Fig. 1. (a) Diagrammatic illustration of the polarization-dependent PIT modulation in the metadevice for OPTP spectroscopy. (b) Schematic of the unit cell of the metadevice. The sizes have been marked in the figure. The black area is the bared Si island, whose sizes are 26 µm in the horizontal direction and 12 µm in the vertical direction, respectively. (c) Optical microscopic image of the periodically arranged unit cells. Inset is an amplified photo of a single unit cell. The periods are 90 µm and 95 µm in directions of x polarization and y polarization, respectively.

Fig. 2. Polarization-dependent modulation of PIT effects in two perpendicular THz polarization directions, with a time delay of 40 ps. Experimentally measured transmission rates of THz waves for (a) x polarization and (b) y polarization of metaphotonic devices, pumped by a series of pumping powers (shown as labels). The numerically simulated transmission rates of THz waves for (c) x polarization and (b) y polarization of metaphotonic devices, with conductivity of Si island varying corresponding to the experimental measurement (shown as labels).

Fig. 3. Experimentally measured THz transient group delay for (a) x polarization and (b) y polarization, with the metaphotonic device pumped by laser beams for a series of fluence (as labels). Numerically calculated group delay of THz waves for (c) x polarization and (d) y polarization with conductivity of Si island changing as labels. The time delay was 40 ps.

Fig. 4. Experimentally measured THz transient color map of transmission rates for (a) x polarization and (b) y polarization, under pump fluence of 2000mW/cm2.

Fig. 5. Negative differential transmission of SOS wafer pumped by laser beams at a series of powers (as labels). The measured data was fitted using a single exponential function.

Fig. 6. Intrinsic coupling of the PIT effect for appearing and vanishing. The relative transmission rate of SRR, CW, and their combination, respectively, with conductivity of Si set as (a) 10 S/m and (b) 80,000 S/m for THz x polarization, and (c) 10 S/m and (d) 80,000 S/m for THz y polarization. Numerically calculated electromagnetic field distributions of these units with conductivity of (e) 10 S/m, (f) 80,000 S/m for THz x polarization (at 0.6421 THz), and (g) 10 S/m, (h) 80,000 S/m for THz y polarization (at 0.7763 THz).