Structural, optical and waveguiding properties improvement of SiO2/TiO2 Bragg reflectors processed by the sol–gel method under the effect of Ni-doped TiO2 and annealing duration

•The formation of anatase phase only, whatever are Ni content and annealing duration.•Transmission and PL spectra redshifted with Ni content and annealing duration.•PL lowering with Ni content is due to the recombination rate of electron–hole reduction.•Annealing duration increases the recombination rate and then the PL intensity rises.•Increasing Ni content improves waveguiding properties and then two TE modes appear.

We investigated the nickel doped TiO2 layer and annealing duration effects on SiO2/TiO2 Bragg reflectors. The films crystallize in pure anatase phase whatever is the Ni content and the annealing duration. In UV–vis-NIR analyses, variations of width, position and transmission coefficient of the stop-band were observed. The PL spectra red-shifted when the Ni content and annealing duration increased. As the annealing duration increases, an additional sharp emission peak appears around 867 nm, indicating a reduced number of defects. As Ni content increased, the M-lines spectroscopy shows two transverse electric polarization guided modes TE0 and TE1, which indicates a decreased refractive index and an increased film thickness.

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