22 results about "Quasi-phase-matching" patented technology

The invention belongs to the technical field of nonlinear optics, and discloses a method and a structure for realizing nonlinear waveguide quasi-phase matching. A plurality of groups of micro-nano structures are formed on the nonlinear waveguide along the waveguide propagation direction, each group of micro-nano structures comprises one or more air holes, the micro-nano structures are utilized to cause relative phases between different wavelength modes to generate jump, phase differences caused by phase mismatch are compensated, and quasi-phase matching is realized. The phase matching scheme provided by the invention is applicable to all nonlinear materials and waveguides, and has the advantage of high universality.

The application discloses a kind of multi-wavelength pumped mid-infrared upconversion spectral detection methods, its characteristics are that the method uses multi-wavelength narrowband laser as the pump source of nonlinear conversion, simultaneously adopt multi-period quasi-phase matching crystal as nonlinear upconversion medium, realize mid-infrared signal broadband and efficient conversion, and combine high-performance near-infrared spectral measurement and control element, finally obtain wide band, high resolution, ultra-sensitive mid-infrared spectral detection.The application has the characteristics of large bandwidth and high efficiency compared with existing upconversion spectral technology, simultaneously can high fidelity resolution mid-infrared spectral information, for realizing wide band, high resolution, ultra-sensitive mid-infrared spectral measurement provides effective means, is expected to be applied to molecular spectroscopy, trace substance detection, infrared remote sensing and atmospheric monitoring and other important fields.

The invention belongs to the technical field of laser technology and nonlinear optical frequency conversion, and discloses an intelligent control method for a PPLN frequency multiplication system, which comprises the following specific steps: step 1, initializing and self-checking the system, and completing initialization of hardware peripherals and a control program after the system is powered on; according to the method, a three-stage progressive optimal working point searching process is adopted, and the problem of optimal matching temperature drift caused by crystal heat absorption and photorefraction effects under high-power operation is effectively solved through the modes of low-power coarse scanning calibration of reference temperature, gradient power approximation real-time tracking of temperature drift and high-power dynamic locking closed-loop control; it is ensured that the system can work in the optimal state of quasi-phase matching under any input power; and meanwhile, through a power-temperature synchronous coordination feedforward + feedback control strategy, an efficient conversion interval is always maintained in a system output power adjustment process, and sudden efficiency drop caused by mismatch is avoided.

A fluid filled fiber for a quasi-phase matched generator and a laser incorporating such a fluid filled fiber. The liquid filled fiber has charge transfer molecules dissolved in a solvent. In another embodiment, the liquid of the LF fiber comprises or consists essentially of highly polar liquids and / or charge transfer molecules having relatively high molecular dipole values. The liquid filled fiber is usable with a laser for differential frequency generation.

The invention discloses a thorium-doped strontium tetraborate crystal as well as a preparation method and application thereof, the chemical formula of the thorium-doped strontium tetraborate crystal is ThxSr1-xB4 + yO7 (Th SBO), and the thorium-doped strontium tetraborate crystal grows by adopting a solution method. The Th: SBO crystal disclosed by the invention is low in melting point, simple in component and beneficial to realizing high-quality crystal growth; the material has a wide band gap, has high transmittance in a vacuum ultraviolet band, is beneficial to reduction of absorption loss in a nuclear transition luminescence band, and is beneficial to excitation and detection of a nuclear transition signal; the SBO crystal is a random quasi-phase matching (RQPM) nonlinear optical crystal, 296.76 nm narrow linewidth laser 148.38 nm frequency doubling light can be used as an excitation source of the nuclear light clock through frequency doubling, and a Th host crystal and a frequency doubling crystal are combined, so that the complexity of a system is remarkably simplified, and a core material is provided for miniaturization of the nuclear light clock.

The embodiment of the invention provides a frequency conversion device based on a lithium niobate ridge waveguide on an insulator and a preparation method, and belongs to the field of integrated optical, nonlinear optical and optoelectronic devices. The device comprises a silicon substrate layer, a silicon dioxide buffer layer, an x-cut lithium niobate film layer and a silicon dioxide cladding from bottom to top, a ridge waveguide with width periodically changing is arranged on the x-cut lithium niobate layer, and light in the waveguide is propagated in the y-axis direction. The waveguide with the width periodically changing is prepared on the lithium niobate film, quasi-phase matching is achieved, and therefore the second harmonic conversion efficiency is greatly improved. By changing the period of the waveguide, second-order nonlinear phase matching conditions under different wavelengths, such as phase matching conditions of second harmonic generation, sum frequency generation and difference frequency generation, can be met. Correspondingly, according to the preparation method, the waveguide structure with the periodically changed width can be formed through a single etching process, and a complex ferroelectric domain inversion step is not needed. The preparation method has the advantages of simple process, controllable morphology and flexible design.

The invention belongs to the technical field of quantum optics and quantum information devices, and discloses a near-infrared-mid-infrared dual-wavelength quantum polarization entangled source generating device which comprises a mounting seat, and a near-infrared light source, a mid-infrared light source, a first entangled crystal, a second entangled crystal, a core crystal module, a polarization controller and a generator are mounted and connected above the mounting seat. High-coherence pump light is output through a near-infrared light source, and the high-coherence pump light is shaped into parallel light beams through an aspheric collimating lens group and then is coupled to a first entangled crystal; under a quasi-phase matching condition, the pump light is converted into a near-infrared entangled photon pair of a communication band of 1.5-1.7 [mu] m through a spontaneous parametric down-conversion process, and then the near-infrared entangled photon pair is input into the core crystal module along a preset optical axis; a mid-infrared light source outputs mid-infrared pump light, linear polarization direction locking and polarization state fine regulation and control are completed through a polarization controller, and interference of pump light polarization fluctuation on subsequent entanglement state generation is eliminated; the regulated and controlled mid-infrared pump light is coupled to the second entangled crystal, mid-infrared entangled photon pairs in the atmosphere window wave band of 3.5-4.0 microns are generated through spontaneous parametric down-conversion, the mid-infrared entangled photon pairs are synchronously input into the core crystal module along the optical axis, and actual application and operation are facilitated.

The present invention relates to a method for preparing optical devices using LiNH4SO4 quasi-phase-matched crystals and their use. The LiNH4SO4 crystals are used in the preparation of deep-ultraviolet quasi-phase-matched optical devices. LiNH4SO4 quasi-phase-matched crystals have advantages such as a short UV absorption cutoff edge, moderate nonlinear optical effects, low refractive index dispersion, stable physical and chemical properties, and excellent mechanical properties, making them suitable for use in deep-ultraviolet quasi-phase-matched optical devices.

This invention provides a multi-channel three-dimensional quasi-phase matching method and apparatus. The method includes: focusing fundamental frequency light through a microscope objective to obtain fundamental frequency light with a modified focusing state; incident the modified fundamental frequency light onto a nonlinear photonic crystal via normal incidence, and obtaining an outgoing second harmonic through the nonlinear photonic crystal; and finally, outputting multi-channel frequency-doubled light waves based on the outgoing second harmonic. This invention focuses fundamental frequency light onto a nonlinear photonic crystal via a microscope objective, changing the direction range of the incident fundamental frequency wave vector simply by altering the numerical aperture of the focusing objective. Combined with the spatial reciprocal lattice vector combination of the three-dimensional nonlinear photonic crystal, the quasi-phase matching condition is satisfied, achieving variable multi-channel frequency doubling. This invention achieves controllable multi-channel second harmonic generation without structural changes.

This invention provides a method, apparatus, device, and readable storage medium for generating a waveguide single-photon source, relating to the field of quantum optics. The method includes coupling a fundamental frequency light output from a laser into free space to form a spatial beam; adjusting the polarization state of the collimated spatial beam to match its polarization direction with the crystal axis of a fully encapsulated waveguide device; coupling the polarization-adjusted spatial beam into a polarization-maintaining transmission fiber to form fiber-optic transmission light; injecting the fiber-optic transmission light into the fully encapsulated waveguide device, and converting the fundamental frequency light into frequency-doubled light at a quasi-phase-matching operating temperature; outputting the frequency-doubled light from the fully encapsulated waveguide device and coupling it again into free space to form an output beam; and performing spatial spectral filtering and intensity attenuation on the output beam to reduce the average photon number per pulse to the single-photon level, obtaining a purified single-photon signal. This invention addresses the polarization matching problem between existing waveguide devices and fiber optic transmission links.

This application provides a nonlinear optical device for generating an annular beam and a method for preparing the same. The method includes the following steps: designing a shaping structure for a hollow cylindrical quasi-phase-matching grating based on the distribution characteristics of a pump beam and the quasi-phase matching mechanism; modifying a ferroelectric crystal using a femtosecond laser to induce the spatial distribution of the ferroelectric crystal's second-order nonlinear coefficient to adopt the shaping structure, thereby preparing a nonlinear optical device; and generating an annular second harmonic beam when the pump beam is incident on the prepared nonlinear optical device. The nonlinear optical device prepared by the preparation method provided in this application can simultaneously generate an annular beam and double frequency. The preparation method provided in this application reduces processing difficulty and effectively controls the dark spot ratio at the center of the beam, providing a competitive nonlinear optical device product for generating annular beams.

A method for constructing a periodically-poled nonlinear crystal may include implanting ions in a bulk crystal of strontium tetraborate (SBO) or lithium triborate (LBO) to generate a damaged layer at a predetermined depth, attaching a handle material to the surface of the bulk crystal, cleaving the bulk crystal at the damaged layer to generate a thin plate, and polishing the thin plate to a thickness suitable for quasi-phase-matching (QPM) to generate laser output light having wavelengths in the range of about 120-200 nm. The surfaces of thin plates generated in this way are optically contacted, and resulting stacks are diced and arranged to generate many-layered QPM crystals. Methods, inspection systems, lithography systems and cutting systems incorporating the laser assembly are also described.

This invention discloses a broadband terahertz electro-optic sampling quasi-phase-matched structure, comprising at least two electro-optic crystals stacked sequentially, with a compensation crystal positioned between each pair of adjacent electro-optic crystals. The electro-optic crystals and the compensation crystals have opposite dispersion relations, facilitating the compensation crystals to compensate for the phase difference accumulated between the terahertz light and the probe light within the electro-optic crystals. This invention selects the type and thickness of the electro-optic crystals as needed, chooses a compensation crystal with an opposite dispersion relation to the electro-optic crystals, calculates its thickness based on the measurement bandwidth and phase-matching conditions, and then determines the number of electro-optic crystal layers according to the measurement bandwidth requirements. Compared with existing technologies, this invention can broaden the measurement bandwidth while maintaining signal strength. This invention does not involve precision micro / nano fabrication, is low-cost and easy to manufacture, does not involve destructive processing of the crystals, is reusable, and can be recombined and rearranged as needed, offering high flexibility.

The application relates to the technical field of strong laser nonlinear frequency conversion, in particular to a method for generating ultra-wideband mid-infrared laser in a single piece of polarized crystal. The method uses laser with a wavelength of 800 nm as pump light, laser with a wavelength of 0.95-1.6 microns as signal light, and a difference frequency conversion process occurs in the polarized crystal, thereby generating mid-infrared laser with a wavelength of 1.6-5 microns. In the method, a polarized crystal with a chirped period structure is used, that is, the polarization period of the crystal continuously changes with the position in the crystal. The polarized crystal is a 5% magnesium oxide doped chirped period lithium niobate crystal. The application utilizes quasi-phase matching technology, can use the maximum effective nonlinear coefficient of the chirped period lithium niobate crystal, and does not need to change the crystal angle or the polarization of the laser when the pump light is at different wavelengths. The application overcomes the shortcoming that the wavelength of the current mid-infrared band laser is difficult to expand due to the limitation of the gain medium.

The present application relates to a kind of single channel multi-entangled photon pair generation method, device, equipment and medium, belong to nonlinear optics technical field.The method improves the method for generating entangled light in existing nonlinear crystal spontaneous parametric down-conversion, by the quasi-phase matching period of nonlinear crystal is designed specifically, based on spontaneous parametric down-conversion process, simultaneously realize the generation of high-dimensional polarization entangled photon pair of two wavelengths, reduce conversion channel, compared with the existing spontaneous parametric down-conversion generation method, the generated entangled photon pair doubles, and compared with the existing non-spontaneous parametric down-conversion generation method, then no complex optical system, reduce the multi-source of experimental error, so comprehensive compared with the existing entangled light generation method has simple, efficient, reliable and flexible design characteristics, greatly reduce the difficulty of preparation high-dimensional entangled source, can better promote quantum entangled source and the development of quantum information technology.

This application relates to the field of hyperspectral imaging technology, specifically to an imaging device and imaging method. The imaging device includes: an infrared light receiving unit, a pump light source, a wavelength tuning up-conversion unit, and a visible light detection unit; wherein the infrared light receiving unit is used to collect infrared light; the pump light source is used to generate pump light that undergoes frequency up-conversion with the infrared light; the wavelength tuning up-conversion unit is disposed in the optical path of the infrared light and the pump light to receive the infrared light and the pump light, and is configured to change the positions of the infrared light and the pump light within the wavelength tuning up-conversion unit, so that infrared light of different wavelengths satisfies the quasi-phase matching condition and undergoes frequency up-conversion with the pump light, thereby generating visible light of different wavelengths; the visible light detection unit is disposed in the optical path of the visible light; this imaging device utilizes the wavelength tuning up-conversion unit to perform frequency up-conversion of infrared light of different wavelengths, simplifying the optical path and improving system integration and reliability.

A wavelength conversion system according to the present disclosure comprises an optical separation unit (110), QPM devices (120a-d) that generate a plurality of wavelength-converted lights by optical parametric amplification, and an optical multiplexing unit (130). The QPM devices (120a-d) are configured such that the spatial distribution of nonlinear constants at a distance z from an incident surface is represented by mathematical expression (2), a quasi-phase-matching condition is represented by mathematical expression (3) using n (where n is an integer), and mathematical expression (4) is satisfied when ZA is the set of all n for which the wavelength λ1(n), which satisfies mathematical expression (3), is a value corresponding to a wavelength band that is intended to be amplified, G(nA) is the parametric gain when the wavelength λ1(n), which satisfies mathematical expression (3), is a value corresponding to a wavelength band that is intended to be amplified, ZB is the set of all n for which the wavelength λ1(n), which satisfies mathematical expression (3), is a value corresponding to a wavelength band that is not intended to be amplified, and G(nB) is the parametric gain when the wavelength λ1(n), which satisfies mathematical expression (3), is a value corresponding to a wavelength band that is not intended to be amplified.

The utility model provides a femtosecond deep ultraviolet laser, and relates to the technical field of laser. The device comprises a pumping source, a pumping laser focus lens and a PPKTP crystal which are sequentially arranged at intervals along a light path, wherein the PPKTP crystal is arranged in a resonant cavity; the pumping laser focus lens is used for focusing the pumping light generated by the pumping source into the PPKTP crystal; the PPKTP crystal is used for generating second harmonics through a nonlinear process, and the resonant cavity is used for reflecting the generated second harmonics to the PPKTP crystal. According to the high-order quasi-phase matching OPO based on the PPKTP crystal, the wavelength of the generated pulse is shortened to green and blue from near infrared and finally shortened to deep ultraviolet (DUV) through multi-stage cascading of the frequency mixing process in the high-order quasi-phase matching OPO based on the PPKTP crystal, and the efficiency and the stability of deep ultraviolet pulse generation are improved.

The application provides a high-efficiency synchronous triple-frequency laser generating device, which comprises a laser module, an optical intensity control module, a nonlinear crystal and a filter module, wherein the nonlinear crystal is a periodically poled crystal, and the synchronous cascade nonlinear frequency conversion of incident fundamental frequency light is completed to obtain triple-frequency light; compared with the prior art, by reasonably designing the domain length of the periodically poled crystal, on the basis of satisfying the quasi-phase matching of the sum frequency process, a certain phase mismatching amount is actively introduced for the frequency doubling process, so that the conversion efficiency of the frequency doubling light is moderately inhibited, the consumed fundamental frequency light is dynamically supplemented, and then the high-efficiency and high-stability triple-frequency laser output is realized.

A method for constructing a periodically-poled nonlinear crystal may include implanting ions in a bulk crystal of strontium tetraborate (SBO) or lithium triborate (LBO) to generate a damaged layer at a predetermined depth, attaching a handle material to the surface of the bulk crystal, cleaving the bulk crystal at the damaged layer to generate a thin plate, and polishing the thin plate to a thickness suitable for quasi-phase-matching (QPM) to generate laser output light having wavelengths in the range of about 120-200 nm. The surfaces of thin plates generated in this way are optically contacted, and resulting stacks are diced and arranged to generate many-layered QPM crystals. Methods, inspection systems, lithography systems and cutting systems incorporating the laser assembly are also described.

The invention discloses a broadband mid-infrared laser generation device and method based on chirp cooperative regulation and control, and belongs to the technical field of ultrafast optics. A broadband mid-infrared laser generating device based on chirp cooperative regulation comprises a pumping source, a signal source, a dispersion management module, a light path delay regulation module and a nonlinear difference frequency module. And the dispersion management module comprises a first dispersion management unit and a second dispersion management unit. According to the invention, preset chirp and time domain broadening of pump light and signal light are introduced through a dispersion management module, controlled relative time slippage of two beams of light is generated during propagation by utilizing a group velocity mismatch effect in a nonlinear crystal, and a linear mapping relation between instantaneous frequency and a crystal space position is constructed; and point-by-point quasi-phase matching of different frequency components in the slippage process is realized in cooperation with a non-linear crystal with a non-uniform crystal polarization period in reverse design. According to the invention, broadband and high-efficiency mid-infrared laser output can be realized, and the device is compact in structure and high in stability.

To fill the need for a mode-locked or CW laser that generates radiation in the range shorter than 133 nm and is suitable for use in inspection of photomasks, reticles, and / or wafers.SOLUTION: A nonlinear crystal including stacked Strontium tetraborate SrB4O7 crystal plates is configured to create a periodic structure for quasi-phase matching and is used in a final frequency conversion stage of the laser assembly to generate laser output light having a wavelength in a range of 125 nm to 183 nm. One or more fundamental light beams having fundamental wavelengths between 1 and 1.1 μm are doubled and / or summed using a plurality of intermediate frequency conversion stages to generate one or more intermediate light beam frequencies, and then the final frequency conversion stage utilizes a nonlinear crystal to either double a single intermediate light beam frequency or to sum two intermediate light beam frequencies to generate a desired laser output light at high power and photon energy levels.SELECTED DRAWING: Figure 1