Mid-Infrared Wavelength Light Transmission in a Suspended Cylindrical Nanowire Hybrid Plasmonic Waveguide

A hybrid plasmonic waveguide (HPW) consisting of a suspended cylindrical nanowire is investigated in this article. The modal properties and waveguide sensitivity of the fundamental mode in the waveguide are analyzed by using the finite element method, and the geometric parameters are optimized. The research results show that the HPW containing a suspended cylindrical nanowire has a normalized mode area ranging from
$3\times 10^{-{2}}$
to
$10^{-{1}}$
and an ultra-long propagation distance of 102–
$409~\mu $
m near the mid-infrared wavelength of
$3.5~\mu $
m, with the figure of merit (FOM) of 2236. This waveguide based on a suspended cylindrical nanowire outperforms the conventional hybrid and plasmonic waveguides, exhibiting longer propagation space under strong field confinement and having high waveguide sensitivity (
${S} _{\text {wg}} = 1$
). Possible fabrication flaws and temperature variations do not affect the guiding properties of the fundamental mode, which is very stable. The exceptional optical performance enables such waveguides as promising building blocks for integrated label-free sensing and building high-performance ultracompact photonic devices.