The photon echo technique has been a useful tool in measuring material parameters for many years. Recent experiments also support its use as a basis for signal processing and quantum information storage. It is within this context that we consider the photon echo of a weak signal pulse and solve the coupled Maxwell-Bloch equations for two-level and three-level thick media having inhomogeneous broadening. We find the conditions under which the pulse shape is preserved in the echo and, thus, can be used for quantum information storage.
