PURPOSE: To obtain superior switching characteristics by selectively applying voltage to plural electrodes at prescribed positions of a principal optical waveguide and a branched optical waveguide so as to prevent a leak of light guided through the principal optical waveguide when light travels straight and to propagate all of light through the branched optical waveguide when light is totally reflected.
CONSTITUTION: A Y-cut single crystal substrate 5 of LiNbO3 having a smooth surface is provided with a principal optical waveguide 6 and a branched optical waveguide 7 contg. diffused Ti in the direction of the X-axis of the single crystal. By applying voltage between electrodes 8, 9, a layer having a reduced refractive index is formed along the boundary between the waveguides 6, 7, and when light travels straight through the waveguide 6, a leak of light from the waveguide 6 to the waveguide 7 can be controlled. By generating an electric field of about 30V/μm between the electrodes 8, 9 with applied voltage, light traveling straight through the waveguide 6 is propagated without causing a leak to the waveguide 7, and ≥20dB extinction ratio can be obtd.
OUCHI KENZOU
KAWAGUCHI TAKAO
ADACHI HIDEAKI
WASA KIYOTAKA
