40 results about "Group velocity dispersion" patented technology

The invention provides a power distribution network line fault testing and positioning method based on optical fiber pulse transmission, and relates to the technical field of power distribution networks, and the method comprises the steps: obtaining a phase voltage signal, a phase current signal and an optical fiber transmission signal of a power distribution network line, and judging a fault through wavelet transformation; when a fault exists, probe light is generated by using a narrow linewidth laser, a scattering signal is obtained after modulation of a Bragg grating array, and gain adjustment and coherent demodulation are performed on the scattering signal to determine a mutation point; based on the catastrophe point, a reflection signal is obtained through bidirectional reflection measurement, and the fault position is determined through combination of a group velocity dispersion equation and self-adaptive multi-stage dispersion compensation. Through photoelectric joint detection and multi-stage signal processing, the accuracy of fault positioning is improved, rapid and accurate positioning of the power distribution network fault is realized, and the method has relatively strong anti-interference capability and environmental adaptability.

The invention belongs to the technical field of photoelectronics, and particularly relates to a wide-spectrum narrow-linewidth semiconductor mode-locked laser, and the collaboration of a saturable absorption region SA and a resonator is reflected in time domain-frequency domain dual optimization. And the resonator optimizes the frequency domain characteristics through nonlinear broadening, phase synchronization and mode purification. The SA adjusts a mode locking threshold value in real time through dynamic bias voltage, the pulse energy stability is ensured, dispersion management of the resonator balances the SPM and group velocity dispersion, spectrum splitting is avoided, and the dissipative soliton form is maintained. Besides, due to heterogeneous integration of the InP-based SA and the SiN-based resonator, wafer bonding of the InP-based SA and the SiN-based resonator is realized, high-efficiency energy transfer is realized through the low-loss conical waveguide, a high-performance frequency comb with a wide spectrum and a narrow pulse width is output, and the high-performance frequency comb can be widely applied to the fields of ultrafast optics, coherent light communication and precision spectroscopy.

The invention discloses a multi-photon optical fiber array endoscopic imaging device and method based on hollow spiral scanning, and belongs to the technical field of biological imaging. The device comprises a laser collimation and beam expansion module, a pulse chirp module, a light beam switching module, an endoscopic detection module and a fluorescence acquisition module. The light beam switching module comprises an optical switch and an optical fiber array composed of at least two low-group-velocity dispersion single-mode optical fibers. The endoscopic detection module drives the optical fiber array to execute hollow spiral scanning through the resonance driver, the track starting point is not located at the view field original point, and central dense sampling is avoided. According to the method, the optical fibers are switched through the optical switch, so that the optical fibers execute spatial non-coincident hollow spiral scanning, multi-photon signals such as fluorescence, second harmonic and fluorescence lifetime are acquired, a central hole is complemented through image reconstruction and fusion, and a complete field imaging result is obtained. Light damage of the central area is remarkably reduced, the imaging resolution uniformity is improved, the fused image is true and reliable based on physical sampling, and the system stability is high.

The invention discloses an on-chip super-continuum spectrum light source based on a cascaded polarized ferroelectric material and a design method thereof. The pump light source is used for providing pump light; the pump light enters the super-continuum spectrum generation waveguide; the super-continuum spectrum generation waveguide meets the requirements that the group velocity dispersion is close to 0 under the wavelength of the pump light, the group velocity mismatch of the wavelength of the pump light and the wavelength of the frequency doubling light is close to 0, and the polarization period of the super-continuum spectrum generation waveguide meets the phase matching of frequency doubling. The polarization period of the super-continuum spectrum expansion waveguide changes along the propagation direction, and the super-continuum spectrum expansion waveguide outputs a super-continuum spectrum; the conical transition waveguide is used for connecting the super-continuum spectrum generation waveguide and the super-continuum spectrum expansion waveguide and eliminating mode mismatch between the super-continuum spectrum generation waveguide and the super-continuum spectrum expansion waveguide. The system has the advantages of low cost, high integration level and wide spectrum coverage, and is suitable for the fields of environmental monitoring, medical diagnosis, spectral analysis and the like.

The present invention discloses a pump light source for generating high-fidelity tensor network states, comprising: a pump laser system, an optical loop system, a polarization adjustment system, and a dispersion compensation system. The pump laser system generates pump laser pulses; the optical loop system periodically pumps a tensor network state generator with the pump laser pulses; the polarization adjustment system regulates the polarization of the pump laser pulses each time they pass through the tensor network state generator; and the dispersion compensation system compensates for the group velocity dispersion generated when the pump laser pulses circulate in the optical loop system. The pulse light source generated by this scheme exhibits stable relative phases between pulses. As a pump light source for an optical tensor network state generator, it can generate high-fidelity tensor network states.

A laser system for the generation of ultrashort optical pulses of light including an oscillator emitting low power and negatively chirped optical pulses with a spectral bandwidth W1, a dispersive connecting segment to maintain the sign of the chirp of the pulses of the oscillator, an optical amplifier for amplifying the optical light pulses and a negative group velocity dispersion segment for compensating phase contributions of the whole propagation process. During the propagation from the output of the oscillator to the end of the optical amplifier, the chirp of the light pulses will change once from negative to positive chirp. After a final compression stage ultrashort optical pulses can be generated.

The utility model relates to the field of optical fiber interference sensors, and discloses an M-Z interference sensor with a small excitation group velocity dispersion difference mode structure. Comprising a light injection single-mode optical fiber, a small-core-diameter step multimode optical fiber, a wide annular core optical fiber, an annular core optical fiber, a gradient refractive index multimode optical fiber, a large-core-diameter step multimode optical fiber and a light receiving single-mode optical fiber which are connected in sequence. The wide annular core optical fiber comprises a third quartz cladding and a third quartz fiber core, and the third quartz fiber core annularly wraps a third quartz layer; the annular core optical fiber comprises a fourth quartz inner wrapping layer, a fourth quartz fiber core and a fourth quartz outer wrapping layer, the fourth quartz inner wrapping layer is annularly wrapped by the fourth quartz fiber core, the fourth quartz fiber core is annularly wrapped by the fourth quartz outer wrapping layer, and the optical fiber radial refractive index distribution index of the gradient refractive index multimode optical fiber is 1.95-2. According to the scheme, the annular core optical fiber is used for injecting light to the gradient refractive index multimode optical fiber, two modes with smaller group velocity dispersion difference can be excited to interfere, and the sensitivity of the sensor is improved.

The application discloses a kind of multi-photon fiber array endoscopic imaging device and method based on hollow spiral scanning, belong to biological imaging technical field.The device includes laser collimation and beam expansion module, pulse chirp module, beam switching module, endoscopic detection module and fluorescence acquisition module.The beam switching module contains optical switch and at least two low group velocity dispersion single-mode fiber array;Endoscopic detection module drives fiber array to perform hollow spiral scanning by resonant driver, its track starting point is not located at the origin of field of view, to avoid central dense sampling.The method switches fiber by optical switch, so that each fiber performs spatial non-overlapping hollow spiral scanning, collects multi-photon signals such as fluorescence, second harmonic and fluorescence lifetime, and completes the central cavity by image reconstruction and fusion, to obtain complete field of view imaging result.The application significantly reduces the central region light damage, improves the uniformity of imaging resolution, and the fused image is based on physical sampling to ensure authenticity and reliability, with high system stability.

The invention discloses a performance analysis method and device based on a hard isolation passive optical fiber network, terminal equipment and a storage medium, and the method comprises the steps: constructing a simulation model used for representing the propagation of an optical signal in each channel according to a group velocity dispersion parameter, a preset attenuation coefficient and a preset nonlinear coefficient of each channel in the passive optical fiber network; and the simulation model is solved to obtain an approximate analytic solution used for representing the change of the optical signal in each channel along with time and space, so that the bit error rate and the achievable information rate of each channel in the passive optical network are calculated according to the approximate analytic solution, and finally, according to the bit error rate and the achievable information rate, the optical signal in the passive optical network is simulated according to the bit error rate and the achievable information rate. And generating a performance analysis result of the passive optical fiber network. Compared with a laboratory test method adopted in the prior art, the method has the advantage that the aim of performing performance analysis on the passive optical fiber network based on hard isolation efficiently at low cost can be achieved.

A dispersion gating-based atmospheric composition measurement laser radar. The atmospheric composition measurement laser radar stretches a femtosecond laser into a broad pulse laser in a time domain by means of dispersion. A femtosecond spectrum is mapped into the broadened laser pulse due to the group velocity dispersion, and then is subjected to time domain gating by means of an intensity modulator (22, 26) for completing the selection of a laser of a preset wavelength. The laser wavelength scanning is achieved by adjusting the delay of an electrical drive signal of the intensity modulator (22, 26). An absorption spectrum of a specific atmospheric composition is obtained by means of laser wavelength scanning so as to measure the concentration of the atmospheric gas composition. The atmospheric composition measurement laser radar can precisely perform free gating on the wavelength where the laser emits, and has high precision in selecting the wavelength. Scanning and detection of a plurality of gases can be achieved by adjusting the center wavelength of a filter.

The invention provides a design method of a LiNbO3 microcavity with a pulley type coupler structure, and aims to generate a broadband dissipation Kerr soliton micro comb and effectively inhibit stimulated Raman scattering. According to the invention, the dispersion engineering design and the dissipation engineering design are combined, the abnormal group velocity dispersion characteristic in the microcavity is optimized, and the coupling efficiency is improved. Through accurate control of geometric parameters, abnormal GVD, phase matching conditions and coupling strength, it is guaranteed that the SRS effect is reduced to the maximum extent in the microcavity with the high-quality factor Q value, and stable generation of DKS is promoted. The output efficiency, the spectral width and the stability of the frequency comb can be effectively improved, and the frequency comb is widely applied to the fields of precision spectroscopy, optical communication, millimeter wave and microwave generation and the like.

An optical system includes an optical source and a pulse shaping waveguide segment in optical communication with the optical source. The optical source is configured to generate a frequency modulated (FM) coherent waveform having a periodic phase profile. The pulse shaping waveguide segment shaping waveguide segment includes a plurality of subsegments. Each of the subsegments has a prescribed dispersion profile and length such that an overall group velocity dispersion (GVD) of the pulse shaping waveguide segment reduces a phase function of the FM coherent waveform in frequency space to provide an output of optical pulses. A waveguide structure may be in optical communication with the pulse shaping waveguide segment. The waveguide structure includes a plurality of alternating segments of normal dispersion (ND) waveguide segments and anomalous dispersion (AD) waveguide segments along a length of the waveguide structure to cause supercontinuum spectral generation of optical pulses traversing the waveguide structure.

The present application relates to a kind of equal optical path adjustment and detection system and method for unpolarized light splitting prism, equal optical path adjustment and detection system includes adjusting mechanism, fixed base, wide spectrum light source, first wedge optical flat, second wedge optical flat, first confocal distance measuring module, second confocal distance measuring module and interference detection component;The plane of first wedge optical flat is towards the first exit surface of first half prism;The plane of second wedge optical flat is towards the exit surface of second half prism;The measuring end of first confocal distance measuring module is towards the inclined plane of first wedge optical flat;The measuring end of second confocal distance measuring module is towards the inclined plane of second wedge optical flat.The present application establishes external optical reference surface by two pieces of wedge optical flat, independently measures air gap of wedge optical flat and corresponding half prism by combining first confocal distance measuring module and second confocal distance measuring module respectively, makes air optical path difference zero, eliminates group velocity dispersion mismatch.

The invention belongs to the related technical field of picosecond laser regulation and control, and discloses a picosecond optical parametric oscillator for realizing near transformation limit output and a design method thereof, the oscillator comprises a pumping source laser, an optical resonant cavity, a nonlinear crystal and a dispersion element; the pumping source laser is used for providing pulse pumping light for the optical resonant cavity; the nonlinear crystal is arranged on a light path in the optical resonant cavity and is used for converting pump light into signal light and idler frequency light, the optical resonant cavity is used for realizing oscillation of the signal light, and the dispersion element is arranged on the light path in the optical resonant cavity and is used for introducing group velocity dispersion for the signal light; signal light and idler frequency light of the near conversion limit pulse are output from the optical resonant cavity, and the dispersion amount of the dispersion element meets the near conversion limit output requirement. The optical parametric oscillator provided by the invention not only can output near-conversion limit pulses, but also has the advantages of wide wavelength tuning range, high conversion efficiency, low cost and low loss.

The invention relates to a dispersive optical arrangement (50, 51) adapted to vary the group velocity dispersion of a pulsed light beam (10). According to the invention, the dispersive optical device comprises a polarizing cube beam splitter (11), a first variable periodic volume Bragg grating (13) and a first quarter-wave plate (12) having flat and parallel faces, one face of the first quarter-wave plate (12) being attached to the input / output face (23) of the first Bragg grating (13), and the other face of the first quarter-wave plate (12) being attached to the input / output face (23) of the first Bragg grating (13). The first variable periodic volume Bragg grating (13) is photoetched in the material along a plane parallel to the input / output face (23) of the first Bragg grating (13). The other surface of the first quarter-wave plate (12) is integrated with one of the two side surfaces (19, 20) of the polarizing cubic beam splitter (11).

The present disclosure relates to a digital filter arrangement (DFA) for compensating group velocity dispersion (GVD) in an optical transmission system (OTS) wherein the DFA is configured to receive a sequence of samples of a digital input signal in the time domain in the form of consecutive blocks of size L. The DFA is configured to generate M discrete Fourier transforms of a current overlap block of a size N greater than the size L and of M−1 delayed versions of the current overlap block. The DFA is configured to filter the entries of the generated M discrete Fourier transforms to generate an output discrete Fourier transform with N entries, wherein the compensation filter is implemented by a delay network and a linear combination algorithm.

This invention discloses a performance analysis method, apparatus, terminal device, and storage medium for hard-isolated passive optical fiber (POB) networks. The method constructs a simulation model characterizing the propagation of optical signals in each channel of the POB network based on the group velocity dispersion parameters, preset attenuation coefficients, and preset nonlinear coefficients. The simulation model is then solved to obtain an approximate analytical solution characterizing the temporal and spatial variations of the optical signal in each channel. Based on this approximate analytical solution, the bit error rate (BER) and achievable information rate (RI) of each channel in the POB network are calculated. Finally, the performance analysis results of the POB network are generated based on the BER and RI. Compared to existing laboratory testing methods, this invention achieves the goal of low-cost and efficient performance analysis of hard-isolated POB networks.

Described herein is a waveguide comprising a first section configured to generate, by a nonlinear optical process, an expanded wavelength spectrum of pulsed radiation provided to an input end of the waveguide, and a second section comprising an output end of the waveguide and configured to exhibit a greater absolute value of group velocity dispersion than the first section, the length of the second section configured to reduce a peak intensity of one or more peaks in the expanded wavelength spectrum by at least 20%. Methods for manufacturing the waveguide are also described herein.

Laser apparatus and control methods providing mode hop-free tuning of the lasing wavelength (frequency) over a broad region of, and possibly, the entire gain bandwidth of the gain medium. Broadly, the apparatus and method incorporate opposite dispersion to compensate the wavelength-dependent group delay and group-velocity dispersion inside a laser cavity for broadband mode-hop free wavelength tuning.

The invention discloses a nonlinear effect and dispersion effect-based performance optimization method for an interferometer and [phi]-OTDR fusion system, and the method achieves the performance optimization of the interferometer and [phi]-OTDR fusion system through the nonlinear effect and dispersion effect generated by pulsed light and continuous light. According to the method, spectrum broadening of a detection signal is realized through pulse light self-phase modulation; frequency conversion is realized through four-wave mixing, and idler frequency light is generated; pulse compression is realized by using a continuous light group velocity dispersion effect, and pulse peak power is enhanced; the obtained pulsed light and continuous light are respectively demodulated to obtain high-fidelity and high-precision external disturbance information, so that the restrictive relationship between the spatial resolution and the sensing distance of the traditional phi-OTDR system is broken, and the spatial resolution and the signal-to-noise ratio of the fusion system are improved.

A control apparatus and control method for an optical pulse output sequence. The control apparatus comprises a beam splitter (4), a carrier-envelope phase detection unit (5) and a chirp coefficient adjustment unit (6), wherein the beam splitter (4) is located on an optical pulse transmission path, and splits an optical pulse into at least output light and monitoring light; the carrier-envelope phase detection unit (5) monitors, by means of receiving the monitoring light, an offset of a carrier-envelope phase (CEP) of the output light to form feedback information, and transfers the feedback information to the chirp coefficient adjustment unit (6); and the chirp coefficient adjustment unit (6) stabilizes the carrier-envelope phase (CEP) of the output light by means of adjusting the group-velocity dispersion of a grating (7) located on an optical fiber (3). The control apparatus and control method can control group-velocity dispersion to compensate for an offset of a carrier-envelope phase (CEP) by means of adjusting a chirp coefficient of a grating (7) on an optical fiber, thereby adjusting and stabilizing the carrier-envelope phase (CEP) of emergent light in real time, and improving the stability of a system; in addition, the structure is simple and flexible and is easily integrated.

The present invention provides a two-dimensional scanning laser imaging system based on spectral angle enhancement and time delay, comprising an incident laser module, a diffraction grating, a first lens, a spectroscope, a second lens, a spectral time delay, an optical system, an arbitrary waveform generator, an acousto-optic modulator, a sample to be measured, and a data acquisition and processing unit. The present invention utilizes the wavelength-independent dispersion effect to introduce group velocity dispersion in free space and introduces 1ns nm in the visible light band. ‑1 The GVD introduces only 4-7dB of loss, which improves both system resolution and imaging clarity, enabling high-definition, accurate imaging. By combining an acousto-optic modulator with an arbitrary waveform generator, the system uses radio frequency signals to modulate the piezoelectric transducer to excite acoustic waves, which in turn influence the crystal inside, changing the crystal's refractive index and, consequently, the angle of the emitted light. This upgrades one-dimensional scanning to two-dimensional scanning, increasing the imaging dimension and enabling the acquisition of more image information.

A polarizer design combines many ideal qualities of crystalline polarizers and many ideal qualities of beam splitting cubic polarizers manufactured with high power processing glass and thin film coating manufacturing processes. That is to say, the design has a wide optical bandwidth (delta lambda / lambda gt; 0.1) to achieve a high extinction ratio (gt; 100000: 1 Tp / Ts), with high power and pulse energy processing, and all four input / output ports are high optical quality surfaces (different from many crystalline polarizers), high transmissivity (Tpgt; 98%) and low and low bulk material dispersion (group velocity dispersion at 500, 1000 and 1500 nm, respectively, is 72, 21 and-22 fs2 / mm) in the film.

An optical system includes an optical source and a pulse shaping waveguide segment in optical communication with the optical source. The optical source is configured to generate a frequency modulated (FM) coherent waveform having a periodic phase profile. The pulse shaping waveguide segment shaping waveguide segment includes a plurality of subsegments. Each of the subsegments has a prescribed dispersion profile and length such that an overall group velocity dispersion (GVD) of the pulse shaping waveguide segment reduces a phase function of the FM coherent waveform in frequency space to provide an output of optical pulses. A waveguide structure may be in optical communication with the pulse shaping waveguide segment. The waveguide structure includes a plurality of alternating segments of normal dispersion (ND) waveguide segments and anomalous dispersion (AD) waveguide segments along a length of the waveguide structure to cause supercontinuum spectral generation of optical pulses traversing the waveguide structure.

Optical soliton pulses are generated using a drive unit to provide pump light at a drive power, a passive optical waveguide ring resonator, a spectral filter in the passive optical waveguide ring resonator, and an output to optically couple optical solitons from the passive optical waveguide ring resonator. The drive power, a net group velocity dispersion (GVD) of the passive optical waveguide ring resonator, a frequency detuning parameter of the passive optical waveguide ring resonator, and the spectral filter are configured to generate one or more optical solitons.

The invention provides a zero dispersion flat optical comb system based on a Fabry-Perot cavity. The system comprises a first grating, a first progressive area, a resonant cavity, a second progressive area and a second grating which are sequentially connected along an optical path. The first grating and the second grating serve as reflecting end mirrors of the Fabry-Perot cavity and are used for providing optical feedback, grating parameters of the first grating and the second grating are adjustable, and the first grating and the second grating are used for regulating and controlling group velocity dispersion of the Fabry-Perot cavity to a zero dispersion point. The first progressive area and the second progressive area are respectively used for realizing mode matching between the first grating and the resonant cavity and between the resonant cavity and the second grating. The resonant cavity is used for providing a resonant channel and determining the free spectral range of the optical comb. The system is configured to directly generate an optical comb having a free spectral range at a zero dispersion point through a dynamic balance of a spectral filtering effect and a Kerr nonlinear effect. The defect that a broadband and ultra-flat optical comb cannot be directly generated due to the fact that an annular resonant cavity is difficult to actively regulate and control to a zero dispersion point due to waveguide dispersion solidification is overcome.

Laser apparatus and control methods providing mode hop-free tuning of the lasing wavelength (frequency) over a broad region of, and possibly, the entire gain bandwidth of the gain medium. Broadly, the apparatus and method incorporate opposite dispersion to compensate the wavelength-dependent group delay and group-velocity dispersion inside a laser cavity for broadband mode-hop free wavelength tuning.

The invention discloses an ultrashort laser pulse wavelength-based beam splitting device and method, and the device comprises an ultrashort pulse laser which is used for generating ultrashort laser pulses; the first grating is used for carrying out spatial dispersion on the ultrashort laser pulse to form multiple beams of light with different wavelengths; the first convex lens is used for propagating the multiple beams of light with different wavelengths according to a parallel trend; the first convex lens array is used for dividing the light propagating in the parallel trend into a plurality of areas according to the wavelength and converging the light of each area to the second grating; the second grating is used for converting the multiple beams of convergent light into multiple beams of parallel light pulses with different spectral ranges; the second convex lens is used for propagating the plurality of beams of parallel light pulses according to a parallel trend; and the emitting element is used for emitting a plurality of beams of parallel light pulses propagating in a parallel trend and realizing beam splitting in space. According to the invention, beam splitting can be realized by adopting a conventional optical element, the structure is simple, the flexibility is extremely high, the energy loss is low, and group velocity dispersion matching is not introduced.

A fiber laser device comprises a ring shaped resonator (1) to generate pulses in a mode- locked regime, the ring shaped resonator (1) comprising a doped fiber (10), a virtual saturable absorber (11) receiving the output of the doped fiber (10), a standard fiber (12) connected to the virtual saturable absorber (11) and connected in loop to the doped fiber (10), the resonator (1) including an isolator (16) for unidirectional laser propagation from the doped fiber (10) to the saturable absorber (11), the virtual saturable absorber (11) comprising a splitter (115) to output a part of the light as main output, The doped fiber (10) is selected to operates in a regime where the group- velocity dispersion is negative within the selected band, the splitter (115) outputting more than 85% of the light power from the resonator (1), the resonator (1) comprising filtering means (17) selecting a band of light coupled to the standard fiber (12). Method of controlling such a device.

The invention discloses a quantum dot optical frequency comb repetition frequency multiplication system and method based on the time Talbot effect. The quantum dot optical frequency comb repetition frequency multiplication system comprises a quantum dot optical frequency comb source and a Talbot dispersion regulator. The optical frequency comb source generates an input optical frequency comb with repetition frequency; and the dispersion regulator calculates and applies a target total second-order group velocity dispersion amount meeting a fractional order time Talbot phase condition according to a preset integer multiplication factor N, so that the input optical frequency comb generates coherent time domain self-imaging and then forms an output optical frequency comb with repetition frequency. And multiplication is realized only through passive dispersion regulation and control, a high-speed active modulator is not needed, the energy efficiency is high, the structure is simple, and different high repetition frequency requirements of 200GHz and above can be met.