I. Introduction
Photo-stimulated luminescence material (PSL) using electron capture characteristic to store the photoelectron signal was discovered forty year ago. [1] Now it is widely used in medical imaging, optical storage, infrared detection, and radiation measurement and other fields. [2]–[4] These materials could be excited by the incident X-ray to generate excited electrons, which was stored in a stable excited state. Further illumination by a longer wavelength, the captured electrons return back to the ground state; the recombination of electron hole pairs resulted in the emission of visible light. Thus, this feature can be used for writing/reading action of light signal.