Microscopic lasers represent a promising tool for the development of cutting-edge photonic devices thanks to their ability to enhance light-matter interaction at the microscale. In this work, we realize liquid microlasers with tunable emission by exploiting the self-formation of three-dimensional liquid droplets into a polymeric matrix driven by viscoelastic dewetting. We design a flexible device to be used as a smart photonic label which is detachable and reusable on various types of substrates such as paper or fabric. The innovative lasing emission mechanism proposed here is based on whispering gallery mode emission coupled to random lasing, the latter prompted by the inclusion of dielectric compounds into the active gain medium. The wide possibility of modulating the emission wavelength of the microlasers by acting on different parameters, such as the cavity size, type and volume fraction of the dielectrics, and gain medium, offers a multitude of spectroscopic encoding schemes for the realization of photonic barcodes and labels to be employed in anticounterfeiting applications and multiplexed bioassays.
Keywords: anticounterfeiting; microlasers; photonic labels; random lasers; self-formation; soft lithography; viscoelastic dewetting; whispering-gallery mode.