Transverse magnetic modes in hybrid nanoslot waveguides

Yongqing Fan, Shaoyong Peng, Youwen Liu
2020 Results in Physics  
Light enhancement and confinement in a nanometer-wide low-index material was proposed and demonstrated in a low index slot waveguide (LISW). To further reduce the mode width, a 5-layer metal/high index/low index/high index/metal hybrid nanoslot waveguide (HNSW) was constructed by replacing the outmost layer of LISW with a metal layer in which only TM modes exist. In this work, we analytically solve the guided-wave modes in the HNSW that are divided into six types according to the effective
more » ... the effective refractive index and the symmetry of the field distribution, and derive their dispersion equations and discuss the cut-off conditions. Two new guided-wave modes appear in HNSW that do not exist in the LISW structure. The abilities of light confinement of zero-order even modes between the HNSW structure and the LISW structure are compared, and the HNSW shows stronger light-confined ability and narrower mode than LISW, which makes it possible to simultaneously increase light-confined ability and reduce mode width in HNSW. For the specific Au/Si/SiO 2 /Si/Au HNSW, considering the metal loss will not change the basic properties of the zero-order modes at 1550nm, except that the mode propagation length is reduced to a few microns.
doi:10.1016/j.rinp.2020.103017 fatcat:6kir6tqsvbhnbm2b65a5fbxc2q