[20p-H137-1~15] 7.5 Ion beams

[20p-H137-8] Long Absorption Tail in Nd-doped Yttrium Aluminum Garnet induced by 15 MeV Gold-ion Irradiation

〇Hiroshi Amekura¹, S. Akhmadaliev², S. Zhou², F. Cheng³ (1.NIMS, 2.HZDR, 3.Shandong Univ.)

Keywords:Nd-doped yttrium aluminum garanet,MeV-ion irradiation,Waveguide

A neodymium-doped yttrium aluminum garnet (Nd:YAG) bulk crystal was irradiated with 15 MeV Au ions to a fluence of 8 × 10¹⁴ ions/cm². The irradiation introduced fringes in the optical transmission spectra in the 0.95–2.2 μm wavelength region and extinguished all the crystalline YAG X-ray diffraction (XRD) peaks. These observations suggest the formation of a ~3.4-mm-thick amorphous layer with refractive index reduction Δn = –0.03. Thermal annealing at 1000°C produced more than ten XRD peaks with intensity ratios matching the YAG crystal powder pattern, indicating a recovery from the amorphous phase to randomly aligned small crystalline grains. Simultaneously, an extraordinarily long absorption tail appeared in the optical spectrum from 240 nm to ~2 μm without fringes. The origin of the tail is discussed based on two models: electronic transitions between defect levels and a YAG host band and enhanced light scattering by randomly aligned small grains.