Coupling between localized resonance and excitation of surface waves in metal hole arrays

Abstract

We investigate the transition of the dominant resonant transmission mechanism from localized resonance to excitation of surface waves and vice versa in metal hole arrays. The transition occurs continuously with a change in the length of the rectangular holes. We also study the effect of the incident-beam diameter and surface condition on the transmission spectrum. Our experimental results show the important differences between the two mechanisms. They also confirm the theoretical prediction of Bravo-Abad et al. ͓Phys In the last few decades, several studies have investigated resonant transmission properties of electromagnetic waves in metal hole arrays ͑MHAs͒. In 1967, Ulrich 1 reported the band-pass transmission characteristics of MHAs and attributed them to the excitation of surface waves ͑ESWs͒, known as Zenneck waves, in the radio-frequency region; these waves are analogous to surface-plasmon polaritons ͑SPPs͒ in the visible region.2 Later, Ebbesen et al. 3 conducted a study similar to that of Ulrich and demonstrated that subwavelength MHAs exhibit extraordinary transmission characteristics in the visible region. Since then, many studies have been conducted to investigate the mechanism of resonant transmission in MHAs.It is widely believed that the main mechanism responsible for resonant transmission is ESWs that is based on the interference of multiple electromagnetic waves scattered by periodically arranged holes. [4][5][6] Klien and co-workers 7-17 have experimentally found that the hole shape also has a strong effect on the transmission characteristics of MHAs; this effect is known as localized resonance, and it has been investigated extensively. Ruan et al. 9 have calculated the transmission spectra of periodically arranged and randomly distributed rectangular holes and found a transmission peak whose frequency is almost independent of the period. Very recently, some studies have investigated the effects of hole size and aspect ratio on transmission characteristics.10 In particular, Lee et al. 11 have experimentally demonstrated the effect of the length of randomly arranged rectangular holes on transmission spectra and showed that the resonant peak clearly depends on the hole length; this result is consistent with the theory of half-wavelength resonance. They have also found that the periodic structure enhances the transmission peak of localized resonance. Molen et al.14 have reported that the dispersion relation of the peak frequency depends on the aspect ratio of rectangular metal holes.In this Brief Report, we describe a study conducted to better understand the effect of localized resonance in an MHA. We investigate the transition of the dominant resonant transmission mechanism from localized resonance to ESWs by examining the changes in the transmission spectra that occur when we change the length of the rectangular holes. The measured transmission peak of the MHA shows a redshift as the hole length increases; the incident polarization is perpendicular to the fixed axis of the holes. When the hole...

Mode splitting transmission effect of surface wave excitation through a metal hole array

“…An attenuation length on the order of the incident wavelength can be achieved even though a perfect electric conductor is used. 32 Figure 5b and 5c show the electric field distribution E x of two resonant frequencies, 0.222 THz ((21,0) mode) and 0.273 THz ((0,21)/(21,1) mode), respectively, at an incident angle of 20 6 . The simulation results also show a clear intensity modulation of E x along the x-direction within individual holes at both resonant frequencies.…”

“…6,7 Because MHAs are novel candidates for use as components in THz devices, such as filters, 8 optical switches, 9 sensors, 10 etc., the features of MHA surface waves at normal incidence have been investigated in detail by changing parameters such as the number of holes, 11 the hole diameter, 12 the coating thickness of the dielectric film on the metal surface, 13 etc. In general, this enhanced transmission characteristic is one type of plasmonic property that has been widely studied in THz plasmonic metamaterial systems, [14][15][16][17][18][19][20] which is typically composed of periodically arranged unit cells.…”

Time-of-Flight Model for the Extraordinary Transmission Through Periodic Arrays of Subwavelength Apertures at THz Frequencies

“…With the wealth of potential applications, both as a sensor [22][23][24][25], or as an aid to THz imaging [26], a model able to both interpret and predict results would prove an invaluable tool in the exploitation of SPPs. Any such model would have to explain, amongst other factors, the dependence on polarization [11], the observed blueshift and broadening of resonances with increasing aperture width [19], the redshift and broadening observed as aperture length is increased [27], the reason asymmetrical apertures produce stronger resonances and the shift in frequency associated with a change in period. All manner of theories have been presented to explain such effects, including localized or shape resonances [27], Fano-type interpretations [19,28] and SPP lifetime considerations [17].…”

Controlling extraordinary transmission characteristics of metal hole arrays with spoof surface plasmons

“…[1][2][3][4][5][6][7] In the 1960s, Ulrich et al reported the interesting band-pass property of MHAs and attributed it to the excitation of Zenneck waves, which is now known as surface waves. 8,9 Today, it is widely believed that the main mechanism responsible for extraordinary transmissions is the excitation of surface waves that originate from the interference of multiple electromagnetic waves scattered by periodically arranged holes.…”