Tufts University engineers have created a chip-sized, high-speed modulator that operates at terahertz (THz) frequencies at room temperature and at low voltages without consuming DC power, which could break the THz gap that has been a limiting the development of new wireless devices that can transmit data at higher speeds than is now possible.
Confined terahertz waves interact with tunable, two-dimensional electron gas in a novel slot waveguide.
(Nano Lab, Tufts University School of Engineering)
Standard cellular networks occupy a much lower region of the electromagnetic spectrum than this new device, according to a report from Tufts. It works by confining THz waves in a slot waveguide along with tunable, two-dimensional electron gas. The scientists demonstrated the prototype’s capability in the range of 0.22-0.35 THz but insist it can work across other ranges as well.
They believe it has the potential to work above 1 THz.
The terahertz band has been the goal of wireless designers and engineers because of the ability to transmit data at faster rates, but the inability to create the components necessary to make it practical, such as modulators, transmitters, and receivers has been a stumbling block.
“This is a very promising device that can operate at terahertz frequencies, is miniaturized using mainstream semiconductor foundry, and is in the same form factor as current communication devices. It’s only one building block, but it could help to start filling the THz gap,” said Sameer Sonkusale, Ph.D., of Nano Lab, Department of Electrical and Computer Engineering, Tufts University.
The work was published in Scientific Reports. The abstract read:
“This paper presents an on-chip device that can perform gigahertz-rate amplitude modulation and switching of broadband terahertz electromagnetic waves. The operation of the device is based on the interaction of confined THz waves in a novel slot waveguide with an electronically tunable two dimensional electron gas (2DEG) that controls the loss of the THz wave propagating through this waveguide.
“A prototype device is fabricated which shows THz intensity modulation of 96% at 0.25 THz carrier frequency with low insertion loss and device length as small as 100 microns. The demonstrated modulation cutoff frequency exceeds 14 GHz indicating potential for the high-speed modulation of terahertz waves.
“The entire device operates at room temperature with low drive voltage (<2 V) and zero DC power consumption. The device architecture has potential for realization of the next generation of on-chip modulators and switches at THz frequencies.”