Dynamic light-driven metasurface: Harnessing quasibound states in the continuum for laser-induced selective crystallization

We present the design of an asymmetric metasurface made of germanium antimony tellurium nanowires that supports quasibound states in the continuum. A fully coupled optothermal model is used to show that, when exposed to brief and intense laser pulses, the metasurface undergoes a partial, geometrically controlled crystallization, thereby inducing an ultrafast dynamic wavelength shift of the quasibound state in the continuum of the order of 350 nm with pump intensities as low as $35{\mathrm{MW}/\mathrm{cm}}^2$. The proposed approach highlights the potential for controlling nanostructures' response through laser illumination, opening avenues for applications in dynamic optical modulation and beyond.