Optical fiber securing structure and laser device

An optical fiber securing structure comprising:

• a plurality of first optical fibers that each include
• a core,
• a cladding that surrounds the core and that has a refractive index lower than that of the core, and
• a coating that surrounds the cladding;
• a second optical fiber that includes
• a core,
• a cladding that surrounds the core and that has a refractive index lower than that of the core, and
• a coating that surrounds the cladding;
• a reinforcement member which has a fiber groove that is formed in a first surface so as to extend in a lengthwise direction, where
• a coating-removed part of each of the plurality of first optical fibers and a coating-removed part of the second optical fiber are disposed in the fiber groove,
• the coating-removed part of each of the plurality of first optical fibers is obtained by removing the coating from each of the plurality of first optical fibers, and
• the coating-removed part of the second optical fiber is obtained by removing the coating of the second optical fiber;
• and
• a securing resin which secures, inside the fiber groove of the reinforcement member, the coating of each of the plurality of first optical fibers and the coating of the second optical fiber, wherein
• the fiber groove has a bottom surface at a depth from the first surface of the reinforcement member, and
• in a cross section of a part of the reinforcement member in which part the securing resin secures the coatings of the plurality of first optical fibers or the coating of the second optical fiber,
• a width of the bottom surface of the fiber groove is greater than a diameter of a minimum circle that encloses the coatings of all of the plurality of first optical fibers, and
• a width of an opening of the fiber groove located on the first surface of the reinforcement member is greater than the width of the bottom surface of the fiber groove.