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[IEEE 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz 2018) - Nagoya (2018.9.9-2018.9.14)] 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Intense THz Source of Sub-Cycle Pulses with Tunable Elliptical Polarization
摘要： We propose a new THz source based on a large aperture photoconductive antenna for the generation of intense THz waves with tunable elliptical polarization. We designed an interdigitated structure with vertical and horizontal electrodes to produce half-cycle THz pulses with horizontal and vertical polarizations, respectively. A time delay between the two polarizations is introduced using a quartz window deposited onto the parts of the antenna with horizontal electrodes forming a phase mask. We demonstrate the generation of sub-cycle THz pulses with tunable elliptical polarization and a 70 kV/cm electric field. We show that the polarization state can be varied from linear to quasi-circular.
关键词： elliptical polarization,photoconductive antenna,sub-cycle pulses,THz source,tunable polarization
更新于2025-09-23 15:22:29
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Polarization-Dependent Lateral Optical Force of Subwavelength-Diameter Optical Fibers
摘要： It is highly desirable to design optical devices with diverse optomechanical functions. Here, we investigate lateral optical force exerted on subwavelength-diameter (SD) optical fibers harnessed by input light modes with different polarizations. It is interesting to find that input light modes of circular or elliptical polarizations would bring about lateral optical force in new directions, which has not been observed in previous studies. By means of finite-difference time-domain (FDTD) simulations, detailed spatial distributions of the asymmetric transverse force density are revealed, meanwhile dependence of optical force on input light polarizations, fiber diameters, and inclination angles of fiber endfaces are all carefully discussed. It is believed that polarization-sensitive reflection, refraction, and diffraction of optical fields occur at the interface, i.e., fiber oblique endfaces, resulting in asymmetrically distributed optical fields and thereafter non-zero transverse optical force. We believe our new findings could be helpful for constructing future steerable optomechanical devices with more flexibility.
关键词： circular polarization,elliptical polarization,optical force,subwavelength-diameter optical fiber
更新于2025-09-12 10:27:22
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Characteristics of Radiation from a Microstrip Antenna on a Substrate Made of a Chiral Metamaterial
摘要： We present a method for electrodynamic analysis of a microstrip antenna on a substrate made of a chiral metamaterial. Singular integral representations of the components of the electric ?eld radiated by such an antenna are presented. A singular integral equation with the Cauchy singularity is obtained, which allows determining the function of the current-density distribution over the antenna surface. The dependences of the magnitude and phase of the electric-?eld components on the coordinates and the radiation patterns of the antenna are calculated. It is shown that the electromagnetic waves radiated by such an antenna have the elliptical polarization.
关键词： electrodynamic analysis,singular integral equation,chiral metamaterial,elliptical polarization,microstrip antenna
更新于2025-09-10 09:29:36