Solid-state inorganic luminescent photochromics have potential applications in high-density opticalstorage fields due to their good chemical and thermal stability. However, the failure in simultaneouslyachieving a high luminescent contrast and non-destructive readout capability restricts their practicalapplications. Herein, a new and unique route of avoiding the crosstalk between the photochromicabsorption and luminescent excitation energy is proposed to design high-performance photochromic materials via the non-linear optical process of upconversion. The fabricated novel rare earth orthoniobate photochromics (RNbO4, where R = Yb, Er, Tm or Ho) with self-activated upconversionemissions exhibit reversible coloring-bleaching processes upon light stimuli (365 and 405 nm).Benefiting from the lower excitation energy and larger anti-Stokes shift of upconversion, the secondaryabsorption to an excitation energy of 980 nm can be effffectively avoided. A non-destructiveluminescence readout can then be realized whilst maintaining a near 100% luminescent switchingcontrast (99.2%), which is superior to conventional downshifting or downconversion readoutapproaches. A developed prototype storage memory with a single-level cell can be visually displayed inbright or dark fields by commercially available 365 nm (writing), 405 nm (erasing) and 980 nm (reading)lasers. These results provide new insights into future high-performance inorganic photochromicmaterials and promote their practical applications in advanced optical storage.
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