Fiber module

A fiber module comprising:

• an input-side optical fiber;
• an output-side optical fiber;
• a ferrule in which the input-side optical fiber and the output-side optical fiber are insertable in both ends and includes a V-shaped groove formed in a direction orthogonal to a longitudinal direction;
• a dielectric multilayer film filter inserted in the V-shaped groove and arranged inclined at greater than or equal to 5° and less than or equal to 10° with respect to a plane orthogonal to an optical axis;
• and
• an input-side graded index fiber and an output-side graded index fiber joined by fusion to respective terminal portions of the input-side optical fiber and the output-side optical fiber, wherein
• the dielectric multilayer film filter is interposed between an end surface of the input-side graded index fiber and an end surface of the output-side graded index fiber in the longitudinal direction, and
• the end surface of each of the input-side graded index fiber and the output-side graded index fiber abuts the dielectric multilayer film filter while the dielectric multilayer film is inclined at greater than or equal to 5° and less than or equal to 10° with respect to the plane orthogonal to the optical axis and are optically polished.