Patent ID: 7340116

Claim:
An optical switch comprising: a Mach-Zehnder interferometer having a 3-dB coupler placed on an input side, a 3-dB coupler placed on an output side, and two three dimensional optical waveguides connecting said input-side 3-dB coupler and said output-side 3-dB coupler together; and at least one electrode for applying electric fields to one or both of said two three-dimensional optical waveguides; wherein said two three-dimensional optical waveguides have a crystal material including KTa 1−x Nb x O 3 (0<x<1) and K 1−y Li y Ta 1−x Nb x O 3 (0<x<1, 0<y<1), or KTa 1−x Nb x O 3 or K 1−y Li y Ta 1−x Nb x O 3 .