Spectroscopic properties of Gd3Ga5O12-Er3+ films that are grown by the
epitaxial method are investigated. It is shown that excitation relaxa
tion from the S-4(3/2) State occurs in the frame of ion-ion interactio
ns. The microparameters of donor-donor and donor-acceptor energy trans
fer from the S-4(3/2) State are obtained. Both spectroscopic and techn
ological data indicate that epitaxial Gd3Ga5O12-Er3+ films hold much p
romise as an active medium for a 3-mu m laser.