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We have theoretically and experimentally designed and demonstrated an all-fiber polarization interference filter (AFPIF), which is formed by a polarization-maintaining (PM) fiber cavity structure utilizing two 45 $^{circ}$ tilted ...
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We have theoretically and experimentally designed and demonstrated an all-fiber polarization interference filter (AFPIF), which is formed by a polarization-maintaining (PM) fiber cavity structure utilizing two 45 $^{circ}$ tilted fiber gratings (45$^{circ}$-TFGs) inscribed by UV laser on the PM fiber. Such a filter could generate modulated transmission of linear polarization status. It has been revealed that the modulation depth of the transmission depends on the coupling angle between the 45$^{circ}$-TFGs and the PM fiber cavity. When the two 45$^{circ}$-TFGs in PM fiber are oriented at 45$^{circ}$ to the principal axis of the PM fiber cavity, the maximum modulation depth is achievable. Due to the thermal effect on birefringence of the PM fiber, the AFPIF can be tuned over a broad wavelength range just by simple thermal tuning of the cavity. The experiment results show that the temperature tuning sensitivity is proportional to the length ratio of the PM fiber cavity under heating. For 18 and 40 cm long cavities with 6 cm part under heating, the thermal tuning sensitivities are 0.616 and 0.31 nm/$^{circ}$ C, respectively, which are almost two orders of magnitude higher than normal fiber Bragg gratings.
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Ambichiral layered structures can be designed to function reasonably well as rejection filters for elliptical polarization states, although the proposed design strategy is inadequate for linear and quasilinear polarization states.
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A hydrogen-rich sample with dynamically polarized hydrogen nuclei was tested as a wavelength-independent neutron transmission spin polarizer. The experiment used a modified setup of the dynamic nuclear polarization target station ...
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A hydrogen-rich sample with dynamically polarized hydrogen nuclei was tested as a wavelength-independent neutron transmission spin polarizer. The experiment used a modified setup of the dynamic nuclear polarization target station at the GKSS research center. The standard solvent sample at the GKSS DNP station was used. It is 2.8 turn thick and consists of 43.4wt% water, 54.6wt% glycerol, and 2wt% of EHBA-Ci-(v) complex. The wavelength of the incident neutrons for the transmission experiment was lambda= 8.1 Angstrom with Deltalambda/lambda = 10%. The polarization of neutron beam after the target sample was analyzed with a supermirror analyzer. A neutron polarization of -52% was achieved at the hydrogen polarization of -69%. Further experiments will test the feasibility of other hydrogen-rich materials, such as methane, as the polarizer. A theoretical calculation shows that a polarized methane target would allow over 95% neutron polarizations with more than 30% transmission. (C) 2004 Elsevier B.V. All rights reserved.
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A new method on radar signal polarization filtering using only single sample of signal is proposed. The algorithm is very simple and it is suitable for the filtering processing of a stationary or unstationary polarization signal. ...
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A new method on radar signal polarization filtering using only single sample of signal is proposed. The algorithm is very simple and it is suitable for the filtering processing of a stationary or unstationary polarization signal. Some simulation results on radio disturbance suppression are given.
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Underwater imaging is a crucial and challenging problem. The backscattering caused by particles in turbid water can severely degrade the image. In this paper, A novel image dehazing method is devised, which combines optics with im...
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Underwater imaging is a crucial and challenging problem. The backscattering caused by particles in turbid water can severely degrade the image. In this paper, A novel image dehazing method is devised, which combines optics with image processing technology. This method can directly remove part of the backscattering through polarization technology, and then quickly solve the dehazing image through our algorithm. Experimental results show that our method is valid and robust for targets of diverse materials, grayscale images and color images in diverse scattering environments. Furthermore, our method takes only 2 percent of the time of the fast dark channel prior (DCP) method when processing 1 K resolution images, which meets the requirements of real-time.
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The spin Hall effect of light (SHEL) is the photonic analogue of the spin Hall effect occurring for charge carriers in solid-state systems. This intriguing phenomenon manifests itself when a light beam refracts at an air-glass int...
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The spin Hall effect of light (SHEL) is the photonic analogue of the spin Hall effect occurring for charge carriers in solid-state systems. This intriguing phenomenon manifests itself when a light beam refracts at an air-glass interface (conventional SHEL) or when it is projected onto an oblique plane, the latter effect being known as the geometric SHEL. It amounts to a polarization-dependent displacement perpendicular to the plane of incidence. In this work, we experimentally investigate the geometric SHEL for a light beam transmitted across an oblique polarizer. We find that the spatial intensity distribution of the transmitted beam depends on the incident state of polarization and its centroid undergoes a positional displacement exceeding one wavelength. This novel phenomenon is virtually independent from the material properties of the polarizer and, thus, reveals universal features of spin-orbit coupling.
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In this paper, we discuss a potential multiple access and modulation scheme based on polarized states (PS) of electromagnetic (EM) waves for line-of-sight (LOS) communications. The proposed scheme is theoretic different from the e...
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In this paper, we discuss a potential multiple access and modulation scheme based on polarized states (PS) of electromagnetic (EM) waves for line-of-sight (LOS) communications. The proposed scheme is theoretic different from the existing polar modulation for EDGE and WCDMA systems. We propose the detailed bit representation (modulation) and multiple access scheme using PS. Because of the inflexibility of polarization information in the time and frequency domains, as well as independence of frequency and space, the polarization information can be used independently for wireless communications, i.e., another independent resource domain that can be utilized. Due to the independence between the PS and the specific features of signals (such as waveform, bandwidth and data rate), the discussed polarization division multiple access (PDMA) and polarization modulation (PM) are expected to improve the spectrum utilization effectively. It is proved that the polarization filtering technique can be adopted in the PDMA-PM wireless communications to separate the multiuser signals and demodulate the bit information representing by PS for desired user. Some theoretical analysis is done to demonstrate the feasibility of the proposed scheme, and the simulation results are made to evaluate the performance of the suggested system.
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We investigate spin-dependent bandgap structures and spin filtering in graphene with multiple ferromagnetic barriers. Using the transfer matrix method, we have calculated the spin-dependent transmission coefficients, the spin pola...
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We investigate spin-dependent bandgap structures and spin filtering in graphene with multiple ferromagnetic barriers. Using the transfer matrix method, we have calculated the spin-dependent transmission coefficients, the spin polarization, the conductance, and the electronic energy spectra of the systems. It is shown that the spinup and spindown electrons possess different bandgap structures. As a result, full spin polarization can be achieved within several separated energy zones. The width of the energy zone with full spin polarization can be effectively manipulated by adjusting the exchange field. Correspondingly, conductance steps with full spin polarization are observed in the systems. Our investigations may have potential applications in the design of carbon-based spin filters.
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Short-term forecast of the polar motion is considered by introducing a prediction model for the excitation function that drives the polar motion dynamics. The excitation function model consists of a slowly varying trend, periodic ...
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Short-term forecast of the polar motion is considered by introducing a prediction model for the excitation function that drives the polar motion dynamics. The excitation function model consists of a slowly varying trend, periodic modes with annual and several sub-annual frequencies (down to the 13.6-day fortnightly tidal period), and a transient decay function with a time constant of 1.5 days. Each periodic mode is stochastically specified using a second-order auto-regression process, allowing its frequency, phase, and amplitude to vary in time within a statistical tolerance. The model is used to time-extrapolate the excitation function series, which is then used to generate a polar motion forecast dynamically. The skills of this forecast method are evaluated by comparison to the C-04 polar motion series. Over the lead-time horizon of four months, the proposed method has performed equally well to some of the state-of-art polar motion prediction methods, none of which specifically features forecasting of the excitation function. The annual mode in the χ_2 component is energetically the most dominant periodicity. The modes with longer periods, annual and semi-annual in particular, are found to contribute more significantly to forecast accuracy than those with shorter periods.
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The building blocks of polarization interference filters are polarizers and retarders. In fixed type filter tunability can be achieved by changing the azimuths of polarizers or retardance of retarder plates. In the present article...
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The building blocks of polarization interference filters are polarizers and retarders. In fixed type filter tunability can be achieved by changing the azimuths of polarizers or retardance of retarder plates. In the present article the transmission characteristics of the polarization interference filters are studied where magneto-optic rotator is used at each stage. The wavelength tunability can be achieved by changing the applied magnetic flux density. Transmission characteristics and spectral bandwidth variation for magneto-optic materials made up of Terbium Gallium Garnet (TGG) and Terbium Doped Glass (TDG) are studied. Possibility of obtaining a narrow transmission band over a wide wavelength range for continuous tunability is shown.
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