scholarly journals Wavelength Dependence of the Polarization Singularities in a Two-Mode Optical Fiber

2012 ◽  
Vol 2012 ◽  
pp. 1-7
Author(s):  
V. V. G. Krishna Inavalli ◽  
Vijay Pottapinjara ◽  
Nirmal K. Viswanathan
Keyword(s):  
Optical Fiber ◽  
Edge Dislocation ◽  
Wavelength Dependence ◽  
Experimental Demonstration ◽  
Input Beam ◽  
Left Handed ◽  
Linearly Polarized ◽  
Intermodal Dispersion ◽  
Fiber Output ◽  
Elliptically Polarized

We present here an experimental demonstration of the wavelength dependence of the polarization singularities due to linear combination of the vector modes excited directly in a two-mode optical fiber. The coherent superposition of the vector modes excited by linearly polarized Gaussian beam as offset skew rays propagated in a helical path inside the fiber results in the generation of phase singular beams with edge dislocation in the fiber output. The polarization character of these beams is found to change dramatically with wavelength—from left-handed elliptically polarized edge dislocation to right-handed elliptically polarized edge-dislocation through disclinations. The measured behaviour is understood as being due to intermodal dispersion of the polarization corrections to the propagating vector modes, as the wavelength of the input beam is scanned.

scholarly journals Complete Terahertz Polarization Control with Broadened Bandwidth via Dielectric Metasurfaces

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Dacheng Wang ◽  
Song Sun ◽  
Zheng Feng ◽  
Wei Tan
Keyword(s):  
Polarized Light ◽  
Terahertz Wave ◽  
Circularly Polarized Light ◽  
Transmission Coefficients ◽  
Polarization Control ◽  
Left Handed ◽  
Linearly Polarized ◽  
Huygens Principle ◽  
Elliptically Polarized Light ◽  
Elliptically Polarized

AbstractWe demonstrate terahertz dielectric metasurfaces with anisotropic multipoles within the framework of the generalized Huygens principle, in which the interference among these multipoles achieves giant phase shift with broadened bandwidth and high transmission coefficients. More importantly, owing to the anisotropic design, various phase delays between π/2 and 3π/2 are obtained, which convert the incident linearly polarized terahertz wave into right/left-handed circularly polarized light, elliptically polarized light and cross-polarized light. Both simulation and experimental results verify complete terahertz polarization control with the ellipticity ranging from 1 to − 1, which paves a way for polarization-related applications of terahertz meta-devices.

scholarly journals Complete Terahertz Polarization Control With Broadened Bandwidth via Dielectric Metasurfaces

2021 ◽  
Author(s):  
Dacheng Wang ◽  
Song Sun ◽  
Zheng Feng ◽  
Wei Tan
Keyword(s):  
Polarized Light ◽  
Terahertz Wave ◽  
Circularly Polarized Light ◽  
Transmission Coefficients ◽  
Polarization Control ◽  
Left Handed ◽  
Linearly Polarized ◽  
Huygens Principle ◽  
Elliptically Polarized Light ◽  
Elliptically Polarized

Abstract We demonstrate terahertz dielectric metasurfaces with anisotropic multipoles within the framework of the generalized Huygens principle, in which the interference among these multipoles achieves giant phase shift with broadened bandwidth and high transmission coefficients. More importantly, owing to the anisotropic design, various phase delays between π/2 and 3π/2 are obtained, which convert the incident linearly polarized terahertz wave into right/left-handed circularly polarized light, elliptically polarized light and cross polarized light. Both simulation and experimental results verify complete terahertz polarization control with the ellipticity ranging from 1 to -1, which paves a way for polarization–related applications of terahertz meta-devices.

scholarly journals High-Efficiency Polarizer Reflectarray Antennas for Data Transmission Links from a CubeSat

Electronics ◽  
2021 ◽  
Vol 10 (15) ◽  
pp. 1802
Author(s):  
Eduardo Martinez-de-Rioja ◽  
Daniel Martinez-de-Rioja ◽  
Rafael López-Sáez ◽  
Ignacio Linares ◽  
Jose A. Encinar
Keyword(s):  
Circular Polarization ◽  
Data Transmission ◽  
High Efficiency ◽  
High Gain ◽  
Dual Band ◽  
Left Handed ◽  
Linearly Polarized ◽  
Flat Profile ◽  
First Time ◽  
Collimated Beam

This paper presents two designs of high-efficiency polarizer reflectarray antennas able to generate a collimated beam in dual-circular polarization using a linearly polarized feed, with application to high-gain antennas for data transmission links from a Cubesat. First, an 18 cm × 18 cm polarizer reflectarray operating in the 17.2–22.7 GHz band has been designed, fabricated, and tested. The measurements of the prototype show an aperture efficiency of 52.7% for right-handed circular polarization (RHCP) and 57.3% for left-handed circular polarization (LHCP), both values higher than those previously reported in related works. Then, a dual-band polarizer reflectarray is presented for the first time, which operates in dual-CP in the frequency bands of 20 GHz and 30 GHz. The proposed antenna technology enables a reduction of the complexity and cost of the feed chain to operate in dual-CP, as a linear-to-circular polarizer is no longer required. This property, combined with the lightweight, flat profile and low fabrication cost of printed reflectarrays, makes the proposed antennas good candidates for Cubesat applications.

An automated Rayleigh-wave detection algorithm

1997 ◽  
Vol 87 (1) ◽  
pp. 157-163
Author(s):  
Eric P. Chael
Keyword(s):  
Rayleigh Wave ◽  
High Reliability ◽  
Detection Algorithm ◽  
Arrival Times ◽  
Long Period ◽  
Wave Detection ◽  
Linearly Polarized ◽  
Automated Data Processing ◽  
Component Wave ◽  
Elliptically Polarized

Abstract The desire to operate denser networks in order to monitor seismic activity at lower thresholds leads to greater emphasis on automated data processing. An algorithm for detecting and characterizing long-period Rayleigh-wave arrivals has been developed and tested. The routine continuously monitors all directions of approach to a station, in a manner similar to beamforming. The detector is based on cross-powers between the Hilbert-transformed vertical and rotated horizontal signals, so it is sensitive to both the power and polarization properties of the three-component wave field. Elliptically polarized Rayleigh arrivals are enhanced, while linearly polarized Love waves and body phases are suppressed. A test using one month of data from station ANMO demonstrated that this technique can, with high reliability, detect Rayleigh arrivals that are visible on the records. The measured arrival times and azimuths are accurate enough to permit automated association of the detections to events in a bulletin.

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