Patent ID: 8446923

Claim:
A fiber laser device comprising: a seed laser light source configured to output seed laser light; a pumping light source configured to output pumping light; an amplification optical fiber doped with a rare-earth element to be pumped by the pumping light and configured to receive the seed laser light and the pumping light, amplify the seed laser light, and output the amplified seed laser light as laser light; an output unit configured to output the laser light output from the amplification optical fiber; a control unit configured to control at least the seed laser light source and the pumping light source; an output setting unit configured to input, to the control unit, an output setting instruction to set an intensity of the laser light output from the output unit such that the laser light output from the output unit has a variable intensity in accordance with the output setting instruction; and an output instructing unit configured to input, to the control unit, an output instruction to cause the output unit to output the laser light, wherein when the output instruction is input to the control unit, the control unit controls the seed laser light source and the pumping light source so that the seed laser light source and the pumping light source are switched from a pre-pumped state to an output state, in the pre-pumped state, the seed laser light source does not output the seed laser light and the pumping light source outputs pumping light with a predetermined intensity based on the laser light intensity set by the output setting unit for a predetermined period of time, in the output state, the seed laser light source outputs the seed laser light and the pumping light source outputs the pumping light, so that laser light with the intensity set by the output setting unit is output from the output unit, and the control unit sets the intensity of the pumping light in said pre-pumped state in accordance with the laser light intensity set by the output setting unit such that when the laser light intensity is set to a higher value, the intensity of the pumping light in said pre-pumped state is set to a higher intensity, and when the laser light intensity is set to a lower value, the intensity of the pumping light in said pre-pumped state is set to a lower intensity.