Chinese Physics Letters
Abnormal Dielectric Response in an Optical Range Based on Electronic Transition in Rare-Earth-Ion-Doped Crystals
Xiaojian Fu, Yuanda Xu, Ji Zhou
Abstract
A new scheme to realize an abnormal dielectric response at optical wavelength is developed on the basis of two-level electronic transition of rare-earth ion doped crystals. Based on the semi-classical theory and the Judd—Ofelt theory, the electric dipole transition under a weak field is analyzed, and a general expression for the frequency-dependent dielectric constant is obtained. As an example, the permittivity of (Er x Y 1−x ) 3 Al 5 O 12 is calculated numerically in consideration of the transition between 4 I 15/2 and 4 F 9/2 . An optimized dielectric property with a negative real part and low absorption is achieved. This proposes a new mechanism for building extraordinary electromagnetic media at optical frequencies by using a quantum process.