Patent ID: 8494023

Claim:
A composite optical waveguide comprising: a first optical waveguide comprising a silica-based core, a second optical waveguide comprising an Si-based core, the second optical waveguide being joined to the first optical waveguide, a first ring resonator including a ring having a circumferential length longer than a waveguide corresponding to a permissible propagation loss of the second optical waveguide, a second ring resonator including a ring having a radius smaller than a physical minimum bend radius of the first optical waveguide, and a joint portion jointed to the first ring resonator and the second ring resonator, and for outputting light with a wavelength selected by the first ring resonator or the second ring resonator, the first optical waveguide having a length corresponding to the permissible propagation loss of the second optical waveguide, the second optical waveguide including a sharply curved portion having a radius smaller than the physical minimum bend radius of the first optical waveguide, the first ring resonator including the first optical waveguide, and the second ring resonator including the second optical waveguide.