Abstract. Plasmonic waveguides have attracted much attention owing
to the associated high field intensity at the metal–dielectric interface and
their ability to confine the modes at the nanometer scale. At the same time,
they suffer from relatively high propagation loss, which is due to the
presence of metal. Several alternative materials have been introduced to
replace noble metals, such as transparent conductive oxides (TCOs). A
particularly popular TCO is indium tin oxide (ITO), which is compatible with
standard microelectromechanical systems (MEMS) technology. In this work, the feasibility of ITO as an
alternative plasmonic material is investigated for infrared absorption sensing
applications: we numerically design and optimize an ITO-based
plasmonic slot waveguide for a wavelength of 4.26 µm, which is the absorption
line of CO2. Our optimization is based on a figure of merit (FOM), which
is defined as the confinement factor divided by the imaginary part of the effective mode
index (i.e., the intrinsic damping of the mode). The obtained optimal FOM is
3.2, which corresponds to 9 µm and 49 % for the propagation length
(characterizing the intrinsic damping) and the confinement factor,
respectively.
Asymmetric hybrid plasmonic waveguides with centimeter-scale propagation length under subwavelength confinement for photonic components
