معرفی نانو تشدیدگرها در دستگاه آنتن موج‌بر فلز–دی الکتریک–فلز برای میسر نمودن دستکاری اشعه

ABSTRACT Introducing nanoresonators into a metal–dielectric–metal waveguide array to allow beam manipulation

Plasmonic waveguides have attracted tremendous interest from researchers in recent years due to the potential for guiding and manipulating light at deep subwavelength scales [1–3]. As regards guiding surface plasmon waves (SPWs), different photonic elements with a variety of geometries have been introduced and investigated; examples include metallic nanowires [4], metallic nanoparticle arrays [5], V-shaped grooves [6], metal–dielectric–metal (MDM) waveguides [7–13], and so on. Among these, the MDM waveguide is considered to be a particularly key element in the fields of waveguide couplers [7, 8], subwavelength scale light confinement [9–11] and integrated optical devices [12, 13]. One of the most interesting areas relating to MDM waveguides, which has been the subject of several recent papers, is the construction of waveguide–cavity systems by side-coupling a stub resonator, consisting of an MDM waveguide of finite length, to an MDM waveguide [14–23].

The MDM waveguide and MDM stub resonators have deep subwavelength widths, so only the fundamental TM mode is propagating. Thus, one can use transmission line theory or scattering matrix theory to account for the behavior of the system. In addition, channel drop filters with disc resonators [24], rectangular geometry resonators [25, 26] and ring resonators [24, 27] have been proposed; the positions of transmission peaks can be easily modulated by changing the parameters of the ring, and thus the aforementioned structures can be used in band-pass and stop-band filters.

Recently, positional modulation through use of a metallic slit array was demonstrated numerically and experimentally [28–30]. In this paper, we extend the previous studies and examine ways of controlling the phase front of the transmitted beam by introducing stubs and circular ring-shaped resonators. The position of the constructive interferences of the decoupled EM waves transmitted through the MDM waveguide array depends strongly on the phase delay profile, and is expressed as a beam modulation effect. With different combinations, multi-beam splitting has been demonstrated through numerical calculation. When the resonator is filled with nonlinear material, the radiation direction and focal length can be changed by varying the intensity of the incident light. Making the appropriate choice of parameters, the proposed structure can be fabricated by focused ion beam (FIB) techniques and there is no need to change the period of the array, or the length and width of the slits.