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- 摘要
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- 实验方案
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22.3: Low cost fabrication of high contrast ratio and high transmission wire grid polarizer by nanoimprint lithography
摘要： This paper proposes a novel approach for low cost fabrication of large area wire grid polarizer (WGP). WGPs regarded as one potential alternative to traditional rear polarizer and DBEF possess the advantages of large contrast ratio (CR), high transmission. To date WGPs can be fabricated through electron beam direct write, which is slow and expensive, therefore not suitable for large area application. With the development of nano-fabrication methods, for instance, nanoimprint lithography (NIL), large area WGP can be made at low cost and fast speed. Furthermore, flexible polarizer can also be made through roll-to-roll (R2R) NIL. In this paper, a WGP with high TM transmission of around 85% and low TE transmission down to 0.2% through the visible light spectra will be realized through nanofabrication. The contrast ratio of the WGP can reach >450 with peak value >3000. For the fabrication process, atom layer deposition (ALD) will be utilized to prepare imprint mask which can achieve highly precise control of expected structure. In this paper, characterization of the designed WGP will also be narrated in the back part, including transmission, CR and the SEM schematic diagram. We believe that low cost fabrication method shows the potential to be adopted for industrial fabrication of polarizer in the future.
关键词： atom layer deposition (ALD),large area fabrication,low cost fabrication,wire grid polarizer (WGP),high contrast ratio,nanoimprint lithography (NIL),high TM transmission
更新于2025-09-23 15:22:29
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[IEEE 2018 International Conference on Optical MEMS and Nanophotonics (OMN) - Lausanne (2018.7.29-2018.8.2)] 2018 International Conference on Optical MEMS and Nanophotonics (OMN) - Nanofabricated Infrared Polarization and Color Filters for Cloud Thermodynamic Phase Determination
摘要： Polarization and wavelength filters for the short-wave infrared based on metal-coated subwavelength-period silicon gratings are designed and fabricated. The nanostructure-based approach enables the realization of the desired polarization and wavelength selectivity for each filter element while also facilitating the integration of these elements into an array with varying polarizer orientation and passband center wavelength. These filters are optimized for a polarimetric imaging application in atmospheric science, namely, the discrimination of cloud thermodynamic phase (ice/water composition). Preliminary results support the viability of this approach.
关键词： wire-grid polarizer,polarization,atmospheric science,optical nanostructures,polarimetry,form-birefringence
更新于2025-09-23 15:21:21
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Fabrication of large-scale freestanding THz wire grid polarizers by femtosecond laser micromachining
摘要： High-performance THz polarizers, as a quasi-optical device to manipulate THz waves, are highly demanded for THz spectroscopy and imaging applications. In this work, we have employed the femtosecond laser micro-machining technique to fabricate freestanding THz wire grid polarizers with two kinds of reinforced line structures which weaken the e?ects of gravity sagging and entanglement of long free wires, thus enabling large-scale processing. The e?ect of the reinforced lines on the polarizers were simulated by the Finite-Di?erence Time-Domain (FDTD) method, and the performances of the polarizer were characterized by THz time-domain spectroscopy and compared with that of a commercial wire gird polarizer. The calculated transmittance is in good agreement with the FDTD results. The degree of polarization and the extinction ratio of the polarizer with discontinuous reinforced lines are better than those of a commercial wire grid polarizer.
关键词： Time-domain THz spectroscopy,THz,Femtosecond laser micro-machining,Wire grid polarizer
更新于2025-09-23 15:21:01
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Filterless frequency octupling circuit using dual stage cascaded polarization modulators
摘要： This paper demonstrates the photonic generation of millimetre-wave carriers by frequency octupling of a radio frequency (RF) carrier using a circuit with two parallel arms each containing two polarization modulators in series. The low RF drive power required and the absence of optical filters make this architecture suitable for generating highly stable and tunable optical millimetre-waves. A transfer function representation is used to analyse the operation and a simulation using Virtual Photonic Inc. software package is presented as a proof of concept. The simulation results show very high unwanted optical and electrical side harmonic suppression ratio for a wide range of modulation index compared to the prior art. Further, considering the practical scenario, operating tolerance against the imbalances in the key parameters is established. The unwanted RF sidebands are more than 19 dB and 30 dB below the desired signal power even when a deviation of ±3° is considered in individual RF phase and polarizer angle respectively.
关键词： Optical millimetre wave generation,polarization modulator,frequency octupling,polarizer
更新于2025-09-23 15:19:57
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[IEEE 2018 Asia-Pacific Microwave Conference (APMC) - Kyoto, Japan (2018.11.6-2018.11.9)] 2018 Asia-Pacific Microwave Conference (APMC) - Reconfigurable Metasurface as Microwave Reflectors and Polarization Converters
摘要： An ultrathin metasurface is made reconfigurable through the use of unit cells incorporating voltage-controlled varactor diodes. The phase characteristics of each unit cell are individually controlled for reconfigurability mechanisms. Two main applications are proposed in the domain of microwave devices and antennas. The planar metasurface is illuminated by a primary source and is firstly used as reconfigurable reflector allowing beam steering performances and frequency agility. A second functionality is also demonstrated, where the metasurface is used as a reconfigurable polarizer. Measurements are performed on a fabricated prototype to validate the concept.
关键词： frequency agility,reconfigurable reflector,polarizer,antennas,planar metasurface
更新于2025-09-19 17:15:36
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Polymer dispersed nematic liquid crystal films with conical boundary conditions for electrically controllable polarizers
摘要： Polymer dispersed nematic liquid crystal (PDNLC) ?lms with conical boundary conditions at the LC-polymer interface are considered. The conical surface anchoring with tilt angle 40° initiates forming the axial-bipolar director con?guration inside nematic droplets. This droplet structure exhibits the strong scattering of light polarized parallel to the bipolar axis. In the initial state, the bipolar axes in all droplets are oriented randomly, and therefore PDNLC ?lm scatters a light of any polarization. Electric ?eld applied along the ?lm plane orients the bipolar axes unidirectionally in the whole droplet ensemble, that results in its high polarization-dependent transmittance. Such PDNLC ?lms can be used in the electrically controllable linear polarizers characterized by 89% value of the transmittance for the perpendicular polarized light and high extinction ratio 590:1 at the electric ?eld 0.34 V/μm.
关键词： Light polarizer,Nematic droplets,Polymer dispersed liquid crystal ?lms,Scattering anisotropy,Electro-optics
更新于2025-09-19 17:15:36
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Package structure of polarized white chip-on-board light-emitting diode with high thermal conductivity
摘要： The package structure of high power white chip-on-board (COB) light-emitting diode (LED) is investigated. The temperature-dependent performance of the white COB LED combined with a polymeric wire-grid polarizer film (WGF) is optimized. The optimized packaging structure is with a modified phosphor resin layer encapsulated to blue COB LED and an optically transparent plate deposited on the modified phosphor resin layer. The modified phosphor resin comprises a mixture of yellow phosphor and AlN resin for reducing thermal resistance. Results show that the extinction ratio is 83 and the luminous efficacy is 61.4 lm/W at an input power of 8 W for the polarized white COB LED. Without the WGF, the luminous efficacy of the package structure of the COB LED is 90 lm/W.
关键词： Wire-grid polarizer,Packaging, polarization,Light-emitting diode,Chip-on-board
更新于2025-09-19 17:13:59
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Gate controlled valley polarizer in bilayer graphene
摘要： Sign reversal of Berry curvature across two oppositely gated regions in bilayer graphene can give rise to counter-propagating 1D channels with opposite valley indices. Considering spin and sub-lattice degeneracy, there are four quantized conduction channels in each direction. Previous experimental work on gate-controlled valley polarizer achieved good contrast only in the presence of an external magnetic field. Yet, with increasing magnetic field the ungated regions of bilayer graphene will transit into the quantum Hall regime, limiting the applications of valley-polarized electrons. Here we present improved performance of a gate-controlled valley polarizer through optimized device geometry and stacking method. Electrical measurements show up to two orders of magnitude difference in conductance between the valley-polarized state and gapped states. The valley-polarized state displays conductance of nearly 4e2/h and produces contrast in a subsequent valley analyzer configuration. These results pave the way to further experiments on valley-polarized electrons in zero magnetic field.
关键词： valley polarizer,quantized conduction channels,gate-controlled,Berry curvature,bilayer graphene
更新于2025-09-19 17:13:59
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A Quantum Dot Polarizer for Liquid Crystal Displays with Much Improved Efficiency and Viewing Angle
摘要： In this paper, a down-conversion polarizer with quantum dots (QDs) integrated is designed for liquid crystal displays (LCDs). By a special optical microstructure design between Polyvinyl Alcohol (PVA) and QDs layers, a raise of luminance by nearly 60% can be achieved both in simulation and experiments. In addition, the viewing angle of such a LCD increases from 55° to 130° and the color gamut expands from 72% to 94% National Television Standards Committee (NTSC) standard which implies a broad prospect for this QD polarizer.
关键词： polarizer,liquid crystals,quantum dots,microstructure
更新于2025-09-16 10:30:52
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P‐4.8: High Efficiency Wire Grid Polarizer for Quantum Dot Color Filter LCD
摘要： In quantum dot color filter (QDCF) LCD blue backlight is converted to red/green light separately by red/green quantum dot materials. In cell polarizer is necessary due to the depolarization of quantum dot material. WGP is more promising as in cell polarizer. Therefore it is particularly important to insure the transmittance of blue light as high as possible. In the article, the stacks of WGP and the upper and lower layers were designed to improve the transmittance of blue light. WGP with the upper and lower layers by chemical vapor deposition was fabricated by using nano-imprinting lithography. The blue light transmittance of WGP in the panel without the upper and lower layers was about 24%. We optimized the design of thin film without changing the structure of WGP to make the transmittance to be increased to 40%. Experimental results showed that the proposed design could achieve a fairly high transmittance 39%.
关键词： Wire grid polarizer (WGP),Transmittance,Optical thin film
更新于2025-09-16 10:30:52