Optical waveguide with prism for inlet or exit coupling of light - where waveguide and prism are made of the same anisotropic crystalline material but have different axial orientations

摘要

The waveguide and prism are made of the same anisotropic crystalline material, but the crystal axis co-ordinates (CAC) of the waveguide possess a different orientation to the CAC of the prism. The crystalline material is pref. LiNbO3; LiTaO3; BaNaNbO5O15; NdAl3(BO3)4; or SrxBa1-x-Nb2O3 in which x = 0-1. The waveguide may contain dopant(s); and the pref. crystalline material is LiNbO3, the waveguide being doped with Ti. Two corresp. axes of the waveguide and prism are pref. aligned in the same direction whereas their co-ordinates are rotated at 90 degrees w.r.t. each other. The light inlet surface of the prism is pref. at 60-89 degrees, esp. 75 degrees, w.r.t. the surface of the prism in contact with the waveguide. As compared with conventional waveguides, more light can be fed into the waveguide.