Permanent Tailoring of BIC Resonances Using Temperature

Dielectric metasurfaces have applications in wavefront shaping, sensing, and imaging. We show that the quasi bound states in the continuum (BIC) resonance in the hydrogenated amorphous silicon (a.Si:H) metasurface structure can be permanently fine tuned by gradual and short-term heating. The increase of refractive index of a.Si:H with the temperature resulted in the redshift of resonance. Here we quantitatively analyze the modifications in the resonance wavelength and the Q-factor due to gradual heating. The q-BIC could be tuned over a wavelength of 50 nm by gradual heating while maintaining high Q-factors. The effect of temperature on two types of metasurface structures designed to have resonances at 683 nm (visible) and 825 nm (NIR) is demonstrated in the following figure. The visible metasurface had a considerable reduction in the Q-factor above 350 ◦ C whereas the NIR metasurface could retain a high Q-factor till 550 ◦ C.