392 results about "Optical comb" patented technology

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 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).

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 spread spectrum waveform generator has a photonic oscillator and an optical heterodyne synthesizer. The photonic oscillator is a multi-tone optical comb generator for generating a series of RF comb lines on an optical carrier. The optical heterodyne synthesizer includes first and second phase-locked lasers, where the first laser feeds the multi-tone optical comb generator and the second laser is a single tone laser whose output light provides a frequency translation reference. At least one photodetector is provided for heterodyning the frequency translation reference with the optical output of the photonic oscillator to generate a spread spectrum waveform. A receiver pre-processor may be provided to operate on the spread spectrum waveform.

The present invention provides a multi-wavelength interference real-time absolute distance measurement device on the basis of femtosecond optical comb synchronization frequency locking. The multi-wavelength interference real-time absolute distance measurement device on the basis of femtosecond optical comb synchronization frequency locking comprises: a multi-wavelength generator on the basis of the femtosecond optical comb synchronization frequency locking configured to emit a plurality of high-frequency stable object wavelength lasers; a heterodyne interferometer configured to receive lasers outputted by the multi-wavelength generator after the femtosecond optical comb synchronization frequency locking, returning measurement light and reference light after generation of interference through the heterodyne interferometer being coupled in single mode fibers by lens focusing to form mixed multi-wavelength heterodyne interference signals; and a synchronization phase demodulation module configured to separate the mixed multi-wavelength heterodyne interference signals obtained by the heterodyne interferometer through wavelength demodulation to obtain interference signals corresponding to each wavelength and perform synchronization phase measurement processing of the interference signals corresponding to each wavelength to finally obtain an accurate absolute distance value. The multi-wavelength interference real-time absolute distance measurement device on the basis of femtosecond optical comb synchronization frequency locking is high in traceability of values, high in measurement precision, large in non-fuzziness measuring range, fast in update rate and easy to measurement on site in real time, and is applicable to the fields of the industrial production, the equipment manufacture and the large-size precision measurement.

The invention relates to a frequency combination-based optical frequency domain reflection method and system. According to the frequency combination-based optical frequency domain reflection method and system, electro-optic modulation and acousto-optic modulation are performed on local light, so that optical pulses can be obtained; the optical pulses, adopted as detection pulse optical signals, are inputted into a test optical fiber; coupling and frequency beating are performed on obtained Rayleigh backscattered optical signals and the local light; obtained optical signals are subjected to photoelectric conversion and demodulation; and therefore, an optical frequency reflectometer can be obtained. According to the electro-optic modulation, single-frequency signals are adopted to perform modulation. According to the acousto-optic modulation, pulse signals are adopted to perform modulation. A plurality of frequency components of optical combed signals obtained through the electro-optic modulation are simultaneously subjected to frequency sweeping, so that optical pulses can be obtained. The frequency combination-based optical frequency domain reflection method and system have the advantages of large detection range, high spatial resolution, low hardware cost and low software complexity.

Provided is an optical film comprising a substrate and an optical layer formed on the substrate, ein the surface of the optical layer has a concavoconvex shape. The concavoconvex shape is obtained by coating the substrate with a coating material containing microparticles and resin, allowing the convection of the coating material to unevenly distribute the particles, and hardening the coating material. The resin contains from 3 wt% to 20 wt% polymer. The microparticles are organic microparticles having an average particle size of 2 [mu]m to 8 [mu]m. The ratio ((D / T) x 100) of the average particle size (D) of the microparticles to the average film thickness (T) of the optical layer is 20% to 70%. The value of the transmitted image clarity measured using a 0.125-mm wide optical comb is 45 or higher.

The invention discloses a coherent anti-stokes raman scattering (CARS) optical comb spectrum detection method for improving the precision. The method comprises the steps of: after two femtosecond optical comb generators as a pumping-detecting light source and a stokes light source of a CARS system pass a CARS spectral measurement system, performing beat frequency and double-optical comb optical heterodyne detection on generated anti-stokes signal light and reference optical combs; eliminating the interference introduced by pumping light by utilizing a polarization dependent balance detection technology at a detecting part so as to realize the quick and real-time CARS optical spectrum detection with high sensitivity and high frequency resolution precision. The method provided by the invention can be used for effectively improving the resolution precision of spectral measurement, realizing the high-precision optical comb imaging within a wide spectral range, effectively inhibiting the environmental noises, eliminating the non-resonant background noise introduced by the pumping light, improving the time and frequency resolution precision and realizing the quick and real-time spectral detection.

The invention provides an all-optical-fiber current transformer system with a temperature measurement function. The all-optical-fiber current transformer system comprises a current sensing optical path and a temperature sensing optical path, the current sensing optical path comprises a laser device, an optical fiber coupler, an optical fiber circulator, an optical fiber polarizer, a phase modulator, an optical fiber delay ring, a current transformer sensing ring and a first photoelectric detector in sequence connection, and the first photoelectric detector is connected with an end D3 of the optical fiber circulator. The temperature sensing optical path comprises a laser device, an optical fiber coupler, an optical fiber temperature sensor and an optical comb shaped filter in sequence connection, and the optical comb shaped filter is connected with an end C of the optical fiber coupler. The all-optical-fiber current transformer system has the advantages that the temperature sensing optical path is added, current and temperature measurement functions are integrated, temperature compensation can be performed for the current transformer sensing ring, a corrected current value serves as a judgment basis of relay protection, the optical fiber temperature sensor and the current transformer sensing ring can jointly participate in relay protection, and accordingly accuracy of relay protection judgment is improved.

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.

A system and method for generating an optical comb are provided. The system comprises at least one modulator for modulating a continuous wave sequentially by using at least one signal, respectively so as to generate a comb wave having a first plurality of subcarriers; and a nonlinear medium for causing the respective subcarriers of the comb wave to perform four-wave mixing to thereby generate a comb wave having a second plurality of subcarriers as the optical comb. With the present system and method, an ultra-wide spectrum optical comb with stable frequencies may be generated.

An optical comb filter has polarizers placed before and after two or more birefringent elements, each having a fixed retarder and an aligned tunable liquid crystal. The birefringent elements are equal in birefringence and thickness and are tuned in unison. Wavelength-dependent polarization state changes are contributed by retardation in unequal proportions on the fast and slow axes of the successive birefringent elements. The filter is tolerant of rotational alignment errors. A two element filter uses angles of 22.5 and 67.5°; a three element version has 12.5, 45 and 77.5°; and a four element filter has 7.5, 29.5, 60.5 and 82.5°; all these angles being ±5°.

In a composition layering one layer on a transparent substrate, the present invention provides an optical film which can balance anti-glare function, high contrast, color reproducibility, and anti-glittering enough. The optical film in the present invention comprises a transparent substrate, and a resin layer layered on the transparent substrate, the resin layer including transparent resin fine particles and a radiation-curable resin composition, and having a fine rugged structure of an average inclination angle in a range of 0.8° to 3.0° on the top surface of the resin layer; a haze value which is in a range of 40% to 60%; and a transmitted image clarity which is measured by using an optical comb having width of 0.5 mm and is in a range of 5% to 35%.

A comb source includes a continuous wave frequency source to provide a continuous wave radiation; a first modulator in optical communication with the continuous wave frequency source; a second modulator in optical communication with continuous wave frequency source; and a waveform driver in electrical communication with the first modulator and the second modulator. A process for producing an analyte spectrum includes producing a first comb from a continuous wave frequency and a first waveform; producing a reference comb and a probe comb from the first comb; subjecting a sample to the probe comb; producing a sample comb in response to subjecting the sample to the probe comb; producing a composite comb from the reference comb and the sample comb; producing a second comb from the continuous wave frequency and a second waveform; and combining the second comb and the composite comb to produce the analyte spectrum

A device used for generating QPSK millimeter wave of radio frequency optical fiber transmission system consists of semiconductor laser of central station, polarization controller, optical phase modulator, optical comb fiber, optical QPSK modulator, optical branching unit / combining unit, optical detector of base station, narrow band band-pass filter, millimeter wave amplifier and millimeter wave antenna. Its optical modulating method for obtaining QPSK modulated millimeter wave signal is also disclosed.

The invention discloses a millimeter wave generating device based on an optic-fiber ring resonator and a method thereof. The optic-fiber ring resonator is formed by connecting a semiconductor optical amplifier, a 1*2 polarization maintaining coupler, a Mach-Zehnder intensity modulator, a three-port polarization maintaining circulator, a polarization maintaining fiber grating and a polarization maintaining optical delay line in sequence, the output of the optic-fiber ring resonator obtained through the other output end of the 1*2 polarization maintaining coupler is connected with a high-speed photoelectric detector through an optical comb filter with an adjustable wavelength, and when the Mach-Zehnder intensity modulator modulates a microwave source with the frequency being fm, and millimeter wave signals with the being 4fm are generated at the radio-frequency output end of the high-speed photoelectric detector through controlling the DC offset voltage of the Mach-Zehnder intensity modulator and the length of the fine-tuning polarization maintaining optical delay line. The invention has the advantages of high millimeter-wave efficiency, compact structure, stable operation, electromagnetic interference resistance and the like.

The invention discloses a radio frequency channelization method based on optical comb double modulation sidebands and an implementation device. The method comprises the following steps: generating coherent signal light and local oscillation light; the signal optical comb generation module modulating an optical comb with a comb tooth interval of FSRsignal; wherein the local oscillation optical combgeneration module modulates an optical comb with a comb tooth interval of FSRlocal, the modulation module modulating an RF signal based on the signal optical comb, the RF signal being filtered by thefilter, and performing coherent receiving processing after channel division is performed based on an output signal of the filter and the local oscillation optical comb. The device comprises a coherent light generation module, a signal optical comb generation module, a local oscillator optical comb generation module, a modulation module, a periodic filter, a channel separation module and a coherent processing module. According to the method and the device, the comb tooth interval of the local oscillation optical comb can be reduced, the requirement on the number of comb teeth of the signal optical comb is reduced, the energy utilization rate is improved, and the channelization difficulty is reduced.

The invention discloses a polarization multiplexing channelization receiver based on an optical comb. The polarization multiplexing channelization receiver comprises a flat optical comb generator, a light intensity modulator connected with the flat optical comb generator, an optical coupler connected with the light intensity modulator, an acoustic optical modulator connected with the optical coupler, a variable attenuator connected with the optical coupler, a first polarization controller connected with the variable attenuator, a second polarization controller connected with the acoustic optical modulator, a polarization beam combiner connected with the first polarization controller, an F-P standard tool connected with the polarization beam combiner, a third polarization controller connected with the F-P standard tool, a polarization beam splitter connected with the third polarization controller, a first wavelength division multiplexer and a second wavelength division multiplexer respectively connected with the polarization beam splitter, and a first photoelectric detector array and a second photoelectric detector array which are respectively connected with the first wavelength division multiplexer and the second wavelength division multiplexer. On the basis that the number of spectral components of the optical comb is not changed, the measurement range and the measurement precision are improved.

The invention discloses a method for generating a broadband OFC (Optical Frequency Comb). A 50 line broadband optical frequency comb is generated by adopting a cascade structure of a DPMZM (Double-Parallel Mach-Zehnder Modulator) and two Mach-Zehnder IMs (Intensity Modulators) and adjusting a radio frequency amplitude and a direct current offset voltage of each modulator, the power is smooth, and the interval between spectral lines is adjustable. The optical comb performance generated in the scheme is relatively good, and great significance is achieved for the application and development of the broadband OFC in the optical communication field. The system structure of the device and method for generating the broadband OFC is relatively simple, easy to implement, and conductive to reducing the system cost.

The invention discloses an injection locking millimeter wave frequency divider based on a self-oscillation optical frequency comb and a frequency division method of the injection locking millimeter wave frequency divider. The frequency divider comprises a photoelectric hybrid oscillator, an optical comb modulator is arranged in an optical link of the photoelectric hybrid oscillator, and a band-pass filter is arranged in an electric link of the photoelectric hybrid oscillator; a millimeter wave signal to be subjected to frequency division is injected into the photoelectric hybrid oscillator; wherein the central frequency of the millimeter wave signal is an integral multiple of the central frequency of the band-pass filter, the optical frequency comb sideband generated by the photoelectric hybrid oscillator and the modulation sideband of the signal to be converted output a fundamental frequency signal in a beat frequency mode, and the fundamental frequency signal is located within the locking bandwidth range of the photoelectric hybrid oscillator. When a super-harmonic signal is injected into the oscillation loop and locked, the frequency division function of the injected millimeterwave signal can be realized, and the frequency divider has the characteristics of wide band, low phase noise and large frequency division ratio.

The invention discloses a real-time absolute ranging method and system based on single-chamber dual-femtosecond optical comb cross-correlation analysis. The method comprises steps: S1, two simultaneously-outputted femtosecond optical combs with different repetition frequencies are generated, the two different repetition frequencies are fr1 and fr2, and the repetition frequencies are locked to an atomic clock by frequency stabilization control; S2, after the beam of the two femtosecond optical combs passes through an interferometer optical path module, the orthogonal polarization components ofoptical comb pulse return light (reference light and measurement light) and local optical comb pulses are measured, and after combination, two groups of femtosecond laser pulse pairs with mutually-perpendicular polarization directions are generated; S3, two-path optical balance cross-correlation signals for reference and measurement are generated, and the signales can be generated by a femtosecondpulse cross-correlation analysis unit in the embodiment of the invention; and S4, the balance cross-correlation signals are subjected to high-speed digital signal analysis processing to obtain a ranging result. The system is the device used for executing the above method. The method and the system disclosed in the invention have the advantages of large ranging range, fast updating speed, high measuring precision and simple operation and the like.

The invention provides an astronomical optical frequency comb device based on an all-solid femtosecond laser. The astronomical optical frequency comb device based on the all-solid femtosecond laser comprises the all-solid femtosecond laser, an optical fiber amplifier and a Fabry-Perot cavity filter, wherein the all-solid femtosecond laser is used for generating a first laser pulse sequence with first repetition frequency, a component with selected wavelength is contained in the first laser pulse sequence, the optical fiber amplifier is used for amplifying power of the first laser pulse sequence, the working wavelength of the optical fiber amplifier comprises the selected wavelength, the Fabry-Perot cavity filter is used for carrying out filter on the first laser pulse sequence to output a second laser pulse sequence with second repetition frequency, and the second repetition frequency is larger than the first repetition frequency. The astronomical optical frequency comb device based on the all-solid femtosecond laser is mainly used for carrying out high-precision calibration on high-resolution astronomical spectrometers. Compared with a traditional calibration mode and an astronomical optical comb calibration mode based on an optical fiber laser, the astronomical optical frequency comb device based on the all-solid femtosecond laser has lower phase noise and side-mode suppression and enables the astronomical spectrometer to obtain higher radial velocity accuracy.

A dual-optical frequency comb spectrum focusing coherent anti-stokes Raman scattering detection system comprises a dual-optical comb light source module, a stokes light generation module, a microscopyfocusing and sample scanning module, a sampling trigger module and coherent anti-stokes signal detection, acquisition and analysis processing module, wherein the dual-optical comb light source modulecomprises a path of optical frequency comb light source and the other path of optical comb light source, the path of optical frequency comb light source is used for as pumping light and detection light, the other path of optical comb light source is used as stokes light and is generated, tiny repeated frequency difference exists between the two paths of optical frequency comb light sources, the stokes light generation module is used for achieving optical frequency deviation by a fiber non-linear effect and acquiring the stokes light, and the sampling trigger module is used for acquiring a pulse coincidence position of two light combs by a secondary harmonic wave generation technology to achieve pulse positioning trigger spectrum acquisition. By the dual-optical frequency comb spectrum focusing coherent anti-stokes Raman scattering detection system, rapid wideband coherent anti-stokes Raman scattering detection without mechanical scanning is achieved, and the capability of a wideband coherent anti-stokes Raman scattering technology in high-dynamic and multi-constituent detection analysis application is remarkably improved.

A spread spectrum waveform generator has a photonic oscillator and an optical heterodyne synthesizer. The photonic oscillator is a multi-tone optical comb generator for generating a series of RF comb lines on an optical carrier. The optical heterodyne synthesizer includes first and second phase-locked lasers, where the first laser feeds the multi-tone optical comb generator and the second laser is a single tone laser whose output light provides a frequency translation reference. At least one photodetector is provided for heterodyning the frequency translation reference with the optical output of the photonic oscillator to generate a spread spectrum waveform. A receiver pre-processor may be provided to operate on the spread spectrum waveform.

The invention relates to a tunable optical comb filter combining a G-T resonant cavity and a birefringence element, comprising a beam inputting structure, a polarization light-splitting part, a filtration module and a beam outputting structure, wherein the beam inputting structure comprises input optical fiber and a collimating lens and is used for outputting collimated and focused parallel beams; the polarization light-splitting part comprises a polarization beam splitter and a phase delay element and is used for generating beams in a certain polarization direction; the filtration module comprises the G-T resonant cavity and the birefringence element, and the polarization beams enter the G-T resonant cavity, are reflected back and forth in the G-T resonant cavity, pass through the birefringence element in many times to change an optical length in order to obtain a plurality of different phases of beams injected from the G-T resonant cavity and are output after being reflected by the polarization beam splitter; and the beam outputting structure comprises a focusing lens and output optical fiber and is used for outputting the reflected output beams after being focused. The invention has the characteristics of tunable bandwidths and centre wavelengths, and moreover, an output spectrum has the characteristics of smooth top bandwidths, steep edges and larger out-of-band inhibition ratio.

The invention provides a temperature and concentration measuring system and method based on a double-optical-comb spectrum technology, and belongs to the technical field of laser absorption spectra. The measuring system comprises two optical frequency combs with the repetition frequency difference smaller than 1 MHz, a 2*2 optical fiber coupler, an optical band-pass filter, a collimator, a low-pass filter, a photoelectric detector, a data acquisition card and the like. The double optical combs are subjected to coupling beam splitting, one path is a measurement light path and is received by thephotoelectric detector after passing through to-be-measured gas and the optical band-pass filter, and the other path is a reference light path and is coupled to the photoelectric detector after passing through the optical band-pass filter. Interference signals generated by the double optical combs on the photoelectric detector are filtered by the low-pass filter and then acquired by the data acquisition card. Fourier transform is carried out on interference signals of measurement and reference light paths to extract absorption spectrum information. Finally, the temperature and the concentration are calculated based on a polychromatic method and a least square method. According to the invention, the precise spectral resolution capability of the optical frequency combs is utilized to realize wavelength-free calibration measurement of temperature and concentration, and the application prospect is wide.

The invention provides a microwave instantaneous frequency measuring device based on an optical frequency comb, which comprises an optical comb generating module, a signal modulation and optical combphase shifting module and a dispersion and wavelength division module, wherein the optical comb generating module comprises an optical comb generator used for generating an optical frequency comb; thesignal modulation and optical comb phase shifting module is connected with the optical comb generating module and is used for modulating a signal to be measured onto each comb tooth of an input optical frequency comb of the optical comb generating module and introducing different phase shifts to each comb tooth of the optical frequency comb; the dispersion and wavelength division module is connected with the signal modulation and optical comb phase shifting module and is used for integrally introducing phase shift to the optical frequency modulated by the signal to be measured and output by the signal modulation and optical comb phase shifting module, and separating optical frequency combs with different frequency components by a wavelength interval to obtain the frequency value of the signal to be measured. According to the invention, the working bandwidth is effectively expanded, the response speed is fast, and the measurement precision is high.

The invention relates to an all-fiber bidirectional mode-locked femtosecond laser ranging device based on time domain scanning and a method thereof, and belongs to the field of laser ranging. The forward pulse emitted by a light source is divided into a beam of reference light pulse and a beam of measuring light pulse through a Michelson interference unit; the reverse pulse emitted by the light source scans the reference light pulse and the measuring light pulse emitted by the Michelson interference unit through a pulse scanning unit so as to generate a ranging signal; and a data acquisition and processing device can obtain the distance value to be measured according to the ranging signal and the repetition frequency value measured by a frequency counter. Compared with the double optical comb ranging device, one laser producing the bidirectional pulses is applied to substitute the optical comb by the device without adjusting the repetition frequency so that the measuring structure canbe optimized, the measuring auxiliary equipment can be greatly reduced, the volume of the ranging device can be reduced, the cost can be saved and the stability can be enhanced.