352results about How to "High damage threshold" patented technology

Apparatus and methods for altering one or more spectral, spatial, or temporal characteristics of a light-emitting device are disclosed. Generally, such apparatus may include a volume Bragg grating (VBG) element that receives input light generated by a light-emitting device, conditions one or more characteristics of the input light, and causes the light-emitting device to generate light having the one or more characteristics of the conditioned light.

The invention discloses a hollow anti-resonance optical fiber, and belongs to the technical field of optics and laser photoelectrons.The basic structure of the hollow anti-resonance optical fiber comprises a fiber core area with low refraction rate and a wrapping layer area with high refraction rate.The wrapping layer area with high refraction rate is divided into an inner wrapping layer region and an outer wrapping layer region.The inner wrapping layer region is composed of one or two layers of micro capillary pipes.The fiber core area with low refraction rate is wrapped by the inner wrapping layer region.Compared with a traditional band gap type hollow-core photonic crystal fiber, the hollow anti-resonance optical fiber has the advantages of being large in spectral bandwidth, small in bending loss, low in transmission loss, high in damage threshold and capable of keeping single-modulus transmission.A high-efficiency and high-sensitivity ideal platform is created for nonlinear frequency conversion, trace gas / liquid detection, high-power pulse compression and other foremost application.

The invention discloses a fabricated concrete column-steel beam energy dissipation type panel point connecting device. The fabricated concrete column-steel beam energy dissipation type panel point connecting device is composed of a beam-beam bolt connection component and a friction energy dissipation device, and comprises a prefabricated concrete column, a pre-buried steel beam, a middle steel beam and a combination connection steel piece, wherein transversal surfaces of the pre-buried steel beam and the middle steel beam are both H-shaped, webs of the pre-buried steel beam and the middle steel beam are connected through a web cover plate, and flanges of the pre-buried steel beam and the middle steel beam are connected through a connection cover plate. Earthquake energy is dissipated by using friction plates attached inside a combination steel piece and through a friction energy dissipation mechanism. Compared with the prior art, the connecting device can reduce adverse effects on a floor and achieve a beam hinge yielding mechanism by moving a plastic hinge outward, the energy dissipation device can improve fabricated structure energy dissipation and reduce damages of main structural members, connection parts and the steel beams can be conveniently maintained, replaced and dismantled for reuse, and simultaneously, the fabricated concrete column-steel beam energy dissipation type panel point connecting device is produced by using a whole prefabricated industrialization standard, and installed only through bolts on site, and has strong engineering practicability.

The present invention relates to a stable solid-state Raman laser (1), the solid-state Raman laser including: (a) a resonator cavity defined by at least two reflectors (M1 and M2), (b) a laser material (2A) located in the resonator cavity and capable of generating a cavity laser beam which propagates within the resonator cavity, (c) a solid Raman medium (7) located in the resonator cavity for shifting the frequency of the cavity laser beam to produce a Raman laser beam which propagates within the resonator cavity; and (d) an output coupler (M2) for coupling and outputting the Raman laser beam from the resonator cavity, wherein at least one parameter selected from the group consisting of (i) the position of the laser material (2A) relative to the position of the Raman medium (7) in the cavity, (ii) the length of the cavity and (iii) the curvature of at least one of the reflectors (M1 or M2), is selected such that changes in the focal lengths of both the laser material (2A) and the Raman medium (7) as a result of thermal effects in the laser material (2A) and the Raman medium (7) during operation of the laser do not substantially cause instability in the power of the output Raman laser beam. A method of maintaining stable operation of a solid state Raman laser is also described.

The invention discloses a generation / three-dimensional reconstruction apparatus and method for a Laguerre Gaussian vortex beam. The Laguerre Gaussian vortex beam generation apparatus comprises: a laser for emitting a Gaussian beam; a first convex lens for expanding the Gaussian beam; a second convex lens for collimating the expanded Gaussian beam; a computer for generating a fork-shaped diffraction grating and loading the fork-shaped diffraction grating onto a digital micromirror device, and subjecting the incident beam of the digital micromirror device to amplitude and / or phase modulation; and the digital micromirror device for subjecting a part of the collimated Gaussian beam to amplitude or / and phase modulation to produce Laguerre Gaussian vortex beams with different orders. The generation / three-dimensional reconstruction apparatus has a high damage threshold and a very fast response speed, is simple in structure, good in stability, and low in manufacturing cost, and is widely used in the fields of mechanical processing, biomedical treatment, military field, information transmission, micro-control and the like.

The invention relates to a coating method capable of improving a laser induced damage threshold of a high-reflectivity film and belongs to the field of film optics. The coating method mainly aims at two key factors of absorption and defects influencing a laser induced damage threshold of a high-reflectivity laser film, and after electron beam evaporation coating of each film layer is finished, utilizes high-energy ion beams to bombard the film layer. The coating method retains unique and beneficial performances of a laser film coated by electron beam thermal evaporation, improves intrinsic absorption and defect density of a film, greatly improves a laser induced damage threshold of a high-reflectivity film, and has the characteristics of strong pertinence, high coating quality, simpleness and good feasibility.

The invention provides an anti-reflective film, which is used for reducing the light reflection of the surface of a solar battery and comprises a silicon nitride film, a silicon oxynitride film and a silicon oxide film which are deposited on the surface of a silicon slice in sequence from inside to outside. The invention also provides a preparation method of the anti-reflective film, which comprises the following steps: (1) depositing the silicon nitride film on the surface of the silicon slice; (2) depositing the silicon oxynitride film on the surface of the silicon nitride film to enable the refractive index of the silicon oxynitride film to be less than that of the silicon nitride film; and (3) depositing the silicon oxide film on the surface of the silicon oxynitride film to enable the refractive index of the silicon oxide film to be less than that of the silicon oxynitride film. The anti-reflective film has even overall refractive index change and good optical / electrical properties and an anti-reflective effect; the preparation method is simple and is easy to realize and can provide the anti-reflective film which has even refractive index change and can effectively improve photoelectric conversion efficiency.

A single-mode fiber laser includes a single mode holding, large mode area optical fiber assembly having a large mode area core, a first cladding and a second cladding. The optical fiber assembly has several unique sections including a gain section having a ytterbium-doped core, first and second reflective sections including fiber Bragg gratings that define a lasing cavity, and an absorptive section also having a ytterbium-doped core, the absorptive section having an output end coupled to an input end of said first reflective section. A broad area, multi-mode diode pump source is configured to pump multi-mode light into a tapered input section and cladding-pump the gain section. The gain section absorbs the multi-mode pump light and emits single-mode light. The absorptive section absorbs emissions at the operating wavelength and prevents operating emissions from reflecting back into said pump source.

The invention discloses a saturated absorption composite material ink, a preparation method and an optical fiber laser based on the ink. Two or more lower-dimension quantum materials with saturated absorption characteristics and a surfactant are dissolved in water so as to prepare a dispersion liquid; a water-soluble polymer is prepared into a water solution; and the two solutions are mixed up and subjected to ultrasonic treatment so as to form the saturated absorption composite material ink with the appointed optical absorption characteristic. The invention further provides a method for depositing the composite material ink on optical fiber laser elements through an ink-jet printing device or a spraying device so as to realize mold locking or Q laser pulse. By utilizing the saturated absorption composite material ink, saturated absorption devices with flexible and controllable optical parameters, high damage threshold and good integration level are realized; and by utilizing the devices, the working reliability and the output power stability of optical fiber lasers are greatly improved, the laser design is simplified, and the cost is saved.

High efficiency reflective volume Bragg gratings with chirped gratings recorded in photo-thermo-refractive glass having an absolute diffraction efficiency exceeding 95% in transmitting and reflecting modes are used to stretch and / or compress ultrashort laser pulses with high efficiency. Robustness, compactness, thermal and laser stability along with placement of multiple elements in the same space provides femtosecond laser system with high efficiency of stretching and re-compression of femtosecond pulses.

The invention relates to a coherent combining device of self-adaption high-order transverse mode lasers, which comprises a solid laser, a deformable mirror, a beam matching system, a CCD camera, a beam splitting reflector, a high-pressure amplifier, a focusing lens, an attenuation system and a computer. High-order transverse mode lasers output by the solid laser are irradiated to the deformable mirror after being expanded by the beam matching system; laser beams reflected by the deformable mirror are gathered on the CCD camera at a focal position after passing through the beam splitting reflector, the attenuation system and the focusing lens in sequence; an optimization algorithm placed in the computer iterates along the direction enabling the strength of the peak value of a focal spot on the CCD camera to work out a voltage signal; the voltage signal is loaded to each driver of the deformable mirror after being amplified by the high-pressure amplifier to drive the deformable mirror to generate corresponding deformation so as to compensate the distortion in the whole wavefront phases of the high-order transverse mode lasers, compensate the pi-phase step of sidelobes of both sides of each nodel line of the high-order transverse mode lasers and improve the coherent feature and the focusable capability of the high-order transverse mode lasers. The invention can improve the coherent performance and the focusable capability among high-order transverse mode beams.

Apparatus and methods for altering one or more spectral, spatial, or temporal characteristics of a light-emitting device are disclosed. Generally, such apparatus may include a volume Bragg grating (VBG) element that receives input light generated by a light-emitting device, conditions one or more characteristics of the input light, and causes the light-emitting device to generate light having the one or more characteristics of the conditioned light.

The invention discloses an optical fiber with a ring-shaped doped layer, which is used in an optical fiber laser and composed of an inner clad layer (101), a ring-shaped doped layer (102), a middle clad layer (103), an outer clad layer (104) and a protective layer (105), wherein the ring doped layer (102), the middle clad layer (103), the outer clad layer (104) and the protective layer (105) are, from inside to outside, sequentially clad on the inner clad layer (101), and the inner clad layer (101) is an undoped optical fire core. The invention also discloses a method for preparing the optical fiber with a ring-shaped doped layer, and a laser taking the optical fiber with a ring-shaped doped layer as a gain medium. According to the invention, the traditional fiber core doping is changed into a ring-shaped doped layer, so that the laser oscillation is actually performed in a ring-shaped waveguide, and then through reasonably designing the thickness of the ring-shaped waveguide, a single-mode operation can be kept; meanwhile, because the cross section area of the doped layer is large, the optical fiber with a ring-shaped doped layer is suitable to high-power output, therefore, the output power of the optical fiber laser using the optical fiber can be improved.

The invention provides a method for improving the damage threshold of a fused quartz optical element. The method comprises the following steps of: performing cleaning, rinsing and spray cleaning on the fused quartz optical element by using a mixed solution including a cleaning agent micro-90 and water; and performing etching, rinsing and spray cleaning on the fused quartz optical element through a hydrofluoric acid aqueous solution. In the whole cleaning process, 40-270 kHz of multi-frequency ultrasonic waves are introduced for cleaning. The method provided by the invention can effectively passivate scratches in a sub-surface damage layer of the fused quartz optical element, and remove polishing scraps and polishing impurities in the scratches with different scales to stabilize a hydrofluoric acid etching process, prevent re-deposition of an etching byproduct, and stably promote the damage threshold of the element sharply.

The present invention provides a microstructured hollow-core optical fiber. The optical fiber comprises first type medium circular tubes, second type medium circular tubes, and a third type medium circular tube; the first type medium tubes are nested in the second type medium circular tubes and are periodically distributed along the circumference of the second type medium circular tubes; intervalsbetween the outer walls of the adjacent first type medium circular tubes are greater than 0; the second type medium circular tubes are nested in the third type medium circular tube; and the first type medium circular tubes, the second type medium circular tubes and the third type medium circular tube are connected with one another in a tangent or intersecting manner. According to the microstructured hollow-core optical fiber of the invention, confinement loss can be lowered by simply increasing the number of the second type medium circular tubes, so that a difficulty that the confinement lossof a negative-curvature anti-resonant hollow-core optical fiber cannot be reduced by simply adopting a means of increasing annular layers which assists in reducing the confinement loss of a hollow-core photonic band gap optical fiber can be eliminated. According to the optical fiber provided by the invention, too many nodes will not be introduced into the cross section of the optical fiber, and anew scheme and idea can be provided for the design and manufacture of a broadband low-loss hollow-core optical fiber.

The invention relates to a full-aperture coaxial laser transmitting and echo receiving system. The full-aperture coaxial laser transmitting and echo receiving system disclosed by the invention comprises a light source, a light beam shaping unit, a polarization spectroscope, a strobing gate, a telescope, a light filter, a focusing unit, a photoelectric detecting and data processing unit and a control unit, wherein the light beam shaping unit and the polarization spectroscope are in sequence arranged on a laser beam optical axis of the light source; the light filter, the focusing unit and the photoelectric detecting and data processing unit are in sequence arranged on a transmission surface of the polarization spectroscope; the strobing gate, the telescope and a target are in sequence arranged on a reflecting surface of the polarization spectroscope; the input end of the control unit is connected to an output end of the light source; the output end of the control unit is connected to the input end of the strobing gate; the photoelectric detecting and data processing unit is connected to the telescope and the focusing unit. By adopting the full-aperture coaxial laser transmitting and echo receiving system disclosed by the invention, the full-aperture coaxial laser transmission and echo receiving of the laser of the same waveband are achieved, the signal to noise ratio of echo signal receiving is improved, the cost of a transmitting-receiving system is reduced and the damage threshold of the system and the utilization efficiency of the transmission laser are improved in a total-reflection laser transmission way.

The invention discloses a beam combining, emitting and receiving method of lasers and a system, which belong to the technical field of photoelectricity and are used for carrying out beam combination, emission and reception on multi-beam multi-band high-power lasers. The beam combination, the emission and the reception of lasers in incidence in a plurality of directions are realized by adopting the reflection of a film at the side face of a prism, the incidence and the penetration of an end face, an optical fibre bar and a collimating mirror. The system contains a plurality of laser light sources, a multi-dimensional beam combiner, a shaper, a collimating mirror, a receiving and detecting unit and a computer system. The multi-dimensional beam combiner contains a multi-face prism and a prism holder, wherein the multi-face prism is provided with an end face and a plurality of reflecting mirror faces. A plurality of lasers are irradiated on the end face and the reflecting mirror faces of the multi-dimensional beam combiner from the periphery, the lasers of which the beams are combined are gathered on the input end face of the shaper at an aperture angle smaller than the numerical value of optical fibers, the output lasers are collimated into quasi-parallel light by the collimating mirror for irradiating a target, and the diffuse reflection lasers and the laser-induced radiation patterns of the target are received by the receiving and detecting unit positioned at the position of the focal point of the collimating mirror so as to realize the detection of the target and the acquisition of images.

The invention discloses a post-processing method to enhance the damage threshold of a fused quartz optical element. First, a fluorescence confocal microtechnique is employed to detect the distribution scope and scale of subsurface defects of the fused quartz optical element; and multi-frequency ultrasonic alternating multiplexing assisted chemical etching technique through KHz and MHz frequencies is used for etching different depths according to subsurface defects in different depth distribution; different frequencies are used for different scales of subsurface defects to peel off the subsurface defects layer by layer, in order to enhance the damage threshold. The post-processing method has global processing capability on optical element; hydrofluoric acid corrosion treatment completely removes a polishing deposited layer to expose the scratches on the subsurface damage layer, and sharp new look of the scratches are well passivated; the introduction of multi-frequency ultrasonic / megasonic assist can act on scratch passivation at different scales to prevent re-deposition of the etching reaction byproducts and improve the process stability. The method can stably and greatly enhance the damage threshold of the fused quartz optical element.

The invention relates to a cleaning method of an optical substrate for a laser thin-film element. The cleaning method includes the specific methods: using a cotton swab dipped with acetone for wiping the optical substrate until the surface of the substrate is free of macroscopic contaminants under the irradiation of an incandescent lamp; placing the wiped substrate in alkaline solution of a first tank, and respectively performing ultrasonic cleaning for the substrate successively by different frequencies; placing the substrate in a second tank, and using deionized water for spraying; and placing the substrate in deionized water of a third tank, successively subjecting the substrate to ultrasonic with different frequencies for 3-6 minutes, observing the surface cleanliness of the substrate under the incandescent lamp, and after the surface of the substrate is free of macroscopic particles, placing the substrate in deionized water of a fourth tank for slow lifting under ultrasonic of 80KHz, and drying the lifted substrate by hot blowing so that the required product is obtained. A cleaning processing and surface detection are combined together, a wiping method, a chemical cleaning method and an ultrasonic cleaning method are combined for comprehensive application, so that high cleaning efficiency and optimal cleaning effect less in damage to the smooth surface of the substrate are achieved.

The invention provides a polarization coupling device. The polarization coupling device comprises a rectangular prism, a rhombic prism and a 1 / 2 wave plate. A first right angle plane of the rectangular prism faces towards the direction of an incident laser. The length of a first long edge plane of the rhombic prism is equal to the length of an bevel edge plane of the rectangular prism, either the first long edge plane or the bevel edge plane or both the first long edge plane and the bevel edge plane are plated by a polarization spectroscopic film layer and are closely attached to the polarization spectroscopic film layer to form a polarizing beamsplitting interface. A second long edge plane of the rhombic prism is plated by a laser all reflective film, a first short edge plane of the rhombic prism faces the direction of the incident laser, and a second short edge plane of the rhombic prism serves as a laser sending plane. The 1 / 2 wave plate is located at the front end of a light path of the first right angle plane of the rectangular prism when the polarization spectroscopic film layer is an S polarized light high permeability P polarized light high reflective film, and the 1 / 2 wave plate is located at the front end of a light path of the first short edge plane of the rhombic prism when the polarization spectroscopic film layer is a P polarized light high permeability S polarized light high reflective film. According to the polarization coupling device, the size of a light beam of a single laser light source can be compressed.

The invention provides a gas detection system based on a hollow-core anti-resonance optical fiber. The gas detection system comprises a laser device, a first gas cavity, a hollow-core anti-resonance optical fiber, a second gas cavity, a spectrograph and a data processing device, wherein two ends of the hollow-core anti-resonance optical fiber are respectively communicated with the first gas cavityand the second gas cavity; the first gas cavity and the second gas cavity are used for injecting to-be-detected gas into the hollow-core anti-resonance optical fiber; the laser device is used for inputting detection laser into the hollow-core anti-resonance optical fiber; the spectrograph is used for measuring Raman scattering light generated by to-be-detected gas; and the data processing deviceis used for processing a Raman spectrum and analyzing the contents and concentration of to-be-detected gas. The hollow-core anti-resonance optical fiber has the characteristics that the transmission loss is low, the transmission bandwidth is wide, the bending loss is low, the damage threshold is high, and single mode transmission is maintained; and the Raman scattering threshold is reduced, and the contents and the concentration of trace gas can be detected by virtue of pump light with relatively low power.

The invention provides a method for repairing laser damage of fused quartz without thermal residual stress. According to the method, rectangular laser pulses with high-peak power are acquired by intercepting peak segments of pulses output from a laser device; the rectangular laser pulses with high-peak power are focused, and single laser pulses with super-high-peak power density are acquired; the single laser pulses are used for peeling a material at a single point of a damaged part on a fused quartz substrate through transient gasification; the interval of the single laser pulses is controlled, so that the substrate is cooled sufficiently; gasification peeling is performed repeatedly through the single laser pulses until the material at the whole damaged part is removed. With the adoption of the method, high-temperature structural relaxation of the fused quartz substrate is effectively controlled, the damage of the fused quartz is repaired without thermal residual stress, the anti-damage capacity of damage points of a fused quartz optical element is improved, surface damage and development of surface damage of the fused quartz optical element are inhibited, the service life of the fused quartz optical element is prolonged, and the method has the advantages of short repair time, simple and efficient process, good process stability, high controllability and high repeatability.

Disclosed is a terahertz parameter source on the basis of potassium titanium oxide arsenate crystals. The terahertz parameter source comprises a laser pumping system, a terahertz parametric device and a cooling system, wherein the terahertz parametric device comprises the potassium titanium oxide arsenate crystals, pumped laser emitted by the laser pumping system illuminates along the terahertz parametric device, and the terahertz parameter source is formed by scattering process of stimulated excitons of the potassium titanium oxide arsenate crystals. The output frequency range of terahertz waves is from 3.5THz to 6.5THz. The terahertz parametric device further comprises a rear cavity mirror and an output mirror, and the laser pumping system emits the laser sequentially along the rear cavity mirror of the terahertz parametric device, the potassium titanium oxide arsenate crystals and the output mirror of the terahertz parametric device. According to the terahertz parameter source and the application thereof on the basis of the potassium titanium oxide arsenate crystals, nonlinear crystals of potassium titanium oxide arsenate are used, the nonlinearity gain of the crystals is high, meanwhile, high damage threshold is achieved, and tunable terahertz radiation waves in the frequency range from 3.5THz to 6.5THz can be obtained through an angle tuning mode.

A metal dielectric film wideband pulse compressed grating used in 800nm center wavelength consists of a metal layer, a matching layer consisting of dielectric films and a grating etching layer which are sequentially arranged on a quartz substrate from the inside out and integrated together, and the outermost layer is SiO2. The rectangular grating has the period of 490-640nm, and the duty cycle of 0.2-0.4. The interlayer of the grating etching layer is a high-refractivity layer, the inner layer and the outer layer of the grating etching layer are low-refractivity layers SiO2; the outer layer of the matching layer is a high-refractivity layer, and the inner layer of the matching layer is a low-refractivity layer; and the thickness of the gold layer is larger than 50nm. By adopting the metal dielectric film wideband pulse compressed grating at the 700-909 nm band, the -1-level reflection and diffraction efficiencies of TE polarization are larger than 90 percent at the incidence angle of 53 DEG; and when the grating is at the 800nm incident wavelength, the -1-level reflection and diffraction efficiencies of TE polarization are larger than 90 percent at the incidence angle of 29-65 DEG. The metal dielectric film wideband pulse compressed grating can be used as a pulse compressed grating of a high-power ultrashort impulse laser system.

The invention relates to a double clad all-solid-state photonic crystal fiber and a preparation method thereof. The double clad all-solid-state photonic crystal fiber comprises a fiber core, an inner cladding and an outer cladding. The optical fiber is provided with the outer cladding of which the outer surface is of a round shape. The inner cladding is of a hexagon shape with a sawtooth structure. The preparation method of the double clad all-solid-state photonic crystal fiber comprises the following steps of: using a metal sleeve with an internal hexagon structure as a die; preparing a photonic crystal fiber per-form rod by a stacking method; replacing cladding air holes with glass with low refractive index, so that the making process and the fusion welding of the optical fiber are more simple and convenient; and forming the optical fiber, of which the outer surface is round and the inner cladding is of the hexagon shape with the sawtooth structure by utilizing the surface tension of the glass in the wire drawing process. A pumping light adsorption coefficient of the optical fiber is improved. The coupling efficiency and the pumping light adsorption coefficient are effectively improved. Compared with a double-layer optical fiber with a conventional structure, the output laser power and efficiency are improved by over twice.

The invention relates to a mode locking pulse optical fiber laser based on an SMS structure. The mode locking pulse optical fiber laser comprises a pumping source, a wavelength division multiplexer, apolarization single-mode-multimode-single-mode structure, an output coupler, a gain optical fiber and a polarization independent isolator, wherein the pumping source is connected with the wavelengthdivision multiplexer; the wavelength division multiplexer is connected with the polarization single-mode-multimode-single-mode structure; the polarization single-mode-multimode-single-mode structure is connected with the output coupler; the output coupler is connected with the gain optical fiber; the gain optical fiber is connected with the polarization independent isolator; the polarization independent isolator is connected with the wavelength division multiplexer; and the wavelength division multiplexer, the polarization single-mode-multimode-single-mode structure, the output coupler, the gain optical fiber and the polarization independent isolator are sequentially connected to form an optical fiber ring cavity structure. The mode locking pulse optical fiber laser achieves full optical fiber mode locking in a SMS structure and polarization controller combined manner; manufacturing of a mode locking structure and a mode locking device is simplified; and compared with the traditional mode locking optical fiber laser, the mode locking pulse optical fiber laser is simpler and more compact in structure and higher in damage threshold.

The invention discloses a 2 [mu] m mode-locked fiber laser based on an SMF-SIMF-GIMF-SMF fiber structure. The laser is of an annular cavity structure and comprises a pumping source, a wavelength division multiplexer, a gain fiber, a non-polarization-maintaining isolator and a polarization controller, an all-fiber saturable absorption device serving as a mode locking device and a coupler serving as an output; the all-fiber saturable absorption device is composed of an input single-mode fiber, a step multimode fiber, a gradient multimode fiber and an output single-mode fiber. The laser mode locking mechanism disclosed by the invention adopts the nonlinear multimode interference effect in the multimode fiber, has the advantages of all-fiber structure, high damage threshold, self starting of model locking, high stability and compact structure, and has a wide application prospect.

A trapezoid metal dielectric film broadband pulse compressed grating is characterized in that the grating is integrally formed through a matching layer and a trapezoid grating ridge, wherein the matching layer is composed of a quartz substrate, a metal layer and two layers of dielectric films, the trapezoid grating ridge is composed of three layers of dielectric films, and the outermost layer is made of SiO2. The cycle of the trapezoid grating is 490-640 nanometers, the duty ratio is 0.2-0.7, the base angle of the grating ridge is 60-89 degrees, the middle layer of the grating ridge is a high-refractive-index layer, and the inner layer and the outer layer of the grating ridge are low-refractive-index layers made of SiO2; the outer layer of the matching layer is a high-refractive-index layer, and the inner layer of the matching layer is a low-refractive-index layer; the thickness of the metal layer is larger than 50 nanometers. The trapezoid metal dielectric film broadband pulse compressed grating can be used as a pulse compressed grating of a high-power ultra-short pulse laser system with the central wavelength of 800 nanometers.

The invention belongs to the field of vascular endoscope imaging, and discloses an intravascular photo-acoustic imaging probe based on conical fibers and capable of simultaneously achieving optical coupling and photo-acoustic exciting. The intravascular photo-acoustic imaging probe comprises a catheter, an ultrasonic transducer coaxial line, the conical fibers, torsion coils, a probe housing, a capillary glass tube, a grin lens, a coated reflector and an ultrasonic transducer, wherein the tail ends of the conical fibers are connected to the grin lens; the front end of the grin lens is connected to the coated reflector and the tail end of the grin lens is connected to the capillary glass tube; one end of the ultrasonic transducer is fixed to the endoscope probe housing, and the coaxial lineis connected to a photoelectric slip ring of a three-dimensional spiral scanning device; and the input ends of the conical fibers, together with the grin lens and the coated reflector, are fixed to the interior of the endoscope probe housing, and the output end is connected to the photoelectric slip ring of the three-dimensional spiral scanning device. According to the intravascular photo-acoustic imaging probe provided by the invention, efficient laser coupling can be achieved through large input core diameters and small output core diameters of the conical fibers and efficient exciting canbe achieved through cooperation with the focusing lens, so that a good advantage is achieved on intravascular photo-acoustic imaging.

The invention discloses a multi-resonance-layer hollow-core optical fiber, which comprises an annular dielectric pipe, wherein a first type hole is formed in the central position in the annular dielectric pipe; a plurality of groups of arc-shaped dielectric layers are arranged around the first type hole, a rectangular dielectric layer is arranged on the inner side of each arc-shaped dielectric layer; a second type hole is formed between every two groups of arc-shaped dielectric layers in the same arc direction; third type holes are formed between each rectangular dielectric layer and the innerwall of the annular dielectric pipe and between each rectangular dielectric layer and the corresponding arc-shaped dielectric layer, a fourth type hole is formed between every two groups of adjacentrectangular dielectric layers, the first type hole, the second type holes, the third type holes and the fourth type holes form a low-refractive-index region, and the arc-shaped dielectric layers, therectangular dielectric layers and the annular dielectric pipe form a high-refractive-index region. The multi-resonance-layer hollow-core optical fiber has the beneficial effects that the damage threshold of the optical fiber is improved; the confinement loss of the optical fiber is reduced, and the low confinement loss features can be obtained conveniently; and high-bandwidth and low-loss opticaltransmission can be obtained in a facilitated manner.