89 results about "Polarization coupling" patented technology

A demodulator is provided for a multilevel differential phase shift keyed signal, capable of eliminating polarization dependence due to birefringence and polarization coupling-induced light resulting from a waveguide structure, and also, polarization dependence due to dynamic birefringence produced at the time of driving a variable phase adjuster. The demodulator is configured of an optical delay line interferometer of a waveguide interference type. The S/N ratio of a demodulated signal in the demodulator formed by the optical delay line interferometer can be also improved. Further, both the polarization dependence and the temperature dependence of the optical delay line interferometer can be reduced. The disposition of a polarization converter and groves filled with a temperature compensation material makes it possible to provide a circuit configuration suitable for eliminating the polarization dependence and the temperature dependence of the optical delay line interferometer.

In an optical interferometer, polarization dependence attributable to the optical path difference has conventionally been eliminated by inserting a half-wave plate at the center of the interferometer. However, light induced by polarization coupling produced in directional couplers used in the optical interferometer causes interference having different interference conditions from those of the normal light. Polarization rotators that effect any one of 90° rotation and −90° rotation of all states of polarization of incoming light are inserted in the optical interferometer, and thereby the interference conditions of light induced by polarization coupling are made the same as those of the normal light. Each of the polarization rotators is implemented by using two half-wave plates and by varying an angle of combination of these half-wave plates. Alternatively, each of the polarization rotators is implemented through a combination of one half-wave plate and a waveguide having birefringence properties.

The invention discloses a dispersion compensation method for a broadband light source. A polarization-preserving fiber polarization coupling testing system based on a Michelson interferometer is formed by the broadband light source, and the Michelson interferometer compensates the optical path difference between an excitation mode and a coupling mode in the polarization-preserving fiber, and a detector acquires an interference signal; specifically, the method comprises the following steps of: intercepting the initial data acquired by the detector through a window function, and taking out the interference data Imain between the excitation modes and the interference data Icoupling between the excitation mode and the coupling mode; respectively executing Hilbert transformation and Gaussian fitting on the Imain and the Icoupling, obtaining envelopes (I)main and (I)coupling of the interference signal, getting a birefringence dispersion coefficient Delta D according to a ratio Eta of the width of the (I)main to the width of the (I)coupling at a 1/e part, obtaining a phase factor needed for the dispersion compensation, and then multiplying the phase factor by a nonlinear frequency spectrum function with dispersion information to eliminate nonlinear phase items causing the widening of the interference signal envelopes; and finally, obtaining the dispersion compensated interference signal Icomp by executing Fourier inversion on the obtained linear frequency spectrum function.

The invention provides a device for reducing an influence of birefringent chromatic dispersion on polarization coupling measurement of a polarization maintaining optical fiber. The device comprises a broadband light source (1), the polarization maintaining optical fiber to be measured (3), a polarization coupling detection device (4), a first connection optical fiber (53), a second connection optical fiber (54), a three-port optical circulator (2), a semi-reflective and semi-transparent light beam polarization light rotator (6), a light rotator (7), a first rotary connector (51) and a second rotary connector (52), wherein the semi-reflective and semi-transparent light beam polarization light rotator divides broadband light into two uniform light beams which simultaneously pass through theoptical fiber to be measured from the clockwise direction and the anticlockwise direction; and by using the same polarization coupling detection device, two pieces of polarization coupling measurement data of which the scanning positions are symmetric with each other are acquired at the same time. The device has extremely important practical value for parameter measurement and performance evaluation of an optic fiber gyroscope sensitive ring and can be widely applied to distributed polarization optical fiber sensing systems.

The invention relates to the technical field of display, and provides a light-guide structure. The light-guide structure comprises a first waveguide layer, a polarization beam splitting structure, a first polarization coupling grating, a second waveguide layer and a second polarization coupling grating; the first waveguide layer is provided with a first light entry surface and a first light exit surface; the polarization beam splitting structure is arranged on the first light exit surface and used for dividing the light given out by a light source into first polarized light and second polarized light; the first polarization coupling grating is arranged on the first light entry surface and used for deflecting the first polarized light, so that the first polarized light is totally reflectedin the first waveguide layer; the second waveguide layer is provided with a second light entry surface and a second light exit surface and arranged above the polarization beam splitting structure; thesecond polarization coupling grating is arranged between the second light entry surface and the polarization beam splitting structure and use for deflecting the second polarized light, so that he second polarized light is totally reflected in the second waveguide layer. When the light-guide structure is used, no light mixing distance exists, and the light and thin design of the light-guide structure is facilitated.

The invention provides a double-end end-pumped solid laser based on polarization coupling, comprising a pumping source (1), a collimating lens (2), a polarization splitting prism (3), a one-half wave plate (4), a reflector (5), a focusing lens, a laser gain medium (7) and a laser resonant cavity. The pumping source (1) is a filter coupling output laser diode and outputs non-polarized laser; and the laser gain medium (7) is an anisotropic uniaxial crystal. The non-polarized laser output by the fiber coupling output laser diode is decomposed into two beams of polarized laser through a polarized beam splitter prism, respectively coupled into the gain medium from both end surfaces of the gain medium through an optical system so that the polarization direction of the pumping laser entering the gain medium is parallel to a certain optical axis in the laser gain medium, and double-end polarized laser end-pumping is realized. The invention can overcome the problems of thermal load distribution unevenness, and the like caused by non-polarized one-end end-pumping so as to improve the output power, the beam quality and the operation stability of the laser.

Disclosed is a method for demodulating the polarization maintaining optical fiber polarization coupling point position based on a multimodal division cycle. An SLD broadband light source is adopted by the method to build a polarization maintaining optical fiber polarization coupling test system based on the Michelson, light emitted by a light source is coupled into a polarization maintaining optical fiber through a polarizer to form excitation modes, part of excitation modes are interfered to orthogonal coupled modes for transmission through the coupling point in the optical fiber, the optical path difference of the excitation modes and the coupled modes is formed, and a Michelson interferometer is adopted to balance the optical path difference to form interference. According to the demodulating step of interference signals, cycle extraction is performed on multimodal division stripes collected by a detector; the multimodal division stripe cycle is utilized for calculating the opposite position and the spatial resolution of the polarization coupling point. The multimodal division cycle in the interference stripes is demodulated to obtain the opposite position of the polarization coupling point, the spatial resolution of the polarization coupling point is improved, and the birefringence dispersion influence of the polarization maintaining optical fiber is reduced. The method is simple and practical and has the higher practicability.

The invention discloses a device and a method for simultaneously detecting a stimulated Brillouin scattering threshold and a Raman scattering threshold of laser transmitted in water. The device comprises a seed injection laser (1). Pulsed laser transmitted by the laser (1) with a wavelength of 532nm is divided into two channels of pulse laser when being injected into a polarization coupling mirror (3) through a half-wave plate (2), wherein the first channel of pulse laser is received by a power meter (4) after being reflected by the polarization coupling mirror (3); and the other channel of pulse laser enters a water tank (6) filled with water through a quarter-wave plate (5). When the laser is transmitted to a 532nm fully reflecting mirror (7), part of light of 532nm in the laser is reflected to a power meter (8), the remaining light with a stimulated Brillouin scattering part directly penetrates through the 532nm fully reflecting mirror (7), and only the stimulated Brillouin scattering laser is left after penetrating through an optical filter (9) and is then received by a power meter (10). Respective attenuation coefficient for stimulated Brillouin scattering and Raman scattering can be calculated through substituting different values of I'2 in the existing formula (1), and further the stimulated Brillouin scattering threshold and the Raman scattering threshold can be obtained.

Aiming to solve the problems in the prior art, such as low accuracy, weak collection signal and poor signal-to-noise ratio, the invention provides a testing method based on the polarization beam-splitting interference technique, which can effectively eliminate the impact of light source power fluctuation on measurement results and greatly improve the measurement accuracy of polarization coupling strength of a polarization maintaining optical fiber. Besides, the control method is simple and the control software is high in integration level.

The invention relates to a signal photon detector based on polarization unrelated frequency up-conversion; the signal photon detector comprises a lithium niobate crystal which is formed by periodically superposing four parts and is periodically polarized, wherein for a first part and a fourth part, the periodic structures are same, the period length is lA and meets the quasi-phase matching condition of frequency up-conversion, and the period number is NA so that all signal lights can be converted into sum frequency lights; a second part is in a periodic structure used by reciprocal lattice vectors for compensating mismatching of wave vectors coupled and polarized by signal lights, and the period length is lB and meets the phase matching condition of signal light polarization rotation; and a third part is in a periodic structure used by reciprocal lattice vectors for compensating mismatching of wave vectors coupled and polarized by sum frequency lights, the period length is lC and meets the phase matching condition of signal light polarization rotation. An external direct-current power supply is applied to y-surfaces of the second part and the third part of a sample so as to realize the periodic modulation of optical coefficients, thereby leading the polarization direction of corresponding light waves to rotate. The signal photon detector is practicable in preparation and has wide application prospect in fields of quantum communication and photo-communication.

The invention discloses a polarization coupling device for a semi-conductor laser device adopting a prism. The device comprises a semi-conductor laser device array, a halfwave plate and a polarization beam split prism, wherein the semi-conductor laser device array comprises a first output light path and a second output light path; the halfwave plate is arranged on the second output light path of the semi-conductor laser device array; and the polarization beam split prism is arranged on the second output light path and the first output light path of the semi-conductor laser device array, and the halfwave plate is arranged between the semi-conductor laser device array and the polarization beam split prism. According to the device, the size of output light beam of the semi-conductor laser device array can be compressed, and the brightness and the quality of the light beam can be improved.

The invention discloses a laser with a low-voltage driven electro-optical crystal. The laser is characterized by sequentially comprising a first cavity mirror, a gain medium, a polarizing film, an electro-optical crystal, a wave plate, a second cavity mirror and a driving power supply for the electro-optical crystal, which have the same optical axis, wherein the polarizing film forms a certain angle with the optical axis; and the two ends of the electro-optical crystal are connected with the adjustable driving power supply. The laser has the advantages that driving voltage to be applied to the electro-optical crystal is low, so that the manufacture difficulty and cost of the driving power supply for the electro-optical crystal are greatly lowered, and the stability and reliability of the laser are improved; and the polarization coupling output rate of the laser can be controlled by changing the driving voltage of the electro-optical crystal.

The present invention relates to an apparatus for mitigating undesired portions of electromagnetic radiation (EMR) associated with an antenna. The apparatus comprises a coupling element EM inductively coupled with the antenna, the coupling element being substantially co-polarized with the antenna. The apparatus further comprises one or more dissipating elements EM inductively coupled with the coupling element, each of the one or more dissipating elements being substantially differently polarized than the antenna, for example cross-polarized to the antenna. The coupling element may be a conductive element configured for predetermined EM inductive coupling with at least the antenna and the one or more dissipating elements. Each of the one or more dissipating elements may be a conductive element configured for predetermined EM inductive coupling with the coupling element. A method of manufacture is also provided.

The invention relates to a multiple-beam composite device in a high-power semiconductor laser system. The device synthesizes light beams with four types of wavelengths sent out by eight groups of semiconductor laser arrays into a beam by adopting a space composite method. The invention belongs to the laser technical field. The device firstly carries out polarization coupling to eight beams of light with four types of wavelengths sent out by a first semiconductor laser array, a second semiconductor laser array, a third semiconductor laser array, a fourth semiconductor laser array, a fifth semiconductor laser array, a sixth semiconductor laser array, a seventh semiconductor laser array and a eight semiconductor laser array by utilizing a polarizing beam combiner to obtain four beams of natural light with four types of wavelengths; then the four beams of light are combined pairwise by utilizing a first wavelength beam combiner and a second wavelength beam combiner; and finally the two beams of beam combining light obtained are combined by a third wavelength beam combiner. The device has the advantages of more reasonable structure, less volume and lower cost.

An ophthalmologic photocoagulator and photoagulation method thereof in which visibility of sighting laser beam which is projected onto the eye fundus of an eye to be examined is improved and a loss in the amount of treatment laser beam can be reduced. The ophthalmologic photocoagulator includes: a treatment laser oscillator that oscillates a treatment laser beam for conducting treatment on a diseased part of the eye to be examined by photocoagulation; a sighting laser oscillator that oscillates a sighting laser beam for conducting sighting on the diseased part of the eye to be examined which is to be irradiated with the treatment laser beam; and a polarization beam splitter for combining an optical path of the treatment laser beam with an optical path of the sighting laser beam by polarization coupling. The treatment laser beam oscillating from the treatment laser oscillator and the sighting laser beam oscillating from the sighting laser oscillator have similar colors.

The invention belongs to the technical field of optical fiber measurement, and particularly relates to a common-path forward-reverse simultaneous measuring device for a fiber optic gyroscope ring. The common-path forward-reverse simultaneous measuring device for the fiber optic gyroscope ring comprises a light source device, a testing device 11, an optical path correlator 12, and a photoelectric signal conversion and signal recording device 13, wherein the optical path correlator 12 consists of a first six-port coupler 121, a second six-port coupler 122, a first collimating lens 123, a second collimating lens 124 and a scanning table 125. By adopting the common-path forward-reverse simultaneous measuring device, the testing time of a fiber optic gyroscope ring polarization coupling measuring device is shortened, the measurement efficiency is improved, the influences of environmental factors such as temperature are eliminated, and the polarization coupling symmetry of the fiber optic gyroscope ring can be obtained accurately.

The invention relates to a full-parallel-feed common-caliber dual-polarized waveguide slot filter antenna array system, which is formed by symmetrically arranging four 1/4 antenna array planes througha sum-difference feed network, and each 1/4 antenna array plane is cascaded with a linear frequency-variable coupling filter; each 1/4 antenna array surface comprises a power division waveguide layerand a plurality of sub-array antenna units arranged above the power division waveguide layer; each sub-array antenna unit comprises dual-polarized radiation antenna units which are arranged accordingto a 2 * 2 structure; each dual-polarization radiation antenna unit comprises a dual-polarization cross-shaped slot unit radiation layer, a four-ridge transmission waveguide layer, a dual-polarization coupling slot layer, a vertical polarization feed network layer, a horizontal polarization coupling slot layer and a horizontal polarization feed network layer which are sequentially arranged from top to bottom. According to the invention, linear polarization radiation in two directions can be realized, interference signals outside the working bandwidth can be effectively suppressed, and the antenna has the advantages of broadband, high gain, low sidelobe, low cross polarization and high integration level.

The invention discloses a sectional type screening method for polarization properties of a long polarization maintaining optical fiber. The method comprises the steps that polarization coupling distribution of the optical fiber with a specific length at the outermost end of an optical fiber drum is obtained through optical path scanning of one interference arm of a nonequilibrium interferometer, and whether the polarization maintaining optical fiber at the outermost end meets the usage requirement is judged according to a polarization coupling amplitude value; the optical fiber section meeting the requirement is distributed step by step according to the usage requirement, and the optical fiber section which does not meet the usage requirement is removed. According to the sectional type screening method, the optical fiber drum is directly connected into a testing system, so that the testing system conducts sectional type screening on the polarization properties of the polarization maintaining optical fiber, the limitation of the instrument measuring range to optical fiber screening is eliminated, the complexity of a testing instrument is lowered, and the screening convenience is improved. When a defect point exists in the optical fiber, it is only required that the part, from the defect point to the outer endpoint of the optical fiber drum, of optical fiber is removed. Compared with the traditional method that the optical fiber is detected after being distributed, the method has the advantages that waste of the optical fiber is reduced, and the production cost is lowered.

The invention provides an orthogonal polarization laser feedback interferometer. The orthogonal polarization laser feedback interferometer comprises an orthogonal polarization laser module outputting two equidirectional lasers which are superposed in space; a spectroscope dividing the laser output by the orthogonal polarization laser module into reflected light and transmitted light; a polarization spectroscope dividing the reflected light emitted by the spectroscope into parallel polarized light and vertical polarized light; a photoelectric detection module converting optical signals into electric signals; one acousto-optic frequency shift module carrying out frequency shift on the transmitted light; a diaphragm transmitting the laser subjected to the frequency shift of the acousto-optic frequency shift module; a half-wave plate arranged on an optical path of the laser emitted from the diaphragm; a polarization coupling lens coupling the laser emitted by the half-wave plate into a first polarization maintaining fiber; a fiber polarization beam splitter dividing the laser into first linearly polarized light and second linearly polarized light; a second polarization maintaining fiber for reflecting the first linearly polarized light to form a reference optical path; and a third polarization maintaining fiber outputting the laser to irradiate an object to be detected to form a measuring optical path.

A self-similar log-periodic antenna is described comprising a plurality of substantially triangular conductive elements, 4, symmetrically disposed in either planar or curved configurations about a central conductive boom to form an antenna arm. Two or more antenna arms are assembled into an antenna by symmetrically locating such antenna arms substantially in the shape of a pyramid (for planar arms) or in a conical shape (for curved arms). Some embodiments include a conductive fin, 5, to reduce cross-polarization coupling between antenna arms. Some embodiments include a grounded conductive shield on the interior of the antenna providing electromagnetic shielding for the interior region of the antenna while preserving the self-similar geometry of the antenna and shield combination.

A cube corner retro-reflector that includes three mutually perpendicular reflecting planes arranged in a pyramidal configuration, wherein at least one of the reflecting planes has a non-isotropic surface causing a polarization state of a ray exiting the cube corner retro-reflector to be orthogonal or substantively orthogonal to a polarization state of a ray entering the cube corner retro-reflector for all linear polarization orientations.

The invention provides a fiber optic gyroscope-used polarization-maintaining fiber ring distribution polarization crosstalk data processing method. Polarization-maintaining fiber ring distribution polarization crosstalk data are measured by an optical coherence domain polarimeter, false polarization coupling data exist, and processing is needed to acquire true polarization coupling data. The data processing process comprises steps: 1) a threshold is set to remove background noise of the distribution polarization crosstalk data; 2) based on a test wide spectrum light source coherent length, coupling state division is carried out on the polarization crosstalk distribution data; 3) based on a built crosstalk interference model, data in different coupling states are subjected to true polarization crosstalk intensity and position calculation; and 4) fiber optic gyroscope-used polarization-maintaining fiber ring distribution polarization crosstalk data unrelated to the test light source are formed. The problem of information aliasing brought by directly using the polarization crosstalk distribution data can be avoided, and as the obtained data through processing are not related to parameters of the test light source, the problem of inconsistency between the test state and the actual application state in the fiber optic gyroscope is solved.

The invention relates to the field of optical devices for hardening rails, in particular to an optical device for hardening the steel rail by using high-power semiconductor laser in running of a train. The optical device comprises semiconductor laser diode stacks, a polarization coupling prism, a wavelength coupling prism, a planar reflector, a symmetric ladder lens, a light beam compression lens, a slow-axis collimating lens, an optical working lens assembly and a laser head, wherein through the plurality of semiconductor laser diode stacks with fast-axis collimating lens, the light is coupled into a beam of light and output by using a wavelength coupling principle and a polarization coupling principle. The laser beam is led into the laser head so as to obtain ideal light spots required for hardening the steel rail by laser through light path design of a complete optical system. The device has the advantages of high energy utilization ratio, compact structure, convenient carrying and field application, high controllability, easy operation, low operation and maintenance cost, long service life, uniform energy distribution of light beam, no need of measures such as phosphorization, blackening and the like of the surface of the steel rail and capability of preventing negative effect brought by spraying an absorption layer.