289 results about "Birefraction" patented technology

The invention relates to the technical field of special optical fibers, in particular to a polarization-maintaining hollow-core anti-resonance optical fiber which comprises an outer cladding, an inner cladding, a fiber core, a first-class anti-resonance unit and a second-class anti-resonance unit. The inner cladding is arranged in the outer cladding, and the fiber core, the first-class anti-resonance unit and the second-class anti-resonance unit are arranged in the inner cladding; the first-class anti-resonance unit does not comprise a coupling thin wall, the second-class anti-resonance unit is provided with a coupling thin wall close to the fiber core side, and the coupling thin walls are two thin walls which are extremely close to each other and are not in contact with each other. According to the invention, high birefringence and broadband low transmission loss can be realized at the same time.

The invention relates to the technical field of optical communication, in particular to a multi-channel shifting circulator. Comprising an optical fiber unit, a birefringent crystal, a polarization unit, a transmission or reflection unit, a polarizer and a reflection element, the optical fiber unit comprises at least four optical fibers, an optical signal can enter and reach the birefringent crystal along any optical fiber, and the birefringent crystal is used for splitting the optical signal into O light and E light; the transmission or reflection unit comprises a plurality of PBS films, and the number of the PBS films is the same as that of the optical fibers; the polarization unit changes the polarization states of the O light and the E light, so that the O light and the E light pass through the corresponding PBS films; the light enters the polarizer and is reflected back to the polarizer through the reflecting element, and the polarization states of the O light and the E light are changed, so that the O light and the E light are reflected to the adjacent PBS films on the corresponding PBS films; and the polarization unit can change the polarization state of the reflected light, so that the reflected light is emitted along the corresponding optical fiber after being combined by the birefringent crystal. Therefore, the method is suitable for a transmission application scene requiring more than three ports to realize optical signals.

The invention relates to an ultralow-loss hollow-core anti-resonance optical fiber with a birefringence structure, which comprises an outer cladding and an inner cladding, the inner cladding is composed of anti-resonance structure units, the anti-resonance structure units are arranged along the circumferential direction of the inner wall of the outer cladding and are connected with the inner wall of the outer cladding, the inner cladding comprises four anti-resonance structure units, and the anti-resonance structure units are arranged along the circumferential direction of the inner wall of the outer cladding and are connected with the inner wall of the outer cladding. The four anti-resonance structure units are evenly distributed at intervals in the circumferential direction and comprise two long-axis anti-resonance structure units and two short-axis anti-resonance structure units, the two long-axis anti-resonance structure units are symmetrically arranged on the two sides of the inner wall of the outer cladding layer, and the two short-axis anti-resonance structure units are symmetrically arranged on the other two sides of the inner wall of the outer cladding layer. A central cavity wrapped by an inner wrapping layer formed by the four anti-resonance structure units forms an elliptical fiber core with a long axis and a short axis. According to the invention, the transmission loss can be reduced while the high birefringence performance is maintained, the shape of each part of the microstructure cladding is regular, and the preparation is convenient.

The invention discloses an integrated optical signal receiver and method, particularly relates to the field of optical communication, is used for solving the problem of video stream transmission quality reduction caused by optical signal distortion in a low optical signal-to-noise ratio environment, and aims to eliminate cross coupling caused by a birefringence effect by constructing a dynamic polarization state transfer matrix. Generating a clear independent polarization state electric signal sequence; time-frequency domain processing is carried out on the electric signal sequences, linear phase noise caused by laser linewidth and phase deviation caused by an optical fiber nonlinear effect are compensated, and signals with higher phase accuracy are output; then, the signals are mapped to a four-dimensional constellation space, a clustering method is used for generating an adaptive judgment boundary, symbol judgment is optimized, and the anti-noise capability is improved; through cooperative work of an inner loop and an outer loop, system parameters are dynamically adjusted according to signal characteristics, and processing stability and adaptability are enhanced. And finally, performing soft decision decoding on the signal, improving the decoding accuracy in combination with phase residual correction, and outputting a reconstructed video data stream.

The invention relates to the technical field of optical fiber device manufacturing, and discloses a femtosecond laser inscribing low-polarization-dependent-loss optical fiber grating method and system, and the method comprises the steps: firstly, synthesizing an initial phase comprising a flat-topped beam phase, an astigmatism correction phase and a defocus phase, and loading the initial phase to a spatial light phase modulator; therefore, a preset circular flat-top focusing light spot is generated. Secondly, collecting a three-dimensional light field image sequence of a focusing light spot in a low-power detection mode, reconstructing light intensity distribution, extracting effective focal depth and ovality characteristic parameters, dynamically optimizing a phase through a closed-loop feedback mechanism until light field characteristics reach a preset target, and obtaining an optimized phase; and finally, loading an optimized phase in a high-power inscribing mode, and controlling the axial scanning of the optical fiber to inscribe the grating. Accurate active regulation and control of the three-dimensional shape of the focused light field and closed-loop self-optimization of process parameters are realized, birefringence caused by anisotropy of a refractive index modulation area is inhibited from a physical mechanism, and polarization dependent loss of the fiber bragg grating is fundamentally reduced.

The embodiments of the present disclosure discloses an optical isolator core and an optical isolator. The optical isolator core comprises: a first birefringent crystal, a first Faraday rotator, a second birefringent crystal, a second Faraday rotator, and a third birefringent crystal that are successively arrange in the forward light path, all of which are parallel plate structures. The embodiments of the present disclosure achieves backward isolation for polarization-independent and non-collimating beam which simplifies the device structure and assembly process, thereby reduce size and cost.

The invention belongs to the technical field of lasers, and discloses a fiber laser for promoting generation of a stable soliton attraction state by using a high-birefringence fiber. The optical fiber laser comprises a laser pumping source, a wavelength division multiplexer, an erbium-doped gain optical fiber, a polarization independent isolator, a polarization controller, a polarization maintaining optical fiber, an output coupler and a mode locking device based on a carbon nanotube saturable absorber, and all the components are sequentially connected through single-mode optical fibers. The polarization-maintaining optical fiber is a panda-shaped polarization-maintaining optical fiber with a high birefringence effect. The polarization direction and the polarization state in the cavity are accurately controlled by adjusting the polarization controller, phase synchronization of soliton pulses is achieved when the polarization maintaining optical fiber is output, soliton energy in the cavity is rapidly accumulated, soliton splitting is triggered, and finally a stable multi-pulse soliton attraction state is formed. The design is simple and convenient to operate, and stability and anti-interference capability of soliton transmission are remarkably improved.

The invention discloses a broadband nonlinear frequency converter which comprises a silicon dioxide coating layer, an x-cut lithium niobate film layer, a silicon dioxide buffer layer and a silicon substrate layer from top to bottom, the x-cut lithium niobate film layer is provided with a weak bending ridge waveguide, and the bending angle of the weak bending ridge waveguide is not larger than 5 degrees. According to the invention, birefringence phase matching is realized on the lithium niobate film in a weak bending waveguide form, so that broadband second harmonic generation, birefringence phase matching wavelength and matching angle correlation are realized, and an included angle between a wave vector of transmitted fundamental frequency light and a crystal optical axis is continuously and slightly changed through the weak bending film, so that the broadband second harmonic generation is realized. Therefore, birefringence phase matching of different wavelengths can be realized at different matching angles, and the purpose of broadband matching is achieved.

An optically active nanocomposite material is provided that may have a textured substrate and a multilayer optic stack with a plurality of layers comprising nanoplatelets. The nanoplatelets may be achiral and formed of a material such as transition metal chalcogenides, Mxenes, or nanocarbons. The optically active nanocomposite material displays both linear birefringence (LB) and linear dichroism (LD) and optional circular dichroism (CD). The nanocomposite may have an optical asymmetry g-factor of greater than or equal to about 1. Further, the nanocomposite is thermally stable, for example, to a temperature of greater than or equal to about 250° C. Different methods of fabricating such nanocomposites using layer-by-layer (LBL) processes are also provided.

The invention relates to an ultra-wideband double-hollow-core optical fiber polarization beam splitter. An optical fiber structure comprises a pear-shaped tube unit, an air fiber core, an outer cladding sleeve and a circular hollow-core nesting tube, the pear-shaped tube unit on the x axis is nested and connected to the inner wall of the outer cladding sleeve around the fiber core; and the pear-shaped tube unit, the fiber core on the y axis and the outer cladding sleeve form the ultra-wideband double-hollow-core fiber polarization beam splitter. According to the invention, by introducing the pear-shaped tube units, asymmetry in x and y directions is increased, so that the effect of increasing birefringence is achieved. According to the optical fiber polarization beam splitter, a mixed structure of the nested tube and the pear-shaped tube unit is designed on the optical fiber cladding, so that the loss of a fundamental mode is reduced, the high-order mode rejection ratio is improved, and the optical fiber polarization beam splitter with more excellent single-mode performance and wider application bandwidth is obtained. The method has great application value in the field of optical communication.

The invention relates to the technical field of fiber bragg gratings, and particularly provides a birefringent FBG-based fiber environment event identification method, which comprises the following steps: constructing a spectral pulse matrix according to fast axis spectrums and slow axis spectrums of a plurality of spectral pulses, the spectral pulses being echo spectral pulses transmitted by a birefringent FBG; solving a joint optimization problem, and separating a first matrix and a second matrix from the spectral pulse matrix; solving a first optimization problem of the first matrix based on a first dictionary learning algorithm to obtain a vibration event recognition matrix used for representing a vibration event signal; and solving a second optimization problem based on a second dictionary learning algorithm to obtain a temperature offset feature vector used for representing the temperature change signal, the second optimization problem being determined according to the merged vector of the second matrix. The problem of difficulty in signal decoupling of the FBG in a complex environment in which temperature change and vibration events exist at the same time in the prior art is solved.

A single-mode high-nonlinearity photonic crystal fiber capable of maintaining circular polarization transmission comprises a solid fiber core and a porous cladding structure arranged periodically, and the nonlinearity of the fiber is improved by optimizing the size of the fiber core and the duty ratio of cladding air holes. The torsion rate alpha introduced in the axial direction of the optical fiber is 0-8 rad / mm to introduce 10 <-3 >-order circular birefringence to maintain the circular polarization state, and effective refractive index change curves in different modes are changed. A plurality of cladding air holes are selected on the cross section of the optical fiber for selective filling or doping to realize phase matching of a fiber core high-order mode and a plurality of cladding modes, so that the fiber core high-order mode with the refractive index changing under torsion is filtered out by means of intermode coupling, the loss of the filtered high-order mode is increased by more than two orders of magnitude, and the high-order mode loss is reduced by more than two orders of magnitude. And single-mode transmission is effectively realized. Meanwhile, the characteristics of circular polarization state transmission and high nonlinearity are kept, and the optical fiber can be applied to application research of high-precision optical fiber sensing, optical fiber lasers with special circular polarization state output and the like.

The invention relates to an anti-resonant hollow core fiber (1000), comprising a fiber cladding (2000) which has an inner bore (2200), a fiber longitudinal axis (2300) and a fiber core radius R_Fiber (2310), a number of anti-resonance units (3000), each comprising • an ARE element (3100), • an NE element (3400), • a DNE element (3900), wherein the anti-resonance units (3000) are spaced apart from one another and arranged contact-free at desired positions on an inner side (2150) of the inner bore (2200), wherein in the anti-resonance units (3000) • the ARE element (3100) has a circular cross-section, • the NE element (3400) is arranged in a first interior space (3170) of the ARE element (3100), and • the DNE element (3900) is arranged at least partially in a second interior space (3470) of the NE element (3400). According to the invention,that in at least one anti-resonance unit (3000) • the NE element (3400) has a circular arc-like cross-section and is connected to the DNE element (3400) along two connecting seams (3700, 3700'), • the DNE element (3900) has an oval cross-section, and • in the cross-section, a sum of the distances of any point on a DNE element wall (3950) from two focal points (4000, 4000') is equal for all points to less than 15% of the sum of the distances.

In some implementations, a phase detector to enable coherent beam combining includes a first half-waveplate may rotate a polarization of a first input beam and a second input beam to 45 degrees. A first birefringent window may divide the input beams into beamlet pairs associated with orthogonal polarizations, and a second birefringent window may shift the first beamlet pair and the second beamlet pair such that a first beamlet of the first beamlet pair and a second beamlet of the second beamlet pair form overlapping beams after the orthogonal polarizations and reversed by a second half-waveplate. An analyzer may then split the overlapping beams into a first output beam associated with a first intensity and a second output beam associated with a second intensity, where a difference between the first and second intensity is related to a phase difference between the first input beam and the second input beam.

The invention provides a broadband infrared polarization device based on a mercurous halide crystal as well as a preparation method and application of the broadband infrared polarization device. The broadband infrared polarization device based on the mercurous halide crystal comprises a right-angle triangular prism based on the mercurous halide single crystal and a hexagonal prism based on the mercurous halide single crystal, and the mercurous halide is Hg < 2 > Cl2 or Hg < 2 > Br < 2 >. The mercurous halide crystal used in the invention is low in cost, can be prepared in a large size, and has stable physical and chemical properties; the transmission range of the infrared polarization device covers middle and far infrared bands, the transmission rate is high, and the birefringence is large; the polarization device based on the mercurous halide crystal can simultaneously realize polarization beam combination and beam splitting of visible-long wave infrared broadband, and has a high laser damage threshold, a high extinction ratio, high beam combination efficiency and high beam quality.

This disclosure provides an optically active nanocomposite material having a textured substrate and a multilayer optical stack comprising multiple nanosheets. The nanosheets may be chiral and composed of materials such as transition metal chalcogenides, MXenes, or nanocarbon. The optically active nanocomposite material exhibits linear birefringence (LB) and linear dichroism (LD), and optionally circular dichroism (CD). The nanocomposite material also exhibits optical asymmetry. g The factor may be greater than or equal to 1. Furthermore, the nanocomposite material exhibits thermal stability, for example, remaining stable at temperatures above or equal to about 250 °C. This disclosure also provides different methods for preparing such nanocomposite materials using a layer-by-layer self-assembly (LBL) process.

This invention relates to an interferometric measurement method and apparatus for large warp wafers, belonging to the field of optical detection and semiconductor measurement technology. The detection light is polarized and birefringently split to form P-beams and S-beams, which are then further divided into P-reference beams, S-silicon beams, S-reference beams, and P-silicon beams, respectively. By adjusting the spatial orientation of the reference mirror and the wafer under test, and using an aperture for spatial filtering, the P-reference beam and S-silicon beam are allowed to enter the subsequent optical path, while the S-reference beam and P-silicon beam are blocked. The S-silicon beam forms a measurement wavefront carrying information about the surface shape of the wafer under test. The P-reference beam is modulated by a deformable mirror to form a modulated reference wavefront similar to the measurement wavefront. The two form a resolvable interference fringe pattern at the camera. A wavefront sensor measures the surface shape information of the deformable mirror, and a calculation system obtains the surface shape information of the wafer under test based on the deformable mirror surface shape information and the relative surface shape change. This invention can reduce the interference fringe density in the detection of large warp wafers, reduce splicing measurement errors, and improve detection efficiency and accuracy.

The present invention relates to the technical field of artificial crystal materials, and more specifically to a birefringent crystal material, its preparation method, and its application. The present invention provides a new birefringent crystal material having the chemical formula [C(NH2)3][ICl4] and exhibiting a large birefringence. The preparation method for this birefringent crystal material utilizes raw materials with low human toxicity, a short crystal growth cycle, low cost, and high crystal purity. This birefringent crystal material can be used as a polarization optical device in the fields of optics and communications.

The invention provides an optical coherence tomography system based on a single-cavity dual-frequency comb ytterbium-doped fiber mode-locked laser, belonging to the technical field of optical coherence tomography; the invention solves the problems of great technical difficulty and high cost in the existing dual-frequency comb for optical coherence tomography; the invention comprises: a single-cavity dual-frequency comb ytterbium-doped fiber mode-locked laser module, an amplification and sample scanning module and a signal acquisition module; in the single-cavity dual-frequency comb ytterbium-doped fiber mode-locked laser module, a polarization-maintaining fiber and a single-mode fiber with a certain amount of polarization birefringence are introduced into a single fiber ring cavity to enhance the intracavity birefringence and nonlinear effects, realize gain spectrum filtering under different wavelength windows, and use a semiconductor saturable absorption mirror to realize passive mode locking of the ytterbium-doped fiber laser, thereby obtaining single-cavity full-positive dispersion dual-frequency comb pulse mode locking; the invention is used for dual-frequency comb acquisition of optical coherence tomography.

The invention relates to the technical field of optical fiber sensing and optical fiber device manufacturing, and discloses a femtosecond laser-inscribing polarization-maintaining fiber grating method and system for vector sensing, and the method comprises the following steps: obtaining a stress region image of a polarization-maintaining fiber through a CCD camera, recognizing the slow axis direction of the fiber through image processing, rotating the fiber, and obtaining the stress region image of the polarization-maintaining fiber; an included angle of 45 degrees is formed between the slow axis direction and a preset incident plane of the femtosecond laser; calculating a conjugate phase of wavefront aberration generated when femtosecond laser penetrates through a fiber coating layer and a cladding and is focused to a fiber core, and generating a phase diagram for loading a spatial light modulator; after being modulated by the spatial light modulator, a light beam emitted by the femtosecond laser enters and is focused on the fiber core along the direction of an included angle of 45 degrees, and a grating structure is formed by combining axial scanning and inscribing. Accurate automatic alignment in the fast and slow axis direction and active compensation of transmission aberration are achieved, refractive index modulation birefringence forming a specific included angle with the inherent birefringence axis of the optical fiber can be effectively induced, and therefore the polarization-maintaining fiber grating with the highly controllable reflection spectrum and the asymmetric double-peak characteristic is engraved.

The invention relates to a device and a method for coupling a laser beam of a laser into a double-clad fiber, comprising a first birefringent optical element which is designed to divide the laser beam entering at a beam entry surface into two sub-laser beams, the two sub-laser beams have a first exit angle and / or a first beam offset relative to a beam exit surface normal; comprising a polarization rotation device configured to adjust the polarization of an incident sub-laser beam and thereby provide a polarization-adjusted sub-laser beam; comprising a second birefringent optical element, the second birefringent optical element being configured to divide each of the polarization-adjusted sub-laser beams into two sub-sub-laser beams, the two sub-sub laser beams have a second exit angle and / or a second beam offset with respect to the beam entry surface normal of the second birefringent optical element; and a coupling-in optical unit, which is designed to couple the sub-sub laser beams having the compensated first exit angle and / or beam offset into the inner core of the double-clad optical fiber and to couple the further sub-sub laser beams into the annular core of the double-clad optical fiber.

The invention relates to a device (4) for coupling a laser beam (3) into a multi-clad optical fiber (5), comprising: a beam splitter (6) for splitting the laser beam (3) into a plurality of sub-laser beams (3.1, 3.2,...), where the beam splitter (6) comprises at least two birefringent optical wedges (9a, 9b,...) and at least one polarization rotation device (12a, 12b,...), at least one polarization rotation device having an adjustable polarization rotation effect and arranged between the birefringent optical wedges (9a, 9b,...); the invention relates to a multi-clad optical fiber (5) comprising a plurality of sub-laser beams (3.1, 3.2,...) emitted from a beam splitter (6), and coupling-in optics (7) for coupling the sub-laser beams (3.1, 3.2,...) emitted from the beam splitter (6) into the multi-clad optical fiber (5), the coupling-in optics (7) being designed to couple at least two of the sub-laser beams (3.1, 3.2,...) emitted from the beam splitter (6) into at least two different light guide cores (14a, 14b,...) of the multi-clad optical fiber (5). The invention also relates to an optical system (1) comprising a multi-clad optical fiber (5) and a device (4) as described above for coupling a laser beam (3) into the multi-clad optical fiber (5).

A kind of ultra-short pulse synchronization testing device and method based on optical Kerr effect. After the high-power density ultra-short pulse of multiple beams to be synchronized passes through optical Kerr medium, induced birefringence effect occurs, which instantaneously changes the polarization characteristics of the reference light beam, and the synchronization between multiple beams of ultra-short pulses is measured by the amplitude or phase change of the reference signal pulse. This method can realize the synchronization measurement of ultra-short pulses with large angle at the target point, and has the advantages of high measurement accuracy, good repeatability and high stability.

A method and system for measuring physical parameters using sensors of the birefringent Fiber Bragg Grating type is provided. In some embodiments, a method and a system for querying a sensor of the birefringent Fiber Bragg Grating (FBG) type (e.g., in birefringent fiber), employing heterodyne optical detection and integrated photonic technology is provided.

The disclosure relates to an optical fiber having multiple light-conducting core regions which extend, mutually spaced, along the longitudinal extension of the optical fiber. In a cross-sectional view, each light-conducting core region is located inside a contiguous signal region which is completely enclosed by a cladding region. Outside the signal region, stress elements of the optical fiber are designed to generate a mechanical stress field in the optical fiber. The stress elements subject each core region to a mechanical stress causing birefringence, and thus polarization-maintaining behavior. One main polarization axis is assigned with each of the core regions. The stress elements may be distributed in groups of two or more stress elements across the cross-section of the optical fiber. In a cross-sectional view, the stress elements have an asymmetrical, namely non-rotationally symmetrical arrangement, which causes the main polarization axes to point in the same direction in all core regions.

The invention relates to an elliptical ring core optical fiber capable of realizing bending radius and bending angle dual-parameter sensing, and belongs to a distributed sensing technology. According to the invention, the asymmetric elliptical ring core structure of the optical fiber is utilized to realize double-parameter sensing of a small bending radius and a bending angle. Through numerical simulation, the ellipticity and the ring core thickness of the optical fiber elliptical ring core are optimized, and the characteristics of the sensing bending radius and the bending angle of the optical fiber with the elliptical ring core are revealed. Brillouin scattering light excited by light field LP01 and LP11e modes is utilized to realize double-parameter sensing, the sensing range of the bending radius is 0.6 cm to 2.0 cm, and the sensing range of the bending radius is 0 degree to 90 degrees. When the bending radius is 0.6 cm and the bending angle is 0 degree, the variation of the Brillouin frequency shift is the maximum, and the value is 31.6 MHz. Meanwhile, the design ensures that the limited loss of the optical fiber is less than 1.5 * 10 <-6 > dB / m and the birefringence of the optical fiber is less than 1 * 10 <-5 >, and the optical fiber has lower limited loss and birefringence compared with the existing mainstream multi-core optical fiber. According to the invention, the bending angle and the bending radius can be sensed at the same time.

A high extinction-ratio rotator includes a collimator that can collimate a signal light from an optical fiber, a pair of polarizing splitting prisms that include a first birefringence crystal wedge and a second birefringent crystal wedge, that can separate two orthogonal polarization components of the signal light into a vertically polarized light and a horizontally polarized light, a non-reciprocal 45-degree polarization rotator which the vertically polarized light and the horizontally polarized light exiting the pair of polarizing splitting prisms pass through, and a reflector. The vertically polarized light and the horizontally polarized light exiting the non-reciprocal 45-degree polarization rotator intersect on a surface of the reflector and are reflected back into the non-reciprocal 45-degree polarization rotator.

To reduce speckle noise using polarization in a display device displaying using polarization of a laser beam.SOLUTION: A display device comprises: a laser source emitting a linearly polarized laser beam; a spatial modulator modulating spatial polarization distribution of the laser beam emitted from the laser source; and a retardation plate including a first region with birefringence and a second region without birefringence, and rotating polarization direction of a laser beam, of laser beams emitted from the spatial modulator, passing through the first region by 90 degrees.SELECTED DRAWING: Figure 1

Liquid crystal (LC) beam control devices utilize dispersion-shaping (DS) half-wave plates (HWPs) with specific physical properties to allow broadened beams to maintain significantly better color cohesion. This paper describes the advantages of using HWPs with appropriate thickness and birefringence, which makes them inefficient in the blue wavelength spectrum, thus reducing blue photon loss at the center of the broadened beam. This paper also describes combinations of vertically aligned LC cells and DS HWP structures for reducing color separation, accelerating relaxation time, and reducing ground-state scattering.

A system and method for measuring pressure inside a pipeline or pressure vessel is disclosed. The system includes one or more units locatable around an external surface of the pipeline or vessel, each unit containing: a light source for generating a light beam; a single fiber Mach Zehnder interferometer (SF-MZI) sensor bendable against an outer surface of the pipeline or vessel, for receiving the light beam; a light receiver for receiving the light bean from an output of the SF-MZI sensor, said light receiver including an optical spectral analyzer; and a local processor for signal conversion; a data acquisition system associated with each of the one or more units to provide power to the elements of the unit; and a central processor in communication with each of the local processors of each of the units, said central processor containing stored strain data, and the stored bend induced birefringence data.