Low loss TiO2 channel waveguides

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TiO2 is gaining interest as material for integrated photonics, due to its high refractive index, large transparency window and high non-linear refractive index. Its low phonon energy makes it attractive for the realization of active devices in the visible frequency range. In this work, we optimize different process steps of the fabrication of low loss TiO2 channel waveguides. The TiO2 layers are deposited by DC sputter deposition, using a mixed Ar/O2 plasma. Removing the hysteresis in the deposition process, results in reduced propagation losses of the TiO2 films (estimated less than 1.5 dB/cm at 632 nm wavelength). An E-beam lithography process is utilized to reduce the sidewall roughness of the waveguides. Different reactive gasses are compared to optimize the reactive ion etching recipe. BCl3 in combination with HBr shows to be most beneficial for etching TiO2 with high selectivity towards negative E-beam resist. A selectivity of 2.7 for TiO2 over the E-beam resist is obtained. The performance of a TiO2 a channel waveguide fabricated with the process before and after optimization is compared. The waveguide fabricated using the non-optimized process exhibited losses of 7.82±0.52 dB/cm at a wavelength of 632.8 nm, after applying an SiO2 cladding. After process optimization, 5.08±0.65 dB/cm were obtained, without an SiO2 cladding.

Original languageEnglish
Title of host publicationIntegrated Optics
Subtitle of host publicationDevices, Materials, and Technologies XXIV
EditorsSonia M. Garcia-Blanco, Pavel Cheben
ISBN (Electronic)9781510633292
ISBN (Print)978-1-5106-3329-2
Publication statusPublished - 25 Feb 2020
EventIntegrated Optics: Devices, Materials, and Technologies XXIV 2020 - The Moscone Center, San Francisco, United States
Duration: 3 Feb 20206 Feb 2020
Conference number: 24

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
ISSN (Print)0277-786X
ISSN (Electronic)1996-756X


ConferenceIntegrated Optics: Devices, Materials, and Technologies XXIV 2020
Country/TerritoryUnited States
CitySan Francisco


  • Channel waveguide
  • E-beam lithography
  • Hysteresis
  • Propagation losses
  • Reactive ion etching
  • Sputter deposition
  • TiO
  • UV contact lithography
  • channel waveguide
  • hysteresis
  • reactive ion etching
  • propagation losses
  • TiO2


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