Circular hybrid plasmonic waveguide with ultra-long propagation distance

Abstract

We propose a novel plasmonic waveguide structure, which is referred to as a circular hybrid plasmonic waveguide (HPW) and consists of a metal wire covered with low- and high-index dielectric layers. The circular HPW exhibits two distinctly different modes, namely, the strongly localized mode and the extremely low-loss mode. Our numerical calculation demonstrates that the strongly localized mode exhibits 10^-4 order scale in normalized mode area and can be performed even in tens of nanometer sizes of waveguide geometry. In the extremely low-loss mode, the HPW exhibits ultra-long propagation distance of more than 10³μm that can be achieved by forming the dipole-like hybrid mode and properly adjusting the radius of the metal wire. It is also shown that, even with this long-range propagation, the mode area of the dipole-like hybrid mode can be maintained at subwavelength scale. The simultaneous achievement of a small mode area and ultra-long propagation distance contributes to the ultra-high propagation distance to mode size ratio of the waveguide. The HPW results are very helpful for plasmonic device applications in the fields of low-threshold nanolasers, ultrafast modulators, and optical switches.

Asymmetric hybrid plasmonic waveguides with centimeter-scale propagation length under subwavelength confinement for photonic components

“…It has a maximum propagation length of 2.69 × 10 4  μm (2.69 cm) with strong subwavelength confinement ( A m / A o = 4.89 × 10 -2 ). More importantly, the maximum corresponding FoM of 139037 is achieved, which is significantly larger than most previously reported ones [11,14,22]. …”

Theoretical analysis of a circular hybrid plasmonic waveguide to design a hybrid plasmonic nano-antenna

“…Up to now several HPWs have been introduced to increase the propagation length of SPPs and confine the light in the coupling region 14 – 19 . For example, rectangular silicon- or InP-based waveguides covered by metal cap 16 , 17 , a metal wire covered by low- and high-index dielectric layers 18 and a high-index dielectric cylinder covered by low-index dielectric and noble metal layers 19 are famous structures of HPWs.…”

Metal Nanoridges in Hollow Si-Loaded Plasmonic Waveguides for Optimal Mode Properties and Ultra-Compact Photonic Devices

“…A recent review paper [29] provides a comprehensive discussion of the mode and propagation characteristics of various SPP-based waveguide configurations. Many studies have been motivated by the HPW structure [24] and primarily report two main types of plasmonic waveguides to optimally leverage the mode confinement and propagation length [30]- [50]. The first type of plasmonic waveguides [30]- [42] aims for a deep subwavelength mode area around 10 −3 (λ 2 /4) with propagation lengths of several tens of micrometers at the telecom wavelength of 1550 nm.…”

“…These plasmonic structures are beneficial for implementing ultra-compact PICs. The second category [43]- [50] focuses on producing ultra-long (mm scale) propagation distances with symmetric plasmonic structures. In the latter, the longitudinal component of the electric field in the metal is minimized [4], thus lowering Ohmic absorptions.…”

“…In the latter, the longitudinal component of the electric field in the metal is minimized [4], thus lowering Ohmic absorptions. However, a disadvantage of long-range SPPs [43]- [50] is weak mode confinement, with the mode areas greater than 10 −2 (λ 2 /4). These types of plasmonic waveguides are suitable for subwavelength photonic interconnects, but not for high-density photonic devices.…”