Researchers from the University of Oxford, including Trevor G. Vrckovnik, D. Arslan, F. Eilenberger, and Sebastian W. Schmitt, have introduced a novel approach to enhance the efficiency of nonlinear frequency conversion in barium titanate (BaTiO₃) waveguides. Their work, published in the journal Optica, presents a practical solution to overcome the challenges associated with traditional periodic poling techniques in BaTiO₃.
Barium titanate is gaining attention as a promising material for integrated photonic applications due to its strong nonlinear properties and improving thin-film waveguide quality. However, the development of efficient nonlinear BaTiO₃ waveguide devices has been hindered by the material’s high coercive fields, strain-clamping effects, and complex switching dynamics, which make accurate periodic poling difficult.
The researchers propose a fabrication-robust alternative based on linear-nonlinear hybrid waveguides. By selectively incorporating titanium dioxide (TiO₂) into BaTiO₃ ridge waveguides, they enhance the nonlinear mode overlap and rely on modal phase-matching rather than periodic poling. This approach leverages the complementary properties of BaTiO₃ and TiO₂ to achieve more efficient frequency conversion.
Using coupled-mode-theory simulations, the team identified phase-matched geometries that demonstrate a 2.75 times increase in normalized second harmonic generation efficiency compared to monolithic BaTiO₃ waveguides. The uniform, lithographically defined cross-section of the hybrid design makes it highly scalable and compatible with complementary metal-oxide-semiconductor (CMOS) processes.
This research positions hybrid BaTiO₃-TiO₂ waveguides as a practical route to high-efficiency nonlinear devices for integrated quantum photonics. The findings could have significant implications for the energy sector, particularly in the development of advanced optical communication systems and quantum technologies for energy monitoring and management.
The practical applications of this research extend to various energy industry sectors, including telecommunications, where efficient frequency conversion is crucial for high-speed data transmission. Additionally, the integration of quantum photonic technologies could enhance energy monitoring and management systems, leading to more efficient and sustainable energy solutions.
This article is based on research available at arXiv.