Laser modification of titanium film in optical waveguides on lithium niobate substrates

It is shown that laser modification of a nanometer titanium film can be used for precise control of the loss level in optical waveguides on lithium niobate substrates. Theoretical estimates of the change in linear losses at the level of 0.95 dB/mm were confirmed by experiments on local laser modification using radiation at a wavelength of 976 nm with a threshold intensity of 1 kW/mm$^2$. The proposed method can be effectively used for precision adjustment of the characteristics of integrated optical devices, such as the modulation contrast of Mach–Zehnder modulators.