43 results about "Cladding mode" patented technology

The present invention belongs to the technical field of optical fiber sensing. Provided are a ring-type small-period long-period fiber grating sensor, and a preparation method therefor and the application thereof. A ring-type small-period long-period fiber grating provided in the present invention matches the cross-sectional shape of an optical fiber, and rings can more effectively expand the area of each refractive index modulation region in the cross section of the optical fiber, such that the ring-type grating has large refractive index modulation regions in both the axial direction and longitudinal direction of the optical fiber, and the intensities of a Bragg resonance peak and a cladding mode resonance peak can thus be simultaneously enhanced. Therefore, the Bragg resonance peak and the cladding mode resonance peak can be simultaneously observed in a transmission spectrum of the ring-type grating, such that simultaneous measurement of an ambient refractive index and temperature can be realized, and there is no longer a need to observe a reflection peak, thereby simplifying multi-parameter sensing test steps of the small-period long-period fiber grating.

The invention discloses a laser cladding method for a wind power sliding bearing, and particularly relates to the technical field of laser cladding. The method comprises the following steps that a wind power gear box pin shaft is fixed to a positioner and adjusted to be axially horizontal, and a laser cladding head is positioned to the position above the central axis of the pin shaft through an industrial robot; laser cladding is conducted in a synchronous powder feeding mode, a cladding head is controlled to horizontally move in the axial direction, meanwhile, a positioner drives a pin shaft to rotate, and a spiral coating is formed on the surface of the pin shaft in a cladding mode; and after single-layer full covering is completed every time, the cladding head is moved reversely to conduct next-layer cladding, coating thickness accumulation is achieved through direction alternation and interlayer superposition, and the technology is terminated till the preset value is reached. By the adoption of the technical scheme, the problem that in the prior art, a sliding bearing is insufficient in friction and wear performance is solved, a flat-topped beam is adopted to replace a traditional Gaussian beam for cladding, the particle size of powder is refined, and the prepared coating has the advantages of being few in crack defect and good in friction and wear performance.

The invention provides a cladding mode efficient filtering method for microstructure optical fibers, and relates to the technical field of optical fibers, and the method comprises the steps: taking two microstructure optical fibers which are different in structure and have a diameter difference value of a fiber core fundamental mode field within a diameter difference value range, and carrying out the non-oblique-angle cutting of the end faces of the two microstructure optical fibers through a cutting knife; and aligning the axial directions of the two sections of cut micro-structure optical fibers, and splicing at the cutting end surface to obtain a spliced micro-structure optical fiber. The method has the beneficial effects that two sections of microstructure optical fibers with different structures but similar fiber core fundamental mode field diameters are selected, oblique-angle-free cutting is carried out, splicing (welding, butt joint or coupler coupling) is carried out at the cutting end face, and it is ensured that splicing points are axially coaxial but cladding waveguide structures have differences. At a continuous connection point, because the cladding microstructures (such as air hole arrangement, number, shape and the like) of the two sections of optical fibers are discontinuous, the continuity of the cladding waveguide is damaged. Therefore, cladding mode energy is efficiently filtered or scattered, and the strength of the cladding mode energy is greatly weakened.

The application discloses a few-mode fiber double-cascaded mode converter and a high-power few-mode fiber laser. A core base mode and a core high-order mode converter and a core high-order mode and a cladding mode converter are cascaded on the few-mode fiber. The refractive index modulation distribution of the core base mode and the core high-order mode converter is uniformly distributed in the core center, and is used for coupling the core base mode to the core high-order mode. The refractive index modulation distribution of the core high-order mode and the cladding mode converter is distributed at the junction of the core and the cladding, and is used for coupling the core high-order mode to the cladding to form loss. The few-mode fiber double-cascaded mode converter is connected before an output end cap of the high-power few-mode fiber laser, and can inhibit stimulated Raman scattering in the large-mode-field few-mode fiber laser, so as to improve the output performance of the fiber laser.

The invention provides a multimode optical fiber connector device based on a thermal expansion core, and relates to the technical field of optical fibers. The multi-mode optical fiber connector comprises a non-core-expanded multi-mode optical fiber core module, a thermal core-expanded multi-mode optical fiber core module, a cladding module and an outer sleeve module, and by introducing the thermal core-expanded multi-mode optical fiber core module, the mode field matching condition of the multi-mode optical fiber connector under the condition of lateral deviation is remarkably improved, the connection loss is effectively reduced, and the service life of the multi-mode optical fiber connector is prolonged. The thermal core expansion multimode optical fiber core module is the core of the optical fiber module, the module uses a thermal core expansion processing technology and a standard TEC technology to expand the diameter of the multimode optical fiber core at the connecting end, and mode field distribution is optimized; and the outer sleeve module is sleeved outside the cladding module, and a standard optical fiber connector packaging process is adopted, so that the stability is high, the durability is strong, and the economical efficiency is excellent.

The invention, which relates to the technical field of the hollow-core optical fiber, provides a hollow-core optical fiber with an anti-resonance layer having a multi-layer opening structure, comprising an outer cladding sleeve, an anti-resonance area and a hollow-core fiber core area enclosed by the anti-resonance area. The anti-resonance area comprises a plurality of anti-resonance units, each anti-resonance unit comprises at least one anti-resonance layer of an opening structure, and the edges of the two sides of an opening of each anti-resonance layer are connected with the inner wall of the outer cladding sleeve through two parallel thin walls. The optical fiber has the beneficial effects that multiple anti-resonance effects are generated through the opening anti-resonance layer, so that a light field is prevented from leaking to the cladding from the fiber core, and the light field is effectively limited in the hollow fiber core area for transmission; each anti-resonance layer is indirectly connected with the inner wall of the outer sleeve through a parallel thin wall, so that a connection node is far away from the fiber core, node coupling is reduced, and leakage of a light field to the cladding is weakened. The anti-resonance layer and the sleeve form a closed cavity, so that a high-refractive-index area is compared with a low-refractive-index medium in the cavity, a specific wavelength is reflected, a light field is prevented from being coupled with a cladding mode, and the light limiting capability is enhanced.

This invention relates to the field of LC connector testing technology and discloses a B-value testing device for LC fiber optic connectors. This invention solves the problem that existing LC connector B-value testing using mechanized equipment does not consider the influence of the fiber cladding mode on the test data. The invention utilizes an electric push rod, a first push plate, a second push plate, and a compression spring. Activating the electric push rod causes the upper clamping block to move upwards and outwards. This raises one end of the output and input fibers connected to the upper clamping block to a certain height, then pulls one end towards the other. Since the lower clamping block remains stationary, the movement of the upper clamping block causes the output and input fibers to be squeezed into a loop. Due to the special shape of this loop, a signal attenuation effect is generated, thereby eliminating the additional optical signal brought by the cladding mode and avoiding deviations in the test values. Furthermore, the looping is controlled mechanically, making it easier to control the loop diameter compared to manual looping, preventing excessively large loop diameters and excessive losses.

The application discloses a kind of magnetic field sensors based on periodic structure filled by optical fiber resonant cavity, it includes broadband light source, first single-mode optical fiber, periodic structure, second single-mode optical fiber, spectrometer;The light output by broadband light source is coupled into the single-mode core of first single-mode optical fiber, then propagates to periodic structure to carry out interference superposition, and the light after interference superposition is transmitted to spectrometer by second single-mode optical fiber;Periodic structure includes multiple single-mode optical fibers and is filled with magnetic fluid between adjacent single-mode optical fibers;Periodic structure satisfies phase condition: so that the light intensity output to spectrometer is interfered and superposed greatly, wherein Δn is the effective refractive index difference between core mode and cladding mode, L is sensor length, and λ is central wavelength.The application also provides a kind of periodic structure manufacturing method.The application solves the problems of insufficient sensitivity and easy leakage failure of existing optical fiber magnetic field sensor.

The invention belongs to the field of optical fiber sensing, and particularly relates to a material and structure combined sensitization optical fiber SPR (surface plasmon resonance) sensor and a manufacturing and using method thereof, the sensor comprises a cladding mode attenuation area, a fiber core angle regulation and control area, an SPR sensing area and a thick core light receiving area which are connected in sequence; the cladding mode attenuation area is a six-core optical fiber of which the surface is provided with a coating layer; the fiber core angle regulation and control region is a torsion type six-core optical fiber; a gold film, an MOF-808 material and a medicine component are sequentially arranged on the surface of the SPR sensing area. Cladding mode light is attenuated to zero under the absorption of the cladding and the high-refractive-index coating layer, SPR incident angles when light beams in the six fiber cores are incident to a gold film in an SPR sensing area are adjusted, and then the intensity of an electric field is enhanced through MOF-808, so that the sensitivity of the sensor is improved; when the drug component is combined with the target spot, the SPR resonance valley moves to realize drug-target spot affinity detection; the invention solves the problem of low sensitivity of the traditional optical fiber SPR sensor, and has the advantage of high mechanical strength.

The application discloses a multimode coupling eccentric core fiber Bragg grating sensor, which comprises the following modules: an optical source module, which is used for generating an optical source with a fixed wavelength range to provide excitation light for an evanescent field sensing area; an evanescent field sensing module, which is used for sensing the refractive index information in the evanescent field by utilizing the eccentric core structure of the Bragg grating and the multimode fiber to excite the evanescent field, so as to detect the refractive index of a to-be-detected liquid and a molecular combination process related to the refractive index; a signal detection module, which is used for collecting spectral signals carrying detection information transmitted by the multimode fiber and performing real-time spectral recording; and a micro flow cell, which is used for placing the evanescent field sensing area and the to-be-detected liquid. The application excites a Bragg cladding mode by using an eccentric core welding technology, simplifies a manufacturing process, avoids the damage of a traditional mechanical processing to a Bragg fiber grating structure, significantly improves the consistency and mechanical strength of a product, enhances the long-term stability of the Bragg fiber grating sensor, and is suitable for large-scale application.

The application discloses a method for suppressing stimulated Brillouin scattering effect by using a cascaded long-period fiber grating. The transmission spectrum of the cascaded long-period fiber grating has a series of comb-shaped resonance peaks, two adjacent resonance peaks are regarded as a passband and two stopbands, the passband bandwidth and resonance wavelength are changed by adjusting the parameters of the cascaded long-period fiber grating, the passband and stopband formed by the adjacent resonance peaks of the transmission spectrum correspond to signal light and Stokes light generated by the stimulated Brillouin scattering effect respectively, so that the non-working side lobe laser is coupled from the core mode to the cladding mode while the signal light passes through. The performance stability of the cascaded long-period fiber grating is improved by using a water ring flow-based desensitization packaging technology, so that the output power level and beam quality of the fiber laser are improved, and the possibility of laser damage is reduced. The application has the characteristics of low cost, high flexibility and strong applicability.

The invention discloses a laser cleaning and cladding cooperative control method and device based on an unmanned aerial vehicle, electronic equipment, a readable storage medium and a computer program product. The method comprises the following steps: determining an operation target; when the surface corrosion depth of the operation target exceeds a preset depth threshold value, the current operation mode of the unmanned aerial vehicle is adjusted to be a cleaning mode; performing laser cleaning operation on the operation target in the cleaning mode; when it is detected that the target metal ion characteristic peak intensity on the surface of the operation target reaches a preset intensity threshold value, the current operation mode of the unmanned aerial vehicle is switched from a cleaning mode to a cladding mode; and performing cladding operation on the operation target in the cladding mode. According to the method, the problems that in the prior art, due to step-by-step cleaning and cladding operation, the exposure time of the metal surface is too long, secondary oxidation is prone to occurring, and the bonding quality and the operation efficiency of a cladding layer are affected can be solved.

The utility model discloses a double-parameter optical fiber sensor based on a conical few-mode fiber grating, which belongs to the technical field of optical fiber sensors and comprises a broadband light source (1), a sensing structure (2) and a spectrum analyzer (3). The sensing structure (2) comprises a first single-mode fiber (201), a coreless fiber (202), a conical few-mode fiber grating (203) and a second single-mode fiber (204); more cladding modes are generated through mode field mismatch of the single-mode optical fiber and the coreless optical fiber and bending of a conical area, the double-parameter sensitivity of the sensor is improved, and two transmission characteristic peaks appear on the fiber bragg grating inscribed on the few-mode optical fiber by using different mode numbers in the few-mode optical fiber. The reliability and repeatability of the sensor are greatly improved, the corresponding double-parameter sensitivity can be respectively calculated by observing the position change of an interference spectrum and a transmission characteristic peak, and a sensitivity matrix is further established, so that the simultaneous measurement of double parameters is realized. The sensor has the characteristics of high sensitivity, strong reliability, strong anti-interference capability, small size, simplicity in manufacturing and the like.

The invention provides a fiber core alignment welding device of a soft glass active optical fiber, which comprises a first monitoring light source, a second monitoring light source, a wavelength division multiplexer, an optical fiber to be welded, a cladding mode stripper, the soft glass active optical fiber, an optical fiber welding machine, a dichroscope, a light spot analyzer and a power meter, the wavelength of the output first monitoring laser is located in an absorption band of the soft glass active optical fiber; a tail fiber of the second monitoring light source is a single-mode optical fiber, the wavelength for outputting the second monitoring laser is located outside the absorption band of the soft glass active optical fiber, and a fiber core of the soft glass active optical fiber is a single-mode waveguide for the second monitoring laser; the dichroscope is used for splitting the first monitoring laser and the second monitoring laser output by the soft glass active optical fiber; and the power meter is used for measuring the power of the first monitoring laser. The invention further provides a fiber core alignment welding parameter optimization method of the soft glass active optical fiber.

The invention belongs to the field of optical fiber interference sensors, and particularly relates to an optical fiber Mach-Zehnder interferometer strain sensor based on a bending structure and a manufacturing and using method of the optical fiber Mach-Zehnder interferometer strain sensor. Comprising a light injection area, a bent optical fiber sensing area and a light receiving area which are sequentially arranged on an optical fiber; the bent optical fiber sensing area is divided into an oxyhydrogen flame heating spiral wave structure and a capillary copper pipe wrapped spring structure; a cladding mode field of the bent optical fiber sensing area deflects to the outer side of the bent structure, and under the action of strain, the strain is concentrated on the inner side of the bent optical fiber sensing area; a cladding mode field offset area and a strain concentration area of the bent optical fiber sensing area are separated in space, the reduction amount of effective refractive index of a cladding mode in the strain process is reduced, and high-sensitivity MZI strain sensing is achieved; the problem that an existing MZI strain sensor is low in sensitivity is solved.

The application provides a kind of optical fiber polarizer based on hollow negative curvature optical fiber, which comprises: a base layer with a hollow structure inside; a core layer arranged at the center of the base layer; an asymmetric cladding structure arranged between the base layer and the core layer, comprising: a pair of first capsule nesting units arranged in the y direction of the core layer, and six second capsule nesting units uniformly distributed in non-y direction.According to the application, the two schemes of air area in the asymmetrically distributed different tube thickness and expanded y direction cladding are combined, which effectively enhances y the coupling of polarization state and cladding mode, realizes excellent single-mode single-polarization performance; effectively increases the confinement loss of y polarization base mode, and further realizes high enough polarization extinction ratio in a larger bandwidth range, and has good bending and spiral resistance.

The invention discloses a few-mode fiber double-cascade mode converter and a high-power few-mode fiber laser. A fiber core fundamental mode and fiber core high-order mode converter and a fiber core high-order mode and cladding mode converter are cascaded on a few-mode fiber; the refractive index modulation distribution of the fiber core fundamental mode and fiber core high-order mode converter is uniformly distributed in the center of the fiber core and is used for coupling the fiber core fundamental mode to a fiber core high-order mode; the refractive index modulation of the fiber core high-order mode and cladding mode converter is distributed at the junction of the fiber core and the cladding, and is used for coupling the fiber core high-order mode into the cladding to form loss. The few-mode fiber double-cascade mode converter is connected in front of an output end cap of a high-power few-mode fiber laser, so that stimulated Raman scattering in the large-mode-field few-mode fiber laser can be inhibited, and the output performance of the fiber laser is improved.

The invention discloses a linear polarization narrow linewidth fiber laser based on fast and slow axis orthogonal gratings, which comprises two polarization-maintaining cladding mode stripping devices, a polarization-maintaining pumping beam combiner, an output head, a polarization-maintaining gain fiber, a polarization-maintaining high-reflectivity grating and a polarization-maintaining low-reflectivity grating, wherein the etching grating surfaces of the polarization-maintaining high-reflectivity grating and the polarization-maintaining low-reflectivity grating are vertically orthogonal; each of the polarization-maintaining high-reflectivity grating and the polarization-maintaining low-reflectivity grating comprises a polarization-maintaining optical fiber and a grating body, the polarization-maintaining optical fiber comprises two stress rods, a fiber core and a cladding, the fiber core is located between the two stress rods, the cladding is used for wrapping the stress rods and the fiber core, and the grating body is arranged in the fiber core. In the invention, due to the application of the orthogonal grating and optical fiber vertical welding mode, the polarization mode of vertical welding is suppressed due to large loss and loss of advantages in competition, otherwise, the laser signal in the other polarization direction obtains advantages in competition and is continuously subjected to gain amplification, so that the laser signal obtains a relatively high linear polarization degree, and the polarization extinction ratio is improved.

An annular small-period-long-period fiber grating (SP-LPG) sensor, a preparation method and applications thereof are provided. The annular (SP-LPG) sensor matches the cross-section shape of the optical fibers, the annulus can expand the area of the refractive index modulation region more effectively in the section of the optical fibers, so that the annular grating has a large refractive index modulation region in both the axial and longitudinal directions of the optical fibers, which can simultaneously enhance the intensity of the Bragg resonance peak and the resonance peaks of the cladding modes. Therefore, the Bragg resonance peak and the resonance peaks of the cladding modes can be observed simultaneously in the transmission spectra. It can realize the simultaneous measurement of the refractive index and temperature of the surrounding environment without the need to observe the reflection peak, which simplifies the multi-parameter sensing test steps of the (SP-LPG) sensor.

The invention provides an optical fiber polarizer based on a hollow-core negative-curvature optical fiber, and the optical fiber polarizer based on the hollow-core negative-curvature optical fiber comprises a base layer which is of a hollow structure; the fiber core layer is arranged at the center in the base layer; the asymmetric cladding structure is arranged between the base layer and the fiber core layer, and the asymmetric cladding structure comprises a pair of first capsule nesting units arranged in the y direction of the fiber core layer and six second capsule nesting units uniformly distributed in the non-y direction. According to the invention, by combining two schemes of asymmetrically distributing different tube thicknesses and expanding an air area of the cladding in the y direction, coupling of a y polarization state and a cladding mode is effectively enhanced, and excellent single-mode single-polarization performance is realized; the limiting loss of a y polarization fundamental mode is effectively increased, the polarization extinction ratio is high enough in a large bandwidth range, and good bending resistance and spiral resistance are achieved.

An optical fiber device has a fiber core, a cladding layer around the fiber core and a plurality of tilted fiber Bragg gratings, FBGs, in the fiber core at a sequence of positions along the optical axis of the fiber core. The tilted FBGs are configured to reflect and transmit respective non zero fractions of the optical power of light with a predetermined optical reflection wavelength defined by the tilted FBG from the fiber core at the position of the tilted FBG. The tilted FBGs having a tilt angle in an angle range wherein the tilted FBG reflects light from the fiber core perpendicularly to the fiber core or with a deviation from perpendicular reflection at which the reflected light does not give rise to cladding mode generation at the predetermined optical reflection wavelength of the tilted FBG. Photo-acoustic conversion material is provided on the cladding layer at least in areas where light reflected by the tilted FBGs at said positions emerges from the cladding layer, the cladding layer extending continuously at said areas.

The invention relates to a method for testing a fiber core absorption coefficient of a high-doping-concentration double-cladding erbium-doped optical fiber, and belongs to the technical field of optical fiber lasers. And performing end face processing on two ends of the first matching passive optical fiber, the double-cladding erbium-doped optical fiber to be measured and the second matching passive optical fiber. One end of the first matching passive optical fiber is connected with the light source output end, and an input cladding light filtering module is arranged on the first matching passive optical fiber; one end of the second matching passive optical fiber is connected with the input end of the optical signal receiving device, and the second matching passive optical fiber is provided with an output cladding light filtering module; the other end of the first matching passive optical fiber is welded with one end of a to-be-tested double-cladding erbium-doped optical fiber to form a first welding point; the other end of the to-be-tested double-cladding erbium-doped fiber is welded with the other end of the second matching passive fiber to form a second welding point; and respectively carrying out measurement and data processing on the transmission light power of the to-be-measured double-cladding erbium-doped optical fibers with the lengths of L1 and L2. According to the invention, effective separation of fiber core signals and cladding light is realized, interference of a cladding mode on fiber core transmission light is eliminated, and the test accuracy is improved.

Optical fiber devices, systems, and methods for separating Raman spectrum from signal spectrum. Once separated, the Raman spectrum may be suppressed (e.g., as a result of a reduction in gain from the signal spectrum, and / or through dissipation of the Raman spectrum energy), while the signal spectrum may be propagated in one or more guided modes of a fiber system. In some embodiments, a fiber system may include a chirped fiber Bragg grating (CFBG) or a long period fiber grating (LPFG), each configured to couple a core propagation mode into a cladding propagation mode with an efficiency that is higher for Raman spectrum than for signal spectrum. A fiber system further may include a cladding light stripper (CLS) configured to preferentially remove cladding modes containing the Raman component.

The present invention discloses a circularly polarized light beam splitter based on a helical dual-core anti-resonant hollow-core fiber. The cladding of the fiber includes six circular nested tubes and two elliptical nested tubes that separate the interior of the fiber into two symmetrical cores. When light propagates in one core, it is mainly coupled to the other core through the gap between the elliptical tubes. At the same time, the fiber is designed into a dual-core helical chiral structure along the light transmission direction, so that the four supermode fundamental modes of the fiber are converted into circularly polarized modes, namely, left-circularly polarized odd mode and coupled mode, and right-circularly polarized odd mode and even mode. Subsequently, the effective refractive index of the two odd and even modes with different polarizations is adjusted by optimizing the fiber structure parameters to obtain a suitable mode coupling length, thereby achieving a good beam splitting effect for circularly polarized light. Finally, by adjusting the size of the nested inner tubes, the coupling between the core high-order mode and the cladding mode is increased, so that the high-order mode confinement loss is increased, thereby ensuring the single-mode performance of the fiber.

The invention provides an anti-resonance hollow-core optical fiber with a special-shaped structure, and relates to the technical field of optical fibers, the anti-resonance hollow-core optical fiber comprises a plurality of groups of first anti-resonance microstructures, the open ends of the first anti-resonance microstructures are connected with the inner wall of an outer cladding layer and form a first microstructure closed cavity, and the closed ends of all the first anti-resonance microstructures face the center of the outer cladding layer and enclose a fiber core area; and each second anti-resonance microstructure forms a second microstructure closed cavity and is connected with the inner wall of the outer cladding layer, and at least one second anti-resonance microstructure is arranged between every two adjacent first anti-resonance microstructures to form a special-shaped structure. The beneficial effects are that the second anti-resonance microstructures are arranged between the first anti-resonance microstructures to form a non-nested special-shaped structure, a novel waveguide core is formed together, simple cascade of a traditional fundamental mode space is not used, physical integration is realized through microstructure topology innovation, phase matching of a fiber core and a cladding mode field is destroyed, ultralow transmission loss is realized, and the fiber core and the cladding mode field are combined to form a novel waveguide core. And low loss is maintained in a wide spectrum range.

The invention discloses a flexible sliding tactile sensor based on a TFBG (Tilted Fiber Bragg Grating) and a preparation method thereof. The sensor is of a sandwich structure formed by an upper parallel stripe ridge packaging layer, a first supporting optical fiber, the TFBG, a second supporting optical fiber and a lower packaging layer. The first supporting optical fiber and the second supporting optical fiber are located on the left side face and the right side face of the TFBG respectively. The directly applied weak positive pressure causes the flexible packaging layer to deform, and gradually wraps the TFBG, thereby increasing the contact angle between the surface of the optical fiber cladding and the packaging layer, and causing the loss of the cladding mode. Along with the change of the contact surface of the packaging layer and the TFBG, the intensity of the cladding mode changes, and by analyzing the transmission spectrum of the TFBG, the pressure and slippage can be measured directly through the change of the intensity of the transmission spectrum. The sensor has the advantages of being simple in structure, high in sensitivity and resistant to electromagnetic interference.

The invention provides a microstructure optical fiber cladding mode efficient filtering method based on angular offset splicing, and relates to the technical field of optical fibers, and the method comprises the steps: selecting two sections of same microstructure optical fibers, and carrying out the non-oblique-angle cutting of the end faces of the two sections of microstructure optical fibers through a cutting knife; angular alignment is carried out on the two sections of cut microstructure optical fibers, so that the cross section structures of the two sections of microstructure optical fibers at the splicing position are completely aligned; applying angular offset to the aligned two sections of micro-structure optical fibers, enabling the two sections of micro-structure optical fibers to be coaxial in the radial direction, and keeping the angular offset splicing state of the two sections of micro-structure optical fibers to splice the two sections of micro-structure optical fibers. The method has the beneficial effects that a specific angular deviation angle is applied to the splicing part of the microstructure optical fiber, so that the key technical problems that a cladding mode passes through a welding point in a lossless or low-loss manner and continuously interferes with a fiber core signal in a subsequent link and the signal-to-noise ratio is reduced due to the fact that the existing welding technology pursues perfect angular alignment in the background technology are solved.

This invention provides an anti-resonant hollow-core optical fiber and its application, comprising a cladding and a core. The cladding is externally fitted with a sheath, and within the cladding are multiple single-layer resonant tubes and multiple double-layer nested tubes tangent to the cladding. The single-layer resonant tubes are evenly distributed circumferentially around the center of the core, with a double-layer nested tube positioned between every two single-layer resonant tubes. The diameter of each single-layer resonant tube is larger than the diameter of the double-layer nested tube. Each double-layer nested tube includes an inner tube and an outer tube, with the inner and outer tubes internally tangent. This invention achieves anti-resonant hollow-core optical fiber (LP) through single-layer resonant tubes. 11 The fundamental mode is coupled with the cladding mode, thereby allowing the higher-order mode capability to leak and achieve single-mode transmission in optical fiber. Then, a double-layer nested tube positioned between two single-layer resonant tubes locks the fundamental mode energy within the fiber core, achieving low-loss transmission of the fundamental mode. This invention effectively reduces fundamental mode confinement loss and achieves single-mode transmission in optical fiber through mode coupling.

Efficient acousto-optic switching of light between two cores of a multicore optical fiber can be achieved using fiber configurations with cores differing in their effective refractive indices, by simultaneously exciting two flexural acoustic waves of different frequencies to transfer the light in a two-step process from one core to an intermediate cladding mode and then from the intermediate cladding mode to the other core. The intermediate cladding mode may be selected to achieve high, similar coupling rates between the two cores and the cladding modes, and sufficient acoustic frequency separation from neighboring cladding modes.

The invention discloses a preparation method of a phase mask plate with nonlinear + / -1-order diffraction efficiency and period distribution. For dispersion fiber grating reflection spectrum flatness degradation caused by dual effects of cladding mode coupling and the Fabry-Perot effect, gate region refractive index modulation depth distribution curve optimization is carried out, and design parameters of phase mask plate nonlinear + / -1 level diffraction efficiency and groove depth distribution are obtained; according to the requirement for femtosecond laser system multi-order dispersion registration, improvement of phase mask plate groove width distribution design parameters is carried out according to the mapping relation between a multi-order dispersion value and a non-linear period, and finally the phase mask plate preparation method with + / -1-order diffraction efficiency and period distribution optimization is obtained. The method provides an effective means for preparation of the dispersion fiber grating which is highly flat in reflection spectrum and can be registered with multi-order dispersion of a femtosecond laser system, and compared with the prior art, the method provided by the invention has the advantages of low cost, high flexibility, high stability and the like.