Experimental demonstration in X-band of dual-negative refraction in photonic crystals

¹ College of Materials Science and Opto- Electronic Techology, University of Chinese Academy of Sciences Beijing 100049, China
² State Key Lab of New Ceramics and Fine Processing, Department of Materials Science and Engineering, Tsinghua University - Beijing 100084, China
³ Department of Optics, Shandong University - Jinan 250100, China

^(a) gydong@ucas.ac.cn
^(b) zhouji@tsinghua.edu.cn

Received: 3 September 2013
Accepted: 3 November 2013

Abstract

The effect of dual-negative refraction (DNR) in a photonic crystal (PhC) is demonstrated experimentally in X-band (8–12 GHz) for the first time. The two-dimensional PhC sample is made of highly pure Al₂O₃ ceramic cylinders close packed in air with a triangular lattice structure. The frequency regions of DNR are predicted by the analyses of wave vector diagrams. Experiments of anomalous refraction in PhCs are carried out in a near-field scanning system to demonstrate the theory and numerical results. The experimental measurements of electric field (real part and spatial intensity) for DNR are in good agreement with the numerical simulations. This work demonstrates that the unique feature of photonic crystals can be realized experimentally in different frequency regions which are proportional to the lattice constant of the PhC. Due to the large design flexibility, we believe this result will be promising for application in the range of optical devices.