Local laser oxidation of titanium film for the post-fabrication trimming of photonic integrated circuits

Abstract

Local laser oxidation of a thin titanium film is considered as a means of a precise adjustment of losses and effective refractive index of dielectric optical waveguides. A fine phase control of an operating point and extinction ratio enhancement up to 57 dB were demonstrated using an integrated optical Ti:LiNbO3 Mach-Zehnder modulator. This technique only slightly affects the dielectric waveguide material and is very promising for a high precision permanent trimming of photonic devices based on dielectric waveguides of different material platforms and fabrication technologies.