Superficial waveguide splitters fabricated by femtosecond laser writing of LiTaO 3 crystal

We report on Y-branch superficial depressed-cladding waveguides fabricated by femtosecond laser writing of MgO∶LiTaO3 crystal. The cladding waveguides with a rectangular cross-section are single mode for both transverse electric and transverse magnetic polarization, and show good transmission properties at a telecommunication wavelength of 1.55 μm. Divergence angles as large as 2.6 deg are successfully achieved in the splitters with nearly equalized splitting ratios (1:1). The fabricated shallow structures are excellent photonic elements for optoelectronic applications.This work was supported by the National Natural Science Foundation of China (Grant No. U1332121) and Ministerio de Economía y Competitividad under Project FIS2013-44174-P, Spain