Fig. 1. Super-multiplexed cell tagging using laser particles with different colors. (a) Schematic of massively multiplexed cell tagging using laser particles, in which each cell is tagged by laser particles with different wavelengths. (b) The principle of the wavelength tuning of laser particles through PEC etching. A pulsed laser is used to illuminate the microdisk, which triggers not only the PEC etching but also the laser emission. (c) The gradual tuning of the characteristic wavelength of a single laser particle by PEC etching.