Influence of pore volume on laser performance of Nd : YAG ceramics

For present study,1.1 at % Nd-doped YAG ceramics with a controlled pore vol ume (150-930 vol ppm) were fabricated by a solid-state reaction method usin g high-purity powders. The scattering coefficients of Nd:YAG ceramics, obta ined from Fresnel's equation, increased simply with increases in the pore v olume. The cw laser output power of Nd:YAG ceramics was clearly related to the scattering coefficients of the specimens examined in the present works, which in turn were affected on the pore volume. The effective scattering c oefficients of Nd:YAG ceramics with a pore volume of similar to 150 vol ppm were nearly equivalent to those of a 0.9 at %Nd :YAG single crystal by Czo chralski method. As the exciting power was increased under excitation by an 808-nm diode laser, however, the laser output power of the Nd:YAG ceramics exceeded that of the Nd:YAG single crystal because of the fairly large amo unt of Nd additives. The lasing performance of the Nd:YAG ceramics changed drastically with change in pore volume. On the other hand, lasing performan ce was not affected by the existence of grain boundaries in the polycrystal line Nd:YAG ceramics. (C) 1999 Kluwer Academic Publishers.