Fig. 1. Design of the WGM microsphere covert photonic barcode based on photoisomerization manipulation.

Fig. 2. (a) Schematic illustration of the WGM microcavity. (b) Numerically simulated electric field distributions of the lasing modes. (c) PL images of the dye-doped microspheres. Scale bar: 50 µm. (d) Emission spectra of the dye-doped microsphere under pulse excitation. (e) Spectrally integrated output intensity and FWHM as a function of pump energy density.

Fig. 3. (a)–(c) Microscopy images of three microspheres with different sizes. Scale bar: 50 µm. (d), (e) WGM modulation and corresponding photonic barcodes of three microspheres with different sizes.

Fig. 4. (a) Scheme of the photoisomerization manipulation of the excited state process in the microsphere. (b) Relationship between energy and twisting angle for typical organic ICT dye molecules. The WGM spectra of E-state (c), E + Z-state (d), and Z-state (e). Inset: dye molecular structures of trans-state and cis-state. (f)–(h) The WGM lasing spectra and corresponding photonic barcodes of three states in the WGM microsphere.

Fig. 5. Proof-of-concept demonstration of dye-doped microspheres based on photoisomerization manipulation for covert photonic barcodes for anticounterfeiting labels.