Low-loss resonant modes in deterministically aperiodic nanopillar waveguides

TL;DR

This paper demonstrates that quasiperiodic and fractal nanopillar waveguides can support high-Q resonant modes with enhanced directional emission, promising improved integration in photonic circuits.

Contribution

It introduces the use of Fibonacci and Cantor aperiodic nanopillar waveguides with high Q-factors and directional emission, advancing photonic integration technology.

Findings

Resonant modes with Q-factors comparable to defect resonators.

Preferential emission into the waveguide direction.

Enhanced coupling with external dielectric waveguides.

Abstract

Quasiperiodic Fibonacci-like and fractal Cantor-like single- and multiple-row nanopillar waveguides are investigated theoretically employing the finite difference time domain (FDTD) method. It is shown that resonant modes of the Fibonacci and Cantor waveguides can have a Q-factor comparable with that of a point-defect resonator embedded in a periodic nanopillar waveguide, while the radiation is preferably emitted into the waveguide direction, thus improving coupling to an unstructured dielectric waveguide located along the structure axis. This is especially so when the dielectric waveguide introduces a small perturbation in the aperiodic structure, breaking the structure symmetry while staying well apart from the main localization area of the resonant mode. The high Q-factor and increased coupling with external dielectric waveguide suggest using the proposed deterministically aperiodic nanopillar waveguides in photonic integrated circuits.