The device, less than 150 nanometers in width, uses upconversion to capture multiple low-energy (infrared) photons and turn them into a single photon with a higher energy (visible light) .
The laser is actually smaller than the wavelength of the light that it generates, and it’s therefore transparent. Only the light that it produces is visible, something that may be advantageous for biological imaging.
The device consists primarily of glass, a biocompatible material, and it may be used not only for imaging from inside deep seated tissues, but perhaps also to stimulate optically sensitive genetically modified cells as a therapy option for neurological disorders.
Flashbacks: Nanolasers to Shine Light on Things Inside Body; Spasers: Nanoscale Lasers Small Enough to Destroy Cancer Cells from Within
Study in Nature Materials: Ultralow-threshold, continuous-wave upconverting lasing from subwavelength plasmons