Enhanced terahertz magnetic dipole response by subwavelength fiber

Abstract

Dielectric sub-wavelength particles have opened up a new platform for realization of magnetic light. Recently, we have demonstrated that a dipole emitter by a subwavelength fiber leads to an enhanced magnetic response. Here, we experimentally demonstrate an enhanced magnetic dipole source in the terahertz frequency range. By placing the fiber next to the hole in a metal screen, we find that the radiation power can be enhanced more than one order of magnitude. The enhancement is due to the excitation of the Mie-type resonances in the fiber. We demonstrate that such a system is equivalent to a double-fiber system excited by a magnetic source. This coupled magnetic dipole and optical fiber system can be considered a unit cell of metasurfaces for manipulation of terahertz radiation and is a proof-of-concept of a possibility to achieve enhanced radiation of a dipole source in proximity of a sub-wavelength fiber. It can also be scaled down to optical frequencies opening up promising avenues for developing integrated nanophotonic devices such as nanoantennas or lasers on fibers. © 2018 Author (s)

Subwavelength fiber: Enhanced THz Magnetic Source

“…It is shown that a subwavelength aperture can be approximated with a MD source provided that the diameter is less than 0.3l [4]. Using numerical modelling (CST microwave studio), we confirm that a 300µm aperture excited with a x-polarized plane wave acts as a y-oriented MD in THz [4]. Moreover, we have shown that maximum transmission of the hybrid system occurs when the fiber diameter is similar to that of the aperture [4].…”

“…1(a). It is shown that a subwavelength aperture can be approximated with a MD source provided that the diameter is less than 0.3l [4]. Using numerical modelling (CST microwave studio), we confirm that a 300µm aperture excited with a x-polarized plane wave acts as a y-oriented MD in THz [4].…”

“…Using numerical modelling (CST microwave studio), we confirm that a 300µm aperture excited with a x-polarized plane wave acts as a y-oriented MD in THz [4]. Moreover, we have shown that maximum transmission of the hybrid system occurs when the fiber diameter is similar to that of the aperture [4]. For experiments, we have used a THz-TDS system with an Hshape antenna as emitter and a near-field microprobe tip as detector.…”

“…Here, we experimentally demonstrate an enhanced magnetic dipole source for THz radiation. We show that by placing a subwavelength fiber in front of an aperture, which acts as magnetic dipole (MD), can lead into more than an order of magnitude enhancement of radiated power [4].…”

Radiated and guided optical waves of a magnetic dipole-nanofiber system

“…This has led to investigation of MD response in vicinity of nanostructures such as planar structures, nanospheres and metamaterials, using Green function approach 33 . Although enhancement of an MD source at the vicinity of subwavelength fiber has been observed experimentally 38 , there is no analytical model to investigate the interaction of MD in the vicinity of a nanofiber.…”