65 results about "Poincare sphere" patented technology

A method generates constant modulus multi-dimensional modulations for coherent optical communications by first projecting points in a constellation of the code onto a Poincare sphere or its higher-dimensional hyper-sphere. By using meta-heuristic procedures, nonlinear programming and gradient search methods, constellation points in the hyper-sphere are optimized in certain criteria, such as maximizing the minimum Euclidean distance, minimizing the union bound, minimizing the bit-error rate, minimizing the required signal-to-noise ratio, maximizing the nonlinear fiber reach, maximizing the phase noise tolerance, and maximizing the mutual information. Some methods use parametric unitary space-time block codes such as Grassmannian packing, and filter impulse response as well as unitary rotation over adjacent code blocks to generate near-constant modulus waveform, not only at the symbol timing, but also over the entire time.

A polarization diversity receiver has an optical section for converting the received optical signal into four or five polarization diverse component optical signals that substantially represent amplitude and polarization state information of the received optical signal, by respective polarization transformations to respective points on a Poincaré sphere, the points being equally spaced apart to maximize polarization diversity, even in the worst case input polarization state. Detectors produce component electrical signals from each of the component optical signals, for electronic processing to compensate for PMD. By reducing the number of component optical signals significant cost and size reductions are enabled. The need for precise polarization tracking in the receiver can be reduced or eliminated completely. Balanced detectors can be used to reduce the number of electrical signals. The electrical processing can use sequence detection.

The invention provides a measurement device independent quantum key distribution system and method. Polarization scrambling is carried out on polarization states of light pulse signals or light quantum signals at quantum state preparation sending ends, so the polarization states of the light pulse signals or the light quantum signals are uniformly distributed on the surface of a Poincare sphere, and the two ways of polarization scrambled light pulse signals or light quantum signals are transmitted to a measuring end for Bell state projection measurement through independent optical channels. At the measuring end, each way of light quantum signal is separated into two orthogonal polarization components, the polarization directions of the two ways of orthogonal polarization components are the same, and the Bell state projection measurement is carried out on the polarization components with the same polarization direction.

A method is provided for measuring Mueller Matrix of an optical system of an exposure apparatus. Light flux from a light source is serially converted into any of a plurality of polarized light beams perpendicular to each other on Poincare sphere and is output. This polarized light beam is injected into a projection optical system or the like to be converted into a converted polarized light beam based on Mueller matrix of each optical system. With a linear polarizer or a linear phase retarder being properly inserted into an optical path of the converted polarized light beam, a light intensity is measured. Stokes parameters of the converted polarized light beam are calculated based on the measured light intensity.

A modulation method for optical communication comprises the step of generating an optical signal modulated between a plurality of different states of polarization and between different phase states. The plurality of states of polarization comprises first states of polarization (SOP1-4). The first states of polarization (SOP1-4) define a single great circle (10) on the Poincare sphere. The method is characterized in that the plurality of states of polarization further comprise one or more second states of polarization (SOP5-6) located outside the great circle (10). Such additional second statesof polarization increase the symbol alphabet.

A method for determining signal-to-noise ratios and noise levels in an optical signal is disclosed, the first polarisation state of which is converted into a second polarisation state by means of number of tunings of a polarisation regulator. Defined changes to the second polarisation state are adjusted on the Poincare sphere by means of the polarisation regulator, whereby power values for the optical signal are determined after selection of a component of the electrical field. Some of the determined power values for the optical signal are stored and serve for the calculation of the signal-to-noise ratio of optical signals. Said method is rapid, requires little complicated equipment and is particularly suitable for a WDM transmission system in which many channels in a WDM signal are transmitted with small channel separations.

A method generates constant modulus multi-dimensional modulations for coherent optical communications by first projecting points in a constellation of the code onto a Poincare sphere or its higher-dimensional hyper-sphere. By using meta-heuristic procedures, nonlinear programming and gradient search methods, constellation points in the hyper-sphere are optimized in certain criteria, such as maximizing the minimum Euclidean distance, minimizing the union bound, minimizing the bit-error rate, minimizing the required signal-to-noise ratio, maximizing the nonlinear fiber reach, maximizing the phase noise tolerance, and maximizing the mutual information. Some methods use parametric unitary space-time block codes such as Grassmannian packing, and filter impulse response as well as unitary rotation over adjacent code blocks to generate near-constant modulus waveform, not only at the symbol timing, but also over the entire time.

The invention discloses a visible light image enhancement method based on polarized imaging. Polarization information is obtained from an image by utilizing a polarized imaging method, the polarization information is clustered in a Poincare sphere to obtain a polarization characteristic image, and the polarization characteristic image is fused with a light intensity image to obtain a final enhanced image. According to the invention, highlighting of objective polarization characteristic is more effectively, the image includes a more complete objective area, the edge is clear, detail information is abundant, and an object in the visible light band can be detected and identified rapidly effectively.

A polarization controller is configured to comprise polarization state monitoring section for monitoring polarization states of input light and output light of a variable polarization light element; and a control section, when the positions on a Poincare sphere expressing each of the polarization states monitored by the polarization state monitoring section are at the positions being symmetric or approximately symmetric for the equator of the Poincare sphere, for rotating the Poincare sphere by π by using the earth axis of the Poincare sphere as a rotation axis by changing the azimuth of the optical axis of the variable polarization light element, and also for inverting the changing direction of the phase shift amount. By this, arbitrary and endless control of polarization light can be realized by a phase shift amount being less than the wavelength λ of the input light.

The invention discloses a control method and system for realizing polarization stability, and belongs to the technical field of optical fiber communication and optical fiber sensing. According to thecontrol method and system of the invention, the output light polarization state of any input light polarization state after passing through a polarization controller is rapidly adjusted to be close toany specified target polarization state on a Poincare sphere through a rapid positioning algorithm, and then the output light polarization state is further stabilized to a target polarization state through a random gradient descent algorithm. Therefore, any polarization state can be stabilized to any set target polarization state. The specific implementation system is composed of an input end polarization analyzer, an output end polarization analyzer, a calibrated polarization controller, a single-chip microcomputer and the like; the input polarization analyzer and the polarization controllerwith the calibrated phase difference and voltage relation are used for rapid positioning, and meanwhile, the output polarization analyzer is combined with the stochastic gradient descent algorithm tofinally stabilize the output polarization state to a set value. According to the polarization stability control method, the searching speed and the local extreme value avoidance are balanced, and thepolarization state can be rapidly and stably changed to any designated target polarization state.

The invention provides a vector light beam generation and dynamic regulation and control device and method. The device comprises the following components which are sequentially designed along a lightpath: a laser light source used for generating a linearly polarized Gaussian light beam; a power adjusting module used for adjusting beam energy and converting the linearly polarized Gaussian beam into a linearly polarized Gaussian beam with a fixed polarization direction; a beam expanding and collimating module used for expanding and collimating the linearly polarized Gaussian beam with the fixedpolarization direction; a light beam modulation module which comprises a liquid crystal phase retarder and a non-uniform polarization converter, wherein the liquid crystal phase retarder is used formodulating and outputting the inputted linearly polarized polarization Gaussian beam into a general elliptical polarization Gaussian beam, the non-uniform polarization converter is used for modulatingthe general elliptical polarization Gaussian beam into a high-order Poincare ball beam or a hybrid polarization vector beam. According to the device provided by the technical schemes of the inventionis simple in structure, the stability of the light beam can be improved, and the dynamic regulation and control function of the high-order Poincare ball light beam and the hybrid polarization vectorlight beam can be achieved.

The invention discloses an all-fiber current sensor and a polarization state control method thereof. The all-fiber current sensor comprises a laser device, a fiber loop assembly for sensing the change of a current magnetic field, a first polarization controller arranged at the input end of the fiber loop assembly, a second polarization controller arranged at the output end of the fiber loop assembly, a fast polarization state detector and a high pass filter which are sequentially arranged. Being different from the all-fiber current sensor in the prior art, the invention has no polarizer and analyzer, but directly detects the change of polarization state on the equator of a Poincare sphere based on the principal state principle and filters temperature interference and other environmental interferences by means of the filter.

The present invention discloses a coupled polarizing plate set and an in-plane switching mode liquid crystal display including the coupled polarizing plate set. In detail, the present invention discloses a coupled polarizing plate set including compensation films designed to have specific optical properties to minimize color distortion in accordance with viewing directions and ensure a wide viewing angle in an in-plane switching mode, and a liquid crystal display including the coupled polarizing plate set and an in-plane switching mode liquid crystal. According to the liquid crystal display of the present invention, since a degree of distribution of changes in polarization state on a Poincare Sphere is small, color distortion in accordance with viewing directions can be minimized and a wide viewing angle can be ensured. Further, it is possible to ensure a wide viewing angle with only one sheet of compensation film for the upper polarizing plate and lower polarizing plate, such that it is possible to implement mass production of thin liquid crystal displays with high yield (reducing defect ratio due to foreign substances).

A polarization controller is configured to comprise polarization state monitoring section for monitoring polarization states of input light and output light of a variable polarization light element; and a control section, when the positions on a Poincare sphere expressing each of the polarization states monitored by the polarization state monitoring section are at the positions being symmetric or approximately symmetric for the equator of the Poincare sphere, for rotating the Poincare sphere by π by using the earth axis of the Poincare sphere as a rotation axis by changing the azimuth of the optical axis of the variable polarization light element, and also for inverting the changing direction of the phase shift amount. By this, arbitrary and endless control of polarization light can be realized by a phase shift amount being less than the wavelength λ of the input light.

Apparatus and methods are disclosed for viewing low-birefringence structures within samples directly, with the eye, in real-time. The sample is placed between an entrance polarizer and analyzer polarizer, the transmission state of one of which is changed dynamically to create a modulated view of the scene; against this background, birefringent structures are visible because of their different appearance when modulated. Modulation rates of 4 or more states per second; use of 4 or more states, or even a continuum of states, which lie substantially on a latitude line on the Poincare sphere; and orientation of the polarization components to produce a uniform background; produce a clear view that does not produce operator fatigue. Broad-band wavelength operation spanning 50 nm or more, or the whole visible range, is achieved, and it is compatible with integration into other microscopy modes such as Hoffman relief contrast.

The invention discloses a method and system for generating a polarization state of a high-order Poincare sphere with robustness. The method comprises the following steps of: loading a vortex phase on a completely coherent vector light beam, and then regulating and controlling the completely coherent vector light beam into left-handed circularly polarized light and right-handed circularly polarized light of the high-order Poincare sphere; synthesizing the left-handed circularly polarized light and the right-handed circularly polarized light into vector polarized light on the high-order Poincare sphere, and generating a polarization matrix of the high-order Poincare sphere through adjustment; reducing the spatial coherence of the polarized light, obtaining a random electromagnetic beam through shaping, and extracting polarization information in a polarization matrix to a spatial correlation tensor of the random electromagnetic beam; transmitting a random electromagnetic beam to a far field, in the far field, transferring polarization information from a space correlation tensor to a polarization matrix of the random electromagnetic beam, and obtaining a high-order Poincare sphere polarization state with robust characteristics. The problems that an existing high-order Poincare spherical polarized beam is difficult to generate, does not have the robust characteristic and is easily damaged by the external environment are solved.

The invention discloses an elliptical polarization maintaining fiber extinction ratio measuring device and method. The device includes a wide-spectrum light source, a polarizer, a polarization controller, a fiber to be measured, a polarization analyzer, a fiber adapter and a computer that are sequentially connected. The wide-spectrum light source forms linearly polarized light with a high extinction ratio through the polarizer, the polarization analyzer is combined with the polarization analyzer, so that the polarization state input to the fiber to be measured is consistent with the polarization intrinsic state of the fiber, and then the stokes parameter changes of the Poincare sphere are recorded, the variance of the power of the polarization intrinsic state and the power of another polarization intrinsic state orthogonal to the polarization intrinsic state, and the extinction ratio of the fiber to be measured at the length is obtained; the decibel difference of the two extinction ratios before and after the shearing can be obtained by a shearing method to be used as the extinction ratio decibel difference of the fiber to be measured. The device and method can measure the extinction ratio of the elliptical polarization maintaining fiber, and can also be used for measuring the extinction ratio of a conventional polarization-maintaining fiber.

To provide a phase modulator for introducing a topological phase, which is designed to produce any desired phase shift between zero and 360°, the phase modulator has means, at least one double-refractive, electrooptical delay element having a rotatable indicatrix, which is / are used to direct the polarization of the light, during transmission through the modulator, over at the light one closed path on the Poincaré sphere, the indicatrix rotating in accordance with the predefined phase shift, and the total encircled surface on Poincaré sphere being equal in terms of absolute value to φ.

A method for reducing the uncertainty in the optical fiber polarization film dispersion test is provided, wherein a polarization disturbance controller is added between an input end and / or an output end of the optical fiber to be tested with the test device, for controlling the inputting and / or outputting polarization state of the optical fiber. According to the method, the polarization disturbance controller is controlled in a plurality of times of optical fiber polarization film dispersion test, causing the output polarization state and / or the input polarization state in plurality of times of test distributed uniformly on the polarization state poincare sphere, and the arithmetic mean or the root mean square average computation of each testing result is performed according to the types of the result limited by the specific testing principle of the tester, to obtain the polarization film dispersion testing value with high precision.

The invention relates to a bit error rate and uncertainty joint feedback photon polarization state compensation method. The method includes the following steps that: a quantum key distribution system publicizes N bits in an original key of which the length is M every time which are used for bit error rate statistics, wherein N is far smaller than M; the quantum key distribution system publicizes an N'-bit pseudo key in an effective detection sequence where the original key is located, wherein the N'-bit pseudo key is used for uncertainty statistics; and simultaneous compensation of two non-orthogonal polarization states |+> and |H> can be realized through utilizing photon polarization states of the bit error rate and the uncertainty on the estimating receiving end of a Poincare sphere. With the bit error rate and uncertainty joint feedback photon polarization state compensation method of the invention adopted, the two non-orthogonal photon polarization states can be accurately compensated in real time under the situation that the communication efficiency and distance of the quantum key distribution system are not affected and the cost of the system is not increased.

The present invention relates to an in-plane switching mode liquid crystal display, and more preciesly, an in-plane switching mode liquid crystal display including an upper polarizing plate, a lower polarizing plate and a liquid crystal cell, designed to have wide viewing angle because the optical properties of the compensation film are determined by changes of the polarization state of liquid crystal alignment on a Poincare Sphere, and the contrast in the inclined visual direction is improved due to the configuration of a slow axis of a first and second compensation films, absorption axis of the polarizer, and the liquid crystal alignment.; The present invention can implement mass production of thin liquid crystal displays with high yield (reducing defect ratio due to foreign substances or impurities) since it is possible to ensure a wide viewing angle with only one sheet of compensation film for the upper polarizing plate and the lower polarizing plate.

The invention is intended to solve the problem of a phase shift by the incidence angle dependence of a composite wave plate which is caused when divergent light is incident directly thereon because of occurrence of a phase shift in addition to a desired phase difference of the composite wave plate. The composite wave plate is composed of two laminated wave plates, and respective parameters are set such that: letting θ1 represent the azimuth angle of the optical axis of the first wave plate with respect to the plane of polarization of incident light thereon in the Poincare sphere representation, θ2 represent the azimuth angle of the optical axis of the second wave plate with respect to the plane of polarization of incident light thereon in the Poincare sphere representation, Γ1 represent a phase rotation about the axis of rotation R1 of the first wave plate in the Poincare sphere representation, and Γ2 represent a phase rotation about the axis of rotation R2 of the second wave plate in the Poincare sphere representation,θ2−θ1≠π / 2;and that a phase difference ΓT of the composite wave plate satisfiesΓT=(2×θ1−π / 2)cos Γ1+(2×θ2−π)cos Γ2.

The invention provides a photon polarization state compensation method based on complete reconstruction. A transmitting end and a receiving end encode and decode the photon polarization state by randomly using three groups of non-orthogonal polarization bases; the photon polarization state to be received in expectation is expressed by a point on the poincare sphere; the error rate of the photon polarization state to the polarization state itself is calculated when the bases are matched, the uncertainty rate of the photon polarization state to one of the groups of non-orthogonal bases is calculated when the bases are not matched, the uncertainty rate of the photon polarization state to the other one of the groups of non-orthogonal bases is further calculated when the bases are not matched, so that the complete reconstruction of the photon polarization state is realized, a polarization control apparatus is adjusted, and the photon polarization state compensation of a quantum key distribution system is realized. According to the invention, without influencing the communication efficiency and distance of the quantum key distribution system and increasing the system cost, the bad influence of trail compensation is eliminated by complete reconstruction, and the timeliness and the accuracy of real-time compensation to the two non-orthogonal photon polarization states are further improved.

The invention discloses a method for detecting damage of a first wall of a tokamak fusion reactor with polarized light. A detection system comprises an optical table bracket, a polarized light source, a polarization analysis meter, a detection probe and the detected first wall. After lasers with the specific wavelength emitted by the polarized light source are reflected by the surface of the first wall, reflected light circular polarization components are obtained by the polarization analysis meter and the detection probe, and the detection for changes of a material on the surface of the first wall can be achieved. The method differs from the common polarized light detection method, an incident light vibration plane is rotated near a Brewster angle, a stockes vector locus of reflected light in a Poincare sphere is utilized, and quick measurement for the reflected light circular polarization components of the first wall is achieved. The method provides a feasible detection method for surface damage of the first wall of the tokamak fusion reactor.

The present invention relates to an optical shape sensing system for sensing a shape of a medical device (24), comprising an input polarization controller (12) for setting an input polarization state of an input light signal, at least one interferometer unit (18) for dividing said polarized input light signal into a device signal and a reference signal, guiding said device signal to be scattered within an optical fiber (19) inserted into said device (24) and coupling said scattered device signal with said reference signal to form an output light signal, and at least one measurement branch (39) comprising an output polarization controller arrangement (26) for setting an output polarization state of said output light signal, a polarizing beam splitter (30) for splitting said polarized output light signal into two signal portions, each being in a corresponding one of two signal portion polarization states, and a detector arrangement (35) comprising two detectors (32, 34), each for detecting a corresponding one of said two signal portions, wherein said input polarization controller (12) is configured to set two pairs of input polarization states, or said output polarization controller arrangement (26) is configured to set two output polarization states each for enabling a corresponding one of two pairs of signal portion polarization states, wherein each pair of input or signal portion polarization states are representable by a corresponding one of two axes in a Poincaré sphere different from each other.

An optical signal quality monitoring apparatus includes a trajectory length acquirer measuring a Stokes vector of an optical transmission signal over an optical signal modulation frequency band and acquiring the length of a trajectory in the optical signal modulation frequency band traced out on a Poincare sphere by the measured Stokes vector as the measurement value; a DGD acquirer acquiring a DGD value of the optical transmission signal the Stokes vector of which is measured by the trajectory length acquirer; and a quality value estimator estimating a quality value by using the length of the trajectory acquired by the trajectory length acquirer and the DGD value acquired by the DGD acquirer.

The invention relates to a surrounding refractive index measurement method based on the thin cladding long period fiber bragg grating polarization property. The radius of a cladding is 20.75 micrometers, detection light waves are any complete polarized light ranging from 1690 nm to 1710 nm, the wavelength interval is 1 nm, and the measurement scope of the surrounding refractive index ranges from 1 to 1.46. When the known environment refractive index is nI, output polarization states P1, P2...PN of the equal-spaced light waves with the wavelengths Lambada1, Lambada2 ...LambadaN after the light waves pass through long period fiber bragg gratings are detected; spherical distance sequences l1, l2... lN-1 between corresponding points of the polarization states P1, P2...PN on a poincare sphere are calculated; the maximum value lmaxI in the spherical distance sequences l1, l2... lN-1 is taken, wherein the lmaxI is a measurement result under the known surrounding refractive index nI; a relation curve between the surrounding refractive index n and the lmax is drawn; after the lmaxI of the certain unknown environment refractive index is calculated, and a corresponding n value of the lmaxI can be obtained through the curve. By means of the surrounding refractive index measurement method, single-color tunable laser light source is adopted for measurement, so that measured values are changed in an approximately-linear mode along with changes of surrounding refractive index; the surrounding refractive index measurement method is relatively simple in technological process and suitable for actual measurement.

The invention discloses an optical fiber sensor capable of measuring stress direction. The optical fiber sensor comprises a laser, a first polarization controller, a sensing fiber, a second polarization controller, a polarization analyzer and a computer Matlab algorithm, which are connected in sequence. When the sensing fiber is subjected to an external stress, the polarization analyzer records information of rotation of a polarization state around a principal axis of the external stress on a Poincare sphere; and the Matlab algorithm calculates an actual direction angle of the external stress based on linear relation between a direction angle of the external stress principal axis with respect to a reference external stress principal axis and the actual direction angle of the external stress.

The invention discloses a light polarization state evaluation method, a light polarization state evaluation device, application, electronic equipment and a medium. The light polarization state evaluation method comprises the steps of: acquiring polarization state data points of to-be-evaluated light on a Bonding ball; separating the polarization state data points according to eight octants of a space rectangular coordinate system; carrying out Delaunay triangular part algorithm fitting on the polarization state data points in each octant; calculating a sum S<Delaunay> of the areas of the triangular parts in the eight octants obtained by fitting; and dividing the S<Delaunay> by the unit Poincare sphere total spherical surface area S0 to obtain a polarization separation degree. Especially for non-polarized light, the polarization state of the non-polarized light changes randomly along with time, and therefore accurate description needs to be conducted in a time sequence. The light polarization state evaluation method is used for quantitatively analyzing the polarization state of the signal light in time, and can provide numerical value reference for improving a depolarizer and improving the precision of an optical fiber sensor. In addition to optical fiber sensing systems, the light polarization state evaluation method can be used in other optical systems (e.g., optical coherencesystems) to quantitatively analyze and evaluate non-polarized light and polarized light.