98 results about "Birefraction" patented technology

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.

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 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.

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.

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.

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.

Three-dimensional reconfigurable vector holographic double-layer cascade super device, design method and equipment belong to the field of holographic technology, solve the problem that reconfiguration of incident wave front often involves changing light source or polarizer operation, which is not only inconvenient but also cannot realize fast switching. The device includes: a hybrid cascade of radiative super surface and birefringent super surface, the intensity and polarization response of hologram in three-dimensional space is reconfigurable and highly customized. The rotatable radiative super surface can be used as an incident wave front modulator to excite the non-rotatable birefringent super surface. By introducing a gradient descent optimization inverse design method, numerical analysis and experimental verification of three-dimensional reconfigurable vector holography are demonstrated in the microwave region. The present application is suitable for integrated encryption devices and holographic display super devices.

To provide a laser oscillator capable of obtaining a desired beam profile by continuously changing the beam profile of a laser beam emitted from an optical fiber.SOLUTION: The laser oscillator 90 includes a laser module 10, a condenser lens 42, an optical fiber 80, a polarization adjustment mechanism 30, and a birefringent plate 43. The laser module 10 emits a linearly polarized laser beam LB. The condenser lens 42 condenses the laser beam LB on the optical fiber 80. The optical fiber 80 has a center core 81 and a ring core 83. The polarization adjustment mechanism 30 has a half-wave plate 31 and changes the polarization direction of the laser beam LB. The birefringent plate 43 branches the laser beam LB into the first laser beam LB1 and the second laser beam LB2, and changes the ratio of the light amounts of the first laser beam LA and the second laser beam LA.SELECTED DRAWING: Figure 2A

This application discloses a method for enhancing the quality of bare fiber sensing signals in vehicle-mounted vibration environments. It relates to the field of fiber optic sensing signal quality enhancement, and utilizes a multi-axis inertial measurement unit and a vibration sensing network to construct a spatiotemporal feature tensor, enabling three-dimensional dynamic perception of the vibration environment. Filtering parameters and gain are dynamically configured based on vibration characteristics to ensure stable signal acquisition under strong vibration conditions. A deep feature decoupling network, combined with vibration environment information, effectively separates noise from the target signal, improving the signal-to-noise ratio. A dynamic compensation module, based on a physical heuristic model, corrects vibration-induced transmission distortion from three dimensions: polarization state, birefringence, and microbending loss, ensuring the physical integrity of the signal. A closed-loop collaborative control mechanism dynamically optimizes the parameters of each module through real-time signal quality feedback, forming an adaptive optimization closed loop. Through spatiotemporal multi-dimensional collaborative processing, high-quality and robust enhancement of bare fiber sensing signals in vehicle-mounted vibration environments is achieved.

A method of accounting for signal noise in a hybrid laser system is described. The hybrid laser system includes a high reflectivity mirror, a nitrogen-vacancy center diamond, a microwave antenna, a dichroic mirror, a half-vertical cavity surface emitting laser (VCSEL), a birefringent filter, an etalon, an output coupler, and a photodiode. The method includes: measuring a shift in a left-hand side frequency as related to an optically detected magnetic resonance (ODMR) frequency peak of an ODMR signal; measuring a shift in a right-hand side frequency as related to the ODMR frequency peak; normalizing the shift in the left-hand side frequency; normalizing the shift in the right-hand side frequency; and comparing the shift in the left-hand side frequency to the shift in the right-hand side frequency to determine a technical noise associated with the ODMR signal.

A method and system for inspecting polarization in a fibered optical path. The method being executed by a computer-implemented system comprising a controller and at least one detector communicatively coupled to the controller, the computer-implemented system being operatively connected to the fibered optical path, including: causing a laser to emit at least one optical pulse into the fibered optical path; detecting a plurality of reflected optical signals from the fibered optical path; determining a plurality of experimental correlation values based on the plurality of reflected optical signals and a reference signal function; and in response to a given experimental correlation value of the plurality of experimental correlation values being less than a threshold, identifying a mechanical disturbance caused by birefringence in the fibered optical path, the mechanical disturbance being located at a location of the plurality of locations corresponding to the given experimental correlation value.

The invention discloses a polarization-maintaining hollow-core anti-resonance optical fiber with an arc-shaped cladding. The polarization-maintaining hollow-core anti-resonance optical fiber comprises a fiber core region and a cladding region, the fiber core area is formed by surrounding of the cladding area and is in a long strip shape. The cladding area comprises a cladding tube, a half-tube structure and an outermost sleeve; the cladding tube comprises two nested circular tubes; the two nested circular pipes are tangent to each other, and the outer circular pipe is in contact with the outermost sleeve; the whole optical fiber structure meets central symmetry. The hollow-core anti-resonance optical fiber has the unique advantages of low loss, low nonlinearity, high temperature stability and the like, and optical signals can be well limited in the fiber core for transmission. The effective mode refractive index of the polarization state is modulated through the y-pol reverse cross coupling of the quartz wall of the half-tube structure to the fundamental mode, and meanwhile the fundamental mode of the air fiber core is effectively limited through the nested tube in the cladding area, so that the low-loss performance is considered while high birefringence is achieved. And support is provided for application in the fields of signal transmission, precision sensing, optical fiber gyroscopes and the like.

The invention belongs to the technical field of optical fiber sensing, and discloses a distributed single detection method and device for group birefringence and phase birefringence of an optical fiber, which is based on clear distinguishing and complete modeling of physical mechanisms of phase birefringence and group birefringence. Noise and various interferences are effectively suppressed, so that the accuracy and reliability of parameter measurement are remarkably improved. Through efficient cross-correlation operation in an optical frequency domain and a distance domain, two types of birefringence distribution information are synchronously obtained in single measurement, the data processing and feature extraction efficiency is greatly improved, and the method is particularly suitable for high-resolution and long-distance distributed sensing analysis. The theoretical model and the solving method provided by the invention have universal applicability, so that the robustness and the stability of the system in different application environments are improved.

System and method for determining distributed birefringence variations in a polarization-maintaining optical fiber (PM fiber). The method includes causing a pump signal to be sent into the PM fiber to generate a Brillouin dynamic grating (BDG) therein, causing a first chirped probe optical pulse to be sent into the PM fiber, receiving a first reflected signal, the first reflected signal being a first portion of the first chirped probe optical pulse reflected by the BDG, receiving a second reflected signal, the second reflected signal being a second portion of the first chirped probe optical pulse reflected by the BDG, and determining a variation of birefringence of the PM fiber indicative of a variation of physical disturbance of the PM fiber between times of reflections on the BDG of the first and second reflected signals.

Method for laser material processing using a processing laser beam (3), wherein a first laser beam (8a), which is coupled into at least a first fiber core (9a) of an optical multicore fiber (9), and a second laser beam (8b), which is coupled into at least a second fiber core (9b) of the multicore fiber (9), are generated from a polarized input laser beam (5) using a birefringent crystal (7), wherein by influencing the polarization of the input laser beam (5) the ratio in which the power of the input laser beam (5) is divided between the first and the second laser beam (8a, 8b) is changed with a modulation frequency (f) between 1 Hz and 100 kHz, in particular between 100 Hz and 100 kHz, and thereby the first and the second laser beam (8a, 8b) can be coupled out of the multi-core fiber (9) alone or together as a processing laser beam (3). characterized by that the polarization is influenced by switching between linearly, circularly or elliptically polarized polarization by means of an electro-optic polarization modulator (6), in particular a Pockels cell or Faraday rotator, which can be controlled with the modulation frequency (f) to change the polarization of the input laser beam (5).

The application relates to the field of high-speed optical communication devices, in particular to a high-bandwidth double-slow-wave-electrode thin-film lithium tantalate electro-optic modulator. The lithium tantalate electro-optic modulator comprises, from bottom to top, a substrate layer, a bonding layer, a thin-film lithium tantalate layer, a cladding layer and an electrode layer. The electrode layer comprises a signal electrode, a first ground electrode, a second ground electrode and a plurality of periodically arranged double-slow-wave-electrode structures combined by sawtooth and T-shaped structures. The application solves the problem that the thin-film lithium niobate modulator is difficult to realize stable work in high-speed and high-power applications due to the inherent strong birefringence and photorefractive effect of the material, realizes the speed matching between the radio frequency signal and the optical carrier, solves the speed mismatching problem in the electro-optic modulator, and improves the electro-optic bandwidth of the modulator.

This invention relates to the field of image recognition technology, specifically a method for identifying transparent foreign fibers in cotton using polarization detection combined with image processing. The method includes the following steps: acquiring images using a polarization sensor and extracting temporal and angular information; calculating pixel phase delay; performing frequency domain analysis to determine the principal direction and generating a birefringence response; screening skeleton points based on grayscale and constructing fiber paths; combining phase gradients for extreme value analysis and intensity reconstruction to obtain global coordinates; and then weighted filtering based on directional differences to eliminate redundancy and obtain fiber position coordinates. In this invention, by combining image acquisition and feature expression paths, polarization response and texture information are fused to form multi-dimensional discriminative features, reducing noise and uneven illumination interference. Combining fiber continuity and optical response analysis enhances the ability to identify weak responses, making boundaries clearer and more stable. Furthermore, redundant points are compressed under directional classification and spatial constraints, improving positioning consistency and recognition accuracy, and achieving stable identification of transparent foreign fibers in complex scenarios.

The application discloses a single-mode fiber to multi-mode fiber mode converter which comprises a single-mode fiber head assembly, a transmitting end C lens, a birefringent crystal sequence, a receiving end C lens and a multi-mode fiber head assembly arranged coaxially; an air gap is arranged between the light emitting end of the single-mode fiber head assembly and the transmitting end C lens, and an outer envelope tube of the transmitting end collimator is coaxially fixed to the outer circumferential side of the single-mode fiber head assembly and the transmitting end C lens; the single-mode fiber to multi-mode fiber mode converter can stably assemble each optical component and ensure the overall assembly precision by means of the outer envelope tubes of the transmitting end and receiving end collimators and the inner and outer envelope tubes of the crystal group; all the components are packaged by the overall outer envelope tube, the internal optical structure is effectively protected, and the firmness of the device structure is enhanced.

Provided is a resin composition that has a low in-plane birefringence (ΔNxy) within a certain range and can be used to form optical components with excellent transparency. [Solution] A resin composition containing a cycloolefin-based resin and particles of a composite carbonate represented by the following chemical formula (1), blended in an amount of 0.1 to 1.0 parts by mass per 100 parts by mass of the cycloolefin-based resin. Ca z Sr 1-z CO3(0.1≦z<0.5) (1)

The invention discloses a multi-parameter sensor based on a butterfly-shaped photonic crystal fiber and a decoupling method thereof, and belongs to the technical field of optical fiber sensing. The multi-parameter sensor based on the butterfly-shaped photonic crystal fiber comprises a section of photonic crystal fiber PCF with a high birefringence effect structure, two fiber bragg gratings with different central wavelengths, namely FBG-A and FBG-B, are written into adjacent or overlapped sections in the fiber through a laser writing method, and the FBG-A and the FBG-B are connected with the photonic crystal fiber PCF. Each FBG respectively forms a pair of reflection peaks in two polarization directions so as to generate four wavelength response signals; the FBG-B section is also provided with a sleeve structure made of glass, metal or polymer materials; the two sides of the butterfly-shaped photonic crystal fiber PCF fiber core are provided with asymmetric air hole structures. According to the invention, the dual-wavelength fiber bragg grating is written into the butterfly-shaped PCF, and the natural high birefringence characteristic of the dual-wavelength fiber bragg grating is combined with air hole filling regulation and control, so that high-sensitivity measurement and decoupling of three parameters of temperature, strain and pressure are realized, and the test precision is improved.

To provide a method of forming a VCSEL with a structurally birefringent resonator.SOLUTION: A method includes a step of growing a bottom distributed Bragg reflector (DBR) and a first portion of a resonator on a substrate to form a bottom structure including a plurality of layers. One or more anisotropic features are etched on an upper side layer of the bottom structure to create a patterned growth interface. On the patterned growth interface, a remaining portion of the resonator and a top DBR are overgrown to form an epitaxial structure. One or more oxide openings are formed within the epitaxial structure.SELECTED DRAWING: Figure 1

This invention relates to a naphthalene-based liquid crystal monomer compound containing an isothiocyanate group. The general structural formula of the liquid crystal monomer compound is shown below: Y is an alkyl or alkoxy group; Z is selected from any one of single bonds, alkyl, phenyl, or benzoynyl groups; R1, R2, R3, and R4 are selected from any one of H, F, alkyl, or alkoxy groups, respectively. The liquid crystal monomer compound is used in liquid crystal compositions or microwave components of high-frequency devices. The microwave components are phase-shifting devices, tunable filters, or electronic beam-controlled antennas. The preparation method of the naphthalene-based liquid crystal monomer compound containing an isothiocyanate group is simple, and the naphthalene-based liquid crystal monomer compound containing an isothiocyanate group has a high birefringence, a wide nematic phase temperature, can improve the clearing point of liquid crystal components, has good solubility, large optical anisotropy, and fast response speed, and can improve the performance of liquid crystal components.

The application discloses a high-sensitivity high-temperature high-pressure sensor based on a high-birefringence grating, which comprises a microstructure optical fiber, the microstructure optical fiber comprises a fiber core and a cladding layer, the fiber core is located at the center of the cladding layer, the microstructure optical fiber has a first polarization direction and a second polarization direction on a radial plane, the first polarization direction is perpendicular to the second polarization direction, symmetrical air hole channels are arranged in the cladding layer on both sides of the fiber core along the first polarization direction, and the air hole channels are parallel to the fiber core; and a high-birefringence grating is formed in the fiber core or the cladding layer of the microstructure optical fiber through periodic refractive index modulation. The high-sensitivity high-temperature high-pressure sensor can directly form two separated Bragg resonance peaks, does not need to use any polarization device for demodulation, and can simultaneously measure temperature and pressure, has high sensitivity to pressure, and can work in a high-temperature environment.

The invention provides a reflective bidirectional light-passing magneto-optical switch, which relates to the technical field of optical communication and comprises an optical fiber collimation coupling unit, a polarization beam splitting and combining unit, a polarization state regulation and control unit, a reflection unit and a magnetic field generation and control unit which are sequentially arranged along an optical path. The 45-degree half-wave plate and the Faraday optical rotation crystal are configured to regulate and control light beam polarization, and it is ensured that optical signals are accurately guided to the output end after passing through the birefringent crystal. According to the design, the input port and the output port are integrated on the same side, compared with a transmission type structure, the magneto-optical switch has the advantages of being small in size, high in material utilization rate and compact in layout, the flexibility and adaptability of the magneto-optical switch are remarkably improved, bidirectional reversible transmission of an optical path is achieved, and the application requirement for bidirectional information interaction between channels is met.

The invention relates to the technical field of optical fiber communication, and provides a lightning stroke disturbance-oriented 100G single-polarization coherent light real-time communication method and system, and the method comprises the steps: detecting lightning stroke electromagnetic pulse time domain characteristics and stress wave propagation characteristics through an asymmetric sliding window, predicting a phase error through an exponential attenuation model, and carrying out the calculation of the phase error; acquiring stress wave delay by using a propagation velocity model; time sequence alignment is carried out, and a layered pre-compensation architecture is adopted to output compensation phase parameters; determining the position of a lightning stroke point according to the stress wave delay, reconstructing a three-dimensional stress field, converting the three-dimensional stress field into birefringence tensor distribution, and reversely solving to obtain a polarization control parameter; polarization control parameters are optimized through parameterization rapid estimation and FPGA parallel processing; and an asymmetric convergence control strategy is adopted to adjust compensation parameters and output a final communication signal. According to the invention, the signal recovery precision and the real-time processing capability of the 100G single-polarization coherent optical communication system in a lightning stroke environment are improved, and the environmental disturbance resistance requirement of high-speed coherent optical communication is met.

The utility model provides a four-channel integrated optical fiber isolator, which relates to the field of optical fiber communication and comprises a tube shell, a first optical fiber collimator and a second optical fiber collimator are respectively arranged at two ends of the tube shell, and four-core optical fibers are arranged in the first optical fiber collimator and the second optical fiber collimator. The four-core optical fibers in the first optical fiber collimator are in one-to-one correspondence with the four-core optical fibers in the second optical fiber collimator; an isolator core is arranged between the first optical fiber collimator and the second optical fiber collimator, the isolator core comprises an outer tube, a first birefringent crystal corresponding to the first optical fiber collimator and a second birefringent crystal corresponding to the second optical fiber collimator are arranged in the outer tube, and an optical rotation sheet is arranged between the first birefringent crystal and the second birefringent crystal. Compared with the prior art, the four-channel integrated optical fiber isolator has the advantages that the functions of four isolators are realized by using the boundary dimension of one conventional isolator, the use space is greatly reduced, only one isolator core and two four-core collimators are used, and the cost is saved.

This invention discloses a liquid crystal compound with high birefringence, a synthesis method, a liquid crystal composition, and its applications. The disclosed liquid crystal compound has the general structural formula shown in Formula I. The disclosed liquid crystal composition includes one or more compounds shown in Formula I. The liquid crystal compound and its composition of this invention not only have ultra-high birefringence but also have the advantages of low viscosity and a wide nematic phase temperature range, and can be used to prepare optoelectronic devices and microwave devices.

Systems and methods for temporal amplitude modulation of an optical beam. An exemplary system may include a birefringent fiber positioned between two polarizers, or between a polarized input light source and an output polarizer. Light may enter the birefringent fiber as linearly polarized. Depending on birefringence and orientation of the birefringent fiber, the polarization state changes as the light propagates through the birefringent fiber. This changed polarization state then enters the output polarizer, for which transmission is a function of the polarization state and the relative orientation of the polarization axis. The polarization state emerging from the birefringent fiber may be changed by modulating the fiber birefringence, for example through application of an external stress. Net transmittance of the system may be varied according to a magnitude of an external force (e.g., pressure) to some or all of the birefringent fiber.