127 results about "Single mode fiber coupling" patented technology

An oxygen concentration measurement system for blood hemoglobin comprises a multiple-wavelength low-coherence optical light source that is coupled by single mode fibers through a splitter and combiner and focused on both a target tissue sample and a reference mirror. Reflections from both the reference mirror and from the depths of the target tissue sample are carried back and mixed to produce interference fringes in the splitter and combiner. The reference mirror is set such that the distance traversed in the reference path is the same as the distance traversed into and back from the target tissue sample at some depth in the sample that will provide light attenuation information that is dependent on the oxygen in blood hemoglobin in the target tissue sample. Two wavelengths of light are used to obtain concentrations. The method can be used to measure total hemoglobin concentration [Hb.sub.deoxy +Hb.sub.oxy ] or total blood volume in tissue and in conjunction with oxygen saturation measurements from pulse oximetry can be used to absolutely quantify oxyhemoglobin [HbO.sub.2 ] in tissue. The apparatus and method provide a general means for absolute quantitation of an absorber dispersed in a highly scattering medium.

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.

The present invention discloses a silicon waveguide spot size converter based on a multilayer polymer structure and a preparation method thereof. The silicon waveguide spot size converter based on themultilayer polymer structure and the preparation method thereof are applied to coupling of silicon nanowire optical waveguides and common single-mode fibers. The structure is made by employing an integrated photoelectron process method, on a silicon substrate on an insulator layer, a taper-type silicon waveguide is made, a lithography technology is employed to continuously nest three layers of combined taper-type optical waveguides with materials of SU-8 photoresist on the insulator layer, and a silicon dioxide upper cladding is deposited to achieve making of a spot size converter. The taper-type portions of the three layers of combined taper-type optical waveguides with materials of SU-8 photoresist are employed to reduce the sizes of spot sizes entering the single-mode fibers in a horizontal direction and a vertical direction, perform cascade with a reverse taper-type silicon waveguide and finally allow a light field to couple into the silicon nanowire optical waveguides. The directend face connection between the silicon nanowire optical waveguides and the common single-mode fibers can be achieved, the matching with the single-mode fiber spot size is improved, the optical coupling efficiency is improved, and it is convenient to perform large-scale optical path integration.

The invention relates to a method for adaptively adjusting the transmitting power of an atmospheric optical communication system according to a channel state. The method is characterized by comprising the following steps: sending and receiving information by using a transmit-receive single-mode optical fiber coupling laser communication transceiver, and forming a bidirectional atmospheric optical communication system by using two transmit-receive single-mode optical fiber coupling laser communication transceivers having the same structure. The bidirectional atmospheric optical communication system can adaptively adjust the peak transmitting power of laser pulse according to the instantaneous channel state, namely, in the case of optical signal fading, the peak transmitting power of the laser pulse is increased at a transmitting end to compensate the negative impact generated by atmospheric turbulence.

The invention discloses a novel scanning method and a novel scanning device of an optical resolution photo-acoustic microscope, belonging to the technical field of photo-acoustic imaging. The device disclosed by the invention has the working process and working principle that after being collimated by using a single mold optical fiber coupling component, pulse laser emitted from a laser emitter is input into a two-dimensional scanning galvanometer system; the two-dimensional scanning galvanometer system focuses the laser onto a target object to generate a photo-acoustic signal, and a linear area corresponding to a focusing area of a linear focusing ultrasonic detector is scanned; photo-acoustic signals generated in different scanning positions are transmitted to the linear focusing ultrasonic detector through a water tank full of an ultrasonic coupling liquid, and are converted into piezoelectric signals; after being amplified by using an amplifier, the piezoelectric signals are acquired by using a data acquisition card, and are stored in a computer for data processing. The optical resolution photo-acoustic microscope and the target object do not need to move relative to each other, the requirements of the optical resolution photo-acoustic microscope on a signal to noise ratio can be met, and meanwhile, a large view field range and a high resolution can be met.

An optical two-channel rotary joint that is also suitable for coupling of single-mode fibers comprises two housing parts that are rotatable relative to each other. Each of these housing parts accommodates a light-waveguide for supplying light and a light-waveguide for withdrawing light. The arrangement has two optical paths adapted to operate in opposite directions, with each light-waveguide for supplying light being coupled with a light-waveguide for withdrawing light. Furthermore, one focuser is disposed on each of the light-waveguides for supplying light, which focuses the light of the light-waveguide for supplying light onto the corresponding light-waveguide for withdrawing light.

A semiconductor laser includes a substrate made of InP, an active layer including a multiquantum well structure, which is formed in a width of 7 to 14 μm on the substrate, and an n-type cladding layer made of InGaAsP and a p-type cladding layer made of InP, which are formed on the substrate with the active layer interposed therebetween. The semiconductor laser oscillates only in the fundamental lateral mode, and light emitted from an exit facet can be optically coupled with an external single mode optical fiber.

The invention provides a refractive index sensor based on an asymmetric double-core optical fiber. The refractive index sensor comprises a light source, a single-mode optical fiber circulator or a single-mode optical fiber coupler, an optical fiber cone, the asymmetric double-core optical fiber, a reflection mirror and a photoelectric detection device, wherein the light source is connected with afirst port of the single-mode optical fiber circulator or the single-mode optical fiber coupler; a second port of the single-mode optical fiber circulator or the single-mode optical fiber coupler is connected with one end of the asymmetric double-core optical fiber through the optical fiber cone; a third port of the single-mode optical fiber circulator or the single-mode optical fiber coupler is connected with the photoelectric detection device; and the reflection mirror is positioned at the other end of the asymmetric double-core optical fiber. By utilizing the refractive index sensor, an integrated Michelson interferometer based on the asymmetric double-core optical fiber is formed by using characteristics that a ground mode effective refractive index of an edge core in the asymmetric double-core optical fiber is sensitive to the change of an outside refractive index and the ground mode effective refractive index of an inner core in the asymmetric double-core optical fiber is insensitive to the change of the outside refractive index, therefore, high-precision measurement for the refractive index can be realized.

The present invention is one coupled high-sensitivity single-mode fiber evanescent wave sensor, and belongs to the field of optical fiber and sensor technology. The sensor consists of mainly light source, optical fiber, fiber evanescent wave sensor element, detector, signal processing unit and container holding measured medium. It features the single-mode fiber; the melting cone type single-mode fiber coupler probe as the fiber evanescent wave sensor element; the basal body with the packed melting cone type single-mode fiber coupler probe, sensing single-mode fiber cone area, single-mode fiber lead-in ends and fixing glue to fix the fiber; the hollow channel for tested gas or liquid to be led in; and the container holding measured medium. The present invention has simple structure, high sensitivity, high selectivity of lowest measurement limit in ppb to ppm level, and other advantages

The invention discloses an interferometry-based optical fiber Verdet constant measuring system. The system comprises an ASE (amplified spontaneous emission) light source, a single-mode optical fiber coupler, a Y-waveguide integrated optical modulator, 1/4 wave plates, Faraday rotator mirrors, a solenoid, a sine alternating-current driving circuit, matching fluid, a probe, an information processing module, a computer and measured optical fibers. The ASE light source, the single-mode optical fiber coupler, the Y-waveguide integrated optical modulator, the measured optical fibers and the Faraday rotator mirrors are connected through optical fibers in sequence. Each 1/4 wave plate is arranged between the Y-waveguide integrated optical modulator and the corresponding measured optical fiber. A signal processing portion comprises a feedback servo circuit, an FPGA (field programmable gate array) module and a phase modulation driving circuit. The system is of an all-optical-fiber structure and simple and convenient to set up; by the aid of the Faraday rotator mirrors, influences of linear birefringence of the optical fibers on measurement can be eliminated, and measurement accuracy is improved; and Verdet constants of various optical fibers can be measured by the system.

The invention discloses a mixed polarized fiber-optic gyroscope light path and a preparation method of a depolarizer of the mixed polarized fiber-optic gyroscope light path. The mixed polarized fiber-optic gyroscope light path comprises a single-mode fiber coupler, a broad-band light source, a depolarizer, a Y waveguide, a polarization-maintaining fiber ring and a detector, wherein the broad-band light source is welded with the first end of the single-mode fiber coupler; the tail fiber of the broad-band light source is a single-mode fiber; the input end of the depolarizer is welded with the second end of the single-mode fiber coupler; the Y waveguide is in shaft coupling with the output end of the depolarizer; the polarization-maintaining fiber ring is welded with the Y waveguide; the detector is welded with the third end of the single-mode fiber coupler; the tail fiber of the detector is the single-mode fiber; the depolarizer is formed by two sections of polarization-maintaining fibers, of which the length ratio is 1 to 2; the lengths of the polarization-maintaining fibers are respectively L1 and L2; L1 is greater than or equal to (LD+L3)*1.3; L2 is greater than or equal to (LD+L3)*1.3, L2-L1 is greater than or equal to (LD+L3)*1.3; and the depolarizer is fabricated by a polarization-maintaining input tail fiber of the Y waveguide. The design of the depolarizer is considered from two aspects of device-level depolarization and avoidance of optical path delay compensation between wave trains generated in subsequent light paths; the demands of the mixed polarized light path on the light source polarization degree are lowered; and the polarization error in the gyroscope light path is reduced.

The invention discloses a structure for improving the coupling efficiency between a submicron silicon waveguide and a common single-mode fiber. In the structure, the substrate material for making a submicron silicon waveguide is a silicon wafer on an insulating substrate, and the silicon wafer includes three layers of materials from bottom to top: substrate silicon, a buried oxide layer and top silicon, wherein the buried oxide layer is doped silicon dioxide; after forming a submicron silicon waveguide on the top silicon of the wafer through photoetching and etching, the doped silicon dioxide in the first layer is deposited on the silicon waveguide and fully covers the silicon waveguide; and after the doped silicon dioxide in the layer is photoetched and etched, the doped silicon dioxide in the second layer is deposited on the silicon waveguide. Therefore, the formed silicon dioxide waveguide is used as a connection channel for a common single-mode fiber, so that the mode field mismatch loss and the reflection loss during the coupling process of the submicron silicon waveguide and the common single-mode fiber, and the coupling efficiency between the submicron silicon waveguide and the common single-mode fiber can be improved.

The invention relates to the technology of multi-frequency fiber interference fringes and three-dimensional topography measurement, in particular to a phase controllable multi-frequency fiber interference fringe projection device. In order to provide the phase controllable multi-frequency fiber interference fringe projection device with high measurement precision, stability and reliability, the invention adopts the technical proposal that: the device comprises a Mach-Zehnder interferometer forming the projection of an emergence end 7 and an emergence end 8, and also comprises a Michelson interferometer; an interference signal generated by the Michelson interferometer is transmitted to a photoelectric detector 10 through a non-incident end of a single-mode fiber coupler 6; the photoelectric detector 10 converts an optical signal into an electric signal and transmits the electric signal to a servo system 11; and the servo system 11 is used for controlling a piezoelectric ceramics PZT driving device 13 by comparing an actual phase and a target phase to drive a fiber stretcher 12 to change the optical path difference of two output arms of the single-mode fiber coupler 6. The device is mainly applied in three-dimensional topography measurement occasions.

A small optical resolution photoacoustic microscope based on a micro-electromechanical scanning galvanometer belongs to the technical fields of automatic control and imaging. The small optical resolution photoacoustic microscope includes a light source assembly, a single-mode fiber coupling assembly, a light beam scanning assembly, a reflective support 4-1, a signal acquisition assembly and a computer, the computer controls pulsed laser emitted from the light source assembly to be collimated by the single-mode fiber coupling assembly and then enter the light beam scanning assembly, the light beam scanning assembly includes the micro-electromechanical scanning galvanometer 3-4 and a function generator 3-5, the computer controls the micro-electromechanical scanning galvanometer 3-4 to rotatethrough the function generator 3-5, the pulsed laser entering the light beam scanning assembly is reflected by the micro-electromechanical scanning galvanometer 3-4, and reacts with a target object through the reflective support 4-1 in order to generate a photoacoustic signal, and the photoacoustic signal is reflected by a light-transmitting and acoustic-reflecting sheet, is acquired by the signal acquisition assembly, is transmitted to the computer, and is stored and processed. The small optical resolution photoacoustic microscope has the advantages of small size, light weight, wide scanningrange and high scanning precision.

The invention discloses an optical fiber holographic interference measuring device. The optical fiber holographic interference measuring device comprises a tunable laser source, a single mode optical fiber coupler, a piezoelectric ceramic cylinder a first polarization controller, a second polarization controller and an image acquisition module, wherein the tunable laser source is connected with an input end of the single mode optical fiber coupler; two output terminals of the single mode optical fiber coupler are respectively and orderly connected with the piezoelectric ceramic cylinder, the first polarization controller and a second optical fiber through a first optical fiber to form a holographic interference reference arm, and are orderly connected with the second polarization controller, a fourth optical fiber and a special optical fiber through a third optical fiber to form a holographic interference signal arm; and output optical waves of the second optical fiber and the special optical fiber are overlaid to form a coaxial holographic interference region or an off-axis holographic interference region, and the formed region received by the image acquisition module. The optical fiber holographic interference measuring device is high in reliability and accuracy and easy to operate, and not only can be used for measuring refraction index profile of the special optical fiber, but also can be used for measuring different types of special optical fibers, phase difference change of holographic interference fringes and outer and inner defects and damages of the special optical fibers.

The invention relates to an arc heater water leakage detection system based on a laser absorption spectrum. A signal generator generates two beams of sawtooth signals and respectively transmits the same to two laser controllers, two beams of laser signals output by the two lasers are coupled and combined into a beam of laser signal by a single mode fiber coupler, collimation and three-dimensionaldisplacement adjustment are performed on the laser signal by a transmitting end of optical adjustment unit, the collimated laser signal passes through supersonic airflow at the outlet of an external spray pipe, the laser signal passing through the supersonic airflow is focused by a receiving end of optical adjustment unit on the other side and is transmitted by a multimode fiber to a detector to perform photovoltaic conversion, so that the laser signal is converted into an electrical signal, and the electrical signal is sent to a data collection and analysis terminal; and the data collection and analysis terminal directly performs collection and real-time analysis on the electrical signal to obtain a spectral absorption signal thereof, and the data collection and analysis terminal processes the spectral absorption signal to obtain an H2O content in the supersonic flow, and performs water leakage judgment on an external arc heater based on a specific value of the H2O content.

A zero-clearance receptacle for single mode optical fiber couplers. The zero-clearance receptacle includes an internally fluted V-groove formed by internally extending legs. The zero-clearance receptacle uses the fundamental action of the V-groove to accurately locate an optical fiber ferrule inserted into the zero-clearance receptacle in the radial direction. The zero-clearance receptacle further includes a slot that receives a biasing element, such as a spring, that biases the optical ferrule against the V-groove legs. This enables accurate positioning of an optical fiber in the optical ferrule relation to an optical element such as a VCSEL or a photoreceptor. The zero-clearance receptacle beneficially fits into an optical coupler, which may have a lens.

The invention discloses an acoustic emission sensing system based on a single mode fiber coupler. A single mode fiber coupling sensor part comprises incident optical fibers, emergent optical fibers, the single mode fiber coupler and a light source; a signal processing part comprises a photoelectric conversion circuit, a differential amplification circuit, a filter circuit, a data acquisition card and a computer; light emitted by the light source enters the single mode fiber coupler through the two incident optical fibers, and output after coupled in a coupling zone of the single mode fiber coupler; two optical signals are transmitted to the photoelectric conversion circuit by the two emergent optical fibers; the photoelectric conversion circuit converts the optical signals into electrical signals which then enter the data acquisition card sequentially through the differential amplification circuit and the filter circuit; and the data acquisition card performs analog-digital conversion on the acquired signals and then transmits to the computer for analysis processing. According to the system, a complicated mechanical device is not required for sensitization, the influence of outside temperature fluctuation is not required to be considered, and the system has the characteristics of low demodulation cost and high resolution.

A structure that allows both axial and radial alignment between a laser diode (16) and optical fiber (24) to be achieved in a single attachment process. The structure incorporates an optics tube (12), fiber holder (14), laser diode (16), and heat sink (18). The fiber holder (14)is affixed to the inside surface at one end of the optics tube (12) and retains a segment of fiber in axial alignment with and close proximity to the laser diode. The heat sink is placed into the opposite end of the optics tube (12) and serves to draw energy in the form of heat away from the laser diode. The laser diode is powered via an electrical lead that attaches to a metalized ceramic substrate located between the laser diode and the heat sink. The symmetrical design of the structure is rigid and substantially insensitive to thermal and mechanical stress that cause misalignment in planar designs of similar dimensional proportion. The optics tube (12) and heat sink elements of the structure are substantially cylindrical in shape to allow high precision parts, as the heat sink and optics tube (12) are easily turned and abrasively finished using standard machining equipment.

The invention discloses an automatic coupling device from an optical fiber laser device to a single mode optical fiber. An input end of a first optical fiber collimator is connected with an output end of the optical fiber laser device; a collimating laser beam is output to a telescope system composed of a first convex lens and a second convex lens fixed to a one-dimensional piezoelectric ceramic translation table, and the collimating laser beam is coupled to the single mode optical fiber through a second optical fiber collimator arranged on a two-dimensional piezoelectric ceramic translation table; the collimating laser beam is divided into two paths through a single mode optical fiber coupler, wherein one path is converted into an electric signal through a photoelectric detector, the electric signal enters into a controller, the controller sends a control signal according to a value of the photoelectric signal to control a driver to drive a one-dimensional piezoelectric ceramic and a two-dimensional piezoelectric ceramic so as to form a closed-loop control system, and the other path is output for use. The automatic coupling device has the advantages of high structural coupling efficiency, self-adaptive temperature, external-environment-change such as vibration and the like resistance, reliable running, low fault rate and the like. The automatic coupling device is widely applied to the fields of precise light spectrum, quantum optics and others using the optical fiber laser device.

An optical two-channel rotary joint that is also suitable for coupling of single-mode fibers comprises two housing parts that are rotatable relative to each other. Each of these housing parts accommodates a light-waveguide for supplying light and a light-waveguide for withdrawing light. The arrangement has two optical paths adapted to operate in opposite directions, with each light-waveguide for supplying light being coupled with a light-waveguide for withdrawing light via an added biconvex lens. Furthermore, one focuser is disposed on each of the light-waveguides for supplying light, which focuses the light of the light-waveguide onto the corresponding light-waveguide for withdrawing light.