Structural color due to guided-mode resonance in silicon-on-insulator irradiated by nanosecond laser pulses

We demonstrate structural color generation in silicon-on-insulator wafers using nanosecond laser irradiation. Laser-induced periodic surface structures on the thin Si film act as grating couplers, enabling optical resonances that produce bright, spectrally selective structural colors at visible wavelengths. The mechanism combines grating-mediated waveguide coupling with Fabry-Perot spectral filtering, yielding optical characteristics resembling guided-mode resonance. The central wavelength is tunable across the visible spectrum by varying Si film thickness (50–70 nm range), with measured samples exhibiting green coloration at 55 nm and red at 70 nm thickness. Numerical simulations qualitatively reproduce the observed optical properties. This non-chemical, non-fading coloration offers potential applications in secure marking and process control for semiconductor manufacturing.