HIGH-FREQUENCY LINE

摘要

The present invention provides a high-frequency line provided with a structure that minimizes impedance fluctuation and generation of excessive loss of electricity in a high-frequency wiring that intersects an optical waveguide. This high-frequency line is a microstrip line configured primarily from a ground electrode (302), a dielectric layer (304), and a signal electrode (305) stacked in the stated order on a SI-InP substrate (301). The optical waveguide core (303) of an InP-type semiconductor intersects the high-frequency line (305) in a transverse arrangement as shown in a transverse cross-sectional view. The width of the signal electrode (305) partially increases along the propagation direction of the high-frequency line in a fixed region that includes the intersection with the optical waveguide. The width of the signal electrode (305) in the microstrip line is increased in part from w1 to w2, and the characteristic impedance is reduced to a greater extent than when the width is uniform at w1. The length l2 of a second signal electrode part (325) that has a width of w2 is set sufficiently shorter than the wavelength of inputted high-frequency electric signals.