Laser device

A laser device comprising:

• a first laser medium and a second laser medium that have a first surface and a second surface opposite to the first surface, and receive input of excitation light and seed light from the first surface side to amplify the seed light;
• a holder that holds the first laser medium and the second laser medium;
• and
• a pair of cooling units that cool the first laser medium and the second laser medium according to change in volume of a refrigerant,
• wherein a first mirror that reflects at least the seed light is provided on the second surface,
• the first laser medium and the second laser medium are disposed at relative positions in which the seed light reflected by the first mirror of the first laser medium is further reflected by the first mirror of the second laser medium,
• the holder integrally holds the first laser medium and the second laser medium so that the relative position is maintained,
• the first laser medium and the second laser medium are disposed such that the first mirror of the first laser medium and the first mirror of the second laser medium are parallel to each other,
• the pair of cooling units include a refrigerator that cools the first laser medium and the second laser medium according to compression and expansion of the refrigerant, and
• the first laser medium and the second laser medium are thermally connected to the pair of cooling units via a respective flexible heat conductive member.