Showing papers on "Polarization rotator published in 2018"
TL;DR: In this paper, a terahertz dynamically tunable broadband metamaterial polarization rotator composed of two metal gratings and two orthogonal graphene grating structures as well as the dielectric spacers is presented.
92 citations
TL;DR: In this paper, a 300mm silicon photonics platform for large-scale device integration was developed, leveraging 40nm complementary metal-oxide-semiconductor technology, which can enable manufacturing of high-speed, low-power optical interconnects.
Abstract: A 300-mm silicon photonics platform for large-scale device integration was developed, leveraging 40-nm complementary metal-oxide-semiconductor technology. Through fabrication using this technology platform, wire waveguides were obtained with low propagation losses for the C-band (0.4 dB/cm) and O-band (1.3 dB/cm). Several types of wavelength filters, including a coupled resonator optical waveguide (CROW), an arrayed waveguide grating, and a cascaded Mach–Zehnder interferometer, were also demonstrated, with low crosstalk and low insertion loss. A polarization rotator Bragg grating with multiple reflection peaks having polarization independence was also obtained. In terms of wafer-scale uniformity, a small standard deviation of 0.7 nm in resonant wavelength for the CROW was confirmed. A grating coupler also exhibited low wafer-scale variations in the maximum coupling efficiency and the diffraction wavelength in optical coupling with a single-mode fiber. Extraction of fabrication deviations for the waveguides was performed using the spectral variation of microring resonators and grating couplers. The extracted wafer-scale variations in waveguide width and height and grating depth well reproduced the results of physical measurements, with subnanometer-level accuracy. The developed technology can thus enable manufacturing of high-speed, low-power optical interconnects.
66 citations
TL;DR: In this paper, a wideband multifunctional and switchable linear polarizer has been presented based on an active metasurface for the X-band, which consists of three metallic layers and two dielectric spacers.
Abstract: In this letter, a wideband multifunctional and switchable linear polarizer has been presented based on an active metasurface for the X-band. The proposed structure consists of three metallic layers and two dielectric spacers. The switchable function is obtained by embedding PIN diodes, which are controlled by four independent sets of external dc bias networks on the top and bottom metallic layers. Two main functions (polarization conversion and polarization separator) and four working states are exhibited by combining four independent sources. As a polarization rotator, the proposed structure converts electromagnetic (EM) waves to cross-polarization from 5.2 to 16.7 GHz with the polarization conversion ratio beyond 90%, while as a polarization separator, the copolarization EM waves can be transmitted and the cross-polarization waves reflected with isolation over 10 dB from 8 to 14.3 GHz. The numerical and experimental results are in a good agreement, which demonstrates the excellent and stable performance of the proposed structure.
50 citations
TL;DR: In this article, the reflected beams are divided into four beams with nearly the same density under illumination of linear-polarized THz waves, while the polarization of reflected beams in each channel is modulated with a rotation angle or invariable with respect to the incident THZ waves, leading to the multi-channel polarization rotator and beam splitter, respectively.
Abstract: Terahertz beam splitters and polarization rotators are two typical devices with wide applications ranging from terahertz communication to system integration. However, they are faced with severe challenges in manipulating THz waves in multiple channels, which is desirable for system integration and device miniaturization. Here, we propose a method to design ultra-thin multi-channel THz beam splitters and polarization rotators simultaneously. The reflected beams are divided into four beams with nearly the same density under illumination of linear-polarized THz waves, while the polarization of reflected beams in each channel is modulated with a rotation angle or invariable with respect to the incident THz waves, leading to the multi-channel polarization rotator (multiple polarization rotation in the reflective channels) and beam splitter, respectively. Reflective metasurfaces, created by patterning metal-rods with different orientations on a polyimide film, were fabricated and measured to demonstrate these characteristics. The proposed approach provides an efficient way of controlling polarization of THz waves in various channels, which significantly simplifies THz functional devices and the experimental system.
48 citations
TL;DR: Inspired by techniques utilized in the design of frequency-selective surfaces, multiband and wideband 90° polarization rotators are proposed in this paper, where the basic structure is constructed from three layers.
Abstract: Inspired by techniques utilized in the design of frequency-selective surfaces, multiband and wideband 90° polarization rotators are proposed in this letter The basic structure is constructed from three layers The front and back layers contain metal wire grids orthogonal to each other, whereas the middle layer consists of resonant elements with 45°-twisted angle, which plays the main role in determining the overall response of the structure Employing single and multiple resonators in the middle layer, first-order single- and multiband are achieved By cascading two first-order middle layers, a second-order response is accomplished A very wideband response is achieved by utilizing a wideband resonant element in the middle layer Several design examples are presented and simulated, two of them are fabricated and tested to validate the simulated results
31 citations
29 Jul 2018
TL;DR: In this paper, an on-chip TEo-TMo polarization rotator with a footprint of 0.96 μm × 4.2 μm and a conversion loss of 2.5 dB and extinction ratio of 10 dB in the wavelength range of 1440-1580nm was proposed.
Abstract: With a genetic algorithm, we designed an on-chip TEo- TMo polarization rotator with a footprint of 0.96 μm × 4.2 μm and experimentally demonstrated its conversion loss of ~2.5 dB and extinction ratio of ~10 dB in the wavelength range of 1440–1580nm.
26 citations
TL;DR: The proposed devices will be basic elements for the two-dimensional photonic system, and will find numerous applications, including integrated photonics, molecular sensing, imaging and micro-manipulation.
Abstract: Both experiments and simulations show that the polarization state and propagation path of the Bloch surface waves sustained on a dielectric multilayer, can be manipulated with the grooves inscribed on this multilayer. These grooves can be easily producible, accessible and controllable. Various nano-devices for the Bloch surface waves, such as the launcher, beam splitter, reflector, polarization rotator, and even the photonic single-pole double-throw switch, were all experimentally realized with the properly designed grooves, which are consistent with the numerical simulations. The proposed devices will be basic elements for the two-dimensional photonic system, and will find numerous applications, including integrated photonics, molecular sensing, imaging and micro-manipulation.
24 citations
TL;DR: In this paper, a reflective polarization rotator (PR) based on metasurface is presented, where the unit cell consists of two oblique symmetry triangle split rings and simulated results show the PR has more than 90% polarization conversion efficiency from 9.24 to 17.64 GHz under normal incidence.
Abstract: A wideband and high efficiency reflective polarization rotator (PR) based on metasurface is presented. The unit cell of the PR consisting of two oblique symmetry triangle split rings and simulated results show the PR has more than 90% polarization conversion efficiency from 9.24 to 17.64 GHz (a relative bandwidth of 62.50%) under normal incidence. The broad polarization conversion bandwidth and high efficiency results from multiple plasmon resonances and nearly 100% polarization conversion is obtained at three plasmon resonances. The mechanism of the proposed PR is analyzed by surface current distributions. Electric and magnetic resonances generate broad polarization conversion bandwidth and high polarization conversion ratio within the operating band. In addition, we analyze the polarization states of the PR unit numerically based on the reflected fields, which serves as theoretical predictions of polarization conversion. To verify the simulation results and analysis, a sample was fabricated and ...
22 citations
TL;DR: In this paper, two polarization convertors based on amorphous silicon metasurfaces are presented to steer cross-polarized light with an angle according to the generalized Snell's law.
Abstract: We have presented two polarization convertors based on amorphous silicon metasurfaces. Results show that the cross-polarized transmission of the first polarization convertor is over 90% with over 95% polarization conversion efficiency across the 300-nm bandwidth and maintains high-efficiency performance with big incident angles in this bandwidth. To steer cross-polarized light with an angle according to the generalized Snell’s law, we have created another polarization convertor by choosing several resonators with different geometries in one supercell, achieving full 2π phase control, guiding the co-polarized and cross-polarized transmitted light spatially separated efficiently with broadband operation.
21 citations
TL;DR: In this paper, a 2D layered black phosphorus (BP) with a nanometer thickness was shown to behave as an ultrathin optical polarization element in a BP-Bi2Se3 stacking structure by inducing the exceptionally polarized Raman scattering of isotropic Bi2Se 3.
Abstract: Manipulating the polarization of light at the nanoscale is essential for the development of nano-optical devices. Owing to its corrugated honeycomb structure, two-dimensional (2D) layered black phosphorus (BP) exhibits outstanding in-plane optical anisotropy with distinct linear dichroism and optical birefringence in the visible region, which are superior characteristics for ultrathin polarizing optics. Herein, taking advantage of polarized Raman spectroscopy, we demonstrate that layered BP with a nanometer thickness can remarkably alter the polarization state of a linearly-polarized laser and behave as an ultrathin optical polarization element in a BP-Bi2Se3 stacking structure by inducing the exceptionally polarized Raman scattering of isotropic Bi2Se3. Our findings provide a promising alternative for designing novel polarization optics based on 2D anisotropic materials, which can be easily integrated in microsized all-optical and optoelectronic devices.
20 citations
TL;DR: In this article, the authors demonstrate a wideband polarization rotator with characteristics of high efficiency and large-range incidence angle by using a very simple anisotropic reflective metasurface.
Abstract: We demonstrate a wideband polarization rotator with characteristics of high efficiency and large-range incidence angle by using a very simple anisotropic reflective metasurface. The calculated results show that reflection coefficient of cross polarization is larger than 71% over an octave frequency bandwidth from ~4.9 GHz to ~10.4 GHz. The proposed metasurface can still work very well even at incidence angle of 60°. The experiment at microwave frequencies is carried out and its results agree well with the simulated ones.
TL;DR: A new family of impedance-matched chiral metasurfaces that offer arbitrary polarization control at two different frequencies is proposed that can be arbitrarily and independently tuned for two orthogonal linear polarizations at each of the two operating frequencies.
Abstract: We propose a new family of impedance-matched chiral metasurfaces that offer arbitrary polarization control at two different frequencies. To this end, two main problems are addressed: (1) determination of the required surface impedances for a certain user-defined chiral functionality at two frequencies and (2) their physical realization at microwaves. The first milestone is achieved through a proposed synthesis method that combines a semi-analytical method and a nonlinear optimization technique. In particular, the impedances are computed such that the devised chiral metasurface is also impedance-matched to a terminating medium. The chiral metasurfaces are then physically realized at microwaves by cascading layers of rotated arrays of multiple concentric rectangular copper rings. We establish that these proposed unit cells offer distinct dual-resonances that can be arbitrarily and independently tuned for two orthogonal linear polarizations at each of the two operating frequencies. This allows simultaneous physical mapping of the required surface impedances at two frequencies. The versatility and generality of the proposed numerical and physical solutions are demonstrated through two design examples: A dual-band circular polarization selective surface (CPSS) and a dual-band polarization rotator (PR). The dual-band CPSS is further confirmed experimentally at 20 GHz and 30 GHz based on a free-space quasi-optical system.
TL;DR: A new electrically tunable color filter to actively adjust the correlated color temperature of white light-emitting diodes, which resembles the Planckian locus, is reported, promising for next generation smart lighting.
Abstract: We report a new electrically tunable color filter to actively adjust the correlated color temperature of white light-emitting diodes. With four passive cholesteric films and an active polarization rotator, both circular polarizations of the incident light are utilized to generate complementary blue and yellow colors. The blue/yellow ratio can be tuned by the applied voltage of the polarization rotator. In experiment, the tunable color filter offers a reasonably wide tuning range (1900 K and 2400 K), which resembles the Planckian locus. This design is promising for next generation smart lighting.
TL;DR: In this article, an active optical switch based on polarization-tuned guided-mode resonance filter (GMRF) for the optical communication wave band is experimentally demonstrated, which consists of a linear polarizer, a twisted nematic liquid crystal (TN-LC) polarization rotator and a GMRF from top to bottom.
TL;DR: An ultrathin dual-band planar chiral metamaterial (CMM) with giant optical activity using Fermat's Spiral structure (FSs) was proposed, which could yield a near polarization angle independent 90° rotation characteristic as mentioned in this paper.
Abstract: An ultrathin dual-band planar chiral metamaterial (CMM) with giant optical activity using Fermat’s Spiral structure (FSs) was proposed, which could yield a near polarization angle independent 90° rotation characteristic. The proposed CMM can convert an incident linear polarization (y-/x-polarized) wave into its cross-polarization (x-/y-polarized) or experience a near 90° polarization rotation at 4.67 and 8.51 GHz, respectively. The experiment results are in agreement well with numerical simulation. The surface current distributions of unit-cell structure of the proposed CMM were analyzed to illustrate the physics mechanism of this giant optical activity with 90° polarization rotation. Good performances and compact design of the CMM suggest a promising application in 90° polarization rotator that need to be integrated with other compact devices.
TL;DR: In this article, a method for photonic generation of a linearly chirped microwave waveform using a frequency-sweeping laser and a dual-polarization modulator is proposed and investigated.
TL;DR: This transmissive optical IPR can conveniently rotate the polarization of linearly polarized light to any desired directions at different spatial locations with high conversion efficiency, which is nearly constant for different rotation angles.
Abstract: In this work, we demonstrate broadband integrated polarization rotator (IPR) with a series of three-layer rotating metallic grating structures. This transmissive optical IPR can conveniently rotate the polarization of linearly polarized light to any desired directions at different spatial locations with high conversion efficiency, which is nearly constant for different rotation angles. The linear polarization rotation originates from multi-wave interference in the three-layer grating structure. We anticipate that this type of IPR will find wide applications in analytical chemistry, biology, communication technology, imaging, etc.
TL;DR: According to the experimental results and theoretical analyses by Jones Calculus, the tandem-2ϕ-TNLC polarization rotator with suitable parameters is achromatic and insensitive to the polarization plane of incident light.
Abstract: An achromatic linear polarization rotator based on a tandem-2ϕ-twisted nematic liquid crystal cell (tandem-2ϕ-TNLC cell, where 2ϕ represents the total twisted angle) is theoretically analyzed and experimentally demonstrated. The tandem-2ϕ-TNLC cell comprises two conventional ϕ-TNLC cells with the required arrangement that the LC director close to the last layer of the first ϕ-TNLC cell should be perpendicular to that close to the first layer of the second ϕ-TNLC cell. With such a simple combination, the TNLC performances are considerably improved. According to the experimental results and theoretical analyses by Jones Calculus, the tandem-2ϕ-TNLC polarization rotator with suitable parameters is achromatic and insensitive to the polarization plane of incident light. Such properties provide these polarization rotators with potential for practical applications.
11 Mar 2018
TL;DR: The silicon platform has successfully integrated a variety of C-band and O-band passive and active optical components, including broad-band edge coupler, polarization rotator/splitter, 90° hybrid mixer, 50GHz WGPD and 35GHz Si Modulators, all exhibiting high performances.
Abstract: We demonstrate a silicon photonic platform for 400G data center 500m to 120km applications. The silicon platform has successfully integrated a variety of C-band and O-band passive and active optical components, including broad-band edge coupler, polarization rotator/splitter, 90° hybrid mixer, 50GHz WGPD and 35GHz Si Modulators, all exhibiting high performances, and successfully demonstrating PSM4, 64Gbaud ICR, 64Gbaud ICTR PIC capable of 400G applications.
TL;DR: In this paper, a C-band polarization rotator-splitter based on a mode-evolution structure and an asymmetric directional coupler is proposed, which is designed in a bi-level taper through which the TM0 mode can evolve into the TE1 mode.
Abstract: A C-band polarization rotator-splitter based on a mode-evolution structure and an asymmetric directional coupler is proposed. The mode-evolution structure is designed in a bi-level taper through which the TM0 mode can evolve into the TE1 mode. Then the TE1 mode is coupled to the TE0 mode at the cross port using the asymmetric directional coupler. The input TE0 mode propagates along the waveguide without mode conversion and output at the through port. From the experimental results, the extinction ratio is lower than 30 dB and the excess loss is less than 1 dB for input TE0 mode at the whole C-band. For input TM0 mode, the ER and the EL are, respectively, lower than −10 and 1.5 dB.
TL;DR: In this article, a dual-polarization electro-optic intensity modulator is proposed that is based on a single silicon waveguide with indium tin oxide (ITO) cladding.
Abstract: For high-speed optical transmission, polarization-division-multiplexing (PDM) is a promising technic to double the link capacity. However, most of on-chip PDM systems include a polarization beam splitter, a polarization rotator, and two modulators, which are costly and complex for integration. In this study, a novel dual-polarization electro-optic intensity modulator is proposed that is based on a single silicon waveguide with indium tin oxide (ITO) cladding. The design is validated by numerical simulation with commercial software Lumerical Solution. Based on the epsilon-near-zero effect of ITO, the device, on a single waveguide, manages to modulate simultaneously transverse electric (TE) and transverse magnetic (TM) modes with independent electrical driving signals. With a 75 μ m-long silicon rib waveguide, the extinction ratios (ERs) of both TE and TM modes can be around 15 dB, and the nonuniformity is around 0.5 dB. The 3 dB modulation bandwidths are 57.8 GHz and 65.9 GHz for TE and TM modulation, respectively. Within 1 dB ER nonuniformity, the device can operate at E -, S -, and C -band, which distinguishes itself by achieving wavelength-division-multiplexing compatible PDM and with only one single waveguide. To our best knowledge, the concept of independent and simultaneous dual-polarization modulation on a single waveguide is proposed for the first time. The modulator offers various merits including ultracompact size, high speed, and complementary metal oxide semiconductor (CMOS) compatibility.
TL;DR: In this paper, a universal plasmonic polarization state analyzer consisting of rectangular holes arranged along an Archimedes spiral in silver film was proposed to detect different polarization states of light including linear, circular, radial and azimuthal polarizations.
Abstract: We propose a universal plasmonic polarization state analyzer consisting of rectangular holes arranged along an Archimedes spiral in silver film. The analyzer can detect different polarization states of light including linear, circular, radial and azimuthal polarizations. The theoretical analysis of its transmitted field is performed on the basis of the dipole radiations, and the analytic expressions of the electric field distributions under different polarized illuminations are provided. The numerical simulations of the near-field transmissions are also conducted to verify the analytic results. The significant differences between the field distributions predict the practicability of the universal plasmonic polarization state analyzer in determining the incident light polarization states.
TL;DR: In this article, the authors proposed a tunable color filter consisting of a linear polarizer, the twisted nematic liquid crystal (TN-LC) polarization rotator, and the GMRF from top to bottom.
Abstract: Tunable guided-mode resonance filters (GMRFs) for multi-primary colors based on a twisted nematic liquid crystal (TN-LC) polarization rotator with high peak efficiencies, narrow linewidths, and low sidebands are experimentally demonstrated. The proposed tunable color filter consists of a linear polarizer, the TN-LC polarization rotator, and the GMRF from top to bottom. The polarization of the linear polarized beam generated by the linear polarizer is controlled using a TN-LC. The resonance wavelengths and resonance peaks of the GMRFs are tuned following the orientation of the TN-LC directors. Thus, 3 ~ 6 high saturated primary colors with tunable intensities can be obtained by controlling the applied voltages on the TN-LC of every filter separately.
TL;DR: In this paper, a novel design of a polarization filter based on photonic crystal fiber (PCF) is proposed, where a gold-coated air hole is added to the air hole to increase the resonance strength in y-polarized direction.
Abstract: A novel design of a polarization filter based on photonic crystal fiber (PCF) is proposed in this paper. With the introduction of a gold-coated air hole, the resonance strength is much stronger in y-polarized direction than in x-polarized direction at some particular wavelengths, which is due to the metal surface plasmon effects. At the wavelength of 1.31 μm, the loss of y-polarized mode is 2138.34 dB/cm while the loss is very low in x polarization. Furthermore, the loss peak can be flexibly adjusted from the wavelength of 1.26 to 1.56 μm by changing the thickness of a gold layer, and the loss in y polarization can be kept above 1200 dB/cm. The significant loss in y polarization makes this PCF a good candidate for developing a polarization filter with high performance.
TL;DR: An InP based polarization rotator is demonstrated using the plasmonic effect and operates as a half-wave retarder with polarization extinction ratio of 20 dB over C-band.
Abstract: we report on an integrated InP based polarization rotator scheme using the plasmonic effect. It operates as a half-wave retarder in ridge waveguide structure. The rotation angle of the eigenmode axes of the half-wave retarder waveguide is determined by the position off a bottom corner of a metal layer placed above the waveguide core in the upper cladding region. The simple rotator structure enables an easy and tolerant fabrication process. The length of the fabricated device is less than 50 μm, and a polarization extinction ratio (PER) of 20 dB has been achieved.
TL;DR: In this paper, the Stokes vector based microscopy was used to measure and characterize the polarization properties of second harmonic (SH) light from starch granule using a pixel-by-pixel image analysis.
Abstract: We report on the measurement and characterization of polarization properties of second harmonic (SH) light from starch granule using a Stokes vector based microscopy. The four-element Stokes parameters are the most complete description of the polarization state of SH light, including any depolarization effects. Various polarization parameters, such as the degree of polarization, the degree of linear polarization, the degree of circular polarization, as well as anisotropy are extracted by implementing a pixel by pixel image analysis from the 2D reconstructed SH Stokes images of starch granule. Furthermore, we implemented the technique by varying the polarization states of excitation light and recording the resulting Stokes parameters at micro-meter depths of resolution in order to investigate the molecular structure and orientation of the samples.
Patent•
02 Jan 2018
TL;DR: In this paper, a polarization multiplexing optical transmission circuit that makes it possible to guarantee a transmission-side PDL for which a decrease in transmission power has been alleviated.
Abstract: The present invention provides a polarization multiplexing optical transmission circuit that makes it possible to guarantee a transmission-side PDL for which a decrease in transmission power has been alleviated. The present invention comprises: an optical branch circuit (154) for branching the light outputted from a light source (152); optical phase shifters (202, 204) arranged in at least one of two waveguides connected to the output of the optical branch circuit; an optical wave synthesizing circuit (206) connected to the two waveguides; a first and a second optical transmitter (156, 158) connected to the two outputs of the optical wave synthesizing circuit, respectively; a polarization multiplexer (160) for polarizing and combining the two optical transmitter outputs of the first and second optical transmitters; and a polarization rotator (164) arranged between the first and second optical transmitters and the polarization multiplexer, the polarization rotator being connected to at least one of the first and second optical transmitters.
15 Dec 2018
TL;DR: In this paper, a chip-scale and highly efficient polarization rotator based on an asymmetric directional coupler geometry involving a horizontal slot waveguide (WG) and a strip WG on a silicon-on-calcium-fluoride (SOCF) platform for the mid-IR regime is presented.
Abstract: We report the design of a chip-scale and highly efficient polarization rotator (PR) based on an asymmetric directional coupler geometry involving a horizontal slot waveguide (WG) and a strip WG on a silicon-on-calcium-fluoride (SOCF) platform for the mid-IR regime. In particular, we have optimized it for rotations of both the polarizations at the operating wavelength of 4.47 µm in two configurations, which relied on single and double-slot WG geometries. Power coupling through appropriate phase matching between the quasi-TM mode of a horizontal slot WG and the quasi-TE mode of a strip WG has been exploited for realizing polarization rotation. Numerical simulations demonstrate that achievable maximum power coupling efficiency (Cm) is as high as ~95% (with a device length of ~0.57 mm) for the single slot WG geometry and ~97% (with an even shorter device length of ~0.47 mm) for the PR based on double-slot WG geometry for both the polarizations. Both the designed PRs exhibit relatively large bandwidth of 50 nm with reasonably high Cm of ~80%. A study on fabrication tolerances show that Cm remains ~80% for variation in width Δw from -2 to +3 nm and -6 to +5 nm for single and double-slot based PRs, respectively.
Patent•
14 Aug 2018
TL;DR: In this article, a near-eye display device based on a polarization contact lens was proposed, where a micro projector, a waveguide, a polarizer, a polarization rotator, and a contact lens are used for light-ray filtering and vision correction.
Abstract: The invention discloses a near-eye display device based on a polarization contact lens. The near-eye display device comprises a micro projector, a waveguide, a polarizer, a polarization rotator and the polarization contact lens, wherein the micro projector is used for projecting images; the waveguide is used for folding light paths, and the surface of the inside of the waveguide comprises at leasttwo diffraction gratings or reflecting layers for coupling in and coupling out of light rays and exit pupil expanding; the polarizer is used for filtering the light rays, and is only used for allowing light rays in specific polarization directions to pass through; the polarization rotator is used for changing polarization directions of the light rays; the polarization contact lens is used for light-ray filtering and vision correction, and is only used for allowing light rays in specific polarization directions to pass through, and the diopter of the polarization contact lens depends on visions of wearers; the near-eye display device can be used for monocular displaying, and can also be binocular displaying. According to the near-eye display device, the functions of the super-large field angle, actual-object shielding of a virtual object and vision correction can be achieved, and the near-eye display device is suitable for a head-mounted display device and an intelligent wearing devicesuch as intelligent lenses.