Abstract: A seed unit (MO) includes a plurality of optical paths sharing a part thereof and causing light to be resonated thereon, an amplification optical fiber (13) serving as a part of each of the optical paths and amplifying respective light beams resonated on the respective optical paths, and; an AOM (14) arranged at a part shared by the respective optical paths and switchable between a first state, in which the AOM (14) vibrates at a predetermined cycle and emits light incident from the optical paths to the optical paths, and a second state, in which the AOM (14) emits light incident from the optical paths to a path other than the optical paths. A resonance cycle of light having highest power out of the light beams resonated on the optical paths and the predetermined cycle at which the AOM (14) vibrates in the first state have a non-integral multiple relationship.

Abstract: A seed unit (MO) includes a plurality of optical paths sharing a part thereof and causing light to be resonated thereon, an amplification optical fiber (13) serving as a part of each of the optical paths and amplifying respective light beams resonated on the respective optical paths, and; an AOM (14) arranged at a part shared by the respective optical paths and switchable between a first state, in which the AOM (14) vibrates at a predetermined cycle and emits light incident from the optical paths to the optical paths, and a second state, in which the AOM (14) emits light incident from the optical paths to a path other than the optical paths. A resonance cycle of light having highest power out of the light beams resonated on the optical paths and the predetermined cycle at which the AOM (14) vibrates in the first state have a non-integral multiple relationship.