3D Polarization-Dependent Waveguide Arrays in LiNbO3 Crystal Produced by Femtosecond Laser Writing

Waveguide arrays are basic photonic elements in integrated optics. We propose a 3D hybrid-integrated waveguide array based on the femtosecond laser writing of lithium niobate (LiNbO
₃
) crystals by engineering the layout of laser-induced tracks. The cross section of the structure is a cross-shaped geometry. The light propagation through this waveguide array shows polarization-dependent behaviors, which enables mode-coupling along either the vertical or the horizontal direction under excitation of linearly polarized light. This work opens new way to produce polarization-dependent optical devices in photonic systems by using femtosecond laser writing of LiNbO
₃
.