Activation of the polyvalent functionality for the optical filters using metamaterials

A multifunctional filtering structure has been obtained, where the filter character can be changed by redirecting the propagating wave through one path of the module or another. A metamaterial with constituents of tens to hundreds of nanometers for filtering in visible and infrared range was used, where commutation was done by interchanging the module pins of the filter connected to a multimode optical fiber. Metamaterial structure was synthesized using simulation methods with HFSS. Structure was reproduced at nanoscopic level in order to model the resonant propagation phenomena of the plasmons. Metal / dielectric constituents have been considered, in complementary geometrical configurations. The S parameters at the field propagation have been obtained in a range of 400 – 1000 nm. Different domains of their evolution in function of wavelength can be extended by adjusting the geometrical parameters of the structure. The optimal geometry for a specific filtering effect (broadband / narrow band / stop band) was set. The Drude-Lorentz model was used to calculate the resonant frequency of the filter with periodic spatial structure. A more reliable model for the real sample has been exploited for simulations

I. Introduction

Optical filters with metamaterials have usually one basic function, depending on the frequency range where the propagation coefficients present a maximum or minimum [1], [4]. We intended to obtain a multifunctional filtering structure, where the filter character can be changed by redirecting the propagating wave through one path of the module or through another path. Considering that the constituents of the metamaterial have dimensions of tens to hundreds of nanometers for filtering in visible and infrared range, commutation can be a matter of varying the incident angle of the propagating wave using a multimode optical fiber, coupled to the modular filtering structure. Waves with different frequencies were thus sent to the metamaterial filter, where these waves are filtered in function of which filter type was set.