Single mode optical waveguide.

摘要

In a single mode optical waveguide having a substrate (1), a cladding layer (3) formed on the substrate (1), a core portion (2) embedded in the cladding layer (3), and an elongated member (4a, 4b; 14; 14a, 14b) for applying a stress to the core portion (2) or a stress relief groove (5a, 5b; 64) for relieving a stress from the core portion (2) in the cladding layer (3) along the core portion (2). A position, shape and material of the elongated member (4a, 4b; 14; 14a, 14b) or the groove (5a, 5b; 64) are determined in such a way that stress-induced birefringence produced in the core portion (2) in accordance with a difference in thermal expansion coefficient between the substrate (1) and the single mode optical waveguide is a desired value.