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Spectral measurements of TM polarized zero-order transmittance (transverse electric data not shown) for cubic arrays of holes in a thin gold film on a glass substrate. Data from several arrays with different periods have been combined for these composite intensity images, where the stitching frequencies appear as horizontal black lines (identical data are also replicated for for viewing). The transmittance has been normalized by the hole area per unit cell, and the intensity range is from 0 (dark) to 1.1 (light). On the right half , the calculated SPP dispersion curves for AM and GM interfaces are seen as white lines. Arrows on the left indicate the position on normalized frequency axis where single frequency laser measurements (shown in Fig. 3) occur. Also sketched (dotted white lines) is the angular spectrum and relative intensity for the incident beam of Fig. 3, with a NA of 0.25.
Schematic of SPP imaging configuration. Illumination on a given sample is from a focused laser (with a microscope objective, MO). The resulting SPP mode is then imaged on to an camera array via a imaging system (MO and Lens). For the case shown, the incident polarization at is decomposed into two orthogonal components which excite (1,0)-type SPP modes which propagate along the grating surface and reradiate in both the forward and backward directions with the illustrated polarization. The radiation is then polarized at to obtain the field in the image plane.
SPPs observed in various hole arrays. Inset is the relative polarizer (solid) and analyzer (dashed) orientation for each image. Intensity scales for (a) and (b) are identical, while (c)–(f) have been adjusted to observe the full SPP extent. Also inset in (f) is a distance bar valid for all optical images, and a scanning electron microscope image that shows a representative array and the hole orientation relative to the optical images. The respective hole period and free-space laser wavelength are (in ): (a) and (b) , ; (c) , ; (d) , ; (e) , ; and (f) , .
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