Solution-derived barium titanate waveguides for integrated electro-optic modulation

TL;DR

This paper presents a scalable, low-cost method for fabricating high-quality barium titanate waveguides for integrated electro-optic modulation using solution-based processes and nanoimprinting, overcoming previous material synthesis challenges.

Contribution

It introduces a monolithic, solution-deposited BaTiO₃ waveguide fabrication process via soft nanoimprinting, enabling efficient, large-scale electro-optic devices without etching.

Findings

Achieved two orders of magnitude reduction in propagation losses.

Demonstrated effective electro-optic modulation with solution-processed BaTiO₃.

Established a scalable, etch-free fabrication route for oxide-based photonic devices.

Abstract

Metal oxides with strong nonlinear optical properties and wide transparency window are key materials for the development of compact and efficient photonic integrated circuits used for electro-optic modulators and entangled photon sources. Among them, barium titanate (BaTiO$_{3}$) is particularly attractive due to its large Pockels coefficient. However, its use has been limited by challenges in material synthesis and in nanopatterning, owing to its chemical stability and inertness. Here, we demonstrate a monolithic electro-optic modulator entirely based on solution-deposited BaTiO$_{3}$, fabricated through a bottom-up soft nanoimprinting lithography process. Fine-tuning the synthesis and nanofabrication enhances the optical properties of the polycrystalline material. By optimizing the process parameters, we achieve a reduction in propagation losses of two orders of magnitude, enabling efficient electro-optic modulation. This scalable, etch-free approach enables direct patterning of high-quality BaTiO$_{3}$ structures, establishing a new route for low-cost, large-scale integrated electro-optic devices entirely based on oxide material compatible with a wide range of substrates.