Composite Nd:YAG/Cr4+:YAG transparent ceramics for thin disk lasers

This work reports the fabrication of composite transparent ceramics consisting of a Nd:YAG central part and a Cr4+:YAG edge cladding. The central part of ceramics was shaped into 14mm-diameter disk or 11mm-side square and an outer diameter of the edge cladding was 18mm or 23mm, respectively. The central part of ceramics exhibited an optical transmittance of ~84% at the wavelength of 1.06µm. The concentration of Cr4+ in Cr4+:YAG ceramics with three different compositions was evaluated using measured transmission spectra and reported absorption cross sections. Taking into account the infeasibility condition for self-excitation, the optimal composition of edge cladding was estimated to be 2.5at% Cr, 0.25at% Ca:YAG.