Nonlinear optical switching in hybrid plasmonic waveguides

TL;DR

This paper explores an all-optical switching mechanism in hybrid plasmonic waveguides utilizing the nonlinear epsilon-near-zero properties of ITO, demonstrating potentially more efficient switching compared to electrical gating.

Contribution

It introduces a nonlinear optical switching approach in hybrid plasmonic waveguides with ITO, analyzing the effects of light intensity and ITO thickness on device performance.

Findings

Optical pumping can induce more efficient switching than electrical gating.

Transmittance and phase vary significantly with light intensity and ITO thickness.

Significant step-like changes in transmittance and phase are observed with increasing light intensity.

Abstract

We investigate an optical switching mechanism for applications in active integrated photonic circuits. The mechanism utilizes a large nonlinearity of indium-tin-oxide (ITO) in epsilon-near-zero (ENZ) regime. The effect of optically induced switching is investigated in hybrid plasmonic waveguides (HPWG) with ITO layer that are often used as a platform for various active photonic components, including optical modulators. To study the effect, nonlinear Maxwell equations are solved numerically in time and frequency domains. The all-optical mechanism of switching in HPWG is quantitatively compared with an electrical gating that is often used to manipulate hybrid modes. It is shown that the optical pumping could potentially cause more efficient switching. The influence of light intensity on HPWG properties and interplay between hybrid modes are investigated numerically in different regimes. Transmittance and phase variation are calculated as a function of light intensity for Si and Si3N4 waveguides. It is shown that the transmittance and its intensity dependence are strongly affected by the ITO thickness. A significant for applications step-like variation of phase and transmittance with intensity is detected. The possibility to control the excitation conditions for surface plasmon polaritons (SPP) in HPWG using active layer of ITO in nonlinear regime is demonstrated and discussed.