University of Twente Student Theses


Optical nonlinearity in titanium dioxide waveguides

Vissers, E.J.P. (2018) Optical nonlinearity in titanium dioxide waveguides.

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Abstract:Due to its high linear- and nonlinear refractive index, titanium dioxide is a promising material for utilizing nonlinear effects in waveguides. The transparency of titanium dioxide for visible light opens possibilities to use these nonlinear effects in the visible range of the spectrum. Using simulations, waveguide designs with minimal dispersion at wavelengths of 1310nm and 1550nm are proposed. A fabrication process is developed that allows fabrication of TiO2 on SiO2 waveguides with a sidewall angle between 76 degrees and 86 degrees, with a maximum thickness of 400 nm. TiO2 waveguides with thicknesses of 74nm and 360nm have been fabricated, and their propagation losses have been measured using a camera. At a wavelength of 785 nm, the 74nm thick waveguide has propagation losses of 8.2 dB/cm. The best propagation loss of the 360nm thick waveguides at 785nm was measured to be 13.4 dB/cm, while at a wavelength of 1310 nm, the losses are 2.20 +- 0.25 dB/cm. It has been found the waveguides with a thickness of 360nm contain polycrystalline anatase TiO2, while the waveguides with a thickness of 74nm were of completely amorphous TiO2. Four wave mixing experiments to verify the nonlinear refractive index at a wavelength of 1300nm were not successful in the proposed waveguide with low dispersion at 1310 nm. This was because the available laser power was not high enough. A measurement setup for measuring four wave mixing at 980nm wavelengths is proposed.
Item Type:Essay (Master)
Faculty:EEMCS: Electrical Engineering, Mathematics and Computer Science
Subject:33 physics, 51 materials science, 53 electrotechnology
Programme:Electrical Engineering MSc (60353)
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