Journal of Sol-Gel Science and Technology

, Volume 84, Issue 3, pp 522–534 | Cite as

Total internal reflection-based optofluidic waveguides fabricated in aerogels

  • Yaprak Özbakır
  • Alexandr Jonáš
  • Alper Kiraz
  • Can Erkey
Invited Paper: Sol-gel and hybrid materials for optical, photonic and optoelectronic applications


Liquid-core optofluidic waveguides based on total internal reflection of light were built in water-filled cylindrical microchannels fabricated in hydrophobic silica aerogels. Silica aerogels with densities ranging from 0.15 to 0.39 g/cm3 were produced by aging of alcogels in tetraethylorthosilicate solution for various time periods, followed by supercritical extraction of the solvent from the alcogel network. Subsequently, the resulting hydrophilic aerogel samples were made hydrophobic by hexamethyldisilazane vapor treatment. The synthesized samples retained their low refractive index (below ~1.09) and, hence, they could serve as suitable optical cladding materials for aqueous waveguide cores (refractive index n core = 1.33). Hydrophobic silica aerogel samples produced by the above technique also had low absorption coefficients in the visible part of the spectrum. Fabrication of microchannels in aerogel blocks by manual drilling preserving nanoporous and monolithic structure of aerogels was demonstrated for the first time. Long channels (up to ~7.5 cm) with varying geometries such as straight and inclined L-shaped channels could be fabricated. Multimode optofluidic waveguides prepared by filling the channels in the drilled aerogel monoliths with water yielded high numerical aperture values (~0.8). Efficient guiding of light by total internal reflection in the water-filled channels in aerogels was visually revealed and characterized by monitoring the channel output. The presented technique is expected to open up further possibilities for creating three-dimensional networks of liquid channels in aerogels for optofluidic applications.

Graphical Abstract

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We thank KUYTAM (Koç University Surface Science and Technology Center) and KUTEM (Koç University TÜPRAŞ Energy Center) for their support.

Compliance with ethical standards

Conflict of interest

The authors declare that they have no competing interests.


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Copyright information

© Springer Science+Business Media New York 2017

Authors and Affiliations

  • Yaprak Özbakır
    • 1
    • 2
  • Alexandr Jonáš
    • 3
  • Alper Kiraz
    • 2
    • 4
  • Can Erkey
    • 1
  1. 1.Department of Chemical and Biological EngineeringKoc UniversityIstanbulTurkey
  2. 2.Department of PhysicsKoc UniversityIstanbulTurkey
  3. 3.Department of PhysicsIstanbul Technical UniversityIstanbulTurkey
  4. 4.Department of Electrical and Electronics EngineeringKoc UniversityIstanbulTurkey

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