Method for exciting light for optical amplification medium fiber, structure for emitting excited light into optical amplification medium fiber optical fiber amplifier, and optical fiber laser

A method for exciting an optical amplification medium fiber, the fiber comprising a core into which a rare-earth element is doped, an inner cladding which is disposed on an outer periphery of the core, a porous layer which is formed on an outer periphery of the inner cladding, and an outer cladding which is disposed on outer periphery of the porous layer, the method comprising:

• removing a part of the outer cladding of the optical amplification medium fiber in a longitudinal direction;
• forming an inner cladding exposure section in which the inner cladding is exposed;
• cementing an end of an optical fiber for excited light incidence onto the outer periphery of the inner cladding which is exposed in the inner cladding exposure section;
• emitting excitation light from the optical fiber for optical light incidence into the optical amplification medium fiber.