Slot ARROW Waveguide: A New Platform for Optical Sensing

Abstract

The realization of high sensitivity integrated photonic sensors requires strong light/matter interaction. Unfortunately, in an optical waveguide, only the evanescent part of the mode interacts with the cladding medium under test. In this context, we have patented a new concept of waveguide [1] called “Slot ARROW”, where the major part of the light is confined in the cladding such as metallic plasmonic and dielectric slot waveguides. This paper presents the modelling, the fabrication and the optical characterization of slot ARROW waveguides. Optical modelling shows that the main advantages of Slot ARROW waveguides are a reduction of propagation losses and the sustaining monomode condition for widths 100 times larger than the slot or plasmonic waveguides. The fabrication process is more robust as it only needs the structuration of the upper layer with standard optical lithography and a RIE etching step. The critical lateral dimension is relaxed to $0.9 \mu \mathrm{m}$ compared to $0.1 \mu \mathrm{m}$ for the grooves of slot or plasmonic 2D waveguides. Basic building blocks for optical routing have been designed and preliminary characterizations demonstrate the validity of this new concept.