Multifunctional Random-Laser Smart Inks

Abstract

With the superiority of laser-level intensity, narrow spectral line width, and broad-angular emission, random lasers (RLs) have drawn considerable research interests for their potential to carry out a variety of applications. In this work, the applications associated with optical-encoded technologies, including security printing, military friend or foe identification (FFI), and anticounterfeiting of documents are highlighted, and the concept of a transient RL “smart ink” has been proposed. The proof-of-concept was demonstrated as invisible signatures, which encoded the messages through the spectral difference of spontaneous emission and RL under specified conditions. Next, the possibility of encoding the data with multibit signals was further confirmed by exploiting the threshold tunability of RLs. Moreover, the transient characteristic of this smart ink and its capability to be attached on freeform surfaces of different materials were also shown. With the advantages of a facile manufacturing process and multiple purposes, it is expected that this ink can soon be carried out in a variety of practical utilities.

Microcavity- and Microlaser-Based Optical Barcoding: A Review of Encoding Techniques and Applications

“…Therefore, not spectral peaks, but the threshold value has been employed for barcode encoding. 68,78 Distributed-Feedback Lasers. In distributed-feedback lasers the cavity is realized as a longitudinal periodic variation of the refractive index, either in the gain medium itself or in the material into which the gain medium is embedded (Figure 2e).…”

“…In the case when the laser threshold is used as a barcode, this threshold can be tuned via the gain and loss of the microcavity, so that various thresholds can be produced. 68,89 For all the cases mentioned above, the number of predefined barcodes that can be controllably produced is relatively small. Therefore, to store any useful amount of information, multiplexing should be used, as discussed in the following subsection.…”

Recent progress and prospects of random lasers using advanced materials

“…Such unique configuration leads to lasers with low spatial coherence. Therefore, it renders RLs as an attractive platform for many applications such as cancer diagnostic 10,11 , Photonic barcodes 12 , a random spectrometer on a chip 13 , speckle-free bio-imaging 14 , speckle-free pulsed imaging technique 15 , sensing 16,17 , optical batteries 18 and optomicrofluidics 19,20,21 . The first type of RLs were dye-based colloidal systems 4,22 and then on many other systems like photonic crystals [23][24] , semiconductors 25,26,27 , quantum dots (QDs) 28,29 , polymeric matrices [30][31] , biological tissues 32 , rare-earth-doped nanopowders 33 , cold atoms 34 , etc.…”

“…Such unique configuration leads to lasers with low spatial coherence. Therefore, it renders RLs as an attractive platform for many applications such as cancer diagnostic, 10,11 Photonic barcodes, 12 a random spectrometer on a chip, 13 speckle-free bio-imaging, 14 speckle-free pulsed imaging technique, 15 sensing, 16,17 optical batteries 18 and optomicrofluidics. 19–21…”

Photothermal Effect Controlled Complex Lasing for Decentralized Key Distribution

“…Light–light or light–matter interaction in complex media has been a promising topic, which provides new perspectives for the development of light control and applications in imaging, sensing, secret communication, and optical network, − wherein chaotic, disordered, or random lasing in deformed cavities, irregular structures, or media has become increasingly attractive for multidiscipline applications. − …”