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

• Published in: Journal of alloys and compounds Vol. 520; pp. 36 - 41
• Main Authors: Zhang, Wei, Lu, Tiecheng, Wei, Nian, Wang, Yuezhong, Ma, Benyuan, Li, Feng, Lu, Zhongwen, Qi, Jianqi
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier B.V 15.04.2012; Elsevier
• Subjects: Assessments; Ceramics; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Defects; Density; Exact sciences and technology; Mie scattering theory; Nd:YAG; Neodymium; Optical constants: refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of bulk materials and thin films; Physics; Pore size; Porosity; Scattering; Scattering loss; Transparent ceramics; YAG; Transparent ceramics; Mie scattering theory; Nd:YAG; Scattering loss; Defects; Scanning electron microscopy; Light scattering; Doping; Laser materials; Etching; Mie scattering; Absorption coefficients; Heat treatments; Scattering theory; Pore size; Neodymium additions; Sintering; Porosity; YAG
• ISSN: 0925-8388; 1873-4669
• DOI: 10.1016/j.jallcom.2011.12.012

► The submicrometer pores as large as visible light wavelength could give rise to a strong scattering effect. ► The scattering was extremely low when the porosity was lower than 0.001% or the pore size was below 0.01μm. ► Miniaturization and/or elimination of the pores were responsible for low scattering loss. ► Low scattering loss (Csca=0.001–0.01cm−1) for Nd:YAG could be achieved by carefully and synergetically controlling pore sizes and porosities to get across the low scattering demarcation curves and enter the region R2. Nd:YAG ceramic samples with different transmittances were fabricated by vacuum sintering with 10°C/min or 2°C/min heating rate. SEM measurements revealed that the average pore size of samples was around 0.18μm 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 0.01μm. 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.