Fig. 3: Characterization of the laser emission for nucleolus in spreading A549 cells.

a Phase contrast image depicting a live A549 cell, with a zoomed-in section highlighting the nucleoli. Scale bar: 10 μm. b Laser emission image within the nucleoli. The separated laser spots were designated as HRIUs within the nucleoli. Scale bar: 5 μm. c Merged image of the phase contrast image and laser emission image. Scale bar: 10 μm. No laser emission was observed when pumping the areas outside of the cell and outside of the nuclei (inset images). d Gray-value profiles along the spatial distance in laser emission image and phase contrast image. e Laser spectrum of the nucleoli within one cell. The nucleoli can be pumped individually or simultaneously to examine their respective spectra. ‘L’, ‘R’ and ‘B’ refer to the top left nucleolus, the top right nucleolus, and the bottom nucleolus, respectively. ‘L + R’ refers to the two nucleoli pumped simultaneously. f, g Far-field laser emission images and hyperspectral images of the lasing modes. The number in the hyperspectral images denotes the Ince-Gaussian mode indices [p,m]. The cells were all pumped under a pump energy of ~ 68.3 μJ mm⁻². Scale bar: 5 μm. h Hyperspectral image of nucleoli within cells. Scale bar: 5 μm. i Laser thresholds of areas with various-size nucleoli, cell regions without nucleoli, and regions without cells (n = 45). j Relationship of the laser peak number and nucleolus diameter (n = 94). k Relationship of laser intensity and nucleolus diameter under a fixed pump energy of ~ 68.3 μJ mm⁻² (n = 124). Source data are provided as a Source Data file.