Terahertz wave, 10 times faster electrical modulation technique developed

 The terahertz modulator integrated with metamaterial. (a) metal-semiconductor-metal cross section. Applying a voltage to a black metal gate electrode, the electrostatic capacitance between the electrodes is changed. (b) Metamaterial shown in unit. The gray portion is active region and the black portion is the gate. When a voltage is applied to the gate, the capacity changes and thus can change the frequency response of the metamaterial unit. (c) Completed modulator consists 1,122 units. (d) Optical micrographs of terahertz modulator.

A research team led by professor Jae-Hyung Jang developed a technique that can control terahertz (THz) 10 times faster than conventional methods.

Terahertz waves are very high frequency, vibrating at 1,012 times per second. It has excellent transmission characteristics for different materials, such as paper, plastic, and fabric. It does not harm the human body.

In order to add information into the THz electromagnetic wave, a modulator is needed to control the intensity of the wave. To do this, mechanically hinder the progress or a photoconductive method was used. But these methods were slow, large, and inefficient.

 Characteristics of THz modulator. (a) Changing THz electromagnetic wave through different voltage to the metamaterial. (b) Showing the modulator can be used to control even at lower than 3V.

Director Jae-Hyung Jang said, “Our research results show that we can control THz wave with 10 times lower voltage while achieving 10 times faster modulation when compared to existing methods. With no sophisticated lasers, we can now build a compact system with low energy consumption and use it for video systems, such as the airport security check points and evaluating cancers.”

The paper was published in the Scientific Report on May 19, 2016.