Experimental demonstration of guiding, bending, and filtering of electromagnetic wave in disordered photonic band gap materials

Abstract

Abstract:We report the first experimental demonstration of guiding, bending, filtering, and splitting of EM wave in 2D disordered PBG materials, along arbitrarily curved paths, around sharp bends of arbitrary angles, and through Y shape junctions.©2012 Optical Society of America OCIS codes: 130.5296, 130.7408, 160.5293, 160.5298 Line defects in photonic band gap (PBG) materials can confine and guide light through narrow channels and around sharp corners, which is important for large scale all-optical circuit applications [1]. An enormous range of technological developments in telecommunication industry, laser engineering, optical computing, spectroscopy, and radiation, have been suggested, when light with selected frequencies can be directed along chosen paths or be confined within a specific volume in PBG materials [2]. Conventional PBG materials are periodic structures, in which only limited numbers of rotational symmetries are allowed. Angular differences make it difficult to form a complete PBG in periodic structures without a large dielectric contrast. The orientations of channels cut in photonic crystals for light guiding are also restricted by the crystal symmetries, limiting potential applications.Contradicting the long standing intuition that periodicity or long-range translational order is required in photonic band gap formation, a new class of disordered hyperuniform (HPU) materials was predicted to possess sizeable and isotropic photonic band gaps [3]. Recently, we have experimentally observed isotropic PBG in these disordered materials [4]. In these isotropic disordered structures there are no preferential symmetry directions; hence it becomes possible to construct wave-guiding and filtering channels with arbitrary bending angles in them.In this paper, we report the first experimental demonstrations of guiding, bending, filtering, and splitting of electromagnetic wave in 2D isotropic disordered PBG materials, along straight or arbitrarily curved paths, around sharp bends of arbitrary angles, and through Y shape junctions. We demonstrate broad band pass through channels of various shapes, as well as versatile and flexible defect tuning abilities for narrow band filtering, in these disordered PBG materials. In our study, nearly 100 percent transmission of electromagnetic waves around sharp corners of arbitrary angles with bending radii smaller than one wavelength is observed experimentally.The 2D isotropic HPU disordered PBG material constructed for this study consists of a network of Al 2 O 3 cylinders and thin sheets.. Each cylinder has three nearest neighbors to which it is connected by sheets. The cylinders are particularly important for forming PBG for the TM polarization, while the connected sheets are important for the TE polarization. There is neither Bragg scattering nor long range order in this structure. It was argued that hyperuniformity, combined with uniform local topology and short-range geometric order can explain the origin of PBGs in these disordered materials [3]. The PBGs are as...

Hyperuniform Disordered Solids with Morphology Engineering

“…Moreover, HUDS devices can support wider PBGs with superior features, such as polarization independence to the top incident light, [12,20] compact device footprints, [21] and temperature insensitivity. [22] To date, photonic devices based on HUDS have been explored for the development of waveguides, [23][24][25] cavities, [23,26] polarizers, [21,27,28] stealthy devices, [29,30] and lasers. [31] To improve the PBGs and light confinement features of HUDS, several methods have been developed in the past few years, namely, the point distribution optimization method [12,32] and the structure coefficient optimization method.…”