Showing papers on "Polarization rotator published in 2013"
TL;DR: In this article, a metasurface lens that focuses light and controls its polarization at a wavelength of 2'μm is presented, which demonstrates high transmission and complete phase control within a subwavelength thickness at near-infrared frequencies.
Abstract: A metasurface lens that focuses light and controls its polarization at a wavelength of 2 μm is presented. This lens demonstrates high transmission and complete phase control within a subwavelength thickness at near-infrared frequencies. By cascading four patterned sheets, the efficiency is dramatically improved over more common single sheet designs. In addition, by utilizing anisotropic sheets, arbitrary birefringence can be achieved. A planar lens that both focuses light and converts its polarization from linear to circular is analyzed.
312 citations
TL;DR: In this paper, a unique approach to efficiently rotate the linear polarization of terahertz wave in a broadband configuration with tri-layer metasurfaces was proposed, where the Fabry-Perot cavity effect was attributed to the underlying mechanism of high transmittance and polarization rotation.
Abstract: Polarization conveys valuable information for electromagnetic signal processing exhibiting tremendous potential in developing application driven photonic devices. Manipulation of polarization state of an electromagnetic wave has drawn a lot of research interests in many different fields, especially in the terahertz regime. Here, we propose a unique approach to efficiently rotate the linear polarization of terahertz wave in a broadband configuration with tri-layer metasurfaces. We experimentally observe a nearly perfect orthogonal polarization conversion with an ultrahigh efficiency, demonstrating a ultrathin terahetz rotator. The Fabry-Perot cavity effect in the tri-layer metasurfaces is attributed to the underlying mechanism of high transmittance and polarization rotation.
308 citations
TL;DR: In this article, a nano-engineered photonic-crystal chiral beamplitter is proposed to split left and right-handed circularly polarized light in the wavelength region around 1.615 µm.
Abstract: The linearly polarizing beamsplitter1, 2 is a widely used optical component in photonics. It is typically built from a linearly birefringent crystal such as calcite, which has different critical reflection angles for s- and p-polarized light3, leading to the transmission of one linear polarization and angled reflection of the other. However, the analogue for splitting circularly polarized light has yet to be demonstrated due to a lack of natural materials with sufficient circular birefringence. Here, we present a nano-engineered photonic-crystal chiral beamsplitter that fulfils this task. It consists of a prism featuring a nanoscale chiral gyroid network4, 5, 6, 7, 8, 9, 10 and can separate left- and right-handed circularly polarized light in the wavelength region around 1.615 µm. The structure is fabricated using a galvo-dithered direct laser writing method and could become a useful component for developing integrated photonic circuits that provide a new form of polarization control.
271 citations
TL;DR: In this article, the authors proposed a method based on general relations between the reflection and transmission coefficients and the polarizabilities of arbitrary bi-anisotropic particles to synthesize different polarization-transforming devices realized as arrays of small particles.
Abstract: We study the possibility of analytically synthesizing different polarization-transforming devices realized as arrays of small particles. The proposed method is based on general relations between the reflection and transmission coefficients and the polarizabilities of arbitrary bi-anisotropic particles. As an example, we reveal all possible types of inclusions which can be used to realize twist polarizers, select one of them and synthesize a novel twist polarizer. The synthesized twist polarizer is then fitted on a standard printed circuit board, optimized numerically, and finally manufactured and measured. The experimental results for the twist polarizer show good correspondence with the simulations and the new method is found to be a useful tool for developing any polarization-transforming devices. As one more example, a novel circular polarization selective surface is synthesized.
209 citations
TL;DR: In this article, the authors present a method to generate vector beams of light having polarization singularities on their axis, via partial spin-to-orbital angular momentum conversion in a suitably patterned liquid crystal cell.
Abstract: We present a convenient method to generate vector beams of light having polarization singularities on their axis, via partial spin-to-orbital angular momentum conversion in a suitably patterned liquid crystal cell. The resulting polarization patterns exhibit a C-point on the beam axis and an L-line loop around it, and may have different geometrical structures such as "lemon", "star", and "spiral". Our generation method allows us to control the radius of L-line loop around the central C-point. Moreover, we investigate the free-air propagation of these fields across a Rayleigh range.
169 citations
TL;DR: In this paper, a broadband reflective polarization rotator was proposed to generate multi-order plasmon resonances at three neighboring frequencies and maintain a polarization conversion efficiency greater than 56% in 2.0-3.5 GHz.
Abstract: We experimentally investigate the electromagnetic (EM) responses of a broadband reflective polarization rotator under normal incidence. It is found that the rotator can generate multi-order plasmon resonances at three neighboring frequencies. At each frequency, the rotator behaves as a high impedance surface along one axis while as a metallic reflective surface along the other axis. Thus, a 180° phase difference is generated between the two orthogonal components of reflected waves. When the incident wave is polarized by 45° with respect to the symmetry axis of the rotator, the polarization of reflected waves is rotated by 90°. The designed rotator presents broadband properties. It can perform perfect 90° polarization rotation at three frequencies and maintains a polarization conversion efficiency greater than 56% in 2.0–3.5 GHz. The rotator provides a route to broadband polarization rotation and has application values in polarization control.
164 citations
TL;DR: In this article, an anisotropic meta-mirror for achromatic polarization tuning was proposed and experimental results showed that linear polarized wave can be achromatically transformed to its cross-polarization state or to arbitrary circular polarization after its reflection from the mirror.
Abstract: Polarization states are of particular importance for the manipulation of electromagnetic waves. Here, we proposed the design and experimental demonstration of anisotropic meta-mirror for achromatic polarization tuning. It is demonstrated that linear polarized wave can be achromatically transformed to its cross-polarization state or to arbitrary circular polarization after its reflection from the mirror. Microwave experiments verified that the fraction bandwidth for 90% transformation efficiency can be larger than 3:1. Furthermore, by utilizing photoinduced carrier generation in silicon, a broadband tunable circular polarizer is demonstrated in the terahertz regime.
155 citations
TL;DR: A mid-IR highly tunable optical polarization converter composed of asymmetric graphene nanocrosses that can convert linearly polarized light to circularly and elliptically polarized light or exhibit a giant optical activity at different wavelengths is presented.
Abstract: We present a mid-IR highly tunable optical polarization converter composed of asymmetric graphene nanocrosses. It can convert linearly polarized light to circularly and elliptically polarized light or exhibit a giant optical activity at different wavelengths. The transmitted wavelength and polarization states can also be dynamically tuned by varying the Fermi energy of graphene, without reoptimizing and refabricating the nanostructures. This offers a further step in developing a controllable polarization converter.
115 citations
TL;DR: In this article, the polarization convertibility of asymmetric split-ring resonators with the polarization selectivity of S-shape resonators was integrated for realizing a composite-metamaterial-based 90-degree ultrathin polarization rotator (UTPR) with a 50.4-μm thickness in the terahertz gap region.
Abstract: We integrated the polarization convertibility of asymmetric split-ring resonators with the polarization selectivity of S-shape resonators for realizing a composite-metamaterial-based 90-degree ultrathin polarization rotator (UTPR) with a 50.4-μm thickness in the terahertz-gap region. By introducing the Fabry-Perot resonance into the UTPR, the measured transmission is maximized to 0.48 at 1.04 THz, leading to the polarization-conversion ratio up to 97.7%. Compared to other waveplates composed by pile-stacking birefringent metamaterials, the UTPR possesses less loss from the intrinsic resonances because it comprises only two layers of the resonators, and can evade from dichroism effects due to the unique working mechanism.
108 citations
TL;DR: In this paper, an ultrathin transparent metamaterial polarization transformer using a circular twist-split-ring resonator was proposed and investigated experimentally and numerically, and the experimental and simulated results exhibit an asymmetric transmission only for forward and backward propagating linearly polarized waves.
Abstract: In this paper, an ultrathin transparent metamaterial polarization transformer using a circular twist-split-ring resonator (TSRR) was proposed and investigated experimentally and numerically. The experimental and simulated results exhibit an asymmetric transmission only for forward and backward propagating linearly polarized waves. An incident linearly polarized wave can convert its polarization nearly completely to the cross direction after transmission under certain conditions. The simulated spatial evolution of the electric field further indicates that the twist structure functions as a perfect polarization transformer at certain frequencies.
89 citations
TL;DR: In this article, a hybrid plasmonic polarization rotator based on mode interference was proposed, operating at the telecommunication wavelength of 1.55 μm, the rotation length is very short (3.2 μm), while the polarization conversion efficiency was as high as 99.5%.
Abstract: We propose a novel hybrid plasmonic polarization rotator based on mode interference. Operating at the telecommunication wavelength of 1.55 μm, the rotation length is very short (3.2 μm), while the polarization conversion efficiency is as high as 99.5%. The total device insertion loss is only 1.38 dB, much smaller than the common level of plasmonic devices. It also has potential to realize integrated waveplates for various polarization states.
TL;DR: A flat polymeric lenticular microlens array using a mixture of rod-like diacrylate monomer and positive dielectric anisotropy nematic liquid crystal (LC) offers several advantages, such as low voltage, fast response time, and temperature insensitivity, and can be used for switchable 2D/3D displays.
Abstract: We demonstrate a flat polymeric lenticular microlens array using a mixture of rod-like diacrylate monomer and positive dielectric anisotropy nematic liquid crystal (LC). To create gradient refractive index profile in one microlens, we generate fringing fields from a planar top electrode and two striped bottom electrodes. After UV stabilization, the film is optically anisotropic and can stand alone. We then laminate this film on a 90° twisted-nematic LC cell, which works as a dynamic polarization rotator. The static polymeric lenticular lens exhibits focusing effect only to the extraordinary ray, but no optical effect to the ordinary ray. Such an integrated lens system offers several advantages, such as low voltage, fast response time, and temperature insensitivity, and can be used for switchable 2D/3D displays.
TL;DR: Laser ablation of Induced Periodic Surface Structures is used to directly verify the state of polarization at the focal plane, enabling a remarkable level of real-time control of the properties of light waves and applied to real- time surface patterning, shows that highly controlled nanostructuring is possible.
Abstract: The polarization state of an ultrafast laser is dynamically controlled using two Spatial Light Modulators and additional waveplates. Consequently, four states of polarization, linear horizontal and vertical, radial and azimuthal, all with a ring intensity distribution, were dynamically switched at a frequency ν = 12.5Hz while synchronized with a motion control system. This technique, demonstrated here for the first time, enables a remarkable level of real-time control of the properties of light waves and applied to real-time surface patterning, shows that highly controlled nanostructuring is possible. Laser ablation of Induced Periodic Surface Structures is used to directly verify the state of polarization at the focal plane.
TL;DR: A high transparency of metasurface-based polarization controller at microwave frequencies, which consists of orthogonal two pairs of cut wires, which is ultrathin (~0.017λ), as opposed to bulky polarization devices.
Abstract: We proposed, designed and fabricated a high transparency of metasurface-based polarization controller at microwave frequencies, which consists of orthogonal two pairs of cut wires. The high transmission and the strong dispersion properties governed by electromagnetically induced transparency-like (EIT-like) effects for both incident polarizations make our device efficiently manipulating the polarization of EM waves. In particular, the proposed polarization device is ultrathin (~0.017λ), as opposed to bulky polarization devices. Microwave experiments are performed to successfully demonstrate our ideas, and measured results are in reasonable agreement with numerical simulations.
TL;DR: In this paper, the authors proposed a compact, temperature-insensitive, and all-silicon Mach-Zehnder interferometer filter that uses the polarization-rotating asymmetric directional couplers.
Abstract: We propose a compact, temperature-insensitive, and all-silicon Mach-Zehnder interferometer filter that uses the polarization-rotating asymmetrical directional couplers. Temperature sensitivity of the filter is for a wavelength range of 30 nm. The device achieves a reduced footprint by making use of different polarizations, which is made possible by the asymmetric directional couplers that act both as a splitter/combiner and as a polarization rotator. Simulation of the device shows that it can also be useful for gas sensing and bio-sensing applications with three times larger response to cladding changes while keeping a thermally robust behavior.
TL;DR: An ultra-compact (4.5 μm long) hybrid plasmonic polarization rotator operating at telecommunication wavelength for integrated silicon photonic circuits is demonstrated.
Abstract: We experimentally demonstrate an ultracompact (3.7 μm long) hybrid plasmonic polarization rotator operating around 1.55 μm for integrated silicon photonics circuits. The TM polarization of a silicon waveguide is rotated to the TE polarization with insertion losses as low as 1.5 dB and polarization extinction ratios larger than 13.5 dB.
TL;DR: In this paper, a dual-band 90° polarization rotator is proposed by using chiral metamaterial composed of two pairs of two-layered twisted split ring resonators (SRRs) in each unit.
TL;DR: A highly efficient electrically tunable color filter is demonstrated, which provides precise control of color output, taking advantage of a nano-photonic polarization-tailored dichroic resonator combined with a liquid-crystal based polarization rotator.
Abstract: We have demonstrated a highly efficient electrically tunable color filter, which provides precise control of color output, taking advantage of a nano-photonic polarization-tailored dichroic resonator combined with a liquid-crystal based polarization rotator. The visible dichroic resonator based on the guided mode resonance, which incorporates a planar dielectric waveguide in Si3N4 integrated with an asymmetric two-dimensional subwavelength Al grating with unequal pitches along its principal axes, exhibited polarization specific transmission featuring high efficiency up to 75%. The proposed tunable color filters were constructed by combining three types of dichroic resonators, each of which deals with a mixture of two primary colors (i.e. blue/green, blue/red, and green/red) with a polarization rotator exploiting a twisted nematic liquid crystal cell. The output colors could be dynamically and seamlessly customized across the blend of the two corresponding primary colors, by altering the polarization via the voltage applied to the polarization rotator. For the blue/red filter, the center wavelength was particularly adjusted from 460 to 610 nm with an applied voltage variation of 2 V, leading to a tuning range of up to 150 nm. And the spectral tuning was readily confirmed via color mapping. The proposed devices may permit the tuning span to be readily extended by tailoring the grating pitches.
TL;DR: It is shown that when a measurement is applied to a single photons, it eliminates exactly one fully polarized state, offering an important insight about the information gained from a single photon polarization measurement.
Abstract: We describe and analyze a method by which an optical polarization state is mapped to an image sensor. When placed in a Bayesian framework, the analysis allows a priori information about the polarization state to be introduced into the measurement. We show that when such a measurement is applied to a single photon, it eliminates exactly one fully polarized state, offering an important insight about the information gained from a single photon polarization measurement.
TL;DR: In this paper, a survey on experimental and modeling results for three regimes of OF in VCSELs: long, short, and extremely short external cavities (ECs).
Abstract: Vertical-cavity surface-emitting lasers (VCSELs) are as sensitive to optical feedback (OF) as edge-emitting lasers as their much higher mirror reflectivity is compensated by the much smaller intracavity round-trip time resulting in a similar OF rate. VCSELs may emit light in multiple transverse modes and may exhibit polarization bistability which adds new features to their behavior when subject to OF. We present a survey on experimental and modeling results for three regimes of OF in VCSELs: long, short, and extremely short external cavities (ECs). We show that for long and short ECs, the Lang-Kobayashi model is in good agreement with experiments on OF-induced polarization switching, mode hopping, and antiphase oscillatory dynamics at the delay time. These last dynamics modify polarization residence-time distribution making it oscillatory. We demonstrate numerically and experimentally coherence resonance in such bistable, time-delayed optical system. We present results on low-frequency fluctuation and pulse-package dynamics in VCSELs and discuss the role of light polarization. We discuss polarization rotating OF for generating high-frequency pulses as a result of EC mode beating. Finally, we demonstrate how OF from extremely short EC can strongly modify VCSEL characteristics and can be used to effectively control their polarization properties by subwavelength changes of the EC length.
TL;DR: The CCMM proposed in this paper can function as a wide-angle 90° polarization rotator for different substrate permittivity without needing to adjust its geometric parameters.
Abstract: We propose a more efficient way to obtain much stronger polarization rotatory power by constructing a composite chiral metamaterial (CCMM) which is achieved via the combination of the cut-wire pairs (CWPs) and a purely chiral metamaterial (PCMM) composed of conjugated gammadion resonators. Owing to the strong coupling between the CWPs and PCMM, the polarization rotation in our CCMM is more gigantic than that of the PCMM. Furthermore, the CCMM proposed in this paper can function as a wide-angle 90° polarization rotator for different substrate permittivity without needing to adjust its geometric parameters. Due to the unique properties, the CCMM may greatly benefit potential applications including designing a tunable 90°-polarization rotator, microwave devices, telecommunication, and so on.
TL;DR: In this article, an optical isolator for transverse electric (TE) polarized light is demonstrated by adhesive bonding of a ferrimagnetic garnet die on top of a 380 nm thick silicon waveguide circuit.
Abstract: An optical isolator for transverse electric (TE) polarized light is demonstrated by adhesive bonding of a ferrimagnetic garnet die on top of a 380 nm thick silicon waveguide circuit. Polarization rotators are implemented in the arms of a nonreciprocal Mach-Zehnder interferometer to rotate the polarization to transverse magnetic in the nonreciprocal phase shifter regions. Calculation of the nonreciprocal phase shift (NRPS) as a function of bonding layer thickness experienced by the TM mode in the interferometer arms is presented, together with the simulation of the robustness of the polarization rotator. Experimentally, 32 dB isolation is measured at 1540.5 nm wavelength using a magnetic field transverse to the light propagation directions. This paves the way to the cointegration of laser diodes and optical isolators on a silicon photonics platform.
TL;DR: The design of a division-of-amplitude complete polarimeter composed of two biaxial crystals, whose measurement principle is based on the CR phenomenon, corresponds to a static polarimeter, that is, without mechanical movements or electrical signal addressing.
Abstract: A method for polarization metrology based on the conical refraction (CR) phenomenon, occurring in biaxial crystals, is reported. CR transforms an input Gaussian beam into a light ring whose intensity distribution is linked to the incoming polarization. We present the design of a division-of-amplitude complete polarimeter composed of two biaxial crystals, whose measurement principle is based on the CR phenomenon. This design corresponds to a static polarimeter, that is, without mechanical movements or electrical signal addressing. Only one division-of-amplitude device is required, besides the two biaxial crystals, to completely characterize any state of polarization, including partially polarized and unpolarized states. In addition, a mathematical model describing the system is included. Experimental images of the intensity distribution related to different input polarization states are provided. These intensity patterns are compared with simulated values, proving the potential of polarimeters based on biaxial crystals.
TL;DR: This work reports on the measurement and analysis of the polarization state of second harmonic signals generated by starch granules, using a four-channel photon counting based Stokes-polarimeter, and can easily infer the polarization states of the input beam from the resulting SH micrograph.
Abstract: We report on the measurement and analysis of the polarization state of second harmonic signals generated by starch granules, using a four-channel photon counting based Stokes-polarimeter. Various polarization parameters, such as the degree of polarization (DOP), the degree of linear polarization (DOLP), the degree of circular polarization (DOCP), and anisotropy are extracted from the 2D second harmonic Stokes images of starch granules. The concentric shell structure of a starch granule forms a natural photonic crystal structure. By integration over all the solid angle, it will allow very similar SHG quantum efficiency regardless of the angle or the states of incident polarization. Given type I phase matching and the concentric shell structure of a starch granule, one can easily infer the polarization states of the input beam from the resulting SH micrograph.
TL;DR: In this paper, the authors numerically designed a Si-based polarization rotator by exploiting power coupling through phase matching between the TM mode of a Si strip waveguide (WG) and TE mode of Si-air vertical slot WG.
Abstract: We numerically design a compact silicon (Si) based polarization rotator (PR) by exploiting power coupling through phase matching between the TM mode of a Si strip waveguide (WG) and TE mode of a Si-air vertical slot WG. In such structures, the coupling occurs due to horizontal structural asymmetries and extremely high modal hybridness due to high refractive index contrast of Si-on-insulator (SOI) structure. Design parameters of the coupler have been optimized to achieve a compact PR of ~135 μm length at the telecommunication wavelength of 1.55 μm. Maximum power coupling efficiency Cm, which is studied by examining the transmittance of light, is achieved as high as 80% for both polarization conversions. Fabrication tolerances and the band width of operation of the designed PR have also been studied.
TL;DR: A polarimetric study of random laser emitted from dye-doped nematic liquid crystals (NLCs) is presented and it is observed linearly polarized light, the orientation of which is in proximity to the bisection between the polarization direction at the maximal scattering in NLCs and the nematic director.
Abstract: A polarimetric study of random laser (RL) emitted from dye-doped nematic liquid crystals (NLCs) is presented. We observed linearly polarized light, the orientation of which is in proximity to the bisection between the polarization direction at the maximal scattering in NLCs and the nematic director. Any arbitrary linear polarization of RLs can be obtained by rotating the NLC sample. The efficiency and output uniformity over the complete direction angle of 2π can be optimized by choosing a proper pump polarization.
TL;DR: In this paper, a novel design of ultra-compact polarization rotator (PR) based on triangular lattice silica photonic crystal fiber is proposed and analyzed, which has a central air hole which can be shifted in x and y directions to achieve complete polarization rotation.
Abstract: A novel design of ultra-compact polarization rotator (PR) based on triangular lattice silica photonic crystal fiber is proposed and analyzed. The suggested design has a central air hole which can be shifted in x and y directions to achieve complete polarization rotation. The influence of the different structure geometrical parameters and operating wavelength on the PR performance is investigated. The simulation results are obtained using full vectorial finite difference method as well as full vectorial finite difference beam propagation method. The numerical results reveal that the reported PR can provide nearly 100% polarization conversion ratio with a device length of 206 μm. It is also expected that over the 1.5-1.6 μ m wavelength range, polarization conversion would be more than 99%.
TL;DR: In this article, a novel design of a passive ultra-compact polarization rotator based on soft glass equiangular spiral photonic crystal fiber (ES-PCF) is proposed and analyzed using full vectorial finite difference approaches.
Abstract: In this letter, a novel design of a passive ultra-compact polarization rotator based on soft glass equiangular spiral photonic crystal fiber (ES-PCF) is proposed and analyzed using full vectorial finite difference approaches. The suggested ES-PCF has eight arms with a central elliptical air hole, which can be shifted in $x$ and $y$ directions to achieve complete polarization conversion. In addition, the major axis of the elliptical hole is rotated by 45 $^{\circ}$ , which offers 99% polarization conversion ratio with ultra-compact device length of 96 $\mu{\rm m}$ . It is also evident from the numerical results that the polarization rotation would be more than 98% over the 1.5–1.6 $\mu{\rm m}$ wavelength range.
TL;DR: In this paper, a chiral metamaterial (CMM) with triple-layer twisted split-ring resonators structure was proposed, which could exhibit a linear polarization conversion as well as asymmetric transmission only for forward and backward propagating linearly polarized waves in a broadband frequency range.
Abstract: In this paper, a chiral metamaterial (CMM) with triple-layer twisted split-ring resonators structure was proposed, which could exhibit a linear polarization conversion as well as asymmetric transmission only for forward and backward propagating linearly polarized waves in a broadband frequency range. The polarization of broadband linearly polarized electromagnetic waves can be rotated in a specific direction by passing it through such a CMM slab with a thickness of about one-twelfth the operational center wavelength. Experiment and simulation calculations are in good agreement, and the polarization conversion rate is above 90% in the frequency range of 5.5–11.1 GHz. The physical mechanism of the broadband linear polarization conversion effect could be further illustrated by simulated electrical field and surface current distributions.
TL;DR: A new method that uses a liquid crystal modulator (LCM) located in the infinity space of a SHG laser scanning microscope that allows the generation of any desired linear or circular polarization state and can be rotated accurately and faster than by manual or motorized control is presented.
Abstract: Second Harmonic Generation (SHG) microscopy coupled with polarization analysis has great potential for use in tissue characterization, as molecular and supramolecular structural details can be extracted. Such measurements are difficult to perform quickly and accurately. Here we present a new method that uses a liquid crystal modulator (LCM) located in the infinity space of a SHG laser scanning microscope that allows the generation of any desired linear or circular polarization state. As the device contains no moving parts, polarization can be rotated accurately and faster than by manual or motorized control. The performance in terms of polarization purity was validated using Stokes vector polarimetry, and found to have minimal residual polarization ellipticity. SHG polarization imaging characteristics were validated against well-characterized specimens having cylindrical and/or linear symmetries. The LCM has a small footprint and can be implemented easily in any standard microscope and is cost effective relative to other technologies.