An optical deflector including an optical waveguide of a dielectric
material having electrooptical effect; and a pair of electrodes opposed to
each other across the optical waveguide. An electric field is applied
between the opposed electrodes to change a refractive index of the
dielectric material to thereby control a propagating direction of signal
light propagating in the optical waveguide, wherein the dielectric
material has a first refractive index in its initial state, has a second
refractive index by application of an electric field of a first polarity,
and retains as a third refractive index a refractive index obtained after
the electric field has been removed. The dielectric material having the
third refractive index has the first refractive index by the application
of an electric field of a second polarity different from the first
polarity and removal of the electric field.
