US 11,901,690 B2
Fiber laser device
Yasuo Nakanishi, Sakura (JP); Yasuhiro Mashiko, Sakura (JP); Shinichi Sakamoto, Sakura (JP); and Kensuke Shima, Sakura (JP)
Assigned to Fujikura Ltd., Tokyo (JP)
Appl. No. 17/416,873
Filed by Fujikura Ltd., Tokyo (JP)
PCT Filed Feb. 21, 2020, PCT No. PCT/JP2020/007066
§ 371(c)(1), (2) Date Jun. 21, 2021,
PCT Pub. No. WO2020/171205, PCT Pub. Date Aug. 27, 2020.
Claims priority of application No. 2019-029366 (JP), filed on Feb. 21, 2019.
Prior Publication US 2022/0085565 A1, Mar. 17, 2022
Int. Cl. H01S 3/067 (2006.01); H01S 3/16 (2006.01); H01S 3/00 (2006.01)
CPC H01S 3/0675 (2013.01) [H01S 3/0078 (2013.01); H01S 3/06716 (2013.01); H01S 3/1618 (2013.01)] 6 Claims
OG exemplary drawing
 
1. A fiber laser device, comprising:
a pumping light source that outputs pumping light;
an amplifying fiber comprising a core doped with a rare earth element excitable by the pumping light;
an input side fiber that is fusion-spliced on an input side of the amplifying fiber and that comprises a high reflectivity-fiber Bragg grating (HR-FBG);
an output side fiber that is fusion-spliced on an output side of the amplifying fiber and that comprises an output coupler-fiber Bragg grating (OC-FBG),
having a reflectivity smaller than a reflectivity of the HR-FBG;
an output end that outputs a laser beam; and
a mode filter that removes at least a portion of a predetermined higher-order mode from the core of the amplifying fiber,
wherein
the input side fiber or an intermediate fiber disposed between the amplifying fiber and the input side fiber is fusion-spliced with the amplifying fiber via a fusion splice portion, and
at least a portion of the mode filter is disposed between the fusion splice portion and a position distant from the fusion splice portion by a coherence length of beating caused by mode interference of signal light propagating in the amplifying fiber.