Showing papers on "Polarization rotator published in 2010"
TL;DR: In this article, a temperature-composition phase diagram is proposed that exhibits compositionally driven phase transitions with easy paths for both polarization rotation and polarization extension, which is best known at temperature-driven ferroelectric-paraelectric phase transitions.
Abstract: Many ferroelectric solid solutions exhibit enhanced electromechanical properties at the morphotropic boundary separating two phases with different orientations of polarization. The mechanism of properties enhancement is associated with easy paths for polarization rotation in anisotropically flattened free energy profile. Another mechanism of properties enhancement related to free energy flattening is polarization extension. It is best known at temperature-driven ferroelectric-paraelectric phase transitions and may lead to exceedingly large properties. Its disadvantage is temperature instability of the enhancement. In this paper a temperature-composition phase diagram is proposed that exhibits compositionally driven-phase transitions with easy paths for both polarization rotation and polarization extension.
519 citations
TL;DR: In this paper, a bilayered chiral metamaterial is proposed to realize a 90° polarization rotator, whose giant optical activity is due to the transverse magnetic dipole coupling among the metallic wire pairs of enantiomeric patterns.
Abstract: A bilayered chiral metamaterial is proposed to realize a 90° polarization rotator, whose giant optical activity is due to the transverse magnetic dipole coupling among the metallic wire pairs of enantiomeric patterns. By transmission through this thin bilayered structure of less than λ/30 thick, a linearly polarized wave is converted to its cross polarization with a resonant polarization conversion efficiency of over 90%. It is demonstrated that the chirality in the propagation direction makes this efficient cross-polarization conversion possible.
358 citations
TL;DR: In this article, a bilayered chiral metamaterial (CMM) is proposed to realize a 90 degree polarization rotator, whose giant optical activity is due to the transverse magnetic dipole coupling among the metallic wire pairs of enantiomeric patterns.
Abstract: A bilayered chiral metamaterial (CMM) is proposed to realize a 90 degree polarization rotator, whose giant optical activity is due to the transverse magnetic dipole coupling among the metallic wire pairs of enantiomeric patterns. By transmission through this thin bilayered structure of less than \lambda/30 thick, a linearly polarized wave is converted to its cross polarization with a resonant polarization conversion efficiency (PCE) of over 90%. Meanwhile, the axial ratio of the transmitted wave is better than 40 dB. It is demonstrated that the chirality in the propagation direction makes this efficient cross-polarization conversion possible. The transversely isotropic property of this polarization rotator is also experimentally verified. The optical activity of the present structure is about 2700 degree/\lambda, which is the largest optical activity that can be found in literature.
298 citations
TL;DR: The proposed micropolarimeter is fabricated by patterning a liquid-crystal layer on top of a visible-regime metal-wire-grid polarizer using ultraviolet sensitive sulfonic-dye-1 as the LC photoalignment material to acquire all components of the Stokes vector.
Abstract: In this paper, we describe the design, modeling, fabrication, and optical characterization of the first micropolarimeter array enabling full Stokes polarization imaging in visible spectrum. The proposed micropolarimeter is fabricated by patterning a liquid-crystal (LC) layer on top of a visible-regime metal-wire-grid polarizer (MWGP) using ultraviolet sensitive sulfonic-dye-1 as the LC photoalignment material. This arrangement enables the formation of either micrometer-scale LC polarization rotators, neutral density filters or quarter wavelength retarders. These elements are in turn exploited to acquire all components of the Stokes vector, which describes all possible polarization states of light. Reported major principal transmittance of 75% and extinction ratio of 1100 demonstrate that the MWGP's superior optical characteristics are retained. The proposed liquidcrystal micropolarimeter array can be integrated on top of a complementary metal-oxide-semiconductor (CMOS) image sensor for real-time full Stokes polarization imaging.
109 citations
TL;DR: In this paper, a mode-evolution-based polarization rotator in silicon waveguide was designed to provide the polarization rotation with polarization extinction ratio of 15 dB, the insertion loss at the transition region was less than 1 dB.
Abstract: A mode-evolution-based polarization rotator in silicon waveguide was designed. The rotator's performance was studied under different launching conditions. The rotator with minimum length of 40 ?m was demonstrated to provide the polarization rotation with polarization extinction ratio of 15 dB. The insertion loss at the transition region was less than 1 dB.
104 citations
TL;DR: In this paper, the authors reported the frequency and polarization characteristics of correlated photon pairs generated in a Si wire waveguide (SWW) and confirmed that the bandwidth for correlated photon-pair generation was at least 2.8 THz.
Abstract: We report the frequency and polarization characteristics of correlated photon pairs generated in a Si wire waveguide (SWW). We confirmed that the bandwidth for correlated photon-pair generation was at least >2.8 THz. Moreover, we carried out a classical four-wave mixing experiment using strong pump and idler lights to estimate the bandwidth for correlated photon-pair generation. The results indicated that it is possible to generate photon pairs over a bandwidth as large as ~12 THz. We also showed that the generation efficiencies of the signal and idler photons for the horizontal polarization mode were much higher than those for the vertical polarization mode. This is probably caused by the large efficiencies in the group indexes and the effective cross-sectional areas for the two polarization modes. Furthermore, the bandwidth for the correlated photon-pair generation in the vertical polarization mode was ~±1 THz, and this was much narrower than that for the horizontal polarization mode. The difference between the bandwidths of the two polarization modes indicates that the SWW dispersion for the vertical polarization mode is significantly larger than that for the horizontal polarization mode. We then confirmed that the noise photons generated by spontaneous Raman scattering in an SWW were suppressed to below the detection limit of our setup.
103 citations
TL;DR: The effect of a magnetic field on a spinor exciton-polariton condensate has been investigated, suggesting that a dynamic condensation in the excited spin state rather than the ground spin state takes place in this magnetic field range.
Abstract: The effectof a magneticfieldon a spinor exciton-polaritoncondensate has been investigated. A quenching of a polariton Zeeman splitting and an elliptical polarization of the condensate have been observed at low magnetic fields B< 2T . The effects are attributed to a competition between the magnetic field induced circular polarization buildup and the spin-anisotropic polariton-polariton interaction which favors a linear polarization. The sign of the circular polarization of the condensate emission at B< 3T is negative, suggesting that a dynamic condensation in the excited spin state rather than the ground spin state takes placeinthismagneticfieldrange.Fromabout 2T on,theZeemansplittingopensandfromthenontheslopeof the circular polarization degree changes its sign. For magnetic fields larger than the 3 T, the upper spin state occupation is energetically suppressed and circularly polarized condensation takes place in the ground state.
79 citations
TL;DR: In this paper, a metamaterial with resonant unit cells coupled by diodes is proposed to achieve a linear polarization with continuously tunable azimuth angle from 0o to 90o at the resonant frequency, or an elliptical polarization with tunable angle of the major axis when off the resonance frequency.
Abstract: We propose a polarization modulation scheme of electromagnetic (EM) waves through reflection of a tunable metamaterial reflector/absorber. By constructing the metamaterial with resonant unit cells coupled by diodes, we demonstrate that the EM reflections for orthogonal polarized incident waves can be tuned independently by adjusting the bias voltages on the corresponding diodes. Owing to this feature, the reflected EM waves can be electrically controlled to a linear polarization with continuously tunable azimuth angle from 0o to 90o at the resonant frequency, or an elliptical polarization with tunable azimuth angle of the major axis when off the resonant frequency. The proposed property has been verified through both numerical simulations and experimental measurements at microwave band, which enables us to electrically modulate the polarization state of EM waves flexibly.
77 citations
TL;DR: In this article, a mode-evolution-based polarization rotator with minimum length of 40μm was demonstrated to provide the polarization rotation with polarization extinction ratio of 15dB at abnormal launching conditions.
Abstract: Mode-evolution-based polarization rotators in silicon waveguides were studied. The rotator's performance
was studied under normal and abnormal launching conditions. The rotator with minimum length of 40μm was
demonstrated to provide the polarization rotation with polarization extinction ratio of 15dB at abnormal launching
condition. The insertion loss at the transition region was less than 1dB.
69 citations
TL;DR: In this paper, the propagation effects of radio waves in a pulsar magnetosphere, composed of relativistic electron-positron pair plasmas streaming along the magnetic field lines and corotating with the pulsar, were examined.
Abstract: We study the propagation effects of radio waves in a pulsar magnetosphere, composed of relativistic electron-positron pair plasmas streaming along the magnetic field lines and corotating with the pulsar. We critically examine the various physical effects that can potentially influence the observed wave intensity and polarization, including resonant cyclotron absorption, wave mode coupling due to pulsar rotation, wave propagation through quasi-tangential regions (where the photon ray is nearly parallel to the magnetic field) and mode circularization due to the difference in the electron/positron density/velocity distributions. We numerically integrate the transfer equations for wave polarization in the rotating magnetosphere, taking account of all the propagation effects in a self-consistent manner. For typical magnetospheric plasma parameters produced by pair cascade, we find that the observed radio intensity and polarization profiles can be strongly modified by the propagation effects. For a relatively large impact parameter (the minimum angle between the magnetic dipole axis and the line of sight), the polarization angle profile is similar to the prediction from the Rotating Vector Model, except for a phase shift and an appreciable circular polarization. For a smaller impact parameter, the linear polarization position angle may exhibit a sudden 90° jump due to the quasi-tangential propagation effect, accompanied by a complex circular polarization profile. Some applications of our results are discussed, including the origin of non-Gaussian pulse profiles, the relationship between the position angle profile and circular polarization in conal-double pulsars, and the orthogonal polarization modes.
60 citations
TL;DR: Through manipulating the incident polarization states of laser beams as well as the apodization of a objective and adjusting the numerical aperture of an objective, focal fields dominantly with either one transverse component or one longitudinal component can be generated.
Abstract: In this paper the polarization states of linearly and radially polarized plane wave and doughnut beams in the focal volume of high numerical aperture objectives are studied. Through manipulating the incident polarization states of laser beams as well as the apodization of an objective and adjusting the numerical aperture of an objective, focal fields dominantly with either one transverse component or one longitudinal component can be generated. Furthermore, tailored polarization distributions with three polarization components of the same strength are also found.
TL;DR: A phenomenological model based on effective semiclassical equations of motion provides a good description of the experimental results and inclusion of interactions with the incoherent exciton reservoir, which provides spin-independent blueshifts of the polariton modes, is found to be essential.
Abstract: The transmission of a pump laser resonant with the lower polariton branch of a semiconductor microcavity is shown to be highly dependent on the degree of circular polarization of the pump. Spin dependent anisotropy of polariton-polariton interactions allows the internal polarization to be controlled by varying the pump power. The formation of spatial patterns, spin rings with a high degree of circular polarization, arising as a result of polarization bistability, is observed. A phenomenological model based on effective semiclassical equations of motion provides a good description of the experimental results. Inclusion of interactions with the incoherent exciton reservoir, which provides spin-independent blueshifts of the polariton modes, is found to be essential.
TL;DR: In this article, the birefringence and loss properties of selectively liquid-filled photonic crystal fibers with the liquid asymmetrically infiltrated into one-line air holes along x -axis were theoretically investigated.
TL;DR: In this paper, the Gauss-Laguerre GL00 and GL01 laser beams are shown to generate a quasi-paraxial field that contains a line of circular polarization, a C line, surrounded by polarization ellipses whose major and minor axes generate multitwist Mobius strips with twist numbers that increase with the distance from the C point.
Abstract: Circularly polarized Gauss-Laguerre GL00 and GL01 laser beams that cross at their waists at a small angle are shown to generate a quasi-paraxial field that contains a line of circular polarization, a C line, surrounded by polarization ellipses whose major and minor axes generate multitwist Mobius strips with twist numbers that increase with the distance from the C point.
TL;DR: The entire emerging beam, expressed in terms of a phase-dependent superposition of linearly polarized modes, demonstrates spatially varying polarization properties.
Abstract: We measure the polarization state of each guided transversal mode propagating in step-index large-mode-area fibers (V≈4) using a correlation-filter based measurement technique in combination with a Stokes parameter measurement. The entire emerging beam, expressed in terms of a phase-dependent superposition of linearly polarized modes, demonstrates spatially varying polarization properties. By knowing the information about modal amplitudes and phase differences, full information about the optical field is available.
TL;DR: In this paper, the authors present theoretical calculations for polarization and ellipticity of high-order harmonics from aligned molecules generated by linearly polarized lasers and show clear species-dependent polarization states, in excellent agreement with experiments.
Abstract: We present theoretical calculations for polarization and ellipticity of high-order harmonics from aligned ${\mathrm{N}}_{2}$, CO${}_{2}$, and ${\mathrm{O}}_{2}$ molecules generated by linearly polarized lasers. Within the rescattering model, the two polarization amplitudes of the harmonics are determined by the photo-recombination amplitudes for photons emitted with polarization parallel or perpendicular to the direction of the same returning electron wave packet. Our results show clear species-dependent polarization states, in excellent agreement with experiments. We further note that the measured polarization ellipse of the harmonic furnishes the needed parameters for a ``complete'' experiment in molecules.
TL;DR: The experimental setup for both dynamic nuclear polarization (DNP) and electron paramagnetic resonance (EPR) detection at 7 T using a quasi-optical bridge for propagation of the 200 GHz beam and the results show an increase in DNP signal enhancement of 28% when using circularly vs. linearly polarized radiation.
Abstract: We present our experimental setup for both dynamic nuclear polarization (DNP) and electron paramagnetic resonance (EPR) detection at 7 T using a quasi-optical bridge for propagation of the 200 GHz beam and our initial results obtained at 4 K. Our quasi-optical bridge allows the polarization of the microwave beam to be changed from linear to circular. Only the handedness of circular polarization in the direction of the Larmor precession is absorbed by the electron spins, so a gain in effective microwave power of two is expected for circular vs. linear polarization. Our results show an increase in DNP signal enhancement of 28% when using circularly vs. linearly polarized radiation. We measured a maximum signal enhancement of 65 times that of thermal polarization for a 13C labeled urea sample corresponding to 3% nuclear spin polarization. Since the time constant for nuclear spin polarization buildup during microwave irradiation is 10 times faster than the 13C nuclear spin T1, the actual gain in detection sensitivity with DNP is much greater.
TL;DR: In this paper, the performance of high-tunable polarization rotator (PR) based on NLC photonic crystal fiber is reported and the tunability of the proposed PR results from the change of the optical properties of the NLC with the temperature and external electric field.
Abstract: In this paper, the performance of high-tunable polarization rotator (PR) based on nematic liquid crystal (NLC) photonic crystal fiber is reported. The tunability of the proposed PR results from the change of the optical properties of the NLC with the temperature and external electric field. The influence of the different structure geometrical parameters, rotation angle of the director of the NLC, temperature and operating wavelength on the PR performance is investigated. The numerical results reveal that the suggested PR can provide a strong polarization conversion ratio of 99.81% with a device length of 1072 ?m. It is expected that over the 1.53-1.6 ? m wavelength range, polarization conversion would be more than 99%. The simulation results are evaluated using the full-vectorial finite-difference method and confirmed by the full-vectorial finite-difference beam-propagation method.
TL;DR: In this article, the polarization effects of surface plasmon polaritons (SPP) in an azimuthally rotated gratings have been investigated and the optimum angle direction has been calculated analytically.
Abstract: The polarization effects of surface plasmon polaritons (SPP) in an azimuthally rotated gratings have been investigated. Mixed s and p modes can be excited using the polarization angle of the incident light to optimize the SPP coupling. Experimental results and simulations show which component of polarization is effective for the SPP excitation. The optimum angle direction has been calculated analytically. The SPR tunability by polarization may uncover important features in SPP applications.
TL;DR: In this article, a novel design of high tunable polarization rotator (PR) based on NLC photonic crystal fiber is proposed and analyzed, where the tunability of the proposed PR results from the change of the optical properties of the NLC with the temperature or external electric field.
Abstract: In this letter, a novel design of high tunable polarization rotator (PR) based on nematic liquid crystal (NLC) photonic crystal fiber is proposed and analyzed. The tunability of the proposed PR results from the change of the optical properties of the NLC with the temperature or external electric field. The simulation results are obtained using the full vectorial finite-difference method as well as the full vectorial finite-difference beam propagation method. The numerical results reveal that the suggested PR can provide a strong polarization conversion ratio of 99.81% with a device length of 1072 ?m.
TL;DR: It is shown that an arbitrary state of polarization of the signal beam can be converted into any other desired state of polarized beam, and an unpolarized signal beam may be repolarized into two specific states of polarization, without loss of energy.
Abstract: We consider the counterpropagating interaction of a signal and a pump beam in an isotropic optical fiber. On the basis of recently developed mathematical techniques, we show that an arbitrary state of polarization of the signal beam can be converted into any other desired state of polarization. On the other hand, an unpolarized signal beam may be repolarized into two specific states of polarization, without loss of energy. Both processes of repolarization and polarization conversion may be controlled by adjusting the polarization state of the backward pump.
TL;DR: A room temperature polariton condensate realized in a microcavity with embedded GaN quantum wells emits linearly polarized light at threshold with the plane of polarization pinned to one of the crystallographic axes resulting in a progressive decrease of the polarization degree of the emitted light.
Abstract: A room temperature polariton condensate realized in a microcavity with embedded GaN quantum wells emits linearly polarized light at threshold with the plane of polarization pinned to one of the crystallographic axes. With increasing pumping power, a depinning of the polarization is observed resulting in a progressive decrease of the polarization degree of the emitted light. This depinning is understood in terms of polariton-polariton repulsion competing with the static disorder potential effect. The polarization behavior differs from that of conventional lasers where the polarization degree usually increases as a function of pumping power.
TL;DR: In this paper, the authors present new optical circular polarization measurements with typical uncertainties 3σ) circular polarization in two blazars with high linear polarization and discuss the implications of this result for quasar physics.
Abstract: We present new optical circular polarization measurements with typical uncertainties 3σ) circular polarization in two blazars with high linear polarization and discuss the implications of this result for quasar physics. In particular, the recorded polarization degrees may be indicative of magnetic fields as strong as 1 kG or a significant contribution of inverse Compton scattering to the optical continuum.
TL;DR: A configuration for real-time measurement of unique, space-variant, polarizations is presented and results reveal that the full state of polarization at each location within the beam can be accurately obtained every 10 msec, limited only by the camera frame rate.
Abstract: A configuration for real-time measurement of unique, space-variant, polarizations is presented. The experimental results reveal that the full state of polarization at each location within the beam can be accurately obtained every 10 msec, limited only by the camera frame rate. We also present a more compact configuration which can be modified to determine the real-time wavelength variant polarization measurements.
TL;DR: In this article, a tunable liquid crystal LC polarization rotator using two nematic LC retarders for the spectral range from 450 to 1000 nm and wider is demonstrated, where the first LC device with tunable retardation determines the rotation, while the second acts as an LC variable quarter-wave plate.
Abstract: We demonstrate a wavelength-independent tunable liquid crystal LC polarization rotator using two nematic LC retarders for the spectral range from 450 to 1000 nm and wider. The first LC device with tunable retardation determines the rotation, while the second acts as an LC variable quarter-wave plate. Integration with tunable optical filters produces a modality for great potential in spectropolarimetry. © 2010 Soci-
TL;DR: Experimental results reveal that more than 85% polarization purity can be retained at the output even with 40 dB amplification and that efficient conversion of the amplified light to linear polarization can be obtained.
Abstract: The results of amplifying either radially or azimuthally polarized light with a fiber amplifier are presented. Experimental results reveal that more than 85% polarization purity can be retained at the output even with 40 dB amplification and that efficient conversion of the amplified light to linear polarization can be obtained.
TL;DR: In this paper, the fabrication and characterization of newly developed photonic crystal (PC) polarization-controlling devices on a silicon-on-insulator wafer for integrated terahertz applications are presented.
Abstract: In this paper, the fabrication and characterization of newly developed photonic crystal (PC) polarization-controlling devices on a silicon-on-insulator wafer for integrated terahertz applications are presented. The polarization converter is composed of periodic asymmetric loaded PC slab waveguide. Square- and circular-hole PC slab waveguides were studied using a 3-D finite-difference time-domain method. For a square-hole PC-based polarization rotator, polarization rotation efficiency higher than 90% was achieved within the normalized frequency band of a/ λ = 0.258-0.267 . In circular-hole PC polarization converter, the polarization conversion efficiency dropped to 70% for the aforementioned frequency band. Low polarization conversion efficiency of the circular-hole PC-based device is attributed to scattering loss at the top loaded layers. Thus, the square-hole PC structure is a better candidate for integrated terahertz polarization-controlling devices. Planar terahertz integrated circuit technology was developed to implement the proposed device. Characterization setup was designed using rigorous numerical methods to use the newly introduced Agilent Millimeter-wave PNA-X network analyzer (up to 500 GHz) as a source. Scattering parameter characterizations provide a good measure of polarization extinction ratio. For the devices designed for the central frequency of f = 200 GHz, it was observed that, within the frequency band of 198-208 GHz (α/λ = 0.26-0.272), the ratio of S21 to S11 was higher than 15 dB. The bandwidth is in good agreement with our preliminary design presented before.
TL;DR: A novel system for the accurate measurement of all polarization related parameters, including polarization mode dispersion and polarization dependent loss, using binary magneto-optic polarization rotators, which achieves unprecedented DGD, SOPMD, and PDL accuracies.
Abstract: We report a novel system for the accurate measurement of all polarization related parameters, including polarization mode dispersion and polarization dependent loss, using binary magneto-optic polarization rotators. By taking advantage of the binary nature of the rotators, we achieved unprecedented DGD, SOPMD, and PDL accuracies of 2.6 fs, 1.39ps2, and 0.06 dB respectively; repeatabilities of 0.022 fs, 0.28 ps2, and 0.034dB respectively; and resolutions of 1 fs, 0.005 ps2 and 0.01dB respectively, from 1480 to 1620 nm.
TL;DR: This work proposes a method of polarization shaping in the focal region with the polarization modulation of incident light by using an iterative optimization based on a vectorial diffraction calculation with the help of the fast Fourier transform, which provides a novel way to control the vectorial feature of the focal volume with thehelp of polarization tailoring.
Abstract: We proposed a method of polarization shaping in the focal region with the polarization modulation of incident light. By using an iterative optimization based on a vectorial diffraction calculation with the help of the fast Fourier transform, we can tailor the polarization structure in the focal plane. This provides a novel way to control the vectorial feature of the focal volume with the help of polarization tailoring, which is different from the method using wavefront shaping. The capability of polarization-only modulation on the incident light is demonstrated by optical experiments.
Patent•
14 Jul 2010
TL;DR: In this paper, a dual-frequency laser ranging method and a device based on polarization state regulation and wavelength synthesis belong to the technical field of laser application, which adopts the same frequency stabilized laser as a measuring light source, realizes organic integration of absolute distance measurement and relative displacement dynamic measurement through the control of a polarization rotator and wavelength tuning of acoustooptic frequency shifters.
Abstract: A dual-frequency laser ranging method and a device based on polarization state regulation and wavelength synthesis belong to the technical field of laser application. In absolute distance measurement and relative displacement measurement, the method adopts the same frequency stabilized laser as a measuring light source, realizes organic integration of absolute distance measurement and relative displacement dynamic measurement through the control of a polarization rotator and wavelength tuning of acoustooptic frequency shifters and simultaneously meets the requirements on extra long distance precise measurement and fast local displacement ultraprecise monitoring. The device comprises an acoustooptic frequency shifter A and an acoustooptic frequency shifter B, a reflecting mirror A and a reflecting mirror B, a frequency control unit A and a frequency control unit B, a polarization rotator, a polarization splitter B and a laser wavelength split and synthesis unit formed by partial optical splitters. The invention has the advantages of both extra long distance ultraprecise measurement capability and integral formation, etc.