1426 results about "Polarization-maintaining optical fiber" patented technology

The invention provides a manufacture method for polarization maintaining fiber and a polarization maintaining fiber, and relates to optical waveguide fibers in the field of fiber-optical communication and fiber optical sensors. The method comprises the following steps that: (1) two oppositely arranged open slots with a same shape are inwardly provided at a side surface of a glass mother rod, stress rods are machined to obtain a shape matching the open slots, and the centers of the cross sections of the two open slots and the center of circle in the cross section of the glass mother rod are in a same line; (2) the stress rods are respectively inserted into each open slot on the glass mother rod, and the assembled glass mother rod and stress rods are put in a cannula to form a preformed rod of the polarization maintaining fiber; (3) the preformed rod of the polarization maintaining fiber is drew to form the polarization maintaining fiber. According to the invention, the glass mother rod is provided with the open slots, and the stress rods are embedded in the open slots, thereby obtaining high process repeatability; inner surfaces of the open slots have high fineness, and the open slots have good symmetry, thereby improving processing efficiency; therefore, the optical performance and reliability of the polarization maintaining fiber are substantially improved.

A polarization-maintaining optical fiber includes a core region and a cladding region formed around the core region. The cladding region has a refractive index lower than a refractive index of the core region. A refractive index profile of the core region is either one of a step shaped or a concave shaped. The cladding region includes two holes formed in such a manner that a shortest distance from the core region is virtually zero at locations in opposite to each other across the core region.

This disclosure presents a non-contact precision optical device, including methods for measuring distances to an arbitrary target and various configuration geometries, for using polarization maintaining (PM) optical fiber components in a polarization diplexing scheme to construct a version of a dual chirp coherent laser radar that is immune to environmental effects.

A modelocked linear fiber laser cavity with enhanced pulse-width control includes concatenated sections of both polarization-maintaining and non-polarization-maintaining fibers. Apodized fiber Bragg gratings and integrated fiber polarizers are included in the cavity to assist in linearly polarizing the output of the cavity. Very short pulses with a large optical bandwidth are obtained by matching the dispersion value of the fiber Bragg grating to the inverse of the dispersion of the intra-cavity fiber.

Generally, and in one form of the present invention, is a polarization-maintaining fiber-based polarization sensitive optical low coherence reflectometer for depth resolved birefringence measurement. With the present invention, linear birefringence of a sample may be measured from data recorded in a single A-Scan. In addition, the present invention provides for the simultaneous measurement of retardation and orientation of birefringent axes, wherein measured retardation is insensitive to sample rotation in the plane perpendicular to ranging.

This disclosure presents a non-contact precision optical device, including methods for measuring distances to an arbitrary target and various configuration geometries, for using polarization maintaining (PM) optical fiber components in a polarization diplexing scheme to construct a version of a dual chirp coherent laser radar that is immune to environmental effects.

The invention relates to a full-distributed optical fiber strain and vibration sensor based on coherent heterodyne detection, which comprises a laser (1), a coupler, a pulse modulation module, a programming gain amplifier (4), an optical amplifier, a circulator (6), a sensing fiber (7), a polarization-preserving fiber (8), the coupler, a balancing photoelectric detector (10), a reversal switch, a mixer, a microwave source, a band-pass filter, and a signal processing unit, wherein the continuous light output by the laser (1) is divided into two paths after passing through the coupler (2); an output end of the balancing photoelectric detector is connected to the reversal switch; the reversal switch is switched to a channel 1 and a channel 2; when the channel 1 is switched on, the system utilizes the Brillouin optical fiber time domain reflection to measure; and when the programming gain amplifier (4) is closed and the channel 2 is switched on, the system utilizes the polarization optical time-domain reflection to measure. By using the full-distributed optical fiber strain and vibration sensor provided by the invention, the full-distributed measurement for strain as well as the weak vibration and the full-distributed measurement for vibration can be performed on a single optical fiber.

The invention provides a method and device for detecting a polarization extinction ratio of an optical polarizer. The detection method comprises the following steps of: making linear polarized light incident along a principal axis of an optical polarizer to be detected, and obtaining two light signals on two orthogonal optical axes at an outgoing end due to polarization crosstalk; interfering and carrying out photoelectric conversion and data acquisition on interfering light signals to obtain one group of discrete voltage signal values reflecting the interfering light intensity signals; and calculating coupling intensity h at each coupling spot based on a formula (1), and calculating an extinction ratio of the optical polarizer to be detected based on a formula (2). The device sequentially comprises a light source, an isolator module, a polarization module, the optical polarizer to be detected, a projection direction regulating module, an interferometer module, a data acquisition module and a central processor module. The invention has the advantage that the coupling intensity of the coupling spots is detected to induce the polarization extinction ratio, so that the measurement result is accurate. The invention is suitable for various optical polarizers, such as polarization maintaining fibers, polarization maintaining fiber couplers, polarizers and the like and has certain universality.

The invention provides array optical tweezers based on multicore polarization-preserving fiber and a manufacturing method thereof. The array optical tweezers comprise the multicore polarization-preserving fiber, standard single-mode fiber and a laser light source, wherein the laser light source is connected with one end of the standard single-mode fiber, the other end of the standard single-mode fiber is connected with the multicore polarization-preserving fiber in a fusion conical pull coupling mode, and the other end of the multicore polarization-preserving fiber is manufactured into a centrum shape through fusion conical pull processing equipment. In the invention, a plurality of optical waveguide fiber cores are integrated in one fiber, thus not only saving physical space but also significantly reducing system input light power and reducing harm on particles to be captured. Meanwhile, the multicore fiber composite optical tweezers can capture particles more flexibly and accurately, and has adjustability, thus greatly improving the practicability of fiber and optical tweezers technologies. More importantly, the array optical tweezers can form a compact interference grid optical field array, so as to form optical potential wells at coherence enforcement points to realize functions such as filtering particles.

The invention discloses a four-state quantum encoder and decoder for phase modulation polarization encoding and a quantum key distribution system. The encoder and the decoder have intrinsic stability, namely, the working stability is not influenced by the external environment or connecting optical fibers which can be common mono-mode optical fibers. The quantum encoder and decoder can be applied to the field of quantum key distribution, the whole system comprises a transmitting end and a receiving end, and the transmitting end and the receiving end are connected through a quantum channel to complete the key distribution process. The quantum encoder and decoder can achieve BB84 protocol four-state quantum key encoding and decoding with intrinsic stability. The common mono-mode optical fibers can be used as all the connecting optical fibers without using polarization-maintaining optical fibers, and interference with the phase drift and polarization change of the system from the external environment has no influence on the encoding or decoding process at all.

The invention discloses a sensing device of optical fiber distribution type temperature and stress and mainly comprises a light source module (1), a frequency discriminator module (2), and a thermo tank module (3), which are all connected with one another by polarization-preserving fiber. The invention is a direct detection method which is based on optical fiber Raman scattering used as a carrier wave of temperature information, brillouin scattering used as a carrier wave of stress, rayleigh scattering used for measuring relative frequency of a outgoing laser beam to a frequency discriminator and Fabry-Perot etalon used for discriminating frequency and distributing sensing temperature and stress. The invention has the advantages of simple structure, fine stability, avoidance of outgoing power of the light source during coherent detection, outgoing frequency of the light source. Instability of acoustic modulation or electro-optic modulation frequency is directly referred to measure errors and the direct detection technology of the frequency discrimination is not sensitive to frequency drift of the light source and fluctuation of signal intensity.

An optical frequency comb calibration-based dual-color laser scanning absolute distance measuring device and a method are characterized in that the device comprises a laser light source system, a polarization-maintaining optical fiber system, a Michelson interference system and a laser frequency calibration system. The method comprises the steps of controlling two tunable lasers in the laser light source system to continuously simultaneously adjust the output light frequency without mode skips, wherein the laser frequency calibration system records the interference signal of the Michelson interference system and a beat frequency signal of the tunable lasers and the optical frequency comb; computing the scanning range of the lasers and the period integer and period decimal of the phase change of the interference signal in the scanning process according to the collected data; and finally computing to obtain the absolute distance of a to-be-measured light path refractive face. The optical frequency comb calibration-based dual-color laser scanning absolute distance measuring device and the method have the advantages of simple system structure, high measuring precision, compensating effect on air refractive index, and traceable measuring outcome, and are suitable for the measuring field of space absolute distance.

The invention discloses a detection method suitable for a sensing device of optical fiber distribution type temperature and stress. The sensing device of the optical fiber distribution type temperature and stress mainly comprises a light source module (1), a frequency discriminator module (2), and a thermo tank module (3), which are all connected with one another by polarization-preserving fiber. The detection method of the invention is a direct detection method which is based on optical fiber Raman scattering used as a carrier wave of temperature information, brillouin scattering used as a carrier wave of stress, rayleigh scattering used for measuring the relative frequency of a outgoing laser beam to the frequency discriminator and Fabry-Perot etalon used for discriminating frequency and distributing sensing temperature and stress. The invention has the advantages of simple structure, fine stability, avoidance of outgoing power of the light source during coherent detection, and outgoing frequency of the light source. Instability of acoustic modulation or electro-optic modulation frequency is directly referred to measure errors and the direct detection technology of frequency discrimination is not sensitive to the frequency drift of the light source and the fluctuation of signal intensity.

The invention discloses a distributed optical fiber vibration sensor. The distributed optical fiber vibration sensor is characterized in that: on the basis of the optimized combination of the interference principles of a Sagnac interferometer and a Mach-Zehnder interferometer, the distributed optical fiber vibration sensor comprises a signal processing device, a first sensing optical fiber, a second sensing optical fiber, a third sensing optical fiber, a wideband light source, a narrowband light source, an optical circulator, a first optical wavelength division multiplexer, a second optical wavelength division multiplexer, a first coupler, a second coupler, a third coupler, a fourth coupler, a Faraday rotating mirror, a first photodetector, a second photodetector, a third photodetector and an optoisolator. The distributed optical fiber vibration sensor has a simple structure and can be used for monitoring outside disturbance and positioning multi-point interferences in real time; the demodulation work is relative simple and polarization maintaining optical fibers can be prevented from being used; and by adopting the Faraday rotating mirror, the phenomenon of polarization state fading due to double refraction can be also compensated.

The invention discloses a dual-polarization interferometric fiber-optic gyro which belongs to the field of communication technology. The fiber-optic gyro comprises a light source, two linear polarized light generating circuits, two signal detection light paths, a polarized beam splitter / combiner, a polarization-maintaining coupler, a phase modulator and a polarization-maintaining fiber-optic ring; wherein the light source is connected with the input ends of the two linear polarized light generating circuits by optic fibers; two output ends of the two linear polarized light generating circuits are respectively connected with two ports at the same side of the polarized beam splitter / combiner by optic fibers through one signal detection light path; the port at the other side of the polarized beam splitter / combiner is connected with the polarization-maintaining fiber-optic ring through the polarization-maintaining coupler; and the phase modulator is connected between the polarization-maintaining fiber-optic ring and the polarization-maintaining coupler by optic fibers. Compared with the prior art, the fiber-optic utilizes the dual-polarized light to carry out the detection, thereby greatly improving the measuring precision and the measuring stability of the rotating angular velocity; meanwhile, the fiber-optic gyro has the advantages of simple structure, low cost, small volume, high sensitivity and wide application range simultaneously.

A mechanism for achieving symmetrical stress loads on operating optical fibers (16) held in fiber optic arrays includes, in one embodiment, the provision of a pair of non-operating or dummy fibers(26), each located outboard of the outermost or curb fibers(16″) of the array. All of the fibers, whether operating or dummy, are held in corresponding grooves (18, 24) in a substrate (12). A cover plate (14) may be positioned thereover while a low stress glue or potting compound (22) is introduced or applied so as to completely encapsulate the fibers. The glue or potting compound will symmetrically surround all of the operating fibers whereby not only any inboard operating fibers (16′), but also the outboard operating curb fibers (16″), are symmetrically encapsulated. In this manner all of the operating fibers are subject to the same stresses and consequently will exhibit essentially the same polarization maintaining behavior. The invention is primarily beneficial with polarization-maintaining optical fibers, but will work effectively with other types of optical fibers as well, wherever stress are a concern.

The invention relates to a device for detecting polarization-maintaining optical fiber, belonging to the technical field of optical measurement and optical fiber sensing. The device comprises a light source, a polarizer, a light beam splitter, a light delayer, a light beam combiner, a light detector and a circuit. A linearly polarized light beam is provided by the light source; after the light beam passes through the optical fiber to be detected, the polarization state of the light beam is turned by an angle through the polarizer; then the light beam enters the light beam splitter and is divided into two light beams; one light beam is delayed by the light delayer and is combined in the light beam combiner for interference; the light detector receives the interfered light and converts the interfered light into electric signals; and finally the circuit processes the electric signals to obtain the conditions of all parts of the optical fiber. The invention has the advantages that the conditions of the polarization-maintaining optical fiber can be accurately, conveniently and rapidly detected and the realization of the application of the polarization-maintaining optical fiber in fields such as sensing and the like is facilitated.

The present invention discloses a polarization relevant output multi-wavelength and passive mode-locking optical fiber laser which belongs to laser and light communication field. A ring laser cavity includes Er-doped fiber that is taken as gain medium; a 980nm / 1550nm wavelength-division multiplexer is used to couple pumping laser of 980nm into the Er-doped fiber; a polarization relevant isolator with tail optical fiber on two ends guaranties the laser work in one way, meanwhile plays the role of a polarizer; two polarization controllers respectively on two side of the polarization relevant isolator are used to control polarization state, a 10dB coupler with 10% of the terminal port used to output optical signal and 90% of the optical signal stays in the cavity for cycle. A segment of long single mode fiber is inserted in the laser cavity and used to increase nonlinear effect inside the laser cavity; a piece of polarization maintaining optical fiber and a polarization relevant isolator constitute a birefraction optical fiber periodicity filter; the optical fiber laser is provided with two different output modes, namely mode locking pulse output and multi- wavelength continuous wave output, and can adjust polarization and switch between the two output modes.

The invention discloses a microwave optical fiber link device for long-distance transmission of radar reference frequency signals and relates to the technology of radar detection. The microwave optical fiber link device consists of an optical emitter, an optical receiver, a Faraday rotating mirror, an optical circulator, a polarization maintaining optical fiber, a radio-frequency power amplifier and the like. By subjecting microwaves to electric-optical and optical-electric conversion and utilizing the advantages of low insertion loss and high-temperature phase stability of the optical fiber, the microwaves are transmitted in low phase fluctuation and loss in the long distance. The microwave optical fiber link device can be used for transmission of rate-aided signals of spatial long-base line interference synthetic aperture radar (SAR) and transmission of reference frequency signals of radar systems such as phased array radars and multi-base radar monitoring net. Besides, phase changes caused by environmental factors such as temperature and irradiation can be accurately compensated during long-distance transmission of X-wave band microwave signals, and meanwhile, the microwave optical fiber link device has ultrawide radio-frequency (RF) working band and can be developed for transmission of radar reference frequency signals ranging from 50MHz to18GHz.

The invention discloses a super-resolution imaging system. The imaging system comprises a first laser, a second laser, a first half-wave plate, a first pulse beam splitter, a spectrometer, a first battery of lens, a glass rod, polarization maintaining optical fibers, a spatial light modulator, a first object lens, a battery of reflectors, a second battery of lens, a reflector, single mode fibers, a second half-wave plate, a retroreflector, a reflector, a first dichroic mirror, a second dichroic mirror, a scanning system, a one fourth slide, a spacial object lens, a second pulse beam splitter, and a photomultiplier. A coherent optical adaptive technique is adopted to carry out aberration correction so as to increase the spatial resolution of a STED super-resolution microscopic imaging system, thus the aberration caused by uneven surface of a biological sample and uneven distribution of inner refractive index of a sample is eliminated, and the spacial resolution is increased.

A polarization maintaining optical fiber, for guiding a measuring light beam, is provided within a probe. The probe is configured to be rotatable in the circumferential direction of the polarization maintaining optical fiber. A polarization direction rotating means, for rotating the polarization direction of the measuring light beam that enters the polarization maintaining optical fiber accompanying rotation of the probe, is provided in order to maintain a state in which the polarization direction of the measuring light beam that enters the polarization maintaining optical fiber and the direction of the polarization axis of the polarization maintaining optical fiber are matched.

A fiber optic gyroscope using a low-polarization and polarization-maintaining hybrid light path comprises an optical meter head and a circuit signal processing part, The optical meter head comprises: a light source, a multi-functional integrated optic chip, a detector, a coupler and a fiber coil, wherein the light source is a low polarization light source and single mode fiber pigtail coupling; the input terminal of multi-functional integrated optic chip uses a single mode fiber, and the output terminal of multi-functional integrated optic chip adopts a polarization-maintaining fiber; the input fiber pigtail of the said detector is a single mode fiber; the coupler is a 2×2 polarization independence single mode fiber coupler; the fiber coil is a polarization-maintaining fiber. By adopting the scheme of the low-polarization and polarization-maintaining hybrid light path and the signal processing methods such as all-digital closed loop control and random overmodulation etc., the present invention can reduce the effect of light path polarization crosstalk, simplify the assembling technology, enable large scale production and guarantee the good scale factor linearity performance and the lower noise level. Furthermore, by temperature modeling and compensating, the invention enables the bias of the fiber optic gyroscope to drift more slightly within the all-temperature range, and therefore the fiber optic gyroscope with good performance and engineering application can be achieved.

The invention discloses an atomic spin precession detection method and device based on circular polarization detection light. The atomic spin precession detection method is based on spinning light characteristics of polarized atoms of an atom air chamber, left circular polarization light and right circular polarization light are formed through double refracted light paths, the left circular polarization light and the right circular polarization light are fed into the atom air chamber, phase position difference in direct proportion to atomic spin precession is generated from left spinning circular polarization light and right spinning circular polarization light of the air chamber, outgoing circular polarization light is fed back along the original path by using a reflection mirror, the left and right spinning directions of the left spinning circular polarization light and the right spinning circular polarization light are switched, the phase position difference is multiplied, the left spinning circular polarization light and the right spinning circular polarization light are interfered according to a circular polarization light interference technique, and thus phase position difference measurement and high-sensitivity detection on atomic spin precession detection are achieved. Atomic spin precession detection can be achieved, and the atomic spin precession detection device is high in precision, sensitivity, and anti-interference capability and small in size. The method and the device are practical, and super high in sensitivity and precision when provided for an atomic spin precession sensor based on atomic spin precession detection.

A fiber-laser comprises a laser cavity including a gain-fiber. A polarization maintaining fiber coupler (PM-coupler) located in the laser cavity and configured such that the fiber-laser delivers plane-polarized output radiation. The laser cavity may be configured as a linear cavity or as a ring cavity and operated in either cavity configuration in CW or pulsed modes. The PM-coupler, while providing the function of a intra-cavity polarizing element, can additionally function as a wavelength division multiplexing (WDM) coupler. Preferred embodiments of the laser include an intracavity polarization maintaining WDM element functioning jointly as an intra-cavity polarizing element and an element for coupling pump light into the cavity.

The invention discloses a passive mode-locking fiber laser with a double-wavelength short pulse output. The invention has the characteristics of high stability, high efficiency, high power, high pulse repetition rate, synchronous passive laser impulse, single-line polarization, tunability, double wavelength and ultrashort pulse output. The ultrashort pulse fiber laser of the invention uses two polarization-preserving rare-earth doped (Er3+ / doped Yb3+) fibers as laser grain media, adopts a broadband polarization beam splitter spectrum and a broadband chirp polarization-preserving fiber grating and the like as cavity surface reflecting elements and chromatic dispersion compensation elements and utilizes a semiconductor saturable absorber as mode-locked elements and the like to achieve double-wavelength passive synchronous ultrashort pulse mode-locked fiber laser output. The passive mode-locking fiber laser with the double-wavelength short pulse output is a fiber laser with a novel structure of double-wavelength mode-locked ultrashort pulse output, which can achieve full-fiber.

The invention relates to a hollow photonic crystal optical fiber gyro, which is characterized in that a hollow optical fiber resonant ring coiled by hollow photonic crystal optical fibers is adopted; laser light emitted by a tunable narrow linewidth laser is divided into two equal parts by an integrated optical modulator; the two parts enter an optical coupling module respectively through two polarization-maintaining fiber couplers, then are output from the optical coupling module and injected into the hollow optical fiber resonant ring; a convex spherical mirror adopted by the optical coupling module has high reflectivity and transmissivity, and a resonant cavity for the gyro is formed between the optical coupling module and the hollow optical fiber resonant ring to realize input and output of light; a small part of harmonic light penetrates the resonant cavity and returns to two detectors respectively through two polarization-maintaining fiber couplers, frequency difference of the harmonic light in the clockwise / anticlockwise direction is measured according to signals detected by the two detectors, and the angular speed of a carrier can be obtained through a testing circuit, so as to realize the function of a gyroscopic instrument. The optical fiber gyro has the advantages of small volume, convenient realization, high reliability, high radiation-resistant capacity and suitability of space application.

The invention discloses a difference double-interference type optical fiber gyroscope based on birefringence modulation. The optical fiber gyroscope comprises a light source, a modulator, a coupler, an optical fiber ring, a polarization beam splitter, a first detector and a second detector, wherein the light source and the modulator are welded at a melting point O1 with an angle of 45 DEG; the modulator and a port A of the coupler are welded at a melting point O2 with an angle of 45 DEG; an end C of the coupler and one end of a polarization-maintaining optical fiber ring are welded at a melting point O3 with an angle of 0 DEG; an end D of the coupler and the other end of the optical fiber ring are welded at a melting point O4 with an angle of 90 DEG; an end B of the coupler and an input end of the polarization beam splitter are welded at a melting point O5 with an angle of 0 DEG; and two output ends of the polarization beam splitter are respectively welded to the first detector and the second detector. According to the invention, closed-loop control of the difference double-interference type optical fiber gyroscope is realized; and a wide-spectrum light source with very weak coherent characteristics is adopted, thereby avoiding strong noise brought by various stray wave interferences which are caused by strong coherent characteristics of a laser light source.

The invention discloses a single longitudinal-mode optical fiber laser with low noise, narrow linewidth and high power. Polarization maintaining optical fiber is rare-earth-doped phosphate single-mode glass optical fiber, the component of a fiber core is phosphate glass which consists of 70P2O5-8Al2O3-15BaO-4La2O3-3Nd2O3, the fiber core of the polarization maintaining optical fiber is doped with high-concentration luminous ions, the luminous ions are one or combination of more than one of lanthanide ions and transition metal ions, the doping density of the luminous ions is greater than 1*10<19>ions / cm<3> and the luminous ions are evenly doped in the fiber core. A polarization maintaining fiber Bragg grating with the narrow linewidth and a dichroscope form a front cavity mirror and a rear cavity mirror of the optical fiber laser, a centimeter-sized erbium-ytterbium co-doped phosphate glass polarization maintaining optical fiber is taken as a laser working substance, and polarization maintaining output laser generated by a single-mode semiconductor laser is taken as a pumping source, thus achieving the single longitudinal-mode laser output by designing and manufacturing the reflection spectrum width of the polarization maintaining fiber Bragg grating and controlling the cavity length of the whole laser cavity.