401 results about "Birefraction" patented technology

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 relates to a high-precision wide-range low-coherent interference shift demodulation device, which comprises a light source, an optical circulator, a self-focusing collimation lens, a fixed reflecting mirror, an optical fiber splicer, a beam extender lens, a polarizer, a birefringent optical wedge, a stair-shaped birefringent phase shifter, an analyzer, a planar array camera and a processing unit. A demodulation method comprises the following steps: dividing the light emitted from the light source into two parts after the light passes through the optical circulator and reaches the self-focusing collimation lens at the sensing side, wherein one part is directly reflected and the other part is reflected after entering the reflecting mirror fixed on an object to be detected, and the two parts of reflection light have an optical path difference (OPD); guiding the two parts of reflection light to pass through the optical circulator again so as to reach the optical fiber splicer and then reach the birefringent optical wedge and the stair-shaped birefringent phase shifter through the beam extender lens and polarizer; realizing the wide-range optical path difference (OPD) scanning under the combined action of the birefringent optical wedge and the stair-shaped birefringent phase shifter; generating an interference fringe behind the analyzer; receiving the interference fringe by using the planar array camera; and detecting the shift information through digital processing by a computer or an embedded system.

Disclosed is a liquid crystal cell having contiguous to a surface of a constraint thereof one or more compensator layers, each containing a transparent amorphous polymeric birefringent material having an out-of plane birefringence more negative than −0.005. The invention also provides a liquid crystal display and a process for making such a cell.

The present invention provides improved optical switches in which no mechanical movement is required to direct optical pathways between plural fiber ports and light transmission is bi-directional. Advantageously, the inventive switches permit bi-directional light transmission. The inventive switches also incorporate light bending devices to allow two fibers to be coupled to the light beams using a single lens for compactness. In the inventive switch, an optical signal is spatially split into two polarized beams by a birefringent element, which passes through a polarization rotation device that comprises waveplates, walk-off elements, and an electrically controllable polarization rotator, and recombine into an output fiber, achieving polarization independent operation. The switches of the present invention rely on electro-magnetically or electro-optically switching the beam polarizations from one state to another to rapidly direct the light path.

A detector (110) for determining a position of at least one object is proposed. The detector (110) comprises: —at least one angle dependent optical element (130) adapted to generate at least one light beam (131) having at least one beam profile depending on an angle of incidence of an incident light beam (116) propagating from the object (112) towards the detector (110) and illuminating the angle dependent optical element (130), wherein the angle dependent optical element (130) comprises at least one optical element selected from the group consisting of: at least one optical fiber, in particular at least one multifurcated optical fiber, in particular at least one bifurcated optical fiber; at least one diffractive optical element; at least one angle dependent reflective element, at least one diffractive grating element, in particular a blaze grating element; at least one aperture stop; at least one prism; at least one lens; at least one lens array, in particular at least one microlens array; at least one optical filter; at least one polarization filter; at least one bandpass filter; at least one liquid crystal filter, in particular a liquid crystal tunable filter; at least one short-pass filter; at least one long-pass filter; at least one notch filter; at least one interference filter; at least one transmission grating; at least one nonlinear optical element, in particular one birfringent optical element; —at least two optical sensors (113), wherein each optical sensor (113) has at least one light sensitive area (121), wherein each optical sensor (113) is designed to generate at least one sensor signal in response to an illumination of its respective light-sensitive area by the light beam (131) generated by the angle dependent optical element (130); at least one evaluation device (133) being configured for determining at least one longitudinal coordinate z of the object (112) by evaluating a combined signal Q from the sensor signals.

A liquid crystal display in which a negatively birefringent layer is used as both an orientation film and as a retarder in the display. An improved method of making such a display is also disclosed. In preferred embodiments, each of the orientation layers has a retardation value of from about -80 to -200 nm.

An optically active linear single polarization device includes a linearly birefringent and linearly dichroic optical waveguide (30) for propagating light and having single polarization wavelength range (48). A plurality of active dopants are disposed in a portion (34) of the linearly birefringent and linearly dichroic optical waveguide (30) for providing operation of the waveguide in an operating wavelength range (650) for overlapping the single polarization wavelength range (48).

The present invention discloses a precise tunable multi-wavelength ring optical fiber laser structure. 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 on-line birefraction optical fiber filter simplifies structure of the optical fiber laser, makes the optical fiber laser be more easily integrated, and allow the multi- wavelength optical fiber laser with precise tenability.

A method and a device using a birefraction polarization beam splitter to generate a vector beam are provided; the device is that a computed hologram is arranged on a front focal plane of a first fourier lens; the birefraction polarization beam splitter is arranged between the front focal plane of the first fourier lens and the first fourier lens; a filter bore diameter is arranged on a rear focal plane of the first fourier lens, and a second fourier lens is arranged between the filter bore diameter and an output plane. The method is to use a plane beam or a gauss beam to irradiate the computed hologram, the beam passing the computed hologram is converted by the birefraction polarization beam splitter and the first fourier lens, and is filtered by the filter bore diameter; the beam passing the filter bore diameter passes the second fourier lens, and the needed vector beam can be obtained on the output plane. No element is needed between the computed hologram and the birefraction polarization beam splitter, extinction ratio of two cross-polarized components of the generated vector beam is better than 10-5, thus obtaining the high quality vector beam.

The invention discloses a method and device for measuring distributed-type polarization maintaining optical fiber double refraction based on Brillouin dynamic grating, belonging to the field of optics and aiming at solving the problems that in the traditional technology for measuring the polarization maintaining optical fiber double refraction, the measuring time is very long, and the long distance resolution and the high spatial resolution cannot be met at the same time. The method disclosed by the invention comprises the following steps of: incoming a pumping pulsed light from one end of the polarization maintaining optical fiber to be tested, incoming a continuous pump light from the other end of the polarization maintaining optical fiber to be tested after incoming a probe pulse light, incoming the continuous pump light and the pumping pulsed light to the same optical principal axis, incoming the probe pulse light to the other optical principal axis, and generating the Brillouin dynamic grating as the continuous pump light and the pumping pulsed light are met in the polarization maintaining optical fiber to be tested and are simulated by Brillouin scattering; and reflecting the probe pulse light by the grating, injecting pumping pulsed light and the probe pulse lights with different frequencies repeatedly, obtaining the reflection light intensity of the polarization maintaining optical fiber to be tested in each position point in different frequencies, and thus obtaining the double refraction of the polarization maintaining optical fiber to be tested in each position point.

The invention aims at designing a quantum key distribution network scheme that is easy to construct, enables the cost to be low, has high anti-interference capability, and is capable of realizing communication between any users and overcoming the defect caused by imperfect performances of parts of key devices. The provided scheme has the following advantages: firstly, combination of quantum channels, phase modulators, 90-degree faraday rotator mirrors is used, the birefrigent effect of the optical fiber and the optical device can be compensated automatically, the system stability is enhanced, and the anti-interference capability of the quantum key distribution system is improved; secondly, on the basis of the optical switch control, quantum key sharing between any two users in a network can be realized; thirdly, besides the master control side, each controlled side only needs one phase controller, faraday rotator mirror, and attenuator, so that the networking cost is substantially reduced; and fourthly, the master control side only serves as the auxiliary communication end in the network and will publish modulation information and detection results after communication completion, so that immunity to an attack strategy caused by the imperfect performance of the detector in the actual system can be realized.

The general field of the invention is that of fiber-optic sensors comprising at least one measurement optical fiber having an optically pumped doped amplifying medium, the optical characteristics of which are sensitive to a physical quantity, the fiber having at least one Bragg grating. The fiber is designed so as to generate, in the amplifying medium, two optical waves having different optical frequencies that propagate in the same direction after reflection on the Bragg grating and are emitted by the amplifying medium, the two optical frequencies depending on the physical quantity. The two waves may be generated using either a birefringent polarization-maintaining fiber or a DBR (Distributed Bragg Reflector) laser cavity. Notably, this sensor may be used as a hydrophone.

The invention discloses a single-polarizer liquid crystal dimming automotive rearview mirror. A layered structure of the rearview mirror comprises a front polarizer, a front substrate, a front substrate electrode, a front direct action membrane, a liquid crystal layer, a rear direct action membrane, a rear substrate electrode and a rear substrate with a reflector from front to back in turn, wherein the front substrate electrode and the rear substrate electrode respectively comprise an ion infiltration-preventing SiO2 film and an indium tin oxide (ITO) transparent conductive film; and the product of the birefraction rate of the liquid crystal and the thickness of the liquid crystal layer is more than 0.2 and less than 1.6mu m. Compared with the prior art, the single-polarizer liquid crystal dimming automotive rearview mirror has better dimming effect and temperature characteristic, good reflectivity in a bright state and a dark state, and low cost, and is easy to popularize.

The invention discloses a high-sensitivity micro-nano optical fiber refractive index sensor and a preparation method thereof, and the sensor comprises a broadband light source, an optical fiber loop mirror and a spectrum analyzer, which are sequentially connected along a light transmission path, wherein the optical fiber loop mirror comprises an optical fiber coupler, a birefraction micro-nano optical fiber and a polarization controller, which are connected along the light transmission path; and after light emitted by the broadband light source enters into the optical fiber loop mirror, the formed light spreading in two opposite directions can generate the polarization phase difference by virtue of the birefraction micro-nano optical fiber, the polarization interference is formed after the light passes through the polarization controller, and the light is finally detected and outputted by the spectrum analyzer. The sensor performs sensing by virtue of the birefraction micro-nano optical fiber which has a rectangular or quasi-rectangular dyad symmetric structure; based on the unique birefraction and birefraction scattering effects of the birefraction micro-nano optical fiber, the obtained polarization interference spectrogram can change along with the surrounding refractive index, and the ultra-high sensing sensitivity can be further obtained.

The invention relates to s double-clad optical fiber comprising a fiber core and a cladding. The optical fiber is characterized in that the fiber core is a silica-base glass core layer doped with ions, the cladding comprises an inner cladding body and an outer cladding body, the inner cladding body is a total solid silica-base glass layer composed of two doping stress areas with the low refractive index, the doping stress areas are symmetrical about the fiber core, the outer cladding body is an annular silica-base glass layer formed by air holes, the outer cladding body is provided with a supporting layer, the supporting layer is a total solid silica-base glass layer, and the outermost layer of the optical fiber is a coating layer. Special coating with the lower refractive index is needless to serve as the outer cladding body, so that coating cost is greatly reduced. The outer cladding body is silica-base glass with air holes, and is resistant to high temperature, safe, suitable for being used in a high-power optical cable laser and an optical fiber amplifier, and meanwhile suitable for optical fiber preparation in a large mode field area. The double-clad optical fiber has the advantages of being high in birefringence rate, keeping linear polarization, being large in mode filed area and the like.

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 duplication of array brightness enhancement film by a large-viewing angle micro lens and a production method of a duplicating mould. The invention continuously duplicates micro lens array on a film base without birefraction using halogen free and sulphide free resin containing nano particle. On all directions of a horizontal projection, the micro lens array has the function of gathering and condensing view angle to ordinary light or vibration light through utilizing the refraction and reflection of light from high refraction medium to low refraction medium, and the axial brightness can be improved in a larger range of viewing angle. Through using novel hair metal casting technology, the invention provides a mould which can continuously duplicate micro lens array. The invention is used in backlight source module of a liquid crystal display.

The invention discloses an optical fiber disturbance system polarization control method and control system based on an annealing algorithm. In the polarization control, an analogue annealing algorithm is used as a control algorithm, and a polarization controller is used for modulating an interference optical wave polarization state. The relevance between two interference signals received by a detector in a distributed optical fiber disturbance positioning system is used as a feedback signal, and the analogue annealing algorithm is used for searching an extra voltage of a corresponding polarization controller when the difference between signals is the smallest. The polarization control system comprises a continuously distributed optical fiber sensing system based on dual Mach-Zehnder optical fiber interferometer, an extrusion type polarization controller, a LiNbO3 birefraction phase modulator, a singlechip system, a computer and algorithm software. The optical fiber disturbance system polarization control method provided by the invention can effectively improve the anti-polarization induced fading ability of the system by controlling the polarization state of the interference light, and can greatly eliminate the influence of the single-mode optical fiber birefraction to the system positioning precision.

A photonic crystal fiber with the high birefringence characteristic comprises a fiber core and a piece of cladding, wherein the fiber core is placed in the center of the photonic crystal fiber and is not provided with air vent holes. The cladding is composed of an inner cladding body and an outer cladding body. The inner cladding body which wraps the fiber core is provided with eight circular large air vent holes and four circular small air vent holes, wherein the eight circular large air vent holes are symmetrically distributed, and the four circular small air vent holes are arrayed in a rectangular mode and symmetrically distributed. The outer cladding body which wraps the inner cladding body comprises circular air vent holes, wherein the circular air vent holes of the outer cladding body are distributed according to grid nodes, namely, every three adjacent circular air vent holes are arrayed on the cross section of the photonic crystal fiber to form a regular triangle structure. The photonic crystal fiber has the advantages that the photonic crystal fiber is novel in structure, the photonic crystal fiber has double-rotation symmetry due to the fact that the structural arrangement of the photonic crystal fiber is changed, the photonic crystal fiber is very high in birefringence and high in nonlinear coefficient, the photonic crystal fiber can be used for manufacturing a polarization maintaining optical fiber which is nonlinear or has the polarization characteristic and for manufacturing other related optical fiber devices, due to the fact that the birefringence of the photonic crystal fiber is achieved when the physical dimension of the air vent holes is changed, the photonic crystal fiber is hardly influenced by the temperature and the pressure, and the photonic crystal fiber is good in stability and more suitable for application.

A multilayer compensator includes one or more polymeric first layers and one or more polymeric second layers. The first layers comprise a polymer having an out-of-plane (Δn_th) birefringence not more negative than −0.01 and not more positive than +0.01. The second layers comprise an amorphous polymer having an out-of-plane birefringence more negative than −0.01 or more positive than +0.01. An overall in-plane retardation (R_in) of the multilayer compensator is greater than 20 nm and the out-of-plane retardation (R_th) of the multilayer compensator is more negative than −20 nm or more positive than +20 nm. The in-plane retardation (Rin) of the one or more first layers is 30% or less of the overall in-plane retardation (Rin) of the multilayer compensator.

The invention discloses a medium slit optical waveguide. The cross section of the waveguide structure comprises a substrate layer (1), a high-refractive index buffer layer (2), a high-refractive index medium layer (3), a low-refractive index medium layer (4), a high-refractive index medium area (5), a low-refractive index medium area (6), a high-refractive index medium area (7) and a wrapping layer (8), wherein the high-refractive index buffer layer (2), the high-refractive index medium layer (3) and the low-refractive index medium layer (4) are sequentially arranged from bottom to top on thesubstrate layer; and the high-refractive index medium area (5), the low-refractive index medium area (6) and the high-refractive index medium area (7) are sequentially arranged from left to right on the low-refractive index medium layer. The waveguide can realize relatively strong mode field restriction on two polarized lights at the same time, and can realize multiple characteristics such as positive and negative birefringence, zero birefringence and the like through regulation and control on the structure size. The medium slit waveguide is matched with the existing silicon substrate processing technology and can be used for realizing multiple photon devices.

The invention discloses a tunable multi-wavelength optical fibre laser with ultra-density wavelength interval based on a semiconductor optical amplifier, belonging to the field of laser and optical communication. A gain medium in the laser is a semiconductor optical amplifier; a polarization controller is arranged at the input end of the semiconductor optical amplifier and used for regulating thepolarization state of the incidence light of the semiconductor optical amplifier; another polarization controller is arranged at the output end of the semiconductor optical amplifier and used for regulating the polarization state before light enters into the relative isolator for polarization. A birefraction optical fibre environment is formed by a 3dB coupler, the polarization controller and a polarization-preserving fibre to form a periodical filter. 90 percent of a port of a 10dB coupler is connected with a laser so that optical signals circulate continuously in a cavity, and 10 percent ofthe port is used for laser output. The nonlinear polarization rotation effect in the semiconductor optical amplifier is used for generating multi-wavelength laser with a wavelength interval less thanthe even broadened linear width of the semiconductor optical amplifier, and the polarization relevant gain property of the semiconductor optical amplifier is used for realizing tuning within a large-wavelength range of the multi-wavelength laser.