615 results about "Fiber coupler" patented technology

A protection cap for use with a fiber coupler having at least a first housing comprises a casing defining a passage therethrough for receiving at least a portion of the housing, and a covering lid pivotally assembled to the casing for enclosing an end of the passage.

PCT No. PCT / GB94 / 02067 Sec. 371 Date Apr. 10, 1996 Sec. 102(e) Date Apr. 10, 1996 PCT Filed Sep. 23, 1994 PCT Pub. No. WO95 / 10907 PCT Pub. Date Apr. 20, 1995A cryptographic receiver (10) includes photon detectors (52, 54, 56, 58) arranged to detect photons arriving from filters (22) and (24). A fiber coupler (14) randomly distributes each received photon (16) from an optical fiber toone of two photon channels (18, 20). The filters (22, 24) are each unbalanced Mach-Zehner interferometers with a phase modulator (34, 44) in one arm (28, 38). The filters (22, 24) impose non-orthogonal measurement bases on photons within the respective channels (18, 20). A signal processor (60) derives a cryptographic key-code by analysis of signals received from the photon detectors (52, 54, 46, 58).

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 discloses a multi-wavelength high-sensitivity online monitor of multi-component NH3 and H2O based on semiconductor laser absorption spectroscopy. It contains host chassis and open long-path system. Equip power receptacle, switch, fiber connector and data transmission interface. It is characterized in that: there are near-infrared semiconductor laser, semiconductor laser controller, phase-locked amplifier, signal generator, data collecting and controlling module and infrared detector in host chassis which is connected with field optical system by fiber. Open optical system contains send-receive optical telescope and multielement reflector array. Optical telescope has input and output fiber couplers. The device realizes simultaneous testing of gas multi-component by using multi-wavelength and frequency division multi-signal detecting technique.

An endoscope for an optical fiber provides for inflow and outflow of irrigant. A telescope is included having a field of view directed into a working region. The endoscope defines a “hooded region” with an extended, blunt tip. The optical fiber fits within the endoscope has a side or end firing tip with an emission surface. A guide element is adapted to movably support the optical fiber in a position spaced away from the working region, and limit lateral movement of the tip without preventing longitudinal and rotational movement. An irrigant flow arrangement operates to direct inflowing irrigant over the emission surface of the tip. The fiber is assembled with a fiber coupler, a handle, a fiber port cap, and a travel limiter fixed to the fiber at a predetermined distance from the tip. The travel limiter cooperates with the endoscope and the fiber port cap to limit longitudinal and rotational movement of the fiber.

The invention relates to full parallel distributing type optical fiber grating temperature sensing method and its system. The method includes the following steps: processing high speed modulation for the wide band light source to form pulse sequence with certain width and duty ratio; adopting parallel connection for the sensor each of which is corresponding with different time delay optical fiber; making the pulse light source signal enter into the sensor array by splitter; making each reflected light signal of the sensor enter into photo-electricity detecting unit by one and the same fiber coupler or optical circulator; receiving a series of pulsing signals in one light source modulating cycle each of which is corresponding with one sensor; gaining light signal center wavelength information by a special filter; detecting each of them to gain corresponding sensor temperature information.

An optical multimode fiber including a graded index core and an extended gradient core which has a negative refractive index difference with respect to the cladding. The fiber improves the bandwidth, reliability and complexity of the telecommunication systems that are based on multimode fibers. The fiber reduces the differential mode delay among modes. The fiber thereby allows achieving large bandwidth even in the case when the highest order modes are excited. This has positive effects to the conditions that need to be fulfilled by the components such as optical sources, connectors, fiber couplers, other optical components, cables, etc. The fiber eliminates negative impact of the cladding that allows for reduction of fiber core size and the difference between the cladding and the core and thereby allows for achieving the larger bandwidth of optical fiber at lower fiber production cost.

In a method and a corresponding apparatus for performing chaotic optical time domain reflectometer, the chaotic laser signal, generated by the chaotic laser transmitter, is split into probe signal I and reference signal II by a fiber coupler. Through an optical circulator, the probe signal I is launched into the test fiber and the echo light is converted into electrical signal by a photodetector and digitalized by an A / D converter. The reference signal II is converted into electrical signal by a photodetector and digitalized by another A / D converter. Two digital signals received from two A / D converters are correlated in a signal processing device to locate the exact position of faults in fibers. The result output is then displayed on a display device. This invention was developed to overcome the tradeoff between resolution and dynamic range of the pulse-based OTDR. This method can improve the dynamic range and spatial resolution significantly; enhance the anti-jamming capability and noise tolerance. Also it has merits of simple structure and lower cost.

The invention provides a method for detecting on-line a multi-component gas and the testing arrangement for the method. The method comprises the following procedures: the current and temperature are tuned by a semi-conductor laser; after double modulation, the laser emitted from the semi-conductor laser passes an optic-fiber coupler, partial laser reaches to an open multi-optic-path pond, in which the emitted light that is absorbed by the gas to be measured is again transmitted through an optic fiber to a balance receiver; another partial laser from the optic-fiber coupler is also sent into the balance receiver; the signals picked up by the balance receiver is sent into a phaselocking amplifier after passing a pre amplifier, and then sent into a computer for processing after passing an A / D converter. The testing arrangement comprises a modulation signal generator, a laser driver, a laser spectrum light path, a signal conditioning circuit and a computer that are connected in sequence; the computer is additionally connected with the modulation signal generator, and connected with the laser spectrum optic path through a temperature detector / controller. The invention converts the precision controlling of temperature into the precision controlling of temperature, improves the sensitivity and opaqueness of the detection, so as to achieve the simultaneous testing of a plurality of components.

An optical power combining system. The system may comprise: a means for splitting an optical source into multiple channels; amplifiers in the multiple channels; and waveguide couplers for coherently combining the multiple channels into a single output.

The invention provides an optical fiber acceleration transducer probe and an optical fiber acceleration transducer system based on the phase generated carrier modulation technique. The system comprises a laser light source, optical fibers, a fiber coupler, the optical fiber acceleration transducer probe, a photoelectric detector and an electric demodulating system of phase generated carrier modulating signals, wherein the laser light source is a phase generated carrier modulated laser light source; the fiber coupler is respectively connected with the laser light source, the acceleration transducer probe and the photoelectric detector through the optical fibers; the photoelectric detector is connected with the electric demodulating system of the phase generated carrier modulating signals through wires or cables; and the optical fiber acceleration transducer probe comprises an acceleration detecting structure, at least one back plate, an acceleration transducer frame and at least one fiber sensor head. By adopting a double back plate structure and a fiber reading and detecting method, the system of the invention is improved and enhanced in the aspects of shock resistance and overload resistance performances, anti-electromagnetic interference, sensitivity and the like.

This invention discloses to a type of fiber gas lasers and fiber ring laser gyroscopes based on these fiber gas lasers. The fiber gas lasers comprise of excitation gases, optical resonator and excitation source, etc. The optical resonator is made by connecting two selected arms of a single mode fiber coupler to the two ends of hollow-core fiber to form a ring resonator. The hollow-core of the fiber is filled with excitation gases to act as gain medium. The fiber laser is simple to construct, lower cost, and has adjustable size and good amplification performance. The fiber ring laser gyroscopes based on this novel type of gas lasers can be applied on robotics, automobile navigation, etc.

It is a distribution light fiber and grating temperature measurement system used in high press electricity device, which belongs to measurement field and comprises wide band laser source, light fiber coupler, light fiber, light fiber and grating sensor, tunable fiber filter, and light detector. Setting light spectrum analysis unit and the unit of control and data process characterize it. Its laser source is connected with one sub-light of the light fiber coupler and the other sub-light is connected with input light end of the light detector through tunable light filter. The joining path end of the light coupler is connected in series with multiple fiber and grating sensor with different centers through light fiber. The laser source, tunable fiber filter, light detector are electrically connected with light spectrum analysis unit and the unit of control and data process through a bus.

The invention provides an acoustic emission signal sensing system based on fiber Bragg grating (FBG). The system comprises a fiber grating sensing unit and a signal processing unit; the fiber grating sensing unit comprises an FBG sensor, a light source, an isolator and a Y-type fiber coupler; the signal processing unit comprises a photoelectric switching circuit, an amplification circuit, a filter circuit, an A / D circuit and an FPGA (field-programmable gate array); the FBG sensor is firmly fixed in a packaging material, and a couplant is added between the packaged FBG sensor and a member to be detected. The system provided in the invention has the following advantages: a wide detection frequency band, detection scope being in a range of 50 KHz to 300 KHz; high sensitivity, strain resolution being 2 (mu epsilon) microstrani; a fast response speed more than 10 MHz; a long transmission distance which enables long distance between a detection spot and a monitoring spot to be feasible thanks to low loss transmission of fibers; strong capability in resisting electromagnetic interference, vibration, dampness, corrosion, etc., which enables the system to be used normally for a long time in a severe environment. A sensor made of fibers in the invention has the advantages of light weight, small volume, good imbedibility, etc.

The invention discloses an all-fiber current sensor consists of a 3x3 polarization-maintaining fiber coupler. One embodiment of the invention, a straight-through type interferometric all-fiber current sensor, comprises a light source, a 3x3 polarization-maintaining fiber coupler, fiber polarizers, a 1 / 4 fiber wave sheet and a transduction fiber ring. The light source is connected with one end of the 3x3 polarization-maintaining fiber coupler; the two ports of the 3x3 polarization-maintaining fiber coupler are respectively connected with two fiber polarizers; and the other ends of the two fiber polarizers are respectively connected with the transduction fiber ring by the 1 / 4 fiber wave sheet; one port of the 3x3 polarization-maintaining fiber coupler is vacant; and the rest two ports of the 3x3 polarization-maintaining fiber coupler are respectively connected with a signal processor by two photoelectric detectors. In addition, another embodiment of the invention, a reflection type interferometric all-fiber current sensor, also uses the 3x3 polarization-maintaining fiber coupler. The all-fiber current sensor avoids phase differences made artificially and makes the current transduction system woke more stably.

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 a fiber optical device dispersion measurement device and method, belonging to the field of optical measurement. The device includes: a fixed wavelength laser, a tunable laser, a fiber coupler, an electro-optic modulator, a microwave signal source, a first optical connector, a second optical connector, an optical fiber optic device to be tested, a photodetector, and data acquisition and processing system. The invention solves the technical problems of low dispersion measurement precision and complicated measurement process in the prior art, and has the advantages of strong anti-interference ability, high measurement precision and convenient operation.

The invention relates to a real-time monitoring system and a method based on an optical time domain reflection and fiber grating distributed type. The real-time monitoring system is characterized in that a laser control unit is respectively connected with a laser device and a computer in an electric mode, the laser device is connected with a combined end of a first fiber coupler in an optical mode, two optical splitting ends of the first fiber coupler are respectively connected with a first optical circulator port and a laser device wavelength monitoring unit, a second optical circulator port is connected with a combined end of the second optical fiber coupler in an optical end, one shunting end of the second fiber coupler is connected with a group of fiber gratings in an optical mode, the other shunting ends are respectively connected with the other corresponding groups of fiber gratings in an optical mode through a delayed optical fiber, a third optical circulator port is connected with a photoelectric detector in an optical mode, and the laser device wavelength monitoring unit, the photoelectric detector and the computer are respectively connected with a signal collecting and processing unit in an electric mode. According to the real-time monitoring method, the central wavelength of the fiber gratings can be rapidly demodulated in a real-time mode, and changes of the central wavelength of the plurality of the fiber gratings which are coincided in a working waveband on a sensing periodic line can be distinguished.

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 double-ring coupled all optical buffer storage based on 3x3 fiber coupler stores light signal has its read / write operation under control of one other light signal. Two side ports of the 3x3 fibercoupler constitute the double-ring structure via fiber feedback and the middle ports are used as the input and output of the buffer storage. Control light is led in and led out one fiber ring via twoWDM fiber coupler, and the phase difference between the two ring light signals is altered by means of cross phase modulation effect to realize the write-in and real-out of light signal in fiber ring.The control light signal may be positive logic one or negative logic one. If necessary, light amplifier may be added into the fiber ring for power compensation. Several buffer storages can be constituted into one parallel signal light buffer storage.

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 relates to an optoelectronic integration three-dimensional electric field sensor system, and belongs to the technical field of electric field measurement. The system comprises a laser source, a polarization-maintaining fiber coupler, an input polarization-maintaining optical fiber, a polarizer, a polarization-maintaining tail optical fiber, a sensing head, a polarization beam splitter, an output single mode fiber and a photoreceiver, wherein the output end of the laser source is connected with the input end of the sensing head through the polarization-maintaining fiber coupler, the input polarization-maintaining optical fiber, the polarizer and the polarization-maintaining tail optical fiber in turn, and the output end of the sensing head is connected with the input end of the photoreceiver through the polarization-maintaining tail optical fiber, the polarization beam splitter and the output single mode fiber. The sensing head comprises three parallel through optical waveguides which are formed on the surface of a lithium niobate plate through titanium diffusion; and a vertical dipole antenna and an electrode are laid on two sides of the surface of the first optical waveguide, and a shielding electrode is laid on the surface of the third optical waveguide. The optoelectronic integration three-dimensional electric field sensor system is suitable for detecting three-dimensional electric fields, has the advantages of simple process and high spatial resolution, and can realize close measurement.

A interferometer-based fouling detection system and method are described. The system may include a fiber optic cable, a light source in communication with the fiber optic cable, at least one photo detector in communication with the fiber optic cable, and at least one interferometric spectrometer. The fiber optic cable may include a long period grating and a fiber Bragg grating or it may include a facet edge. The system may instead include a fiber optic cable, a light source in communication with the fiber optic cable, at least one photo detector in communication with the fiber optic cable, a fiber coupler, a reference probe including a mirror, a sample probe, and an interferometer.

The invention relates to a fiber laser hydrophone signal demodulating system. The laser output by a fiber laser hydrophone is transmitted to the terminal b of a 3x3 fiber coupler (3) through a single mode fiber (2) from an input terminal (1), the laser is output in three ways through the 3x3 coupler, wherein the terminal e is vacant, the laser is divided into two ways by the terminal d and the terminal f, the laser signal after interference of the two lasers is output by the terminal a and the terminal c of the 3x3 coupler, the laser signals of the terminal a and the terminal c are received by a photoelectric detector (8), and V1(t) signal and V2(t) signal output by two photoelectric detectors are transmitted to a demodulation operation processing system (10) by a signal transmission wire (9) to obtain sound pressure size. The fiber laser hydrophone demodulating system of the invention demodulates a sound pressure signal in high resolution and high stability based on a Michelson nonequilibrium fiber interferometer and eliminates influence of polarization random change on an interference demodulating signal in a common single mode fiber interferometer.

A manufacturing method of a laser-ablated fiber device is proposed. The fiber cladding is removed by laser beam until the evanescent field is accessed. The depth of ablation is controlled by measuring the distance between the interference fringes of the laser. The effective interaction length is tuned by varying the radius of curvature of the fiber. The ablated fibers are mated to act as a fiber coupler. Subsequently, the interaction region is fused or fused-tapered to make a fiber coupler, an add / drop multiplexer, a fiber filter, etc.

The invention applies to a distributed fiber sensing monitoring system, and specifically relates to a chaotic Brillouin light time domain / coherence domain fusion analytical equipment and method; the equipment comprises a chaotic laser, a first optical isolator, a 1*2 fiber coupler, a first fiber polarization controller, a first high speed electric light modulator, a microwave signal source, a fiber grating, a first light circulator, a second fiber polarization controller, a second high speed electric light modulator, a pulse generator, a light scrambler, a light amplifier, a second optical isolator, a sensing fiber, a second light circulator, a tunable light filter, and an optical power detector; the equipment combines the advantages of an existing BOCDA system and a BOTDA system; the conventional BOTDA system spatial resolution is limited; the conventional BOCDA system uses continuous light as a detection signal, so the sensing distance has fuzzy distance problems, wherein the continuous light frequency is modulated by the sine or the continuous light phase is modulated by the pseudo random sequence; the long distance and high spatial resolution of the conventional distributed sensing system cannot be fully considered; the chaotic Brillouin light time domain / coherence domain fusion analytical equipment and method can solve said problems.

The invention discloses a power transformer partial discharge detection system based on a fiber bragg grating, which comprises an LD (Lead Detector) pumping source, a wavelength multiplexer, an erbium doped fiber, an isolator, a first fiber coupler, a second fiber coupler, a first fiber bragg grating, a second fiber bragg grating, a photoelectric detector, an acoustic emission collection card anda computer, wherein two input ends of the LD pumping source, the wavelength multiplexer, the erbium doped fiber and the first fiber coupler are in the same loop to form an annular cavity erbium dopedfiber laser; one output end of the first fiber coupler is connected with the first fiber bragg grating, the other output end of the first fiber bragg grating is connected with one input end of the second fiber coupler; one output end of the second fiber coupler is connected with the second fiber bragg grating, the other input end of the second fiber coupler is connected with the photoelectric detector; and the photoelectric detector is connected with the computer through the acoustic emission collection card. The power transformer partial discharge detection system is used for carrying out inservice real time and continuous monitoring on a transformer, and has the advantages of strong anti-electromagnetic interference capacity, small temperature influence, high detection precision and good flexibility.

The invention provides an acoustic emission signal sensing system based on matching-type fiber Bragg grating (FBG), which aims to overcome limitation of the prior art and introduce an FBG sensor into the acoustic emission detection field. The acoustic emission signal sensing system comprises a broadband light source, a first fiber coupler, a second fiber coupler, the FBG, a tunable FBG filter, a first photoelectric detection circuit, a second photoelectric detection circuit, an analog-to-digital conversion circuit, an FBG array (FBGA) and a computer. The acoustic emission signal sensing system is mainly applied to structural safety monitoring of an aerospace plane and damage detection of important components, and has the advantages of high sensitivity, high response speed, long transmission distance and strong resistance to electronic interference; and compared with the power-type FBG acoustic emission sensing system, the acoustic emission signal sensing system based on the matching-type FBG provided by the invention has the beneficial effects that wavelength shift information is demodulated by a matching grating method so as to obtain information of an original acoustic emission wave, the detection object is optical wavelength rather than optical power, and optical wavelength information is not affected by optical power loss during the optical transmission process, thus the detection precision is higher, the resolution power is higher and the noise is smaller.

A fiber coupler for synchronous test of spatial multi-channel aser adjust fluorescence inclues a laser beam coupled into an exciting fiber with equal power via a beam split mirror and a focussing lens. The output terminal of the exciting fiber is surrounded by exciting collect probes grouped by equal quantity of fluorescent collect fibers and housed with positioning liners. The fluorescent collect fibers in linear array are put in the liner diaphragm and aligned with the slit of spectrometer with a photoelectric transducer on its exit focus surface. This invention can guarantee the same test conditions for laser adjust fluorescent test spots with different spaces including same density of exciting light energy of the test spots, same fluorescent collect spatial angles and same fluorescent spectrom density with same samples.