Generation of a two-dimensional limited-diffraction beam with self-healing ability by annular-type photonic crystals

Abstract

In this work, we present the design of a photonic structure for the generation of in-plane two-dimensional (2D) limited-diffraction beam. We have numerically investigated the characteristics of the light propagation passing through a 2D square-lattice annular-type photonic crystal shaped in an axicon configuration. Careful selection of the operating frequency as well as the optimization of the apex rod position creates a less diffracted beam whose transverse intensity profile closely resembles a zero-order Bessel function. The created beam dramatically resists against the spatial spreading over a propagation distance of 50 μm, after focusing with a spot size of ∼0.23 μm. The self-healing capability of the generated limited-diffraction beam is demonstrated by placing obstacles with different sizes and shapes along the optical axis. The two features that accompany with such beams, i.e., diffraction-limited propagation and reconstruction ability after encountering obstructions, may strengthen its usage in manipulation of light propagation in various environments.