OPTICAL FIBER FOR A FIBER LASER AND FIBER LASER USING THE SAME

• US 20090316733A1
• Filed: 06/18/2009
• Published: 12/24/2009
• Est. Priority Date: 06/20/2008
• Status: Abandoned Application

• Current Assignee: Akihito Hongo, Akio Satou, Bing Yao, Kazumasa Ohsono, Kazuya Saito, Kohei Yanaka
• Original Assignee: Akihito Hongo, Akio Satou, Bing Yao, Kazumasa Ohsono, Kazuya Saito, Kohei Yanaka
• Inventors: Saito, Kazuya, Ohsono, Kazumasa, Yao, Bing, Hongo, Akihito, Yanaka, Kohei, Satou, Akio
• Application Number:
  US12/486,928
• Publication Number:
  US 20090316733A1
• Time in Patent Office: Days
• US Class Current: 372/6
• CPC Class Codes: H01S 3/06729 Peculiar transverse fibre profile
• CPC Class Codes: H01S 3/06741 Photonic crystal fibre, i.e. the fibre having a photonic bandgap
• CPC Class Codes: H01S 3/0675 Resonators including a grating structure, e.g. distributed Bragg reflectors [DBR] or distributed feedback [DFB] fibre lasers
• CPC Class Codes: H01S 3/07 consisting of a plurality of parts, e.g. segments H01S3/067 takes precedence
• CPC Class Codes: H01S 3/0804 Transverse or lateral modes
• CPC Class Codes: H01S 3/094011 with bidirectional pumping, i.e. with injection of the pump light from both two ends of the fibre

Abstract

The present invention provides an optical fiber, for use in a fiber laser, from which a high-quality single-mode laser beam with high optical power is obtained and also provides a fiber laser that uses the optical fiber. The novel optical fiber, which includes a core to which a rare earth element is doped and a cladding formed around the core, amplifies excitation light to oscillate a laser beam. A mode filter is formed at a predetermined position in the longitudinal direction of the optical fiber.

Claims

1. An optical fiber for a fiber laser comprising:

a core doped with a rare earth element;

a cladding formed around the core; and

a mode filter formed at a predetermined position in a longitudinal direction of the optical fiber, the mode filter comprising a plurality of holes.

2. The optical fiber for a fiber laser, according to claim 1, wherein the plurality of holes formed in the mode filter is formed by deforming a plurality of holes formed in the cladding.

3. The optical fiber for a fiber laser, according to claim 1, wherein the mode filter is formed at each of a plurality of positions in the longitudinal direction of the optical fiber.

4. The optical fiber for a fiber laser, according to claim 1, wherein the mode filter is formed at a part that is linearly disposed.

5. The optical fiber for a fiber laser, according to claim 1, wherein the mode filter is a photonic crystal fiber disposed at the leading end of the optical fiber.

6. The optical fiber for a fiber laser, according to claim 1, wherein the mode filter is less than 100 mm in length.

7. The optical fiber for a fiber laser, according to claim 1, wherein a ratio d/A of a diameter d of the hole to a distance Λ

between the holes is less than 0.44.

8. The optical fiber for a fiber laser, according to claim 1, wherein a mode field diameter of the mode filter is not less than 30 μ

m.

9. A fiber laser comprising:

an optical fiber comprising a core doped with a rare earth element, a cladding formed around the core, and a mode filter formed at a predetermined position in a longitudinal direction of the optical fiber, the mode filter comprising a plurality of holes; and

an excitation light incident means for entering excitation light into the optical fiber.