Patent ID: 7564563

Claim:
A laser gyro comprising: a Si substrate; laser light excitation means formed on the Si substrate and configured to excite first and second laser lights propagating in clockwise and counterclockwise directions in a circular ring-shaped path; coupling means formed on the Si substrate, said coupling means formed of a SiO 2 multilayer film optical waveguide and configured to superimpose the first and the second laser lights; and a photodetector disposed on the Si substrate and configured to observe an interference signal generated by the superimposed first and second laser lights, wherein the laser light excitation means includes a circular ring-shaped optical waveguide formed of a SiO 2 multilayer film and a semiconductor optical amplifier coupled to the circular ring-shaped optical waveguide so that the semiconductor optical amplifier and the circular ring-shaped optical waveguide form the circular ring-shaped path, the coupling means includes an optical coupler configured to extract the first and the second laser lights from the ring-shaped path, and the semiconductor optical amplifier and the photodetector are disposed individually in concave portions, each concave portion being formed by removing the multilayer film partly.