Resonance tuning of electric field enhancement of nanogaps

Abstract

We study the electric near-field enhancement of a metallic nanogap by far-field transmission measurement in the 0.6-2.3 mu m wavelength range. The electric field is resonantly enhanced at the gap and the enhancement factor is quantified experimentally. The resonance condition of field enhancement can be controlled to various wavelengths by changing the gap size, which is confirmed by theoretical calculation using a mode expansion method.