Fig. 1. (a) Diagrammatic drawing of a metaphotonic device for OPTP measurement. (b) The schematic of the metadevice unit cell. The parameters are listed as follows: l = 25 μm, w = 5 μm, g = 5 μm, L = 31 μm, W = 13 μm, G = 15 μm, and l_g = 10 μm. The periods of an identical unit cell are 110 μm along the CWRs and 90 μm vertical to the CWRs in the plane. (c) The optical microscopy image of the metaphotonic device; the inset is the atomic force microscope (AFM) image showing the surface appearance.

Fig. 2. The numerical simulations of the transmission spectra in the CWR, SRRs, and their combination with Si conductivity of (a) 10 S/m and (b) 28,000 S/m, respectively. The inserted figure in (a) shows the simulated transmission spectrum in the case of a larger range of frequency.

Fig. 3. (a) Experimentally measured and (b) numerically simulated transmission spectrum of the metadevice considering a series of selected fluences and corresponding conductivities of the embedded Si island. The normalized resonance amplitude (c) under different pump powers and (d) corresponding conductivities, respectively. The inserted figure is a schematic diagram of the resonance amplitude.

Fig. 4. (a) Color map showing an almost entire transient evolution period of THz transmission pumped with a fluence of 2000mW/cm2. (b) The switching-on part of the appearing of the PIT effect in the whole period.

Fig. 5. Experimentally measured and numerically fitted ultrafast relaxation of the SOS wafer considering a selected series of pump fluence.

Fig. 6. (a) Experimentally measured and (b) corresponding numerically calculated group delay against frequency for a selected fluence of pump and conductivities of Si islands.