Optical waveguiding characteristics of TiO2 sol–gel thin films for photonic devices: effects of thermal annealing

Ouissem Chibani; Fatiha Challali; Tahar Touam; Azeddine Chelouche; Djamel Djouadi

doi:10.1117/1.OE.58.4.047101

10 April 2019 Optical waveguiding characteristics of TiO₂ sol–gel thin films for photonic devices: effects of thermal annealing

Ouissem Chibani, Fatiha Challali, Tahar Touam, Azeddine Chelouche, Djamel Djouadi

Author Affiliations +

Optical Engineering, Vol. 58, Issue 4, 047101 (April 2019). https://doi.org/10.1117/1.OE.58.4.047101

Abstract

We have investigated the effects of thermal annealing (450°C, 500°C, and 550°C) on the titanium dioxide (TiO₂) thin film physical and optical waveguiding properties using x-ray diffraction, Raman spectroscopy, scanning electron microscopy, atomic force microscopy, UV–visible spectrophotometry, and m-lines spectroscopy. The results show that the as-deposited film is amorphous, whereas the annealed films are polycrystalline and crystallize only in the anatase tetragonal structure with a preferential orientation of (101). The grain size, morphology, and surface roughness of the TiO₂ films are significantly affected by the thermal annealing. The as-deposited TiO₂ thin films reveal high transparency with an average transmittance >80 % in the visible region. Moreover, a decrease in the optical transmission and energy bandgap with increasing annealing temperature is also observed. All the TiO₂ planar waveguides exhibit only single-mode confinement regardless of the polarization. Both transverse electric and transverse magnetic refractive indices are found to increase upon annealing. Moreover, the as-deposited TiO₂ planar waveguide shows a remarkable propagation loss of as low as 0.8 ± 0.1 dB / cm at a 632.8 nm wavelength, which suggests that the fabricated TiO₂ films are promising for photonic applications.

Citation Download Citation

Ouissem Chibani, Fatiha Challali, Tahar Touam, Azeddine Chelouche, and Djamel Djouadi "Optical waveguiding characteristics of TiO₂ sol–gel thin films for photonic devices: effects of thermal annealing," Optical Engineering 58(4), 047101 (10 April 2019). https://doi.org/10.1117/1.OE.58.4.047101

Received: 6 February 2019; Accepted: 26 March 2019; Published: 10 April 2019

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