Extraordinary infrared transmission through a periodic bowtie aperture array,” Opt

Abstract

The discovery of extraordinary transmission through periodic aperture arrays has generated significant interest. Most studies have used circular apertures and attributed enhanced transmission to surface plasmon polariton (SPP) resonances and/or Rayleigh-Wood anomalies (RWA). Bowtie apertures concentrate light and have much longer cutoff wavelengths than circular apertures and can be designed to be strongly resonant. We demonstrate here that the total transmission through a bowtie aperture array can exceed 85% (4ϫ the open area). Furthermore, we show that the high transmission is due to waveguide modes as opposed to the commonly believed SPP/RW phenomena. This work is focused on IR wavelengths near 9 m; however, the results are broadly applicable and can be extended to optical frequencies. © 2010 Optical Society of America OCIS codes: 240.0240, 240.6680, 050.1220. Classical aperture theory predicts that transmission through a subwavelength hole scales with ͑d / ͒ 4 , where d is the diameter of the aperture and is the free-space wavelength of light In this Letter we investigate transmission through a periodic array of bowtie apertures. The transmission modes are optimized to obtain high transmission around =9 m. The high transmission in IR has the potential as a high-efficiency IR coupler for detection devices. The bowtie aperture is also polarization selective, therefore useful where polarization selectivity is of interest such as IR polarimetry imaging Bowtie apertures are one type of ridge aperture The geometry of the bowtie aperture array studied in this work is shown in 992 OPTICS LETTERS / Vol. 35