Bismuth ferrite as low-loss switchable material for plasmonic waveguide modulator

TL;DR

This paper introduces a plasmonic waveguide modulator using bismuth ferrite, which enables low-loss, high-efficiency signal switching in photonic circuits through voltage-controlled refractive index changes.

Contribution

It presents a novel design of a plasmonic modulator utilizing bismuth ferrite's low-loss ferroelectric properties for efficient phase and amplitude modulation.

Findings

Achieves a π phase shift with 0.8 μm device length and 0.29 dB/μm loss.

Predicts up to 38 dB/μm extinction ratio for amplitude modulation.

Utilizes high field confinement and mode cut-offs for superior modulation depth.

Abstract

We propose new designs of plasmonic modulators, which can be utilized for dynamic signal switching in photonic integrated circuits. We study performance of plasmonic waveguide modulator with bismuth ferrite as an active material. The bismuth ferrite core is sandwiched between metal plates (metal-insulator-metal configuration), which also serve as electrodes so that the core changes its refractive index under applied voltage by means of partial in-plane to out-of-plane reorientation of ferroelectric domains in bismuth ferrite. This domain switch results in changing of propagation constant and absorption coefficient, and thus either phase or amplitude control can be implemented. Efficient modulation performance is achieved because of high field confinement between the metal layers, as well as the existence of mode cut-offs for particular values of the core thickness, making it possible to control the signal with superior modulation depth. For the phase control scheme, {\pi} phase shift is provided by 0.8-{\mu}m length device having propagation losses 0.29 dB/{\mu}m. For the amplitude control, we predict up to 38 dB/{\mu}m extinction ratio with 1.2 dB/{\mu}m propagation loss. In contrast to previously proposed active materials, bismuth ferrite has nearly zero material losses, so bismuth ferrite based modulators do not bring about additional decay of the propagating signal.