390 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).

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.

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.

The invention discloses a method for measuring object surface topography. The method adopts a femtosecond laser optical comb light source and is a novel non-contact optical surface topography imaging method, double-optical-comb beat frequency detection technology and pulse space chirp technology are combined, spatial position information measurement is converted into distinguishable measurement of detecting light spectrum, ultra-sensitive optical surface topography detection with higher resolution accuracy is achieved, a stable phase-frequency relation of the optical comb light source is utilized, imaging sensitivity of an instrument is improved through a coherent measurement way, high solution imaging can be achieved on the surface topography by using optical comb heterodyning beat frequency detection and frequency spectrum coherent identification technology, a double-optical comb and a nanometer mobile platform are used for scanning an object to be tested automatically, a spatial beam expanding function of a detection light spot is combined, and large-area ultra-sensitive rapid imaging can be achieved on the surface of the object to be tested.

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 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 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.

Disclosed is a distance measuring device using an optical comb. In order for the absolute distance to an object to be measured which has a surface with low reflection ratio or a scattering surface and is approximately 10 m apart, to be easily measured with accuracy of 0.1 mm or more using an optical and contactless method, the distance measuring device which measures the distance to the object to be measured is configured such that the distance to the object to be measured is measured by comparing the phase of the beat signal between a light source and a plurality of CW lasers which are reflected or scattered by the object with the phase of the beat signal between the light source and a plurality of CW lasers prior to being irradiated onto the object.

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.

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.