Absorption loss and Kerr nonlinearity in barium titanate waveguides

Abstract

Because of its exceptionally large Pockels coefficient, barium titanate (BaTiO${}_3$) is a promising material for various photonic applications at both room and cryogenic temperatures, including electro-optic modulation, frequency comb generation, and microwave-optical transduction. These applications rely on devices with low optical loss to achieve high efficiency. Material absorption sets a lower limit to optical loss and is thus a crucial property to determine, particularly for integrated photonic devices. Using cavity-enhanced photothermal spectroscopy, we measure the absorption loss of BaTiO${}_3$ ridge waveguides at wavelengths near 1550~nm to be ${\alpha }_{\mathrm{abs}}=10.9$~{\raisebox{0.5ex}{\tiny${}_{-0.4}^{+5.8}$}} dB~m${}^{-1}$, well below the propagation losses due to other sources, such as scattering. We simultaneously determine that BaTiO${}_3$ has a large Kerr nonlinear refractive index of $n_{2,\mathrm{BaTi}{\mathrm{O}}_3}$ = 1.8 {\raisebox{0.5ex}{\tiny${}_{-0.3}^{+0.3}$}} $\times$ 10${}^{-18}$ m${}^2$ W${}^{-1}$. Considering these results, photonic integrated circuits utilizing BaTiO${}_3$ have the potential to achieve significantly higher efficiency than demonstrated to date and are especially interesting for applications exploiting the combination of Pockels and Kerr effects.

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• A manufacturable platform for photonic quantum computing
• Coherent control of a superconducting qubit using light
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Cited by in corpus (4)

• Engineering high Pockels coefficients in thin-film strontium titanate for cryogenic quantum electro-optic applications
• Bidirectional microwave-optical conversion with an integrated soft-ferroelectric barium titanate transducer
• Scattering-Induced Loss in Ferroelectric Photonic Devices
• Integrated Photonic Devices in Thin-Film Barium Titanate: Opportunities and Challenges