Directly writing embedded waveguides in lithium niobate by a femtosecond laser

Abstract

Parallel embedded waveguides are fabricated from a computer-aided design file by scanning the focus spot in z-cut lithium niobate (LiNbO3) using femtosecond laser pulses. The beam coupling in such waveguides is experimentally investigated. The coupling constant of the waveguide structure is obtained by measuring the ratio of output power of each waveguide, and the variation of coupled power in each waveguide as a function of the waveguide length are demonstrated.