We demonstrate amorphous and polycrystalline anatase TiO(2) thin films and submicrometer-wide waveguides with promising optical properties for microphotonic devices. We deposit both amorphous and polycrystalline anatase TiO(2) using reactive sputtering and define waveguides using electron-beam lithography and reactive ion etching. For the amorphous TiO(2), we obtain propagation losses of 0.12 ± 0.02 dB/mm at 633 nm and 0.04 ± 0.01 dB/mm at 1550 nm in thin films and 2.6 ± 0.5 dB/mm at 633 nm and 0.4 ± 0.2 dB/mm at 1550 nm in waveguides. Using single-mode amorphous TiO(2) waveguides, we characterize microphotonic features including microbends and optical couplers. We show transmission of 780-nm light through microbends having radii down to 2 μm and variable signal splitting in microphotonic couplers with coupling lengths of 10 μm.

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We observe spectral broadening of femtosecond pulses in single-mode anatase-titanium dioxide (TiO(2)) waveguides at telecommunication and near-visible wavelengths (1565 and 794 nm). By fitting our data to nonlinear pulse propagation simulations, we quantify nonlinear optical parameters around 1565 nm. Our fitting yields a nonlinear refractive index of 0.16 × 10(-18) m(2)/W, no two-photon absorption, and stimulated Raman scattering from the 144 cm(-1) Raman line of anatase with a gain coefficient of 6.6 × 10(-12) m/W. Additionally, we report on asymmetric spectral broadening around 794 nm. The wide wavelength applicability and negligible two-photon absorption of TiO(2) make it a promising material for integrated photonics.

We demonstrate waveguide-coupled titanium dioxide (TiO 2 ) racetrack resonators with loaded quality factors of 2.2 × 10 4 for the visible wavelengths. The structures were fabricated in sputtered TiO 2 thin films on oxidized silicon substrates using standard top-down nanofabrication techniques, and passively probed in transmission measurements using a tunable red laser. Devices based on this material could serve as integrated optical elements as well as passive platforms for coupling to visible quantum emitters.

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