Photon echo area theorem for Gaussian laser beams

We present the results of experimental and theoretical investigation of pulse area theorem for understanding general properties of two pulse (primary) photon echo in the optically deep Tm3+:Y3Al5O12 crystal. Despite discussed limitations the proposed approach allows us to describe the key feature of area theorem dependence introduced by the Gaussian spatial profile of the pulses: the absence of expected downfall to zero at second pulse area θ20 = 2π in the experimental data.