Enhancement of silicon modulating properties in the THz range by YAG-Ce coating

Y₃Al_5-xGa_xO₁₂:Ce³⁺,V³⁺ (YAG:Ce) has excellent chemical stability and unprecedented luminous efficiency. Its strong photoresponsive property is thoroughly utilized in designing excellent optical information storage device. Here, the remarkable photoconductivity of YAG:Ce is exploited to demonstrate a hybrid YAG:Ce-silicon device that shows high speed terahertz wave spatial modulation. A wide terahertz spectra modulation is observed under different pump powers in frequency range from 0.2 to 1.8 THz. Furthermore, a dynamic control of the terahertz wave intensity is also observed in the transmission system. The modulation speed and depth of the device is measured to be 4 MHz (vs 0.2 kHz)and 83.8%(vs50%) for bare silicon, respectively. The terahertz transmission spectra exhibits highly efficiency terahertz modulation by optically pumping a YAG:Ce film on silicon with low optical pump fluence.