OPTICAL PHASE MODULATOR

摘要

An optical phase modulator comprises a signal electrode, a first earth electrode, and a second earth electrode, which are formed on a substrate made of an electrooptical material, the first and second earth electrodes being provided on mutually opposite sides of the signal electrode. Each of the electrodes is provided so that the size of a first gap between the first earth electrode and the signal electrode is made smaller than the size of a second gap between the second earth electrode and the signal electrode. In addition, although an optical waveguide constituting an optical phase modulation portion is provided in the first gap, the optical waveguide is not provided in the second gap, thereby achieving the problems for reducing a driving voltage necessary for the phase modulation and realizing easy impedance-matching and good high-frequency characteristics.