Co-casting and optical characteristics of transparent segmented composite Er:YAG laser ceramics

A novel colloidal co-casting process was developed to fabricate laser quality, multisegment composite ceramic laser gain materials. The approach was demonstrated for a three segment transparent composite rod 62 mm long by 3 mm diameter consisting of undoped yttrium aluminus garnet (YAG), 0.25% EnYAG, and 0.5% Er:YAG. The Er concentration profile in the composite has steep, controllable gradients at the segment interfaces, while maintaining constant dopant concentrations within each segment. The composite rod has 84% transmittancc at 1645 nm (the lasing wavelength) with a scatter loss of 0.4% cm^-1 . Laser operation of such a compositeEr:YAG ceramic rod was demonstrated for the first time, with nearly equivalent lasing behavior to an EnYAG single crystal rod.