title: Multimode phase-matched third-harmonic generation in sub-micrometer-wide anatase TiO₂ waveguides.
abstract: Third-harmonic generation (THG) has applications ranging from wavelength conversion to pulse characterization, and has important implications for quantum sources of entangled photons. However, on-chip THG devices are nearly unexplored because bulk techniques are difficult to adapt to integrated photonic circuits. Using sub-micrometer-wide polycrystalline anatase TiO₂ waveguides, we demonstrate third-harmonic generation on a CMOS-compatible platform. We correlate higher conversion efficiencies with phase-matching between the fundamental pump mode and higher-order signal modes. Using scattered light, we estimate conversion efficiencies as high as 2.5% using femtosecond pulses, and thus demonstrate that multimode TiO₂ waveguides are promising for wideband wavelength conversion and new applications ranging from sensors to triplet-photon sources.
authors.forename: Christopher C
authors.initials: CC
authors.lastname: Evans
authors.forename: Katia
authors.initials: K
authors.lastname: Shtyrkova
authors.forename: Orad
authors.initials: O
authors.lastname: Reshef
authors.forename: Michael
authors.initials: M
authors.lastname: Moebius
authors.forename: Jonathan D B
authors.initials: JD
authors.lastname: Bradley
authors.forename: Sarah
authors.initials: S
authors.lastname: Griesse-Nascimento
authors.forename: Erich
authors.initials: E
authors.lastname: Ippen
authors.forename: Eric
authors.initials: E
authors.lastname: Mazur