Authors: X. Vidal, A. Baev, E.P. Furlani, P.N. Prasad
Affilation: The Institute for Lasers, Photonics and Biophotonics, United States
Pages: 611 - 614
Keywords: metamaterial, waveguide, de-multiplexing
In this presentation, we propose a novel metamaterial-based waveguide coupler for use as a de-multiplexer at telecommunication wavelengths. Currently, there have been relatively few studies of guided modes in left-handed waveguides; these have indentified some unique properties including the non-existence of a fundamental mode, the double degeneracy of modes and the existence of modes with zero energy flux. For many applications of negative index materials (NIMs) such as lenses and prisms, the narrow bandwidth that is characteristic of resonant-based NIM behavior can be a critical limiting factor, especially when a broadband response is needed. However, limited NIM bandwidth is useful and desired for applications like filtering and multiplexing/de-multiplexing. In this presentation, we discuss a theoretical study of such an application, where a narrow NIM dispersion relation enables efficient de-multiplexing of up to three closely lying telecommunication frequencies. It should be noted that the only way to de-multiplex more than two wavelengths in a single step is to use angularly dispersed devices, which are not well suited for integrated electronics. The proposed waveguide coupler consists of coupled dielectric microchannel waveguides, one of which has a dispersive core with an index of refraction that is negative within a narrow frequency band at telecommunication wavelengths. We study the near field coupling between the waveguides and demonstrate that an effective de-multiplexing of an input signal can be realized at telecommunication wavelengths. We use full-wave electromagnetic analysis to demonstrate that the proposed coupler, with positive/negative dispersion of the refractive index of the output waveguiding component, is an efficient ultra-compact de-multiplexer of more than two telecommunication frequencies. The narrow-band resonant response of state-of-the-art metamaterials is an advantage for this application. We demonstrate that the coupler is well suited for integrated circuitry and holds potential for multiwavelength de-multiplexing.