Optical element for enhanced transmission of light and suppressed increase in temperature

摘要

An optical element structure allowing an increased power density of aperture-transmitted light while suppressing increase in temperature is disclosed. A conductive film has a sub-wavelength aperture formed therein and a periodic surface topography formed thereon. A lens focuses light onto the periodic surface topography with a predetermined diameter. The predetermined diameter of incident light on the conductive film and a period of the periodic surface topography are determined so that a power ratio of aperture-transmitted light to the light beam is greater than that of aperture-transmitted light which would be obtained if no periodic surface topography is provided in the conductive film.