Abstract: A laser device according to one embodiment includes a laser light source configured to output pulsed laser light L1 and a pulse width control unit configured to amplify the pulsed laser light output from the laser light source, change a pulse width of the pulsed laser light, and output the pulsed laser light. The pulse width control unit includes a first laser amplifier configured to amplify the pulsed laser light and a pulse waveform manipulation unit disposed between the first laser amplifier and the laser light source and configured to manipulate a pulse waveform of the pulsed laser light.

Abstract: Both of multi-mode laser beam 8A and excitation beam 34A for amplification are imputed to an amplification gain medium 62 in a relationship in which their optical axes match each other and an effective beam diameter of the excitation beam for amplification is smaller than an effective beam diameter of the multi-mode laser beam. As a result, laser beam of a part of modes progressing in a radiation range of the excitation beam 34A for amplification is selectively amplified. Laser beam 40A subjected to mode cleaning is thereby outputted.

Abstract: Both of multi-mode laser beam 8A and excitation beam 34A for amplification are imputed to an amplification gain medium 62 in a relationship in which their optical axes match each other and an effective beam diameter of the excitation beam for amplification is smaller than an effective beam diameter of the multi-mode laser beam. As a result, laser beam of a part of modes progressing in a radiation range of the excitation beam 34A for amplification is selectively amplified. Laser beam 40A subjected to mode cleaning is thereby outputted.

Abstract: A technique which is suitable in joining an end surface of a laser medium to a transparent heat sink for maintaining thermal resistance therebetween low and avoiding large thermal stress from acting on the laser medium is to be provided. An end coat is provided on the end surface of the laser medium, a same-material layer constituted of a same material as the heat sink is provided on a surface of the end coat, a surface of the same-material layer and an end surface of the heat sink are activated in a substantially vacuum environment, and those activated surfaces are bonded in the substantially vacuum environment. A laser apparatus having low thermal resistance between the laser medium and the heat sink and high transparency at a joint interface therebetween, and no large thermal stress acting on the laser medium is thereby obtained.