Realizing nondestructive luminescence readout in photochromic ceramics via deep ultraviolet excitation for optical information storage

Photochromic materials exhibiting luminescence modulation behavior are regarded as promising for high-density optical information storage media. During the luminescence readout process however, many of these materials are subject to coloration or bleaching, which inevitably destroys the information encoded in the photochromic materials and hence inhibits their use in practical applications. Herein, we report a novel nondestructive luminescence readout in Ca2SnO4:Eu photochromic ceramics by selecting deep UV as the readout wavelength. The obtained Ca2SnO4:Eu ceramics show a reversible brown-gray color change together with a large reflectivity difference of 35% upon alternating 280 nm and 585 nm illumination. Based on the photochromic behavior, a high luminescence modulation of 40.5% with excellent cycling resistance was achieved upon 240 nm excitation without loss of data during the luminescence readout process. Wavelength- and power-dependent coloration and de-coloration processes were studied to obtain a deeper insight into the photochromic behavior. Furthermore, our proof-of-concept experiment demonstrates that Ca2SnO4:Eu ceramics are promising candidates for optical information storage and anti-counterfeiting applications. It is believed that these results will provide a good standard for designing other photochromic materials with nondestructive luminescence readout behavior.