Abstract.  After T. Maiman’s invention, the new type of the laser with the modulation of the Q-factor was proposed during 1961-1962. This type of laser operates in the regime of the accumulation of the excited energy in the active medium at the low level of Q-factor after that it should be fast switched on. It results in generation the very short laser pulse. At that time, nearly 100 J of the laser energy during 10^-9s was available. This corresponds to 10¹¹ Watt power, significantly higher than other pulse power machines.

This was the start point to use the lasers for obtaining the high energy concentration at the focusing of the laser beam on small target for reaching high temperature of the matter nessesary for thermonuclear reaction [1,2].

The next step consists in the idea to use target material compression to increase Lawson condition under laser light irradiation [3].

These two ideas permit to create the new approach in the thermonuclear research, so-called Inertial Confinement Fusion or Laser Fusion which is one of the perspective areas of research.

Details of the historic perception and advances will be discussed.

References :
[1] N.G. Basov, O.N. Krokhin, Proc. Of III Conf. On Quantum Electronics, 11-15 Feb. 1963, Paris, France: Columbia Univ. Press, New York (1964) p. 1373.
[2] N.G. Basov, O.N. Krokhin, Zh. Eksp. Teor. Fiz., v. 46, p. 171 (1964).
[3] N.G. Basov, O.N. Krokhin, New Sientist and Sience J., v. 51, p. 733 (1971).