiment a low phase noise micro-wave source may be implemented with a fiber comb laser having a comb spacing greater than about 1 GHz. The laser system is suitable for mass-producible fiber comb sources with large comb spacing and low noise. Applications include high-resolution spectroscopy.

The application provides a low noise fiber laser frequency combs device with controllable carrier envelope phase shift frequency. The low noise fiber laser frequency combs device with controllable carrier envelope phase shift frequency comprises an optical path structure and a circuit structure, wherein the optical path structure comprises an oscillator, an acousto-optic frequency shifter, an optical fiber amplifier, a pulse compressor, an optical fiber spread spectrum device and a coherent heterodyne beat device; and the circuit structure comprises a feed-forward circuit control phase device and a phase-locked loop circuit control repetition frequency device. The fiber laser oscillator can ensure long-time operation of a system, so that the stability of the system is superior to that of a system adopting a solid laser oscillator; through the technologies of optimizing intracavity net dispersion of the fiber oscillator, introducing an inner cavity modulator in the oscillator, adopting the feed-forward acousto-optic frequency shifter, and the like, the low noise fiber laser frequency combs device can be realized; and meanwhile, due to the application of the acousto-optic frequency shifter, the carrier envelope phase shift frequency of the optical frequency combs can be accurately regulated, so that the optical frequency combs device with precise phase position regulation and secular stability is provided for realizing applications such as optical frequency standard, attosecond science and non-linear optics.

Methods and apparatus for generating a frequency comb and for its use in analyzing materials and in telecommunications. The frequency comb is generated by passing pulsed light from a laser through an optical fiber having a constriction. The frequency comb comprises a plurality of monochromatic components separated in frequency by a substantially constant frequency increment. The monochromatic components are used to probe materials for analysis. In preferred embodiments, the materials are DNA, RNA, PNA and other biologically important molecules and polymers. Optical responses are observed and used to analyze or identify samples. In telecommunication applications, the individual monochromatic components serve as carriers for individual communication channels that can carry information of any of a variety of types, such as voice, data and images.

The invention discloses a multi-antenna parameter configuration method and a multi-antenna parameter configuration device for sounding reference signals (SRSs), which aim to solve the problem that multi-antenna SRS parameter configuration cannot be determined in the prior art. According to the invention, an e-node-B (eNB) informs user equipment (UE) of transmitting the parameters of the SRSs through a high layer signaling, the UE determines the parameter of the SRS transmitted by every antenna port according to the number of the antenna ports which transmit the SRSs and a preset mapping relation, the circulated displacement of every antenna part is distributed at equal intervals, and the maximal value of the interval is taken; when the number of the antenna ports which transmit the SRSs is 4, the frequency combs of the antenna port 0 and the antenna port 1 are kTC; and the frequency combs of the antenna port 2 and the antenna port 3 which correspond to a part of circulated displacement information are kTC, and the frequency combs of the antenna port 2 and the antenna port 3 which correspond to the rest circulated displacement information are 1-kTC. By adopting the technical scheme, a terminal can determine the parameter of the SRS transmitted by every antenna port according to the configured implicit mapping relation, so that the signaling overhead can be saved, and the configuration flexibility can be ensured.

The invention concerns a laser system with a frequency comb generator for generating a comb of optical frequencies having an offset frequency and a plurality of equidistant modes, wherein the laser system further preferably comprises at least one stabilizer for stabilizing the frequency comb onto a certain offset frequency and / or onto a certain mode spacing. The laser system further comprises an optical amplifier for amplifying the frequency comb coupled out of the frequency comb generator, the amplification factor of this amplifier being variable; and the amplifier is followed by a Raman medium for generating a Raman shift of the frequency comb.

Feedback loops can be used to shift and stabilize the carrier-envelope phase of a frequency comb from a mode-locked fibers laser or other optical source. Compared to other frequency shifting and stabilization techniques, feedback-based techniques provide a wideband closed-loop servo bandwidth without optical filtering, beam pointing errors, or group velocity dispersion. It also enables phase locking to a stable reference, such as a Ti:Sapphire laser, continuous-wave microwave or optical source, or self-referencing interferometer, e.g., to within 200 mrad rms from DC to 5 MHz. In addition, stabilized frequency combs can be coherently combined with other stable signals, including other stabilized frequency combs, to synthesize optical pulse trains with pulse durations of as little as a single optical cycle. Such a coherent combination can be achieved via orthogonal control, using balanced optical cross-correlation for timing stabilization and balanced homodyne detection for phase stabilization.

An optical communication device and an optical communication method are provided. The optical communication device includes a laser source, an optical amplifier, and an optical signal generating chip. The laser source generates a laser beam. The optical amplifier is coupled to the laser source and amplifies light intensity of the laser beam in a specific wavelength band. The optical signal generating chip includes a micro-resonator and a modulation module. The micro-resonator is coupled to the optical amplifier and generates a multi-wavelength frequency comb according to the amplified laser beam. The modulation module is coupled to the micro-resonator and modulates a communication signal set to generate a plurality of optical modulated signals according to the multi-wavelength frequency comb.

The invention discloses a coherent light frequency comb based channelized broadband multi-frequency measuring system, which relates to the field of optical communication technology and comprises a seed light source generation module, a signal light frequency comb, a vibration light frequency comb, a first Mach-Zehnder modulator and a coherent receiving module. The seed light source generating module is respectively connected with the signal light frequency comb and the vibration light frequency comb and used for transmitting generated signal light and vibration light to the signal light frequency comb and the vibration light frequency comb respectively, the signal light frequency comb is connected with the first Mach-Zehnder modulator, the first Mach-Zehnder modulator is connected with the coherent receiving module, and the vibration light frequency comb is connected with the coherent receiving module. The coherent light frequency comb based channelized broadband multi-frequency measuring system has the advantages of high flexibility, low amplifying noise and high accuracy, can measure multi-frequency-point radio frequency signals in a real-time, parallel and broadband manner. Besides, testing equipment is simple and cost is low.

The invention relates to a light frequency reference fiber femtosecond light frequency comb with tunable broadband repetition frequency. The comb comprises a hybrid-locking-based erbium-doped fiber femtosecond laser device with tunable broadband repetition frequency, a reference laser locking system based on piezoelectric ceramic, a reference laser locking system based on a pumping current, a computer control system and a temperature control system, wherein the erbium-doped fiber femtosecond laser device is an annular chamber structure and is internally added with an electric control optical delay wire, and the repetition frequency of the laser device can realize continuous tunable broadband. For realizing light frequency reference femtosecond pulse output, rapid and slow piezoelectric ceramics and the pumping current are employed to cooperatively control beat frequency of the femtosecond laser device and two reference laser devices, the rapid piezoelectric ceramics fixing structure which is easy to use is designed, and a temperature control box is further designed to acquire stable beat frequency; the light frequency reference fiber femtosecond light frequency comb has advantages of light frequency reference output, tunable broadband repetition frequency, good stability and small size and further has application potential in the industrial environment.

A WDM communication system having two optical-frequency comb sources (OFCSs) that are substantially phase-locked to one another, with one of these OFCSs used at a transmitter to produce a WDM communication signal and the other OFCS used at a receiver to produce multiple local-oscillator signals suitable for homodyne detection of the WDM communication signal received from the transmitter. In one embodiment, the transmitter has (i) a first OFCS adapted to generate a first frequency comb and (ii) an optical modulator adapted to use the first frequency comb to generate a WDM communication signal for transmission to the receiver, this WDM signal having at least two beacon lines. The receiver has a second OFCS adapted to produce a second frequency comb such that the second frequency comb has at least two comb lines having the beacon frequencies, the phases of which comb lines are locked to the phases of the beacon lines of the received WDM signal.

Embodiments of the invention provide apparatuses and methods for phase correlated seeding of parametric mixer and for generating coherent frequency combs. The parametric mixer may use two phase-correlated optical waves with different carrier frequencies to generate new optical waves centered at frequencies differing from the input waves, while retaining the input wave coherent properties. In the case when parametric mixer is used to generate frequency combs with small frequency pitch, the phase correlation of the input (seed) waves can be achieved by electro-optical modulator and a single master laser. In the case when frequency comb possessing a frequency pitch that is larger than frequency modulation that can be affected by electro-optic modulator, the phase correlation of the input (seed) waves is achieved by combined use of an electro-optical modulator and injection locking to a single or multiple slave lasers.

A method for transmitting sounding reference symbol, a base station and user equipment. The method comprises: configuring, by a base station, user equipment of a CoMP transmission mode, with parameter configuration information for transmitting SRS, the parameter configuration information including a frequency comb of the SRS and one or more pieces of the following information: cyclic shift, root sequence information, power control information, and transmission duration information, of the SRS; and transmitting the parameter configuration information to the user equipment by the base station, such that the user equipment transmits the SRS to the base station according to the parameter configuration information. The method is simple and flexible, efficiently uses limited SRS resources, and solves the problem in the prior art.

An arrangement for generating beat notes with a relatively high signal-to-noise ratio (SNR) utilizes a pulsed laser source coupled into a section of post-processed highly-nonlinear optical fiber (HNLF) to generate a frequency comb having one or more regions of enhanced spectral power. A second laser signal source is overlapped with the frequency comb to form one or more “beat notes” at difference frequencies(y) between the second source and the continuum comb. By virtue of the post-processing, areas of spectral enhancement are formed along the comb, and are positioned to interact with the second laser signal to generate optical beat notes. The second laser signal may be from an external source (forming beat notes from a signal “outside” of the comb), or may be a frequency-multiplied version of the generated supercontinuum (forming beat notes from a signal “within” the comb).

Compact optical frequency sources are described. The comb source may include an intra-cavity optical element having a multi-material integrated structure with an electrically controllable active region. The active region may comprise a thin film. By way of example, the thin film and an insulating dielectric material disposed between two electrodes can provide for rapid loss modulation. In some embodiments the thin film may comprise graphene. In various embodiments of a frequency comb laser, rapid modulation of the CEO frequency can be implemented via electric modulation of the transmission or reflection loss of an additional optical element, which can be the saturable absorber itself. In another embodiment, the thin film can also be used as a saturable absorber in order to facilitate passive modelocking. In some implementations the optical element may be formed on a cleaved or polished end of an optical fiber.

A signal processing apparatus, being configured for transmitting and receiving coherent parallel optical signals, comprises a transmitter apparatus including a first single soliton micro-resonator device and a modulator device, wherein the first single soliton micro-resonator device is adapted for creating a single soliton providing a first frequency comb, wherein the first frequency comb provides a plurality of equidistant optical carriers with a frequency spacing corresponding to a free spectral range of the first single soliton micro-resonator device, and the modulator device is adapted for modulating the optical carriers according to data to be transmitted, and a receiver apparatus including a coherent receiver device with a plurality of coherent receivers and a local oscillator device providing a plurality of reference optical signals, wherein the coherent receiver device and the local oscillator device are arranged for coherently detecting the transmitted modulated optical carriers, wherein the signal processing apparatus further includes at least one second single soliton micro-resonator device having a free spectral range being equal or approximated to the free spectral range of the first single soliton micro-resonator device and being adapted for creating at least one single soliton providing at least one second frequency comb, wherein the at least one second frequency comb provides at least one of additional optical carriers and the reference optical signals. Furthermore, a signal processing method, including transmitting and receiving coherent parallel optical signals via a communication channel is described.

The present invention relates to precision linewidth control and frequency measurements of continuous wave lasers for the near to far IR spectral regions, precision frequency synthesizers and exemplary applications in molecular detection. Methods and systems are disclosed for simultaneous line narrowing of cw lasers, as well as referencing the desired emission wavelength to a frequency comb laser.

Cavity enhanced absorption spectroscopy systems and methods for detecting trace gases using a resonance optical cavity, which contains a gas mixture to be analyzed, and a laser coupled to the cavity by optical feedback. The cavity has any of a variety of configurations with two or more mirrors, including for example a linear cavity, a v-shaped cavity and a ring optical cavity. The cavity will have multiple cavity resonant modes, or a comb of frequencies spaced apart, as determined by the parameters of the cavity, including the length of the cavity, as is well known. Systems and methods herein also allow for optimization of the cavity modes excited during a scan and / or the repetition rate.

The invention relates to scanning pulsed laser systems for optical imaging. Coherent dual scanning laser systems (CDSL) are disclosed and some applications thereof. Various alternatives for implementation are illustrated, including highly integrated configurations. In at least one embodiment a coherent dual scanning laser system (CDSL) includes two passively modelocked fiber oscillators. The oscillators are configured to operate at slightly different repetition rates, such that a difference δfr in repetition rates is small compared to the values fr1 and fr2 of the repetition rates of the oscillators. The CDSL system also includes a non-linear frequency conversion section optically connected to each oscillator. The section includes a non-linear optical element generating a frequency converted spectral output having a spectral bandwidth and a frequency comb comprising harmonics of the oscillator repetition rates. A CDSL may be arranged in an imaging system for one or more of optical imaging, microscopy, micro-spectroscopy and / or THz imaging.

The invention concerns a laser system with a frequency comb generator for generating a comb of optical frequencies having an offset frequency and a plurality of equidistant modes. The laser system further preferably includes at least one stabilizer for stabilizing the frequency comb onto a certain offset frequency and / or onto a certain mode spacing. The laser system further includes an optical amplifier for amplifying the frequency comb coupled out of the frequency comb generator, the amplification factor of this amplifier being variable; and the amplifier is followed by a Raman medium for generating a Raman shift of the frequency comb.

A WDM communication system having two optical-frequency comb sources (OFCSs) that are substantially phase-locked to one another, with one of these OFCSs used at a transmitter to produce a WDM communication signal and the other OFCS used at a receiver to produce multiple local-oscillator signals suitable for homodyne detection of the WDM communication signal received from the transmitter. In one embodiment, the transmitter has (i) a first OFCS adapted to generate a first frequency comb and (ii) an optical modulator adapted to use the first frequency comb to generate a WDM communication signal having at least two beacon lines for transmission to the receiver. The receiver has a second OFCS adapted to produce a second frequency comb having the beacon frequencies, with the phases of the corresponding comb lines being locked to the phases of the beacon lines of the received WDM signal.

The invention discloses an optical micro-cavity light-frequency comb generating system based on comb tooth feedback control and regulation, and belongs to the optical field. The system comprises a pumping laser, an optical micro-cavity, a feedback regulation and control loop and the like. After parts of comb teeth in light-frequency comb signals generated in the optical micro-cavity are filtered, amplified or regenerated by the feedback regulation and control loop, the feedback regulation and control loop and the pumping laser stimulate the optical micro-cavity together, and the high performance of an optical micro-cavity light-frequency comb is realized by the formed feedback regulation and control loop. Compared with the existing system for generating a light-frequency comb by using a single pumping layer, the optical micro-cavity light-frequency comb generating system has the advantages that the threshold value generated by the light-frequency comb can be reduced, the coherence is increased, controlled comb tooth gaps are formed, and tolerance on pumping conditions is improved. Moreover, the optical micro-cavity light-frequency comb generating system is simple in structure and high in repeatability; and the performance improvement effect of the system is remarkable.

Speckle effect in imaging applications is reduced by generating additional speckle patterns on the screen such that the speckle patterns are overlapped and the overlapped speckle patterns average out on the screen to appear as a noise background to the viewers. The speckle patterns are generated by discrete optical signals of a visible frequency comb. A visible frequency comb having discrete optical signals is generated through modulation-instability processes, phase-conjugation processes, and Bragg-scattering processes using a non-linear optical material and a wavelength converter.

A method and an apparatus for shape measurement that is able to observe the deep portion under a skin with high spatial resolution by using a frequency COMB light generator is provided. A frequency COMB light generator for generating multiple frequency COMBs with variable frequency pitch at high operation stability is provided. This apparatus for shape measurement comprises a frequency COMB light generator and an optical interferometer for measuring the distance. The frequency COMB light generator includes a laser light source 11, an optical resonator 13, a COMB pitch regulator 14 and an output port OUT. The optical resonator 13 includes an optical modulator 131, a first mirror M11, an optical fiber F13 which is drawn out from alight waveguide of the optical modulator. The COMB pitch regulator 14 is a modulation signal generator for varying the modulation signal. The optical fiber F13 is equipped with an apparatus (Faraday rotation mirror) for compensating a change in the polarization condition.