scholarly journals Dual-Focuses Metalens for Copolarized and Cross-Polarized Transmission Waves

2018 ◽  
Vol 2018 ◽  
pp. 1-7 ◽  
Author(s):  
Ru Ji ◽  
Kejian Chen ◽  
Yujie Ni ◽  
Yanan Hua ◽  
Kaiwen Long ◽  
...  
Keyword(s):  
Polarization State ◽  
Phase Region ◽  
Imaging Systems ◽  
Orthogonal Polarization ◽  
Frequency Range ◽  
Orthogonal Direction ◽  
Resonator Structure ◽  
Terahertz Communications ◽  
Phase Profile ◽  
Potential Applications

Metasurfaces can reshape the wavefront in the desired manner by manipulating the phase profile and amplitude of the incident wave. In this paper, we demonstrate an ultrathin terahertz metalens based on our designed resonator structure, where the polarization state can be converted to the orthogonal direction and the parabolic phase profile is designed covering a 2π phase region. Many functional metalenses are also engineered to meet the demand of focusing, dual-polarization confocal, and dual focuses for orthogonal polarization in the frequency range from 0.65 to 0.8 THz. The presented metalenses can provide potential applications in terahertz communications and imaging systems.

scholarly journals Design and experimental analysis of dual-band polarization converting metasurface for microwave applications

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Bilawal Khan ◽  
Babar Kamal ◽  
Sadiq Ullah ◽  
Imran Khan ◽  
Jawad Ali Shah ◽  
...  
Keyword(s):  
Electromagnetic Waves ◽  
Polarization State ◽  
Plane Waves ◽  
Microwave Frequency ◽  
Dual Band ◽  
Orthogonal Polarization ◽  
Frequency Bands ◽  
Practical Applications ◽  
Sensor Applications ◽  
Polarized Waves

Abstract The manipulation of polarization state of electromagnetic waves is of great importance in many practical applications. In this paper, the reflection characteristics of a thin and dual-band metasurface are examined in the microwave frequency regime. The metasurface consists of a 22 × 22 element array of periodic unit cells. The geometry of the unit cell consists of three layers, including a 45° inclined dipole shape metal patch on top, which is backed by a 1.6 mm thick FR-4 substrate in the middle, and a fully reflective metallic mirror at the bottom. The proposed surface is exposed to horizontally (x) or vertically (y) polarized plane waves and the co and cross polarization reflection coefficients of the reflected waves are investigated experimentally in the 6–26 GHz frequency range. The metasurface is designed to convert incident waves of known polarization state (horizontal or vertical) to orthogonal polarization state (vertical and horizontal) in two distinct frequency bands, i.e. 7.1–8 GHz and 13.3–25.8 GHz. In these two frequency bands the simulated and experimental results are in good agreement. The polarization conversion ratio (PCR) of the surface is greater than 95% in the targeted frequency bands. A detailed parametric analysis of the metasurface is also discussed in this work and it has been estimated that the surface has the additional ability to convert linearly polarized waves to circularly polarized waves at several distinct frequencies. The proposed metasurface can be utilized in sensor applications, stealth technology, electromagnetic measurements, and antennas design.

Research on Relationship of Polarization and Rayleigh Backscatter in Bidirectional Fiber Communication Systems

2013 ◽  
Vol 312 ◽  
pp. 625-630
Author(s):  
Yan Hong Wang ◽  
Gao Wang ◽  
Ji Liu
Keyword(s):  
Communication Systems ◽  
Polarization State ◽  
Single Mode ◽  
Single Mode Fiber ◽  
Light Polarization ◽  
Polarization Property ◽  
Orthogonal Polarization ◽  
Fiber Communication ◽  
Order Of Magnitude ◽  
Relationship Of

In this paper, the general theory and polarization property of RB in single mode fiber is discussed. According to the theoretical analysis results, the bidirectional carrying system with a polarization rotating device for analog radio frequency (RF) signal is set up. The relationship of the system CRN and the different polarization state by the polarization rotating device is studied. The results show that the RB light polarization state of backward fiber end can keep to perpendicular to that of forward light when backward lights polarization is orthogonal forward lights polarization. So utilizing orthogonal polarization method for decreasing CRN can be carried on. The system performance is analyzed by simulation. The simulation results show that CRN of the bidirectional communication system on a single mode fiber can be inhibited by using the method and RB light can decrease by an order of magnitude.

scholarly journals Polarization-Independent Metasurface Lens Based on Binary Phase Fresnel Zone Plate

Nanomaterials ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 1467
Author(s):  
Xing Li ◽  
Jing Tang ◽  
Jonathan Baine
Keyword(s):  
Fresnel Zone ◽  
Incident Light ◽  
Polarization State ◽  
Zone Plate ◽  
Visible Range ◽  
Fresnel Zone Plate ◽  
Binary Phase ◽  
Nanophotonic Devices ◽  
Potential Applications ◽  
Polarization Independent

Based on the binary phase Fresnel zone plate (FZP), a polarization-independent metasurface lens that is able to focus incident light with any polarization state, including circular, linear, and elliptical polarizations, has been proposed and investigated. We demonstrate that the metasurface lens consisting of metal subwavelength slits can operate in a wide bandwidth in the visible range, and has a higher focusing efficiency than that of an amplitude FZP lens without phase modulation. A multi-focus FZP metasurface lens has also been designed and investigated. The proposed lens can provide potential applications in integrated nanophotonic devices without polarization limitations.

scholarly journals Polarization Holography in 3-Indoly-Benzylfulgimide/PMMA Film

2011 ◽  
Vol 2011 ◽  
pp. 1-20 ◽  
Author(s):  
Neimule Menke ◽  
Baoli Yao ◽  
Yingli Wang ◽  
Yi Chen
Keyword(s):  
Polarization State ◽  
Polymeric Films ◽  
Holographic Recording ◽  
Orthogonal Polarization ◽  
Pmma Film ◽  
Holographic Storage ◽  
Polarization Holography ◽  
Photochromic Compounds ◽  
Storage Media ◽  
Properties Of Materials

The photochromic and photoanisotropic properties of materials can be used in ordinary and polarization holographic recording respectively. Fulgides are well known as thermally irreversible organic photochromic compounds. And it is found that there exists photoinduced anisotropy in fulgide-doped polymeric films. In this report, a 3-indoly-benzylfulgimide/PMMA film was studied as a holographic storage media. First, the spectra and dynamics of photochromic and photoanisotropic properties of the sample are measured or calculated. Second, the diffraction efficiency (DE) dynamics at 633 nm of four kinds of different polarization holograms recorded in this sample are measured. The maximum DE value about 1% was gotten. Third, the DE spectra and DE dynamics are theoretically calculated in detail, and a good correlation of theoretically derived DE dynamic curves and the measured experimental curves was found. From the DE spectra, it is known that at the wavelengths less than 450 nm or greater than 700 nm, the nondestructive reading can be realized. The DWPS obtained in the experiments are same with the theortically deduced ones, which shows that in the orthogonal polarization holography, the polarization state of the diffracted light is orthogonal to that of the reconstruction light, which is very important to increase the SNR of the holographic storage. And all these results are applied and proved to be correct in high-density holographic image storage experiment. The area density of 2×108 bits/cm2 was obtained, and the encoded data was retrieved without error.

MANIPULATING THE POLARIZATION OF TERAHERTZ WAVES WITH METAMATERIAL DEVICES

2014 ◽  
Vol 02 (02) ◽  
pp. 1440008 ◽  
Author(s):  
LONGQING CONG ◽  
JIANQIANG GU ◽  
ZHEN TIAN ◽  
RANJAN SINGH ◽  
JIAGUANG HAN ◽  
...  
Keyword(s):  
Polarization State ◽  
Terahertz Waves ◽  
Optical Components ◽  
Polarization Control ◽  
Design Flexibility ◽  
Potential Applications ◽  
Excellent Control ◽  
Terahertz Frequencies ◽  
Control Devices ◽  
Increasing Demand

As the potential applications of terahertz science and technology become extremely important, there is an increasing demand for improved terahertz optical components. One of such devices on demand is the class of polarization control devices. Recently, metasurfaces have emerged as designer structures with excellent control, design flexibility, and multifaceted functionalities. Metamaterials offer fascinating prospects for manipulating the polarization state of terahertz waves. Here, we discuss different metamaterial device designs that exhibit properties of perfect linear polarization rotation and linear to either linear or circular polarization conversion at narrowband as well as broadband terahertz frequencies.

scholarly journals Resonator-free tunable sub-MHz spectral dip in the Brillouin gain using spun birefringent fibers

2021 ◽  
Author(s):  
Neel Choksi ◽  
Yi Liu ◽  
Rojina Ghasemi ◽  
Li Qian
Keyword(s):  
Slow Light ◽  
Spectral Feature ◽  
Gain Spectrum ◽  
Orthogonal Polarization ◽  
Signal Loss ◽  
Pump Frequency ◽  
Resonant Structures ◽  
Wide Range ◽  
Potential Applications ◽  
Brillouin Gain

Abstract Ultra-narrow spectral features are desirable for a broad range of applications, and they are conventionally realized using ultrahigh Q resonant structures. These structures typically require precision fabrication processes, and moreover, since they are passive, they suffer from signal loss. Here, we demonstrate a novel way to achieve sub-MHz tunable spectral dip in the Brillouin gain spectrum of a spun birefringent fiber (SBF) without loss, and without using a resonator. We show that this dip is unique to SBF, where its polarization eigenmodes are elliptical and frequency-dependent, and the dip only occurs when these orthogonal polarization eigenmodes of the SBF (at the respective pump and signal frequencies) are launched in counter-propagating directions. We experimentally demonstrate a 0.72 MHz spectral dip in the Brillouin gain spectrum of a commercial SBF which is to our knowledge, the narrowest SBS spectral feature ever reported. Furthermore, the linewidth, depth, and spectral location of this dip are tunable on demand by controlling the pump frequency, pump power, and the input polarization of the signal. Its simplicity in implementation, its ultra-narrow linewidth, and its tunability can have a wide range of potential applications, from slow-light to microwave photonics.

scholarly journals Numerical investigation and Comparative analysis of tunable graphene-gold metasurface based polarizer structures for infrared frequency

2021 ◽  
Author(s):  
Vishal Sorathiya ◽  
shobhit patel
Keyword(s):  
Comparative Analysis ◽  
Incident Wave ◽  
Fermi Energy ◽  
Polarization Effect ◽  
Phase Variation ◽  
Basic Building Block ◽  
Frequency Range ◽  
Resonator Structure ◽  
Wide Range ◽  
Different Shapes

Abstract We present the comparative analysis of tunable graphene-based metasurface polarizer structure THz frequency range. This polarizer structures have been numerically investigated over the 10 THz to 25 THz of the frequency range. Reflectance co-efficient, phase variation, and phase difference parameters have been investigated to identify the behavior of polarization effect over the range of 10 THz to 25 THz of the frequency. The proposed polarizer has been also investigated for the different shapes of the top gold resonator structure. The proposed structure is tunable for the range of 0.1 eV to 0.9 eV of the graphene Fermi energy. The proposed structure also works on the wide range of the input incident wave of the X and Y polarization. This structure having small, compact tunable design and it can be used as a basic building block in the large THz circuits and structures.

scholarly journals Spectral EEG Features of a Short Psycho-physiological Relaxation

2014 ◽  
Vol 14 (4) ◽  
pp. 237-242 ◽  
Author(s):  
Michal Teplan ◽  
Anna Krakovská ◽  
Marián Špajdel
Keyword(s):  
Time Course ◽  
Total Power ◽  
Frequency Range ◽  
Eyes Closed ◽  
Beta Power ◽  
Eeg Data ◽  
Physiological Relaxation ◽  
Potential Applications ◽  
Minute Duration ◽  
Eeg Features

Abstract Short-lasting psycho-physiological relaxation was investigated through an analysis of its bipolar electroencephalographic (EEG) characteristics. In 8 subjects, 6-channel EEG data of 3-minute duration were recorded during 88 relaxation sessions. Time course of spectral EEG features was examined. Alpha powers were decreasing during resting conditions of 3-minute sessions in lying position with eyes closed. This was followed by a decrease of total power in centro-parietal cortex regions and an increase of beta power in fronto-central areas. Represented by EEG coherences the interhemispheric communication between the parieto-occipital regions was enhanced within a frequency range of 2-10 Hz. In order to discern between higher and lower levels of relaxation distinguished according to self-rated satisfaction, EEG features were assessed and discriminating parameters were identified. Successful relaxation was determined mainly by the presence of decreased delta-1 power across the cortex. Potential applications for these findings include the clinical, pharmacological, and stress management fields.

LIQUID CRYSTAL BASED ROTATING ORTHOGONAL POLARIZATION IMAGING SYSTEM

2009 ◽  
Vol 02 (03) ◽  
pp. 245-251 ◽  
Author(s):  
QUN ZHU ◽  
IAN M. STOCKFORD ◽  
JOHN A. CROWE ◽  
STEPHEN P. MORGAN
Keyword(s):  
Liquid Crystal ◽  
Imaging System ◽  
Polarization State ◽  
Ease Of Use ◽  
Orthogonal Polarization ◽  
Clinical Use ◽  
Scattering Medium ◽  
Scattering Media ◽  
Polarization Imaging ◽  
Manual Rotation

Rotating orthogonal polarization imaging provides images of the polarization properties of scattering media which are free from surface reflections. Previously the technique has been demonstrated using manually rotated Glan–Thompson polarizers to control and analyze the polarization state of the light entering and emerging from the tissue. This paper describes a system that performs these functions using liquid crystal retarders. The system is tested using a polarizing target embedded within a scattering medium and is compared with Monte Carlo simulations. The results compare well with those obtained with manual rotation of polarizers. The liquid crystal based approach has advantages over the previous system in terms of ease of use, speed, and repeatability and is therefore an important step towards taking the technique into routine clinical use.

Mechanoreceptors for near-field water displacements in crayfish

1976 ◽  
Vol 39 (4) ◽  
pp. 816-833 ◽  
Author(s):  
K. Wiese
Keyword(s):  
Near Field ◽  
Hair Shaft ◽  
The Body ◽  
Sensory Cells ◽  
Lateral Line System ◽  
Frequency Range ◽  
Behavioral Experiments ◽  
Orthogonal Direction ◽  
Line System ◽  
Morphological Studies

1. Mechanosensory hairs on the surface of the crayfish telson are dually innervated, one sensory cell responding to headward, the other to tailward deflection of the hair. The average conduction velocity of headward elements was 0.8 m/s (variance 0.08) and of tailward elements 1.2 m/s (variance 0.19). In a frequency range from 0.05 to 200 Hz, thresholds were lowest near 20 Hz: 0.08 mum (pp) for headward-sensitive and 0.1 mum (pp) for tailward-sensitive cells. 2. The receptors are displacement sensitive since thresholds are of the same order of magnitude over the frequency range 1-70 Hz when the hair is moved by a vibrating wire loop. With natural stimuli (surface waves), the velocity component of the particle movement (and consequently force) becomes influential. The coding of a broad range of stimulus intensities is aided by variations in mechanical properties of the hair. 3. Marked directionality (better than 4:1), in addition to the dual innervation, enhances vector detection. At least part of this characteristic stems from the hingelike articulation of the hair on the body surface: the hair can be moved easily 40 degrees tailward and 20 degrees headward, but must be forced in the orthogonal direction. Morphological studies indicate the presence of a double pivoted hinge, with rigid guides for movement of the hair shaft. Preliminary results of electron microscope examination show a clearly polarized arrangement of densely packed microtubules in the two dendrites; they appear interconnected in groups of two and three along a line parallel to the sensitivity plane of the receptor. 4. The 50-fold threshold difference between the results of behavioral experiments in lobsters (24) and the data for the individual receptors reported here may be due to improvement in signal-to-noise ratio by central nervous averaging of the input from an estimated 2 X 10(3) receptors (Procambarus), and/or to the kind of threshold criteria applied to individual receptor thresholds. As would be expected (35), the sensory cells of each directional class synapse with separate interneurons: in this way, the organism might employ differential microphones to reduce background noise. 5. The receptors are analogous to those of the lateral-line system in lower vertebrates in having receptors with sensitivities polarized by 180 degrees. These similarities suggest that in both cases monitoring of near field water displacements has proved in essential way of orienting in opaque waters.

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