Diodelike asymmetric transmission in hybrid plasmonic waveguides via breaking polarization symmetry

TL;DR

This paper introduces a compact hybrid plasmonic waveguide that achieves optical diode behavior by breaking polarization symmetry, enabling unidirectional light propagation with high extinction ratios over a broad bandwidth.

Contribution

The study presents a novel single-mode hybrid plasmonic structure that induces asymmetric transmission through polarization manipulation, significantly reducing device size compared to previous designs.

Findings

Extinction ratio exceeds 11.8 dB at 1550 nm for both directions.

Device footprint is 2.95*14.18 μm², much smaller than prior devices.

Operational bandwidth is 70 nm with extinction > 10 dB.

Abstract

The ability to control the asymmetric propagation of light in nanophotonic waveguides is of fundamental importance for optical communications and on-chip signal processing. However, in most studies so far, the design of such structures has been based on asymmetric mode conversion where multi-mode waveguides are involved. Here we propose a hybrid plasmonic structure that performs optical diode behavior via breaking polarization symmetry in single mode waveguides. The exploited physical mechanism is based on the combination of polarization rotation and polarization selection. The whole device is ultra-compact with a footprint of 2.95*14.18 {\mu}m2, whose dimension is much smaller than the device previously proposed for the similar function. The extinction ratio is greater than 11.8 dB for both forward and backward propagation at {\lambda} = 1550 nm (19.43 dB for forward propagation and 11.8 dB for the backward one). The operation bandwidth of the device is as great as 70 nm (form 1510 to 1580 nm) for extinction > 10 dB. These results may find important applications in the integrated devices where polarization handling or unidirectional propagation is required.