Optical waveguides in Er:LiNbO3 fabricated by different techniques – A comparison

• We performed comparison of 3 optical-waveguides-fabrication techniques in Er:LiNbO3.
• The best of 3 waveguides-fabrication techniques turned out to be the APE method.
• Better crystallographic cut appeared to be Z cut, as compared to X cut.
• Fabrication of optical waveguides influenced intensity of erbium luminescence.
• Er position in crystal remains unchanged after fabrication of optical waveguides.

We report on the comparison of three techniques used for the fabrication of optical waveguides in erbium doped lithium niobate crystal substrates (Er:LiNbO3). The techniques include ion in-diffusion from a titanium metal layer, annealed proton exchange (APE), and He+ ion implantation. The main focus of the work was placed on the investigation of the influence of the used optical waveguides fabrication techniques on the structural and luminescence properties of Er:LiNbO3 substrates. The results have shown that none of the used optical-waveguide-fabrication techniques significantly affect the position of erbium in the host crystal structure. It turned out, however, that the fabrication process affected luminescence intensities of the characteristic luminescence bands of erbium ions – the most significant decrease in the luminescence intensity was observed in the Ti-indiffused waveguides.