  The paper explores a possible application of the discrete thermodynamics to a
2-level laser. The model accounts for the laser openness to incoming pumping
power and coming out energy with the emitted light. As an open system, a laser
should be in open equilibrium with thermodynamic forces, related to both energy
flows. Conditions of equilibria are expressed by a logistic map with specially
developed dynamic inverse pitchfork bifurcation diagrams for graphical
presentation of the solutions. The graphs explicitly confirm the triggering
nature of a laser where bistability is manifested by pitchfork ground and laser
branches, with the relative population equilibrium values close to 1 and 0
correspondingly. Simulation was run for a 2-level laser emitting light from far
infrared to short wave UV. A newly discovered feature of such a laser is the
line spectrum of up and down transitions of the laser excitable dwellers,
occurring between the laser and the ground pitchfork branches beyond
bifurcation point. The density of the spectra lines tangibly increases as the
branches approach their limits. Transitions of both types are overlapping in
opposite phases. This effect is a new confirmation of the Einstein's
prohibition on practical realization of a 2-level laser. Wide enough gaps
between the lines of the spectra were also discovered in this research. The
gaps are shielding the light irradiation and may be considered as potential
areas of control over the 2-level laser emissions.
