703 results about "Optical frequency comb" patented technology

An optical frequency comb generator includes a laser device arranged for generating input laser light having a predetermined input light frequency, a dielectric micro-resonator having a cavity exhibiting a third order nonlinearity, so that the micro-resonator is capable of optical parametric generation providing parametrically generated light, and a waveguide optically coupled to the micro-resonator, the waveguide being arranged for in-coupling the input laser light into the micro-resonator and out-coupling the parametrically generated light out of the micro-resonator, wherein the laser device, the waveguide and the micro-resonator being arranged for resonantly in-coupling the laser input light to a mode of the micro-resonator with a minimum power level so that an optical field inside the cavity exceeds a predetermined cascaded parametric oscillation threshold at which the parametrically generated light includes frequencies of frequency sidebands of the input light frequency and of the sidebands thereof.

The invention discloses a spectral measurement method based on optical frequency combs. The measurement method is characterized in that firstly, an annular laser resonant cavity based on a phase modulator is actively modulated by use of a first optical frequency comb controllable in time domain and frequency domain so that the annular laser resonant cavity is converted into a second optical frequency comb having tiny difference in repetition frequency with the first optical frequency comb, and spectrum detection is performed on the two optical frequency combs to obtain an interference signal carrying the information of a sample to be tested, and meanwhile, frequency beating is performed on the two optical frequency combs and continuous frequency stabilized laser, respectively, the difference frequency signal of two obtained beat frequency signals is mixed with the interference signal, and a signal obtained by virtue of detection mixing is taken as a spectral signal for Fourier analysis so as to reduce the optical information of the sample to be tested. The spectral measurement method has the advantages that the error of the spectral detection due to own phase drift of a dual-optical comb system can be eliminated, and therefore, the resolution and the detection accuracy of the spectral measurement can be improved.

The invention discloses a microwave photonic transceiver based on coherent optical frequency combs. A signal optical frequency comb and a local oscillator optical frequency comb which are coherent are generated through a seed light source module and are each divided into two paths through two beam splitters; for a transmitting module, one path of the signal optical frequency comb is taken and each comb tooth is separated through a de-multiplexing module, a to-be-transmitted intermediate frequency signal is loaded through electro-optical modulation, the modulated signal optical frequency comb and one path of the local oscillator optical frequency comb are combined, and a high-frequency transmitting signal is obtained through photo-electric detection; for a receiving module, the other path of the signal optical frequency comb directly loads a receiving signal through an electro-optical modulator and sends the receiving signal to a signal light input end of an optical mixer, the other path of the local oscillator optical frequency comb is input into a local oscillator light input end of the same optical mixer, and two paths of orthogonal output light signals of the optical mixer are taken to carry out channel cut and coherent detection respectively. The microwave photonic transceiver disclosed by the invention has large real-time processing bandwidth and large dynamic range, and the system consumption is effectively reduced.

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.

An optical frequency comb calibration-based dual-color laser scanning absolute distance measuring device and a method are characterized in that the device comprises a laser light source system, a polarization-maintaining optical fiber system, a Michelson interference system and a laser frequency calibration system. The method comprises the steps of controlling two tunable lasers in the laser light source system to continuously simultaneously adjust the output light frequency without mode skips, wherein the laser frequency calibration system records the interference signal of the Michelson interference system and a beat frequency signal of the tunable lasers and the optical frequency comb; computing the scanning range of the lasers and the period integer and period decimal of the phase change of the interference signal in the scanning process according to the collected data; and finally computing to obtain the absolute distance of a to-be-measured light path refractive face. The optical frequency comb calibration-based dual-color laser scanning absolute distance measuring device and the method have the advantages of simple system structure, high measuring precision, compensating effect on air refractive index, and traceable measuring outcome, and are suitable for the measuring field of space absolute distance.

The invention relates to a micro-ring waveguide optical device capable of realizing all-optical signal processing by utilizing a high-nonlinearity effect, and aims to overcome the defect that nonlinear coefficients are insufficient when a conventional micro ring performs all-optical signal processing. The provided micro-ring waveguide optical device comprises a straight waveguide and a parallel growth micro ring on a substrate, wherein the micro ring is an annular resonant cavity; the ridge waveguide part of the micro ring adopts a parallel slot structure instead of a single ridge waveguide structure; and the straight waveguide is coupled with the micro ring. According to the micro-ring waveguide optical device, one parallel slot micro-ring waveguide structure is innovated; and when light is coupled into the parallel slot micro-ring waveguide structure, the slot waveguide structure can well limit a light field, the light intensity of resonance light is enhanced greatly due to the resonance effect of the micro ring, accordingly, various nonlinear effects of the micro ring are enhanced, the threshold value is reduced, the efficiency is improved, and the device can be applied to the all-optical signal processing fields such as optical frequency comb, wavelength conversion, logic gate, format conversion and the like.

The invention discloses manufacturing method and equipment of a single optical frequency comb with high stability and high repetition frequency. The method comprises the following specific steps of: outputting femtosecond pulses with high repetition frequency, wide spectrum and pulse width less than 7 fs by using a cycle-grade femtosecond titanium sapphire oscillator; carrying out beat measurement of the CEO of the femtosecond pulses by using a single nonlinear crystal; and simultaneously locking repetition frequency and CEO frequency to a stable external microwave reference source by using a circuit feedback technology. The equipment comprises the cycle-grade femtosecond titanium sapphire oscillator, the single nonlinear crystal beat measurement fceo device and a feedback circuit device controlled on the basis of the phase lock principle. The invention has the characteristics of compact equipment structure, long locking time, high usable output power, small phase noise and the like, and is mainly applied to the scientific researches of absolute optical frequency measurement, optical clock composition, atto-second production and the like.

A receiver architecture for physically-assisted computing of transforms, such as discrete Fourier transforms (DFT) and discrete Hilbert transforms (DHT), employs mutually-coherent optical frequency combs for detection of the coherent beating between an optical signal and a reference optical tone generated by a local oscillator (LO). A signal replication mixer generates a plurality of signal optical tones having a frequency pitch with an input signal mapped thereon. A reference mixer (local oscillator) generates a plurality of reference optical tones having an offset frequency pitch relative to the signal tones. A receiver backplane detects coherent beating between the signal optical tones and the reference optical tones. The input signal may be in the optical domain or in the radio-frequency domain.

Examples of systems and methods for integrated photonic broadband microwave transceivers are disclosed based on integrated coherent dual optical frequency combs. In some cases, when the system is configured as a transmitter, multiple radio frequency (RF) carriers can be generated, which can either be encoded independently, or used for broadcasting the same information into different bands. In some cases, when the system is configured as a receiver, the spectrum of the input signal can be sliced into several spectral segments for low-bandwidth detection and analysis. In some systems, the optics-related functionalities can be achieved via integrated optic technology, for example based on silicon photonics, providing tremendous possibilities for mass-production with significantly reduced system footprint.

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.

The present invention relates to an all-fiber continuous light and optical frequency comb locking device which comprises an optical frequency comb, a continuous laser, a beat frequency apparatus, a frequency shift apparatus, a reference signal source, a frequency synthesizer and a fast phase-locked loop circuit. The optical frequency comb can ensure system long-time stable operation, and repetition frequency and carrier-envelope phase shift frequency of the optical frequency comb are locked to a stable reference signal source; the continuous laser can be an external cavity semiconductor laser or a continuous optical fiber laser, and is used for locking continuous light to some comb tooth of the precision optical frequency comb; and input and output terminals of the frequency shift apparatus and the beat frequency apparatus are connected by using polarization maintaining optical fiber, and the frequency shift apparatus and the beat frequency apparatus are used for assisting completely overlapped locking of the continuous light and the optical frequency comb. The all-fiber continuous light and optical frequency comb locking device has a compact and small structure; the beat frequency structure is simple and easy, and the signal to noise ratio is high; locking is good in stability and high in precision; and the continuous light can be ensured to be completely overlapped with some comb tooth of the optical frequency comb, so that completely overlapped locking can be achieved.

In an optical frequency comb generator the emission frequency of each one of the set of output lasers is repetitively aligned with an associated one of a set of specifically determined frequencies by comparison of that emission frequency with a frequency indicated by an optical frequency meter. The optical frequency meter is repetitively re-calibrated by reference to the emission frequency of each of at least two frequency tuneable calibration lasers emitting at respectively different frequencies. Each of the calibration lasers has its emission frequency continuously or repetitively aligned with the frequency of an associated spectral absorption line frequency standard.

The invention discloses a method and a device for locking laser frequency to an optical frequency comb based on undersampling. The method comprises the steps of performing laser combination processing on to-be-stabilized frequency laser and laser of the optical frequency comb to obtain a detection signal, removing intermode self-beat signals between comb teeth of the optical frequency comb by a filter, performing undersampling acquisition on reserved beat signals into digital signals, reflecting or folding frequency spectra of the beat signals to a first nyquist region during an undersampling course, superimposing the beat signals to obtain a total beat signal, obtaining a phase error signal between the total beat signal and a reference sine signal by a phase locking amplifier, obtaining a frequency feedback control signal by digital PID (Proportion Integration Differentiation) operation, and adjusting output frequency of a to-be-stabilized frequency laser device by the frequency feedback control signal to realize offset frequency locking. The method and the device solve the problem of difficult increase of signal-to-noise ratios of the beat signals in a technology of locking a laser device to the optical frequency comb, improve the laser frequency stability, and can be widely applied to the field of laser precision metering.

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.

The invention relates to a femtosecond laser carrier envelope offset frequency lock system based on a heterodyne interferometric method. The system is characterized by comprising a femtosecond laser light source system, an acousto-optic modulator, a controllable optical path retardation device, a light splitting prism, a first photoelectric detector, a phase lock amplifier, a phase difference voltage conversion device and a PID controller. Heterodyne interferometry can be conducted on first-level phase-shift diffraction light modulated by the acousto-optic modulator and zero-level diffraction light which is not modulated, and after mixing of interference signals with different wavelengths, direct-current level lock pulse envelope alignment is achieved; optical frequency comb envelope offset frequency is locked by means of interference signal phase, the linear process does not exist, high non-linear optical fibers, frequency doubling crystals and the like are not needed, and the system is simple in structure and low in requirement for laser energy.

The invention relates to a broadband multichannel channelization system and an implementation method based on an optical frequency shift, and belongs to the technical field of microwave photonics. Aninterference effect between electrooptical modulators and the optical frequency shift characteristic are utilized, and multi-channel division and high-rejection ratio same-intermediate-frequency frequency conversion of broadband microwave signals are completed. The invention proposes the broadband multi-channel channelization method based on the optical frequency shift by combining optical frequency shift channelization and I/Q down-conversion. According to the broadband multi-channel channelization method provided by the invention, a single-frequency laser is combined with a double-sided bandfrequency shift to complete the channel division of a broadband signal; and the output of several two-way same-intermediate-frequency signals which are mirrored to each other through the I/Q down-conversion is realized, which not only avoids the defect that light filtering out-of-band rejection capability is poor in traditional channelized receiving, but also avoids the defect that high-quality coherent optical comb implementation is complex in channelized receiving based on an optical frequency comb.

The invention discloses an ultra-wideband receiver device based on microwave photonics and a realizing method thereof. The realizing method comprises the following steps: dividing an optical signal output by a laser light source into two paths, wherein one path is used for generating an optical frequency comb with uniformly-spaced frequencies by adopting an external modulating mode, and the other path is used for modulating a to-be-received radio frequency signal through an electro-optical modulator and synthesizing the optical signal of the optical frequency comb; enabling the synthesized signal to pass through a tunable narrow bandpass filter for filtering out optical frequency carried with a to-be-detected signal and the fixed frequency point of the closest optical frequency comb, performing transformation through a high-speed detector, and obtaining difference frequency by realizing frequency beating and synthesizing of two frequencies, namely obtaining a frequency-converted medium-frequency signal under a to-be-measured signal. According to the ultra-wideband receiver device based on microwave photonics and the realizing method thereof, the optical frequency comb technology in microwave photonics is applied to designing microwave signal receiving; an adjustable optical fiber is combined to realize the ultra-wideband signal receiving and down-converting on the condition of a low-frequency intrinsic signal (2GHz-5GHz), wherein the receiving bandwidth is lower than that of the low-frequency intrinsic signal by dozens of times.

The invention discloses a microwave photon full-band radar detection method. The microwave photon full-band radar detection method comprises the steps that suppression carrier single sideband modulation is carried out on an optical carrier with a frequency of fL by using an intermediate frequency chirp signal to obtain a linear frequency swept first-order sideband optical signal; a single comb signal is selected from optical frequency comb signals with frequency distribution fOC=fL+/-Nfc to combine beams with the linear frequency swept first-order sideband optical signal, wherein N=0, 1, 2, 3... L, and L is a positive integer; the obtained combined beam optical signal is converted into an electrical signal, and the electrical signal is transmitted to a target as a radar detection signal; and the combined beam optical signal is taken as a reference optical signal, a target reflected electrical signal is subjected to optical domain frequency conversion and deskewing processing to obtainan intermediate frequency signal carrying target information, and the target information is extracted from the intermediate frequency signal. The invention further discloses a microwave photon full-band radar. The microwave photon full-band radar detection method and the microwave photon full-band radar can quickly and conveniently adjust the working wave band of the radar and the radar signal parameters in the full wave band range, the structure is simple, and the detection efficiency is high.

The invention discloses an optical device measuring method which comprises the following steps that A, a microwave signal with fixed frequency and phase is modulated to a light carrier which is output by a light source through an optical frequency comb modulator, so as to generate an optical frequency comb; a plurality of continuous comb teeth of the optical frequency comb are filtered in sequence by a photonic filter; B, each filtered comb tooth serves as the light carrier, and the transmission functions of an optical device to be measured in a frequency band which corresponds to the comb tooth are measured through the optical device measuring method based on the unilateral modulation of light; and C, the broadband transmission functions of the optical device to be measured in the frequency bands which correspond to a plurality of continuous comb teeth are obtained according to the transmission functions in the frequency bands which correspond to all the comb teeth. The invention also discloses an optical device measuring device which adopts the method. According to the optical device measuring method and the measuring device, the optical frequency comb modulator works together with the photonic filter in a cooperate mode based on the optical device measuring method of the unilateral band modulation of light in the prior art, so that the measuring scope is greatly expanded.

The invention discloses a method and device for monitoring and controlling a high-precision optical fiber optical frequency comb. The method and device are used for monitoring and controlling working conditions of links of the optical fiber optical frequency comb and improving the long-term stability, the operation reliability and the product replicability of the optical fiber optical frequency comb. By means of the device, pulse carrier-envelope phases output by an optical fiber laser oscillator and optical fiber amplifiers in all stages are monitored, transmission and fluctuation of laser phase noise in the power amplification process are observed and controlled, carrier-envelope phase output signals of the main amplifier are negatively fed back to a carrier-envelope phase control unit in the laser oscillator, namely an electronic control polarization controller modulates the pulse polarization evolution process or modulates the pump light strength of the laser oscillator, and stable control over the carrier-envelope phases is achieved. By means of the method and device, the working conditions of the laser oscillator and the amplifiers in all stages can be monitored and controlled in real time, monitoring indexes are timely and comprehensive, and a stable and reliable feedback mechanism is provided.

The invention relates to a device for measuring the arm length difference of a fiber optic interferometer, and mainly solves a problem that a measurement system employing an optical interference method is not high in stability and is low in measurement precision. The device provided by the invention comprises a narrow linewidth laser, a polarization-maintaining fiber coupler, a phase modulator, apolarization state controller, an acousto-optic frequency shifter, a fiber coupler, a to-be-tested fiber optic interferometer, a photoelectric detector, a frequency spectrograph, a signal processing and display module and a microwave signal generator. The device carries out the interference in microwave domain through a double optical frequency comb, and measures an interference signal by using the frequency spectrograph. The device can obtain the arm length difference of the to-be-tested fiber optic interferometer by the bandwidth of the interference signal in one cycle, and can achieve the measurement of the precision changes through changing the frequency interval of the optical frequency comb, thereby improving the measurement accuracy and the stability of the system, and ironing out the defect that a method employing optical interference cannot achieve the measurement of the arm length difference. The device is simple in workflow is simple and is high in generalizability.

An optical frequency comb generator includes an oscillator (117) for oscillating modulating signals of a preset frequency, and an optical resonator (110) formed by an incident side reflecting mirror (112) and an outgoing side reflecting mirror (113), arranged parallel to each other. The optical resonator causes resonation in light incident via the incident side reflecting mirror (112). The optical frequency comb generator also includes an optical phase modulation unit (111) arranged between the incident side reflecting mirror (112) and the outgoing side reflecting mirror (113) for phase modulating the light, resonated by the optical resonator (110), by the modulating signals supplied from the oscillator (117), and for generating a plurality of sidebands centered about the frequency of the incident light at a frequency interval of the modulating signal. The outgoing side reflecting mirror (113) sets the transmittance from one frequency to another responsive to the light intensity of the generated sidebands.