Optical device and manufacturing method for optical device

An optical device comprising:

• an optical element;
• a lens optically coupled with the optical element;
• an optical component provided between the optical element and the lens, optically coupling the optical element and the lens, and multiplexing or demultiplexing input lights, having a light input surface and a light output surface having an oblique face with respect to an optical axis of the input light, and the light input surface and the light output surface being parallel to each other;
• a base having a lower plate having a first convex mounting surface and a second convex mounting surface with the optical component being mounted on the first mounting surface and the second convex mounting surface, the first mounting surface and the second convex mounting surface having the same height and being parallel to a surface of the lower plate, and a side wall with a receptacle being connected thereto,
• wherein the mounting surface of the lower plate of the base has two parallel sides, and a distance between the two sides is smaller than a distance between the light input surface and the light output surface of the optical component, and
• wherein a relationship between the light input surface and the light output surface of the optical component is a relationship of being parallel to the two parallel sides of the mounting surface, and the optical component is arranged on the mounting surface in such a relationship that the two parallel sides of the mounting surface are located in respective inner sides from the light input surface and the light output surface of the optical component.