Patent ID: 7046881

Claim:
A method for manufacturing a planar lightwave circuit type optical coupler/splitter that is provided with plural ports for performing light input and light output inside a cladding layer formed from a glass material, and in which a waveguide core is formed that optically connects said ports, comprising the steps of: setting at least one portion between said ports as a refractive index adjustment area and forming portions of said waveguide core, wherein the waveguide core is not formed in the refractive index adjustment area; inputting signal light into one port and monitoring the signal light outputted from other ports; and adjusting optical characteristics of said optical coupler/splitter by forming the waveguide core in said refractive index adjustment area of said waveguide core by adjusting a refractive index of said refractive index adjustment area by focusing a laser beam onto said refractive index adjustment area during the monitoring.