On the Mechanism of Two‐Photon Absorption by Nd³⁺ Ions in Yttrium Aluminium Garnet and Yttrium Lithium Fluoride in the Region of 1.06 μm

Abstract

A calculation is made of two-photon absorption (TPA) cross-sections by Nd3+ ions in YAG and Y L F crystals in the region of 1.06 pm. It is shown that the experimental results are in good agreement with the general theory taking into account the TPA polarization characteristics and effects (for YAG-crystals) of surrounding ligands on the TPA process. It is found that the lowest Stark component of the Nd3+ ground term in YLF does not correspond to the symmetry type earlier proposed and 8 new identification is given.