| 摘要 |
PURPOSE:To attain higher stability by providing an optical waveguide having branch optical waveguides and electrodes for modulation on a substrate having an electrooptic effect and photoelasticity effect and providing a pressure impressing means which applies a pressure onto one of the branch optical waveguides or near the same. CONSTITUTION:The optical waveguide 2 having the branch optical waveguides 2a, 2b and the electrodes 3a, 3b for modulation which generate a phase difference between the light rays propagating in the branch optical waveguides 2a, 2b are provided on the substrate 1 having the electrooptic effect and photoelasticity effect and are housed in a housing 4 having optcial fiber coupling terminals 41, 42 and signal input terminals 43, 44 for modulation to constitute this optical modulator. The pressure impressing means 5 which applies the pressure onto the branch optical waveguides 2a, 2b or near the same is provided. The photoelasticity effect is generated by applying the pressure to both branch optical waveguides 2a, 2b or near the same without impressing a DC bias voltage thereto. Since the phase difference of the light based on the change in refractive index changes, the operating point changes. The control of the operating point is executed in this way without generating a DC drift. The performance and reliability of the optical modulator for high-speed and long-distance optical communication are improved. |
