Frequency modulation of an electric field inside of an active medium with a very short gain recovery lifetime has become of recent interest due to the observed and calculated behavior of Quantum Cascade lasers (QCLs) exploiting optical nonlinearities to generate frequency combs in the spectral domain. Thus, in support of better understanding this behavior, we have investigated the effects of stochastic, time-dependent detuning (frequency modulation) on the polarization and population inversion of a two-level optical system using the optical Bloch equations. This model confirms that the most efficient mode of a free running QCL is stochastic frequency modulated operation with constant intensity.