Optical fiber amplifier and fiber laser apparatus using the same

An optical fiber amplifier comprising:

• a first pumping source configured to output a first pumping light at a first wavelength;
• a second pumping source configured to output a second pumping light at a second wavelength different from the first wavelength;
• an amplification optical fiber including:
• a core in which an active element is doped, the active element being caused in an excited state by the first pumping light and the second pumping light;
• and
• a cladding covering the core,
• the first pumping light output from the first pumping source entering one end of the amplification optical fiber and the second pumping light output from the second pumping source entering other end of the amplification optical fiber;
• a first optical filter disposed on an optical path from the first pumping source to the one end of the amplification optical fiber and configured to transmit a light at a wavelength the same as a wavelength of the first pumping light and reflect a light at a wavelength the same as a wavelength of the second pumping light;
• and
• a second optical filter disposed on an optical path from the second pumping source to the other end of the amplification optical fiber and configured to transmit a light at a wavelength the same as a wavelength of the second pumping light and reflect at a wavelength the same as a wavelength of the first pumping light,
• a first pumping light propagation fiber coupled to a light source of the first pumping source and the cladding of the amplification optical fiber, and
• a second pumping light propagation fiber coupled to a light source of the second pumping source and the cladding of the amplification optical fiber,
• wherein the first optical filter is disposed between the light source of the first pumping source and the first pumping light propagation fiber, and the second optical filter is disposed between the light source of the second pumping source and the second pumping light propagation fiber.