OPTICAL-SCATTERING CENTERS IN POLYCRYSTALLINE ND-YAG LASER

For the present study, 1.1-at%-Nd-doped YAG ceramics with controlled a mounts of grain-boundary phase mere fabricated by a solid-state reacti on method using high-purity powders, The optical scattering loss of th e Nd:YAG ceramics, obtained from Fresnel's equation, increased simply with increased amounts of grain-boundary phase, The continuous-wave la ser output power of the Nd:YAG ceramics clearly was related to the sca ttering loss coefficients of the specimens that, in turn, were affecte d by the amount of grain-boundary phase, Although the scattering loss coefficients of Nd:YAG ceramics with grain-boundary-free structure and a lower pore volume (similar to 150 vol ppm) were almost equivalent t o those of a 0.9-at%-Nd-doped YAG single crystal grown by the Czochral ski method, the laser output power of the Nd:YAG ceramics exceeded tha t of the Nd:YAG single crystal with increased exciting power under exc itation with an 808 nm diode laser because of the large amount of neod ymium additives, Lasing performance was not affected by the existence of grain boundaries in the polycrystalline specimen.