Optical waveguide type device for reducing microwave attenuation

摘要

In an optical waveguide type device, an optical waveguide is formed in a crystal substrate having an electro-optical effect. A buffer layer is formed on the crystal substrate. Further, an signal electrode is formed on the buffer layer so that microwave signals are given to the signal electrode. In addition, a dielectric substrate is formed under the crystal substrate. With this structure, a groove is formed in the dielectric substrate and below at least the signal electrode. In this case, the groove functions as the air gap for reducing an attenuation of the microwave signals. According to this invention, the microwave attenuation is reduced and further the handling of the chip becomes easy. Alternatively, such a reduction can be accomplished by selecting a first width of an active portion of a signal electrode, a second width of a feeder portion of the signal electrode, and a third width of a connector. Specifically, the second width is wider than the first width and is narrower than the third width.