The research group of Professor Liu Shimin of Yanshan University put forward the strategy of realizing multicolor emission by combining material design, obtaining external dual-wavelength excitation and adjusting the concentration of doped rare earth ions. Under the synergistic effect of 980nm and 1550nm laser excitation, the transition process of electrons can be manipulated by changing the laser power, so as to realize different emission colors. This operation method is simple and convenient, and there is no need to introduce other external stimulus conditions. The related results were published in Advanced Optical Materials, entitled "Dual-wavelength response and wide-range multicolor upconversion luminosity of high-capacity photonic barcodes". Doctoral students should be the first author, and Professor Gu Jianmin from School of Materials Science and Engineering of Yanshan University and Associate Professor from School of Environment and Chemical Engineering are the corresponding authors of this paper. This project is supported by the National Natural Science Foundation of China.
Paper link:
/doi/ 10. 1002/adobe . 202 100 197
Due to the flexible adjustment of laser power, more detailed emission color changes can be obtained. In addition, on the basis of dual-wavelength excitation, based on the energy reverse transfer process, the range of polychromatic emission can be further expanded by adjusting the doping concentration of Yb3+ ions, thus realizing wide-range and fine color regulation from green to red. Based on a large number of up-conversion emission spectrum emission peak position and intensity information as identification code, a photon bar code for advanced anti-counterfeiting is designed. The position and width of each barcode are determined by the position and intensity of the luminescence peak in the emission spectrum. A complete barcode can be obtained by randomly selecting several groups of sub-barcodes corresponding to the emission spectrum and combining them.
Based on the dual-wavelength response characteristics, a large number of sub-barcodes corresponding to spectral information can be further sorted, and a barcode database much larger than ordinary barcodes can be constructed, which can provide up to one million coding combinations at most. These achievements provide a brand-new theoretical basis and technical support for improving the level of advanced anti-counterfeiting technology. This technology has been declared as a national invention patent, and the patent application number is 202110447186.5.
* Thanks to the team of paper authors for their strong support to this article.