435 results about "Birefraction" patented technology

An Optical Coherence Tomography (OCT) device irradiates a biological tissue with low coherence light, obtains a high resolution tomogram of the inside of the tissue by low-coherent interference with scattered light from the tissue, and is provided with an optical probe which includes an optical fiber having a flexible and thin insertion part for introducing the low coherent light. When the optical probe is inserted into a blood vessel or a patient's body cavity, the OCT enables the doctor to observe a high resolution tomogram. In a optical probe, generally, a fluctuation of a birefringence occurs depending on a bend of the optical fiber, and this an interference contrast varies depending on the condition of the insertion. The OCT of the present invention is provided with polarization compensation means such as a Faraday rotator on the side of the light emission of the optical probe, so that the OCT can obtain the stabilized interference output regardless of the state of the bend.

The present invention relates in general to systems for and methods of three-dimensional viewing of displays and projections. One embodiment two layers (50, 90) are uniform polarizing filters and a birefringent layer with individually switchable elements (60) is sandwiched between them. Together these layers (50, 60, 90) constitute a parallax layer (40). This parallax layer (40) is located at a certain distance from a display (10). This placement, and the existence of opaque areas on the parallax layer (40) which permits to a viewer see a three-dimensional image. The individual elements (601–615) of the birefringent layer (60) are controlled by a control element (80), which is in communication with a head-tracking sensor (85). This allows the individual elements (601–615) of the birefringent layer (60) to be selectively turned on and off according to the position of the viewer's head.

Waveplate, planar lightwave circuit incorporating the waveplate, and method of making an optical device. The waveplate is formed of a mesogen-containing polymer film having a backbone and sidechains containing mesogen groups. The waveplate may be formed by producing a mesogen-containing polymer film having a nonzero birefringence of suitable dimensions for insertion into a planar lightwave circuit. The waveplate may be so inserted into an optical circuit of a planar lightwave circuit so that an optical signal traversing the waveplate is changed, for instance, to have two polarization states.

A photonic crystal fiber includes a core region for propagating light in a longitudinal direction of the fiber, a cladding region surrounding the core region, the cladding region including micro-structural elements extending in the longitudinal direction. The cladding region further includes at least one stress element having a coefficient of thermal expansion αT,SAP and extending in the longitudinal direction of the photonic crystal fiber, the stress element(s) being located in a cladding background material having a coefficient of thermal expansion αT,cladback different from αT,SAP. The location of the at least one stress element relative to the core region and the micro-structural elements and the coefficients of thermal expansion αT,SAP and αT,cladback are adapted to provide a stress induced birefringence in the core region of the photonic crystal fiber. An article includes a photonic crystal fiber, a method of manufacturing and the use of a photonic crystal fiber are furthermore provided.

A method for separating the orthogonal polarization components of an incident optical signal into two spatially separated output ports is described. The method comprises a Mach-Zehnder interferometer where one of the two branches has a section of waveguide that exhibits form-birefringence. This integrated optic Polarization Beam Splitter (PBS) is broadband, has high extinction ratio, and has characteristics that are tunable.

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 waveguide cores consisting of a subwavelength grating permits transmission of light without diffraction in a discontinuous manner, wherein the energy is provided by field hopping between subwavelength material segments of higher index. The use of alternating segments permits design of waveguides having desired effective index, mode confinement factor, birefringence, polarization mode or mode dispersions, polarization dependent loss, thermal sensitivity, or nonlinear optical coefficient. An optical system comprises a waveguide having such a core, clad on at least one side, extending between two ends, and wavelength-limiting optical components in optical communication with the ends.

A cantilever beam structural resonant-type integrated optical waveguide accelerometer, includes an input waveguide (1), a dissymmetrical structural Mach-Zehnder interferometer (2), a micro-mechanical vibration cantilever beam (3), a short curved waveguide (4) and an output waveguide (5); all the waveguide structures and the cantilever beam use the integrated optical micromachining technique, and the device single-scale integration can be realized by using the temperature-insensitive organic polymer optical waveguide structure and the organic polymer substrate, the key technique indexes such as detection sensitivity, dynamic range are extensively adjusted. The phase difference of the optical signal can be measured by detecting the optical intensity of the resonant frequency of the optical circuit so as to achieve high sensitive acceleration detection, and to be free from the effect of the ambient temperature disturbance and waveguide birefringence.

A photonic crystal fibre includes a core region for propagating light in a longitudinal direction of the fibre, a cladding region surrounding the core region, the cladding region including micro-structural elements extending in the longitudinal direction. The cladding region further includes at least one stress element having a coefficient of thermal expansion αT,SAP and extending in the longitudinal direction of the photonic crystal fibre, the stress element(s) being located in a cladding background material having a coefficient of thermal expansion αT,cladback different from αT,SAP. The location of the at least one stress element relative to the core region and the micro-structural elements and the coefficients of thermal expansion αT,SAP and αT,cladback are adapted to provide a stress induced birefringence in the core region of the photonic crystal fibre. An article includes a photonic crystal fibre, a method of manufacturing and the use of a photonic crystal fibre are furthermore provided.

Timing alignment between a pulse carver (i.e., intensity modulator) and a phase modulator, e.g., in a return-to-zero (RZ) differential phase-shift keying (DPSK) optical transmitter, is monitored by filtering a signal from the transmitter and measuring the power of the filtered signal. In certain embodiments, the filter has a birefringent device (such as a polarization-maintaining fiber) and a polarizer. The polarizer may be a rotating polarizer with a rotating quarter-wave plate in front of it. In other embodiments, the filter is a periodic filter such as a Mach-Zehnder interferometer or an etalon filter. Regardless, the measured power may be used to generate control signals used to variably delay the signals that drive the phase modulator and / or the pulse carver to compensate for detected misalignment. The measured power may also be used to monitor the bit-error-rate degradation caused by timing misalignment between the pulse carver and the phase modulator.

A system for the in vivo detection of the effects of AD in the interior of an eye. A scanning polarimeter, including a residual retardance canceling system and an improved anterior segment retardance compensator, produces an optical analysis signal representing the birefringence of the retinal nerve fiber layer (RNFL) structures of the eye. The birefringence data is more accurate because of compensation for anterior segment birefringence and residual birefringence of optical components, such as, for example, the beam splitters, lenses, scanners and retarders. An electrical analysis signal representing a large (20 by 40 degrees) retardance map is produced and evaluated by an artificial neural network to produce an analysis classification signal representing the contribution of Alzheimer's disease to the birefringence of the retinal layer corresponding to the relationship of the electrical analysis signal to an analysis signal database.

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.

An optical switch includes an optical waveguide to route an input optical beam. At least one polarization switch receives the input optical beam from the optical waveguide. At least one birefringent wedge is associated with the at least one polarization switch. The at least one polarization switch and at least one birefringent wedge operate to direct the input optical beam to two or more output locations through control of the polarization switch.

The invention relates to an optical fiber polarizer comprising an optical fiber with at least a core, a cladding and surrounding medium (or outer cladding) where one or more sections of the optical fiber include periodic / aperiodic (chirped, quasi-periodic) modulation of the dielectric properties of the fiber in the direction of propagation of the light (the longitudinal axis of the fiber). The modulation of the dielectric properties of the fiber is such that it introduces periodic / aperiodic birefringence along the direction of propagation of the light, such a modulation usually but not necessarily being confined to the vicinity of the core region of the fiber. Means are included to attenuate preferentially some of the modes of propagation of the fiber, specifically modes of one principal state of polarization and not the orthogonal state of polarization.

An optical switch includes an optical waveguide to route an input optical beam. At least one polarization switch receives the input optical beam from the optical waveguide. At least one birefringent wedge is associated with the at least one polarization switch. The at least one polarization switch and at least one birefringent wedge operate to direct the input optical beam to two or more output locations through control of the polarization switch.

The fiber includes central core area, cladding area and coating area. Cladding area includes buried micropore array in axial direction surrounding the core area and coating area. Changing shapes, structures, size and quantity and arrangement etc. forms major effective refractivity between two perpendicular directions in fiber so as to fabricate birefringence microstructure optical fiber. Fabricating method includes steps: preparing pure or doping quartz tiny stick and pure quartz tiny tube with certain wall thickness; fabricating the said sticks and tubes to specific shape; assembling the said sticks and tubes to desired shape; bundling sticks and tubes in quartz sleeve; fiber drawing forms optical fiber.

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.