Optical characterization of mass-productive metal-insulator-metal plasmonic waveguide with a linear taper for...

This paper conducts an experimental evaluation of the optical properties of mass-productive metal-insulator-metal linear taper waveguides for nanofocusing. The vertical linear tapers, with controlled angles in the 12-51 degrees range, were realized with dry etching and mixed gas, while tip-thickness was precisely controlled with atomic layer deposition. The transmission efficiency of the linear taper was measured employing an input grating and a single output slit. The maximum transmission efficiency was estimated at 64% at a taper angle of 30 degrees, which aligned with the calculations. This experimental evaluation provides guidance for the design of practical nanofocusing components.