Patent ID: 8107778

Claim:
A method of producing a waveguide element comprising: forming a lower cladding layer having a refractive index n 1 on a substrate on which surface or side surface a lower electrode is formed; forming an active core layer on a surface of the lower cladding layer, the active core layer having a refractive index n 2 that is larger than the refractive index n 1 of the lower cladding layer, the active core layer exhibiting an electro-optical effect; forming a protective layer on a surface of the active core layer, the protective layer having a refractive index n 4 that is smaller than the refractive index n 2 of the active core layer and larger than the refractive index n 1 of the lower cladding layer; forming a passive core layer on a surface of the protective layer, a refractive index of the passive core layer being changed by exposure to light, the passive core layer having a refractive index n 3 after the exposure, the refractive index n 3 being smaller than the refractive index n 4 of the protective layer and larger than the refractive index n 1 of the lower cladding layer; exposing the passive core layer with a predetermined pattern to form an optical circuit having a refractive index n 3 , the optical circuit introducing light to the active core layer or guiding out the light passing through the active core layer; forming an upper cladding layer on a surface of the passive core layer in which the optical circuit is formed, the upper cladding layer having a refractive index n 5 that is smaller than the refractive index n 3 of the passive core layer after the exposure thereof; forming an upper electrode on a surface of the upper cladding layer, the upper electrode being used to apply an electric field to the active core layer; and performing a polarization orientation treatment after the upper electrode is formed, in which the active core layer is put into a softened or liquid state and cured while the electric field is applied.