Ultra-compact branchless plasmonic interferometers

TL;DR

This paper introduces an ultra-compact, branchless plasmonic interferometer with high coupling efficiency, enabling dense integrated plasmonic circuits and advanced sensing applications through dynamic control of waveguide excitation.

Contribution

It presents a novel branchless interferometer design with ultra-compact antenna couplers and systematic characterization, advancing integrated plasmonic device development.

Findings

Coupling efficiency exceeds 15% for small waveguide separations.

Power distribution between waveguides can be dynamically controlled.

Design can be extended to other configurations for dense circuitry.

Abstract

Miniaturization of functional optical devices and circuits is a key prerequisite for a myriad of applications ranging from biosensing to quantum information processing. This development has considerably been spurred by rapid developments within plasmonics exploiting its unprecedented ability to squeeze light into subwavelength scale. In this study, we investigate on-chip plasmonic systems allowing for synchronous excitation of multiple inputs and examine the interference between two adjacent excited channels. We present a branchless interferometer consisting of two parallel plasmonic waveguides that can be either selectively or coherently excited via ultra-compact antenna couplers. The total coupling efficiency is quantitatively characterized in a systematic manner and shown to exceed 15% for small waveguide separations, with the power distribution between the two waveguides being efficiently and dynamically shaped by adjusting the incident beam position. The presented design principle can readily be extended to other configurations, giving new perspectives for highly dense integrated plasmonic circuitry, optoelectronic devices, and sensing applications.