All-Angle Broadband Negative Refraction of Metal Waveguide Arrays in the Visible Range: Theoretical Analysis and Numerical Demonstration

Abstract

In this Letter, we introduce a simple metal waveguide array for realizing all-angle wide frequency bandwidth negative refraction from the visible to infrared frequencies. Theoretical analysis from the rigorous coupled-wave theory reveals that the negative coupling constant resulting from the anomalous coupling of guided surface plasmon polariton modes contributes to the negative refraction. The analytical results are confirmed by finite-difference time-domain numerical simulations. Our result provides an alternative way to construct robust all-angle negative refractive materials operating in a wide range of frequency from the near-infrared to the visible range. DOI: 10.1103/PhysRevLett.97.073901 PACS numbers: 42.82.Et, 42.25.ÿp, 73.20.Mf, 78.67.ÿn The negative-refraction (NR) effect [1] has currently attracted considerable interest because it underlays the foundation of a variety of new potential applications [2] and the possibility of investigating extraordinary electromagnetic wave propagation phenomena [3]. It has been demonstrated theoretically and experimentally that both left-handed metamaterials [4 -7] and photonic crystals [8][9][10][11][12][13][14][15] can achieve NR from microwave to near-infrared frequencies. Furthermore, all-angle NR (AANR) for lens imaging at microwave frequencies by metamaterials [16,17] and at optical frequencies by photonic crystals [18,19] has also been demonstrated recently, but the operating bandwidth is still limited in a narrower frequency range [16 -19], and the realization of broadband AANR at an optical frequency, especially in the visible region, is still a challenge.Generally speaking, a periodic structure is capable of producing NR for electromagnetic waves. For example, a simple dielectric waveguide array can bend light in the direction opposite to that observed in common media at a limited incident angle within a narrow frequency bandwidth [20,21]. However, less attention was paid to its metallic counterparts, especially the nanoscale ones [22], until a very recent exploration that nanoscale metal waveguide arrays (MWGAs) show an interesting lens effect at a fixed optical wavelength [23]. In this Letter, we will reveal that nanoscale MWGAs can actually achieve AANR over a wide frequency bandwidth from visible to infrared ranges. We show the NR effect by the coupled-wave theory and further establish the effect by finite-difference timedomain (FDTD) numerical simulations. Further analysis on the conditions for AANR implies that MWGAs are suitable for visible wavelength operation in a wide bandwidth. We attribute the NR effect to coupling of propagating surface plasmon polaritons (SPPs) among the adjacent guides.Our work begins with the analysis of a simple discrete system containing two adjacent two-dimensional (2D) metal waveguides by a rigorous field analysis approach, where linear coupling of propagating SPPs in the guides is considered. The structure is schematically drawn in Fig. 1(a); h is the guide width and d is the thickness of the metal film. " 1 >0 and ...

Are negative index materials achievable with surface plasmon waveguides? A case study of three plasmonic geometries

“…This characteristic renders planar waveguides particularly useful for on-chip applications, where optical components are interconnected in-plane. However, plasmonic waveguides can also potentially serve as basic elements of fully three-dimensional metamaterials, when arranged in stacked geometries [17,20].…”

Electromagnetic Response and Broadband Utilities of Planar Metamaterials

“…8 (a)], giving rise to all-angle negative refraction. We note that the silver/dielectric multilayered structure also supports all-angle negative refraction in a certain optical frequency regime under the same incidence configuration of our study (Fan, Wang et al 2006). The long range SPPs play an important role for the negative refraction.…”

Bloch Oscillations of Surface Plasmon-Like Modes in Waveguide Arrays That Comprise Perforated Perfect Conductor Layers and Dielectric Layers

“…Finally, the beam reaches the point (x c , 0.0) again, having completed one Bloch cycle. The beam moves in the opposite direction to k x , implying that the structure has an effective (transverse) negative refraction index [5,27]. The permittivity gradient of the dielectric layers in the waveguide arrays drives the beam.…”

“…However, the mutual interaction between the electromagnetic fields on both surfaces causes the SPs to split into even and odd modes. In metal-dielectric waveguide arrays (MDWAs), since the evanescent electromagnetic fields of neighboring MDM waveguides couple with each other, SPs exhibit complexly collective behaviors, including beam focusing and diffraction [3,4], effective negative refraction [5] and Bloch oscillation [6,7], among others.…”