A variety of imaging techniques and technologies, such as optogenetics, could benefit from devices that can emit visible laser light from inside tissues. Conventional lasers are too large, while nanolasers tend to be inefficient, heating up too much, and typically require damaging ultraviolet light to power them.
Now, researchers at Northwestern and Columbia Universities have developed a nanolaser that can be powered by deep-penetrating and safe infrared light while emitting visible light.
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.
Study in Nature Materials: Ultralow-threshold, continuous-wave upconverting lasing from subwavelength plasmons