Figure 1. Conceptual illustration of the laser-emission based microscope.

a, Illustration of the laser-emission based microscope (LEM) configuration when a human cancer tissue is sandwiched within a high-Q Fabry-Pérot cavity and integrated with a 2D raster scanning stage. The laser emission from fluorophores is achieved upon external excitation. The inset shows the details of using nucleic acid staining dyes and antibody-conjugated dyes to achieve multiplexed laser emissions from a tissue. Laser emissions are achieved only when probes are bound to the nucleus or targeted nuclear biomarker within the tissue. Here only one antibody is plotted for example; however, multiple targeted antibodies/fluorophores can be used. b, Comparison between the traditional fluorescence emission (top) and “star-like” laser emission (bottom) from a single nucleus. c, (Left) Output intensity of laser emission as a function of pump intensity. P_c, lasing threshold of cancer cell lasing; P_n, lasing threshold of normal cell lasing. A higher/lower nucleic acid concentration leads to a lower/higher lasing threshold. (Right) Laser emission (red solid line) has a much narrower emission profile than traditional fluorescence (blue dashed line) d, Fluorescence emission is detected in both normal and cancer cell nuclei, whereas laser emission can be detected only in cancer cell nuclei when pump energy density is set between P_c and P_n.