Recently, random lasing in complex networks has shown efficient lasing over more than 50 localized modes, promoted by multiple scattering over the underlying graph. These network lasers can lead to fast-switching multifunctional light sources with synthesized spectrum if controlled.

In new research by Imperial College London with partners in Italy and Switzerland, scientists have developed a method to precisely control a network laser so that it only emits a single color or color combination at a time. They have devised a laser system based on a network like a spider’s web. Their system could be used in new sensing and computing applications.

The system operates by shining distinctive “illumination patterns” on the network laser; each fine pattern causes a different laser color, or group of colors, to be produced. A digital micromirror device (DMD) creates illumination patterns. The DMD is optimized by an algorithm that selects the best pattern for a particular laser color.

Scientists noted, “The new network laser systems could have many applications, particularly as they can be integrated into chips. For example, they could be used as highly secure hardware keys, where the illumination patterns become the secure keys that generate the password in the form of the laser spectrum.”

The network lasers could be employed as sensors that can track even minute changes on surrounding surfaces because they are also very sensitive to the proper illumination patterns.

Co-author Professor Riccardo Sapienza, from the Department of Physics at Imperial College London, said: “We have combined the mathematics of network theory with laser science to tame these complex lasers. We believe this will be at the heart of light processing on chips, and we are testing it now as a machine learning hardware.”

Co-author Professor Mauricio Barahona, from the Department of Mathematics at Imperial, said: “This is an example where we saw maths and physics coming together, showing how the properties of a network can affect and help control the lasing process. The next big challenge is to design networks and illumination patterns to control the temporal profile of the laser light and encode information in it.”

Journal Reference:

  1. Saxena, D., Arnaudon, A., Cipolato, O. et al. Sensitivity and spectral control of network lasers. Nat Commun 13, 6493 (2022). DOI: 10.1038/s41467-022-34073-3