Laser particle stimulated emission LASE microscopy
We introduce an optical microscopy technique that utilizes microor nano lasers embedded in a sample as imaging probes. The narrow spectra and nonlinear power dependence of stimulated emission from the laser particles yield optical sectioning, sub diffraction resolution, and low outof focus background. A proof of concept is demonstrated using perovskite nanowires. Stimulated emission allows light amplification and build up of cavity modes in lasers. While numerous types of lasers are available, recent advances in micro fabrications and gain materials made it possible to realize lasers with microor nano sized cavities. Stand alone lasers, such as micro spheres containing optically excitable gain elements, may be injected or embedded in other materials [1,2] For example, micro lasers have been recently incorporated in biological cells [3,4] Moreover, exploiting plasmonic resonance, nanoscale lasers have been demonstrated [5 7] These microand nano lasers may serve as internal light sources, generating coherent stimulated emission with distinct properties from spontaneous emission. Here we describe the measurement of the output emission from such laser particles using laserscanning optical microscopy. We demonstrate that such a system offers a unique set of capabilities including super resolution, 3 dimensional optical sectioning, and low out of focus background, all of which are desirable for imaging thick samples such as biological tissues. Fluorescence microscopy is an established, powerful tool for studying biological samples, such as cells and tissues. This technique uses a pump beam that excites fluorescent probes, such as organic dyes or semiconductor quantum dots, and their spontaneous emission (fluorescence) is detected. The principle of stimulated emission has been implemented in optical microscopy in two schemes. First, stimulated emission depletion (STED) microscopy [8] employs an intense