26 results about "Nonlinear polarization" patented technology

A chip-scale mode-locked laser including a cavity including a gain medium for amplifying signal electromagnetic radiation (signal) through stimulated emission, the signal comprising a signal wavelength; and a passive or active mode-locking device to enforce pulse formation in the laser. The mode-locking device includes a thin-film waveguide having a thickness on the order of the signal wavelength so as to confine and guide the signal along the thin-film waveguide, and a material comprising a second-order nonlinear susceptibility to enable active or passive mode-locking of the signal. The mode-locking device leads to generation of pulses of the signal outputted from the mode-locked laser.

The invention discloses an O-band harmonic mode-locked laser based on double-pumping nonlinear polarization evolution, which comprises a first pumping source, a second pumping source, a first wavelength division multiplexer, a second wavelength division multiplexer, a gain fiber, a first polarization controller, a polarization dependent isolator, a second polarization controller and a coupler, which form a bidirectional pumping ring laser resonant cavity. Wherein the first polarization controller and the second polarization controller are arranged on the two sides of the polarization dependent isolator respectively to form a nonlinear polarization evolution mode locking structure together. By improving the power of the double pumping sources and adjusting the polarization state in the cavity, switching from fundamental frequency mode locking to multi-order harmonic mode locking can be achieved, the highest order can reach 33, the repetition frequency upper limit of an O-band all-fiber mode-locked laser is broken through, and the all-fiber mode-locked laser has the advantages of being compact in structure, high in damage threshold, low in cost and easy to integrate all fibers and is suitable for the field of optical communication and the like.

The application provides a nonlinear optical effect generation method, relates to the field of optoelectronic technology, and comprises the following steps: fixing and placing a polar ion crystal as a nonlinear medium, the polar ion crystal being a diatomic crystal or a polyatomic crystal with an optical phonon mode; using a modulated terahertz wave to excite a stimulated phonon polariton in the nonlinear medium, so as to enhance the nonlinear efficiency of signal light incident on the nonlinear medium; and adjusting the polarization angle and the incident angle of the signal light and / or the modulated terahertz wave, so as to generate a nonlinear optical effect. The application is based on the characteristics of the interaction between light and matter modulated by the stimulated phonon polariton, and the nonlinear polarizability is greatly improved by using the stimulated phonon polariton, so that the weak light nonlinear effect of most wavelengths of light can be realized efficiently; and the nonlinear optical effect has the advantages of high refresh rate, wide spectral response, low threshold and low power consumption.

The application discloses an interference filter type multi-wavelength erbium-doped fiber laser based on optical path difference regulation, relates to the technical field of a ring-shaped tunable multi-wavelength erbium-doped fiber laser, and comprises a pump source, a wavelength division multiplexer, an erbium-doped fiber, an isolator, a first optical fiber coupler, a three-paddle polarization controller, a polarizer, a Mach-Zehnder interferometer filter containing an adjustable delay line, a black phosphorus saturable absorber and an extrusion type polarization controller which constitute a ring cavity. By connecting a 0-6.6 cm continuous adjustable delay line to one arm, the optical path difference of the filter two arms is accurately regulated, and continuous precise tuning of wavelength spacing of 0.3 nm to 1.54 nm is realized; meanwhile, by combining the nonlinear polarization rotation effect and the hybrid mode-locking mechanism of the few-layer black phosphorus, the mode-locking threshold is significantly reduced, and the long-term stability of the pulse is improved. The laser can realize stable emission of up to six wavelengths at the same time, the wavelength drift is less than 0.75 nm, and the power fluctuation is less than 7.0 dB.

The invention discloses a fiber laser polarization locking system and method based on genetic algorithm and proportional integral differential cooperative control, and belongs to the technical field of fiber laser control. The invention provides a cooperative control architecture of global searching, gradient sensing and local locking for solving the problems of difficult starting and easy lock losing caused by multiple extreme values of an unlocking space and non-uniform sensitivity distribution of a nonlinear polarization rotation mode-locked laser. When the system starts or loses lock, firstly, the global traversal capability of a genetic algorithm is utilized to quickly pull a polarization state to a quasi-steady-state mode locking interval; before switching to closed-loop locking, a local sensitivity calibration mechanism is introduced, the response gradient of a current working point to control voltage is detected in real time, and gain parameters of a PID controller are adaptively configured according to the response gradient, so that the non-uniform characteristic of a solution space is matched, and overmodulation oscillation is prevented; and then smoothly switching to a PID control mode based on negative feedback to realize continuous fine tuning and compensation of environmental disturbance. Meanwhile, a local backtracking self-healing mechanism based on gradient is built in the system, and quick recovery can be achieved when lock losing is caused by disturbance. According to the invention, through seamless cooperation of the genetic algorithm and PID control, rapid self-starting, high-precision locking and strong anti-interference capabilities are effectively considered, and the long-term operation stability of the fiber laser is significantly improved.

The invention relates to the field of nonlinear optical materials, and discloses a mixed bonded isothiocyanate nonlinear optical crystal and a preparation method thereof.The preparation method comprises the following steps that a zinc source is dissolved in deionized water to obtain a zinc source solution, and a sulfur source is dissolved in deionized water to obtain a sulfur source solution; mixing the solutions, heating and stirring to form a [SZn4] covalent core precursor suspension; sequentially adding 1, 2, 4-triazole, thiocyanate and triethanolamine into the suspension liquid, and uniformly stirring; and placing the obtained mixture in a reaction kettle for temperature programming reaction and constant-temperature reaction, then performing temperature programming cooling to room temperature, and filtering, washing and drying to obtain the crystal. By constructing a stable [SZn4] covalent core and regulating and controlling directional arrangement of NCS-and C2H2N3 ligands, effective superposition of microscopic nonlinear polarizability is realized, so that the material obtains higher second harmonic response, the thermal stability of the crystal is improved, and the optical band gap is widened.

The invention discloses a fusion-free femtosecond fiber laser only containing a gain fiber and a laser generation method. The laser is characterized in that an annular cavity comprises a polarization beam splitting crystal, a first fiber collimator, an erbium-doped fiber, a polarization controller and a second fiber collimator which are sequentially distributed in the annular direction; the two ends of the erbium-doped fiber are respectively connected with the first fiber collimator and the second fiber collimator in a screwed manner through two connection joints. The erbium-doped optical fiber is used for absorbing the pump light and generating emission laser; the input end of the third optical fiber collimator is connected with the output tail fiber of the pumping source through a connector, and the output direction of the third optical fiber collimator is aligned with the incident port of the polarization beam splitting crystal. The method comprises the following steps: exciting the erbium-doped fiber to radiate a long-wave-band gain pulse; under the combined action of the polarization controller and the polarization light splitting crystal, an equivalent saturated absorption effect is generated by utilizing nonlinear polarization rotation generated when the pulse is propagated in the gain optical fiber, so that the output of femtosecond pulse is realized. The femtosecond pulse generator can realize self-starting, long-term stable femtosecond pulse output with an extremely simple structure.

The invention discloses a method and a system for realizing multispectral switching by cooperatively regulating and controlling pumping and polarization states, and belongs to the technical field of ultrafast fiber lasers and automatic control. The method comprises the following steps: inputting an output signal of an ultrafast fiber laser into a residual neural network for identification and obtaining an ensemble solution of voltage and pumping power corresponding to a spectrum; searching optimal set solutions corresponding to different spectrum states by using a self-adaptive gradient optimization algorithm; a search result is fed back to an electric control polarization controller and a pump, so that automatic switching of spectrum states is realized; if it is monitored that the spectrum state disappears, an adaptive recovery algorithm is executed, and random extraction is carried out in the set solution for recovery; and if recovery fails, searching through a random search algorithm until recovery. The problem that a passive mode-locking fiber laser based on nonlinear polarization rotation cannot rapidly switch the pulse state and is difficult to stabilize is solved, meanwhile, full-automatic control over the fiber laser is achieved, the universality of an algorithm is improved, and the structure is simple and easy to achieve.

The invention discloses a beam-expandable dispersion-adjustable high-nonlinearity polarization-maintaining preform, an optical fiber and a manufacturing method of the polarization-maintaining optical fiber, and a core rod, the core rod comprises a core layer and an inner cladding, the core layer has a first type of doping, and the first type of doping is germanium doping; the inner cladding has a second type of doping, and the second type of doping is germanium-fluorine co-doping; the stress rod is provided with a third type of doping so as to realize a birefringence function; the sleeve is provided with a first sleeve inner hole which is located in the center of the sleeve and matched with the core rod, and two second sleeve inner holes which are symmetrically distributed on the two sides of the first sleeve inner hole and matched with the stress rods. According to the method, the problem of core cracking of the polarization-maintaining preform with the high numerical aperture during processing is solved, the problem of overlarge welding loss between the high-nonlinearity optical fiber and the conventional polarization-maintaining optical fiber is solved by controlling the expansion coefficient of the inner cladding, and meanwhile, the prepared optical fiber has the properties of high nonlinearity effect, capability of expanding beams to reduce the welding loss, adjustable dispersion and the like.

A device for a nonlinear optical frequency-conversion of laser radiation comprises a multipass arrangement being arranged such that a laser radiation coupled into the multipass arrangement carries out multiple roundtrips in the multipass arrangement. The device further comprises a nonlinear optical medium-arranged at least partly within the multipass arrangement such that at least in several of the roundtrips the laser radiation coupled into the multipass arrangement passes through the nonlinear optical medium to carry out a nonlinear optical conversion of a part of the laser radiation propagating through the nonlinear optical medium into frequency-converted components based on a second order susceptibility χ(2) of the nonlinear optical medium. The device is configured such that the laser radiation- and the frequency-converted components propagate in the multipass arrangement-along a common beam path including at least five passes through the nonlinear optical medium.

A single-mode fiber laser and method for generating bright solitons and dark solitons, the laser comprising: a wavelength division multiplexer connected to a pump source; an erbium-doped fiber connected to one end of the wavelength division multiplexer; a first polarization controller connected to the other end of the erbium-doped fiber; a polarization analyzer connected to an input end of the first polarization controller; a second polarization controller connected to an output end of the polarization analyzer; an output coupler connected to an output end of the second polarization controller, a second output port of the output coupler serving as an output port of the fiber laser; a fiber isolator connected to a first output port of the output coupler; and a band-pass filter connected to an output end of the fiber isolator, the output end of the band-pass filter being connected to the wavelength division multiplexer. The method comprises: using a nonlinear polarization rotation mode-locked technique to make the laser operate in an equivalent saturated absorption region and an equivalent anti-saturated absorption region, respectively, to output bright solitons and dark solitons, respectively. The laser and method can generate bright solitons and dark solitons, respectively.

The application belongs to the field of femtosecond laser technology, and particularly relates to a few-cycle high-energy fiber chirped pulse amplification system and method. The system comprises a seed source module, a chirped pulse amplification module and a hybrid compression module. The seed source module adopts a nonlinear polarization rotation mode-locked resonator with an integrated tunable filter to generate linear chirped wide spectrum seed pulses with tunable central wavelength. The chirped pulse amplification module realizes energy amplification while effectively suppressing gain narrowing effect through a three-stage structure of pre-chirp management, pre-amplification and main amplification. The hybrid compression module adopts a cascaded scheme of a diffraction grating compressor and a fiber soliton self-compressor to finally compress the pulse width to two optical periods. The application solves the problem that high energy and few cycles are difficult to be considered in a C-band fiber amplification system, and can output high peak power pulses of hundreds of nanojoules and two optical periods.

The invention belongs to the technical field of optical devices, and particularly discloses a two-dimensional material integrated microcavity and a nonlinear optical frequency conversion device and system composed of the two-dimensional material integrated microcavity. The two-dimensional material integrated microcavity comprises an echo wall microcavity and a two-dimensional material monomolecular layer, the two-dimensional material monomolecular layer is modified on the surface of the echo wall microcavity, and the two-dimensional material nonlinear dielectric layer induces resonance light existing in the echo wall microcavity to generate a nonlinear optical effect. The nonlinear optical effect at least comprises a second-order nonlinear optical effect. According to the two-dimensional material integrated microcavity, the two-dimensional material molecular layer is modified on the surface of the echo wall microcavity, and a nonlinear polarization coefficient matched with a resonant light mode is introduced through the nonlinear dielectric layer, so that resonant light in the cavity is induced to generate nonlinear polarization light waves; and meanwhile, the high-efficiency nonlinear optical effect is realized by utilizing dynamically coordinated double-resonance phase matching between the multi-mode resonance light in the cavity and the nonlinear polarized light wave.

The application discloses a kind of O band harmonic mode-locked lasers based on double-pumping nonlinear polarization evolution, including first pump source, second pump source, first wavelength division multiplexer, second wavelength division multiplexer, gain fiber, first polarization controller, polarization-dependent isolator, second polarization controller and coupler, constitute bidirectional pumping ring laser resonator.Coupled with the first and second polarization controller is placed in polarization-dependent isolator two sides, jointly constitute nonlinear polarization evolution mode-locked structure.By improving the power of double pump source and adjusting the polarization state in the cavity, the switching from fundamental mode-locked to multi-harmonic mode-locked can be realized, with a maximum of 33 orders, breaking through the upper limit of the repetition frequency of O-band all-fiber mode-locked laser, with the advantages of compact structure, high damage threshold, low cost, easy to integrate into all-fiber, suitable for optical communication and other fields.

The invention relates to the technical field of lasers, and discloses an all-polarization-maintaining 9-shaped mode-locked fiber laser which comprises a pumping source and a 9-shaped oscillation cavity, the 9-shaped oscillation cavity comprises a linear arm structure and an annular cavity, and the annular cavity comprises a wavelength division multiplexer, a gain fiber, a high-nonlinearity polarization-maintaining fiber, a first light beam adjusting module and a second light beam adjusting module. Two connecting ends of the wavelength division multiplexer are respectively connected with one end of the gain optical fiber and one end of the high-nonlinearity polarization maintaining optical fiber, an output end of the pumping source is connected with the wavelength division multiplexer, and light beams output by the high-nonlinearity polarization maintaining optical fiber are output to the linear arm structure through the first light beam adjusting module. According to the invention, the highly nonlinear polarization maintaining optical fiber is asymmetrically added into the annular cavity, and the nonlinear phase difference accumulation process between clockwise / anticlockwise propagation light is accelerated, so that the mode-locked self-starting capability of the laser is remarkably improved.

The invention belongs to the technical field of image processing, and particularly relates to a visual guidance positioning method and system for a radiator assembly line, and the method comprises the steps: carrying out the pixel-level classification of a radiator image, and obtaining an initial probability graph containing noise; in combination with the confidence of the initial probability and the structural information of the image, iterative edge-preserving propagation is carried out, edge details are kept while error classification is corrected, and a final probability graph is obtained; according to gradient information of the final probability graph, nonlinear polarization transformation of the dynamic slope is executed to sharpen the boundary of the target and the background; and accurately outputting a positioning result of the target area through adaptive threshold segmentation and geometric analysis. According to the method, the problems of much classification noise and fuzzy edge in a traditional method are reduced, and the accuracy and robustness of radiator assembly line positioning are improved.

The application discloses a wide-bandgap high-laser-damage-threshold second-order nonlinear optical film and a preparation method thereof. The film is a-axis oriented Li-doped Zn 1‑x Mg x O[0.3 < x < 0.56 and 0 < Li / (Zn+Mg+Li) < 0.09] film, which has a high χ (2) (2) and a high laser damage threshold while having a 4.5 eV band gap. The preparation method comprises the following steps: epitaxially growing an a-axis oriented Li-doped Zn 1‑x Mg x O film on an R-face Al2O3 substrate by radio frequency magnetron co-sputtering of a Mg-doped ZnO ceramic target and a Li-doped ZnO ceramic target; and the crystal direction of the film is parallel to the crystal direction of the Al2O3. The Li-doped Zn 1‑x Mg x O film prepared by the application can be applied to frequency doublers, electro-optical modulators and optical switches and other photonic devices, and has a wide application prospect in the fields of integrated photonics and nonlinear optics.

The invention belongs to the technical field of femtosecond laser, and particularly relates to a few-period high-energy optical fiber chirped pulse amplification system and method, and the system comprises a seed source module, a chirped pulse amplification module and a mixed compression module. The seed source module adopts a nonlinear polarization rotation mode-locked resonant cavity integrated with a tunable filter to generate a linear chirp wide-spectrum seed pulse with a tunable central wavelength. The chirped pulse amplification module effectively suppresses a gain narrowing effect while realizing energy amplification through a three-stage structure of pre-chirp management, pre-amplification and main amplification. The hybrid compression module adopts a scheme of cascading a diffraction grating compressor and an optical fiber soliton self-compressor, and finally realizes that the pulse width is compressed to two optical periods. According to the invention, the problem that high energy and few periods are difficult to consider in a C-band optical fiber amplification system is solved, and high-peak power pulses with hundred nanojoule magnitude and two optical periods can be output.

The invention discloses a method and a device for regulating and controlling a high-order Poincare spherical beam, and provides a method for effectively regulating and controlling the high-order Poincare spherical beam with complex vector polarization distribution in multiple dimensions such as angular momentum, light intensity distribution, polarization state and the like by using a nonlinear optical crystal based on a nonlinear effect of second harmonic. And different phase matching conditions in the second harmonic generation process are set, so that the regulation and control results of the second harmonic of the high-order Poincare spherical beam are enriched. According to the method and the device, a good effect is achieved during nonlinear regulation and control of the high-order Poincare spherical beam, the structure is simple, the cost is low, regulation and control of multi-dimensional optical properties are achieved, and the method and the device are suitable for design of optical nonlinear polarization imaging elements.

The present application belongs to the technical field of image processing, and particularly relates to a visual guidance positioning method and system for a radiator assembly line, which comprises the following steps: performing pixel-level classification on a radiator image to obtain an initial probability graph containing noise; combining the confidence of the initial probability and the structural information of the image to perform iterative edge-preserving propagation, thereby correcting the wrong classification while maintaining the edge details, and obtaining a final probability graph; performing a dynamic slope nonlinear polarization transformation according to the gradient information of the final probability graph to sharpen the boundary between the target and the background; and accurately outputting the positioning result of the target region through adaptive threshold segmentation and geometric analysis. The present application reduces the problems of multiple classification noises and fuzzy edges in the traditional method, and improves the accuracy and robustness of the positioning of the radiator assembly line.

The application provides a polarization-dependent device and an optical fiber laser, wherein self-made polyester transparent adhesive is used as a transmission tool, tantalum palladium sulfide is accurately placed in the center of the end face of an optical fiber jumper under a microscope, and the tantalum palladium sulfide is connected with another optical fiber jumper by using an optical fiber sleeve to form the polarization-dependent device. The tantalum palladium sulfide has excellent nonlinear polarization optical response, under the condition that the input pump power is constant, the polarization-dependent device based on the tantalum palladium sulfide can realize stable soliton and noise-like dual-mode controllable switching in a single superfast optical fiber laser. In a single superfast optical fiber laser system, the controllable stable switching of different superfast laser pulse modes has great expansion application potential. The polarization-dependent device based on the tantalum palladium sulfide in the application has simple structure, simple preparation and low cost, and has good nonlinear optical performance and long-term working stability.

The application belongs to the technical field of microwave photon and optical communication, and specifically relates to a full-optical microwave oscillator under single-mode optical fiber twist radial mode vernier effect, which comprises a self-excited erbium-doped fiber amplifier, a tunable optical filter, an isolator, a first polarization controller, a second polarization controller, a third polarization controller, a first single-mode optical fiber, a second single-mode optical fiber, a polarizer, a first optical coupler, a second optical coupler, a third optical coupler, a spectrometer, a photoelectric detector and a spectrum analyzer. The application realizes passive mode-locking based on twist radial mode by using nonlinear polarization rotation (NPR) technology, narrows the linewidth to the order of hertz by using a passive intrinsic resonant cavity, effectively suppresses the side mode based on double-ring vernier effect, breaks the limitation that a conventional twist radial mode full-optical microwave oscillator signal cannot generate high-performance twist radial mode full-optical microwave oscillator signal, has unique and innovative advantages, and finally realizes twist radial mode single-longitudinal-mode oscillator signal output with high side mode suppression ratio.

The application discloses a near-transform limit nanosecond pulse mode-locked fiber laser with periodic bifurcation and a producing method. The laser is a fiber ring cavity which comprises a wavelength division multiplexer, an erbium-doped fiber, a first polarization controller, a polarization detector, a dispersion control unit, an output coupler, a fiber isolator and a second polarization controller which are connected in sequence in a closed loop. The method comprises the following steps: coupling pump continuous light into the laser through the wavelength division multiplexer; absorbing the pump continuous light by the erbium-doped fiber and radiating gain pulses in a long-wave band; oscillating the generated pulses in the fiber laser cavity; through the cooperation of the first polarization controller, the polarization detector and the second polarization controller, generating equivalent saturated absorption effect by using the nonlinear polarization rotation generated when the gain pulses propagate in the fiber, and realizing pulse mode-locking; and making the fiber laser work in an abnormal dispersion region so that the generated pulses satisfy the soliton area theorem and near-transform limit pulses are generated. The application can realize nanosecond pulse periodic bifurcation output of a short-cavity fiber laser.

This invention belongs to the field of microwave photonics and optical communication technology, specifically a single-longitudinal-mode all-optical microwave oscillator based on torsional radial mode parity-time symmetry. It solves the technical problems of existing microwave photonics generation devices having complex structures, all-optical microwave oscillators lacking research on torsional radial acoustic modes, and significant energy waste in single-longitudinal-mode generation. It includes a self-excited erbium-doped fiber amplifier, a tunable optical filter, an isolator, a circulator, a parity-time symmetric Sagnac ring, a first optical splitter coupler, a second optical splitter coupler, a first polarization controller, a second polarization controller, a single-mode fiber, a polarizer, a spectrometer, a photodetector, and a spectrum analyzer. The parity-time symmetric Sagnac ring includes a third optical splitter coupler, a third polarization controller, a fourth polarization controller, and a polarization beam splitter. It utilizes nonlinear polarization rotation technology to achieve passive mode-locking based on the torsional radial mode; and utilizes a parity-time symmetric structure to achieve single-longitudinal-mode output with a high side-mode suppression ratio.

This application provides an intelligent mode-locked fiber laser based on nonlinear polarization interference and its control method, belonging to the field of fiber laser and intelligent control technology. The application includes: scanning a waveplate, setting the angle corresponding to the maximum power as the mechanical zero point, and establishing a correspondence between angle and power; using the mechanical zero point as a reference and the correspondence between angle and power, scanning the waveplate with a first-step scanning length, marking states that meet the spectral width condition and exhibit a comb-like structure as mode-locking candidate points; using the mode-locking candidate points as the center, scanning with a second-step scanning length, determining mode-locking when the spectral bandwidth reaches a threshold and the power standard deviation is less than a stability threshold, recording the current power standard deviation as the reference fluctuation value, and recording the corresponding angle as the target mode-locked operating point; monitoring output parameters, calculating the power standard deviation and comparing it with the reference fluctuation value, and triggering a local search to restore mode-locking when the deviation exceeds the allowable range. This application can achieve automatic tuning of the intracavity polarization state and phase shift.

An Er: YAG composite optical fiber laser based on nonlinear polarization rotation mode locking comprises a pumping source and an optical fiber annular resonant cavity, and the optical fiber annular resonant cavity is formed by connecting a wavelength division multiplexer, an Er: YAG composite optical fiber, an extrusion type polarization controller, a polarization dependent optical fiber isolator, a three-ring rotation type polarization controller and an optical fiber coupler through single-mode optical fibers. The pumping source is connected with the pumping end of the wavelength division multiplexer, and stable mode-locked laser pulses are output through 20% of the output end of the optical fiber coupler; or the optical fiber annular resonant cavity is formed by sequentially connecting a wavelength division multiplexer, an Er: YAG composite optical fiber, an optical fiber coupler, an extrusion type polarization controller, an optical fiber polarizer, a three-ring rotary type polarization controller and a polarization independent optical fiber isolator through optical fibers; an extrusion type polarization controller, an optical fiber polarizer and a three-ring rotary type polarization controller jointly achieve an artificial saturable absorber equivalent to nonlinear polarization rotation, and passive mode locking is achieved. The antenna has the advantages of ultra-wide gain spectrum, strong anti-interference capability and the like.