Recoverable and rewritable waveguide beam splitters fabricated by tailored femtosecond laser writing of lithium tantalate crystal

• Opposite refractive index modifications by fs-laser writing are realized in LiTaO 3 . • The waveguide of positive refractive index change is recovered after heat treatment. • The waveguides with two type modifications are integrated into one beam splitter. • The recoverable optical beam splitter can be reconfigured in a short time. We report on an integrated 1 × 5 beam splitter based on optical waveguides with type I and type II modifications of femtosecond laser (fs-laser) writing in lithium tantalate (LiTaO 3 ) crystal. The cladding waveguides consisting of type-II modified tracks are used for optical signal transmission, photon crosstalk reduction, and mode field regulation. The single-line waveguides with type I modification are utilized for light beam splitting. Type-I single-line waveguides are with relatively weak thermal stability, which are utilized to produce a recoverable and rewritable optical beam splitter, and the structure still possesses good transmission properties after the reconstruction. Especially, the type-I modified waveguides can be rewritten in very short time (1–2 min). The beam splitter shows good performance in outputting programmable optical signals, which provides a possible strategy for the development of erasable photonic data processors.