FIBER LASER HAVING EXCELLENT REFLECTED LIGHT RESISTANCE

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(11)

EP 2 164 140 A8

(12)	CORRECTED EUROPEAN PATENT APPLICATION
	published in accordance with Art. 153(4) EPC

(15)	Correction information:
	Corrected version no 1 (W1 A1)

(48)	Corrigendum issued on:
	14.07.2010 Bulletin 2010/28

(43)	Date of publication:
	17.03.2010 Bulletin 2010/11

(21)	Application number: 08790601.2

(22)	Date of filing: 25.06.2008

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International Patent Classification (IPC):

H01S 3/06^(2006.01)
H01S 3/108^(2006.01)

G02F 1/35^(2006.01)

(86)	International application number:
	PCT/JP2008/061534

(87)	International publication number:
	WO 2009/001852 (31.12.2008 Gazette 2009/01)

(84)	Designated Contracting States:
	AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MT NL NO PL PT RO SE SI SK TR

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Priority:

27.06.2007 JP 2007169042

(71)	Applicant: FUJIKURA LTD.
	Tokyo 135-8512 (JP)

(72)	Inventor:
	KITABAYASHI, Tomoharu Sakura-shi Chiba 285-8550 (JP)

(74)	Representative: Cabinet Plasseraud
	52, rue de la Victoire 75440 Paris Cedex 09 75440 Paris Cedex 09 (FR)

(54)	FIBER LASER HAVING EXCELLENT REFLECTED LIGHT RESISTANCE

(57) An MO-PA fiber laser having a master oscillator; and a first power amplifier which uses as a gain medium, a rare earth-doped optical fiber which is connected to a later stage of the master oscillator, wherein the MO-PA fiber laser has a wavelength conversion portion between the master oscillator and the power amplifier, and has a wavelength filter between the wavelength conversion portion and the master oscillator which only allows wavelength components of pulse light emitted from the master oscillator to pass, thereby making it possible to prevent breakage to a fiber laser which is caused by reflection light without using high-cost optical components.