Laser apparatus and laser processing method
The present invention relates to a laser apparatus having a structure for removing a skirt portion contained in pulsed light, and a laser processing method using the laser apparatus. The laser apparatus comprises a MOPA fiber laser light source which outputs pulsed light having a skirt portion with a light intensity lower than a predetermined value, and a saturable absorber which removes a skirt portion from the pulsed light outputted from the MOPA fiber laser light source.
1. A laser apparatus, comprising:
a laser light source which outputs pulsed light having a skirt portion with a light intensity lower than a predetermined value; and
a light path changer which changes light path of the pulsed light outputted, from the laser light source from a first light path to a second light path that is different from and in parallel to the first light path, the light path changer comprising:
a first saturable absorbing mirror provided on the first light path and at a position where the pulsed light outputted from the laser light source reaches, the first saturable absorbing mirror reflecting the pulsed light, which has propagated along the first light path, in a third light path different from the first and second light paths, after removing first part from the skirt portion of the pulsed light, the first part having a light intensity lower than the predetermined value; and
a second saturable absorbing mirror provided on the second light path and at a position where the pulsed light reflected by the first saturable absorbing mirror reaches, the second saturable absorbing mirror reflecting the pulsed light, which has propagated along the third light path, in the second light path, after removing second part from the remaining skirt portion in which the first part is removed, the second part having a light intensity lower than the predetermined value,
wherein each of the first and second saturable absorbing mirrors has: a substrate composed of a material preventing the pulsed light passing therethrough; a saturable absorber provided on a main surface of the substrate, the saturable absorber having an entrance surface on which the pulsed light is incident, and a rear surface opposing the entrance surface; and a Bragg reflecting mirror provided between the main surface of the substrate and the rear surface of the saturable absorber, and
wherein each of the first and second saturable absorbing mirrors are disposed so that the entrance surface of the saturable absorber therein inclines with respect to the first to third light paths.
2. The laser apparatus according to claim 1 , wherein the pulsed light outputted from the laser light source is comprised of a plurality of successive pulse components, and
wherein the predetermined value is set to a minimum light intensity between pulse components adjacent to each other among the plurality of pulse components.
3. A laser processing method of processing a target to be processed, by irradiating the target to be processed with pulsed light outputted from the laser apparatus according to claim 1 .