  We are concerned with the study of the system of coupled equations of motion
for a system of two-level atoms interacting with a single-mode field in the
laser cavity on resonance. The passage from the equation of motion to the
Lorenz equations is established. Some theoretical aspects of the slowly time
-varying phenomena in cavities are discussed and the linear stability analysis
is presented. A new approach to solve this nonlinear coupled differential
equations is explored and its generalization to the case of variable
coefficients is performed.
