Generalised non-linear optical master equations taking into account the correlation time of relaxational perturbations

Generalised master equations in two equivalent forms, namely differential master equations (DME) and integro-differential master equations (IDME), are obtained. Both differ from the Bloch ones in that they take into account the density matrix dynamics during the correlation time tau C of the relaxational perturbations. On the basis of these equations, the non-linear optical problems of high-power radiation absorption, the resonance fluorescence spectrum and the free induction decay signal are discussed.