Compressing and routing light through a silicon nanorod array

Abstract

Over the past two decades, great efforts have been made in the study of routing and manipulating light waves at the subwavelength scale with open nanostructures such as photonic crystal waveguides (PCWs), surface plasmon waveguides (SPWs), and coupled resonator optical waveguides (CROWs), for their great potential in many photonic technologies such as highly integrated photonic signal-processing systems and sensors. To date, however, there have been some significant challenges for the open nanostructures in application, i.e., PCWs have relatively large sizes and complex structures, SPWs have large unavoidable metallic losses, and CROWs are disorder-sensitive and frequency-sensitive. Recently, we propose a new platform for the design of open nanostructures. Based on the flat form, we design an open nanostructure composed of a periodic subwavelength-nanoparticles chain, which is simple, ultrathin, compact, and can be compatible with CMOS. Our ultrathin open nanostructure provides a strong function not only in routing light at the subwavelength scale, but also in sharply bending and/or splitting light beams below the diffraction limit, exhibiting low-loss, broadband, incident-angle-insensitive, and robust against disorder. Experimental and numerical observations validate our findings.