Patent ID: 7116852

Claim:
A optical signal processing circuit comprising: a substrate on which an optical waveguide is held; first and second optical waveguides formed on said substrate; and a reflecting structure having a single reflecting surface that disposes a first coupling end of said first optical waveguide and a second coupling end of said second optical waveguide, which are formed on said substrate, in a position where an image Fourier transformation of each other is established, and couples the first and second optical waveguides together, wherein said reflecting structure is shaped to be an arc of a circle whose radius is r; and said first coupling end and said second coupling end are disposed so that the optical axes thereof pass through the same point Q on said reflecting structure, and the coupling ends are disposed at a symmetrical position with respect to a straight line including the center P of the arc of said reflecting structure and said point Q, and are further disposed on an arc of a circle whose radius is r, centering around a termination point T that is provided by extending a line segment PQ by r/2 in the direction of said point Q.