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The macro size pyramidal horn probe such as klystron horn antenna has been used to provide the excellent focusing capabilities in microwave region. In the similar way, the pyramidal probe with the micron size mirror (pyramidal horn probe) has been fabricated with a nano-size aperture with diameter ranging from 30 to 330 nm on its apex. Light transmission through the micro-fabricated pyramidal horn probe has been measured to enhance the light transmission due to resonant effects between the cavity mode and the slit modes in the probe, along with directionality of the transmitted beam. The resonant tunneling between two standing waves in the input groove and in the output groove can provide the transmission enhancements. Below ~170 nm, the output power normalized to the input power (ratio) has been increased with decreasing diameter. On the other hand, for the diameter ranging from 330 to 170 nm, the ratio has been decreased with decreasing diameter. The transmission (T) is measured to be inversely proportional to the area (A), and TA value for input wavelength 532 nm is found to be constant, 0.136 for the diameter below 160 nm, and to be 0.053 for diameter greater than 160 nm.

The Al-coated-oxide pyramids have been fabricated with and without Ti wetting layer. The nano-size aperture surrounded by the periodic structure on the fabricated oxide pyramid has been fabricated using focused ion beam milling system. The significantly reduced light transmittance from the Al metal aperture with Ti wetting layer have been measured, and compared it with the sample without Ti layer. This can be the evidence for surface plasmon polariton contribution to the enhancement of light transmittance through the metallic subwavelength size aperture in the visible range.Keywords-component; formatting; style; styling; Ti wetting layer, Surface plasmon polariton, Al thin film, subwavelength size metal aperture, enhancement of light transmission, elliptic periodic grooves, periodic patterns on the exi tside