OPTICALLY AMPLIFYING FIBER, OPTICALLY AMPLIFYING METHOD, LASER OSCILLATING METHOD, LASER AMPLIFIER, LASER OSCILLATOR, LASER APPARATUS, AND LASER FINISHING MACHINE

摘要

PROBLEM TO BE SOLVED: To provide a small-sized highly efficient laser oscillator whereby a laser beam of high power/high beam quality can be obtained. SOLUTION: The laser oscillator comprises a first optical waveguide 21 (refractive index=n1) for transmitting a pumping beam, a core 23 (refractive index=n3) for generating a laser beam, a second optical waveguide 22 comprising a clad 24 (refractive index=n2) for transmitting the pumping beam, and a third optical waveguide 25 (refractive index=n4) including the first and the second optical waveguides 21, 22. An optical amplifying fiber 20 wherein the respective refractive indexes satisfy a relation of n1