Non-Bragg bandgaps of quasi-one-dimensional comb-like structures composed of positive and negative index materials

Abstract

Quasi-one-dimensional comb-like periodic and aperiodic structures composed of positive index materials branch resonators and negative index materials backbone waveguide are physically fabricated by using transmission line approach. It is theoretically shown that the structures possess a non-Bragg band-gap which is invariant with a change of scale length and robust against disorder. The gap edges are determined by zero average permittivity of the branch and the backbone and zero permeability of the backbone materials, respectively. The transmission properties of the structures are investigated by changing the (average) resonator size dBand the resonator spacing dArespectively. The experimental results agree well with the theoretical predictions and numerical simulations, which demonstrate the independence of the special gap on the scaling and disorder in the structures.