Abstract: This optical coupler for coupling a plurality of visible light beams having different wavelengths includes: a substrate made of a material different from lithium niobate; and an optical coupling function layer formed on a main surface of the substrate. The optical coupling function layer includes: two multimode-interference-type optical coupling parts; optical-input-side waveguides and an optical-output-side waveguide connected to one multimode-interference-type optical coupling part, and optical-input-side waveguides and an optical-output-side waveguide connected to the other multimode-interference-type optical coupling part. The multimode-interference-type optical coupling parts, the optical-input-side waveguides, and the optical-output-side waveguides are made of a lithium niobate film.

Abstract: A sealing member for a cap featuring excellent cap performance as well as excellent safety and environmental friendliness, and a metallic cap. A foamed polyurethane elastomer having a JIS A hardness of from 15 to 65 and a foaming magnification of from 1.1 to 10 times is used as the sealing member so as to obtain excellent sealing performance, durability, safety and environmental friendliness. The sealing member is provided for a metallic cap shell that has a polyester film formed on the inner surface of the cap, thereby to obtain a cap featuring excellent sealing performance, durability, safety and environmental friendliness.

Abstract: A sealing member for a cap featuring excellent cap performance as well as excellent safety and environmental friendliness, and a metallic cap. A foamed polyurethane elastomer having a JIS A hardness of from 15 to 65 and a foaming magnification of from 1.1 to 10 times is used as the sealing member so as to obtain excellent sealing performance, durability, safety and environmental friendliness. The sealing member is provided for a metallic cap shell that has a polyester film formed on the inner surface of the cap, thereby to obtain a cap featuring excellent sealing performance, durability, safety and environmental friendliness.

Abstract: A sealing member for a cap featuring excellent cap performance as well as excellent safety and environmental friendliness, and a metallic cap. A foamed polyurethane elastomer having a JIS A hardness of from 15 to 65 and a foaming magnification of from 1.1 to 10 times is used as the sealing member so as to obtain excellent sealing performance, durability, safety and environmental friendliness. The sealing member is provided for a metallic cap shell that has a polyester film formed on the inner surface of the cap, thereby to obtain a cap featuring excellent sealing performance, durability, safety and environmental friendliness.