Fiber laser device

A fiber laser device comprising:

• a plurality of optical paths sharing a part thereof and causing light to be resonated thereon;
• an amplification optical fiber serving as a part of each of the plurality of optical paths and amplifying respective light beams resonated on each of the plurality of optical paths;
• and
• an acoustic optic modulation arranged at a part shared by each of the plurality of optical paths and switchable between a first state, in which the acoustic optic modulation vibrates at a predetermined cycle and emits light incident from the plurality of optical paths to the plurality of optical paths, and a second state, in which the acoustic optic modulation emits light incident from the plurality of optical paths to a path other than the plurality of optical paths,
• wherein a resonance cycle of light having highest power out of the respective light beams resonated on each of the plurality of optical paths and the predetermined cycle at which the acoustic optic modulation vibrates in the first state have a non-integral multiple relationship,
• wherein the plurality of optical paths include a specific optical path and an optical path including the specific optical path and a loop optical path which is connected in the middle of the specific optical path and is formed in a looped shape, and
• wherein light propagating through the specific optical path deviates to the loop optical path at a predetermined branching ratio, and light propagating through the loop optical path couples with the specific optical path at the predetermined branching ratio.