Fig. 1. THz wave transmission spectra under different conditions[18]. (a) Without laser excitation; (b) with laser excitation

Fig. 2. Highly efficient THz wave modulators with organic materials/silicon bilayer structure[20]. (a) Schematic of THz wave transmission measurement of sample under photo-excitation; (b) energy-level diagrams for charge transfer processes under photo-excitation at 785 nm; (c) THz wave transmission spectra under different conditions

Fig. 3. THz wave transmission characteristics of SRRs[21]. (a) Microscope image of fabricated metal SRR on CuPc/Si film; THz wave transmission spectra of fabricated metal SRR on (b) CuPc/Si film and (c) bare Si substrate under different laser intensities

Fig. 4. THz optical modulation characteristics of silicon-based AlClPc, CuPc, and SnCl2Pc[22]. (a) Contrast of modulation factors; (b)-(d) optical modulation spectra

Fig. 5. THz optical modulation characteristics of silicon-based MEH-PPV[23]. (a) Optical modulation test system for THz-CW; THz wave transmission intensities of devices based on MEH-PPV/Si structure (b) without illumination and (c) with illumination; THz wave transmission intensities of devices based on Si structure (d) without illumination and (e) with illumination; (f) THz wave transmission intensities and modulation factors of devices with different structures

Fig. 6. THz wireless communication system based on organic-material THz wave modulator[30]. (a) Transmission of "THz"; (b) reception of "THz"

Fig. 7. THz optical modulation characteristics of silicon-based DAST[32]. (a) Schematic of experimental configuration based on backward-wave oscillator (BWO) THz source; (b) optical modulation rate of DAST-Si heterojunction sample

Fig. 8. THz optical modulation characteristics of silicon-based PVA[33]. THz wave transmission spectra of (a) bare Si, (b) PVA/Si without laser heating, and (c) LP-PVA/Si samples under photo-excitation at different intensities of pumping laser; (d) THz wave modulation depth as a function of power density of pumping laser from bare Si, PVA/Si without laser heating, and LP-PVA/Si samples

Fig. 9. THz optical modulation characteristics of silicon-based CH3NH3PbI337. (a) THz wave transmission spectrum versus laser power density; (b) THz wave transmission intensity versus laser power density

Fig. 10. Spatially optical modulation pattern[37]. (a) Spatially optical modulation pattern based on bare-Si THz wave modulator; (b) spatially optical modulation pattern based on CH3NH3PbI3/Si THz wave modulator

Fig. 11. Ultrafast modulation of Fano resonators[40]. (a) Analysis of electric field distribution and surface current distribution in Fano resonant structure; (b) structural diagram of ultrathin flexible metamaterial and schematic of OPTP measurement system

Fig. 12. Organic THz electrical modulation[43]. (a) Structure diagram of organic THz electrical modulation device; (b) THz wave transmission spectrum versus external bias voltage

Fig. 13. Transmitted intensity of electrically modulated THz waves with different structures under different photoexcitation[45]. (a) Structure of MEH-PPV/PEDOT∶PSS∶DMSO/Si/PEDOT∶PSS∶DMSO; (b) structure of EDOT∶PSS∶DMSO/Si/PEDOT∶PSS∶DMSO; (c) structure of MEH-PPV/Si/PEDOT∶PSS∶DMSO