Cladding waveguide splitters fabricated by femtosecond laser inscription in Ti:Sapphire crystal

Highly-compact devices capable of beam splitting are intriguing for a broad range of photonic applications. In this work, we report on the fabrication of optical waveguide splitters with rectangular cladding geometry in a Ti:Sapphire crystal by femtosecond laser inscription. Y-splitters are fabricated with 30 gm x 15 mu m and 50 mu m x 25 mu m input ends, corresponding to two 15 mu m x 15 mu m and 25 mu m x 25 mu m output ends, respectively. The full branching angle theta between the two output arms are changing from 0.5 degrees to 2 degrees. The performances of the splitters are characterized at 632.8 nm and 1064 nm, showing very good properties including symmetrical output ends, single-mode guidance, equalized splitting ratios, all-angle-polarization light transmission and intact luminescence features in the waveguide cores. The realization of these waveguide splitters with good performances demonstrates the potential of such promising devices in complex monolithic photonic circuits and active optical devices such as miniature tunable lasers. (C) 2018 Elsevier Ltd. All rights reserved.