Dye assisted enhanced transmission in near field optical lithography

Surface plasmon lithography using embedded-amplitude masks has received considerable attention in recent times for its ability to produce high density features with resolution beyond diffraction limit. However plasmon damping caused due to intrinsic metal absorption restricts the achievable aspect ratio of the fabricated features. One possible way to rectify this issue is to use a gain medium to amplify the surface plasmons and thereby increase their propagation length. In this context this paper proposes a novel concept of employing dye medium to enhance plasmon propagation in mask based surface plasmon lithography, so as to obtain higher transmission depth in the writing medium. The proposed concept is supported by numerical simulations and the results obtained indicate a 14.5 fold field enhancement in presence of dye (gain) medium.