Assessment of light scattering by pores in Nd:YAG transparent ceramics

Nd:YAG ceramic samples with different transmittances were fabricated by vacuum sintering with 10 degrees C/min or 2 degrees C/min heating rate. SEM measurements revealed that the average pore size of samples was around 0.18 mu m while the porosity ranged from 0.0053% to 0.0022%. Mie scattering theory was applied to calculate the scattering coefficients as a function of the ratio between pore size and incident wavelength, pore size and porosity. The results showed that the simulated transmittances were in good agreement with the experimental values. The scattering loss was extremely low when the porosity was lower than 0.001% or the pore size was below 0.01 mu m. A novel approach, to synergetically control the parameters of sizes and densities of the pores quantitatively for low scattering loss Nd:YAG ceramics, was presented. This quantitative insight into the pore scattering effects of Nd:YAG ceramics would allow a more targeted experimental optimization of this laser material. (C) 2011 Elsevier B. V. All rights reserved.