The present disclosure discloses a CO2 laser and a method for the CO2 laser. The CO2 laser comprises an unstable laser cavity in the form of a first optical resonator having a semi-transparent output coupler (3), a laser medium (2) in the unstable laser cavity, and means (1) for exciting the laser medium (2). A part of the laser beam propagating beyond the light aperture of the output coupler (3) is directed to a second resonator, the second resonator comprising at least one focusing member (6), and the optical length of the second resonator being equal or multiple to the optical length of the first optical resonator. The part of the laser beam passing through the focal plane of the focusing member (6) is modulated by using a Q-switching device (8) in a manner that the excitation of the laser medium is in synchrony with the operation of the Q-switching device (8).