A straightforward approach for high-end anti-counterfeiting applications based on NIR laser-driven lanthanide doped luminescent glasses

Abstract

The increase in forgery in documents and authentic products has motivated the search for new high-end anti-counterfeiting strategies. Various chameleon-like luminescent materials such as up-conversion nanoparticles or perovskite nanocrystals have drawn attention due to their favorable properties. However, these materials are fabricated through complex processes and often suffer from system instability. In this work a facile and inexpensive approach for color tuning of thermally and chemically stable Ho³⁺/Tm³⁺/Yb³⁺ doped tellurite glasses is experimentally demonstrated for the first time. The emission band ratios are successfully manipulated by focusing/defocusing the NIR laser beam irradiating the glass samples. Impressive up-conversion quantum yield values up to 4.56% are obtained along with high lifetime values from ∼100 to 200 microseconds. As proof of concept, a series of anti-counterfeiting patterns are created using the screen-printing method and different emission colors are observed by easily changing the distance between the sample and the laser focal point. The applicability of the presented strategy along with the remarkable properties of the studied lanthanide doped glasses proves the capability of these materials to be used in anti-counterfeiting applications.