Terahertz waves—known for their higher frequencies and shorter wavelengths than radio waves—have long been considered the future of data transmission, medical imaging, and radar technology. However, generating these waves using compact semiconductor chips has been a major hurdle.
Now, a team of MIT researchers has found an innovative solution that could open up a world of possibilities for terahertz applications.
Current methods to generate terahertz waves often rely on bulky silicon lenses to amplify signals. While these lenses help boost the radiating power, they’re more significant than the chip, making integration into devices impractical. This has limited terahertz technology from scaling into applications like next-generation security scanners, pollutant detectors, and advanced communication systems.
To address this limitation, MIT researchers developed a compact terahertz amplifier-multiplier system that eliminates the need for silicon lenses. The team created a highly efficient and scalable terahertz wave generator by attaching a specially designed, thin sheet of material to the back of the chip and using advanced Intel transistors.
“To take full advantage of a terahertz wave source, we need it to be scalable. A terahertz array might have hundreds of chips, and there is no place to put silicon lenses because the chips are combined with such high density. We need a different package, and here we’ve demonstrated a promising approach that can be used for scalable, low-cost terahertz arrays,” said Jinchen Wang, an EECS graduate student and lead author of the study.
The material sheet, featuring tiny laser-cut holes, equalizes the interaction between the waves and the silicon. This method allows more terahertz waves to radiate outward instead of being reflected, significantly boosting efficiency.
Terahertz waves occupy a unique space on the electromagnetic spectrum between radio waves and infrared light. They can carry vast amounts of data while safely penetrating various materials, making them ideal for applications like faster wireless communication, precise medical imaging, and high-resolution radar systems.
A property called the dielectric constant affects how electromagnetic waves pass through materials. Silicon has a much higher dielectric constant than air, causing most terahertz waves to reflect back instead of transmitting smoothly.
To solve this, researchers used a method called “matching” to balance the dielectric constants of silicon and air, minimizing signal loss without relying on bulky silicon lenses.
They attached a thin sheet of material with a dielectric constant between silicon and air to the back of the chip. This sheet balances the interaction of waves at the boundary, allowing more terahertz waves to pass through instead of being reflected.
They improved the chip’s performance by using Intel’s special transistors, which can handle higher frequencies and voltages than standard CMOS transistors.
With their innovative chip design, the researchers achieved a peak radiation power of 11.1 decibel milliwatts, outperforming current state-of-the-art solutions. Unlike bulky lenses, their scalable, low-cost chip design could be used to fabricate terahertz arrays, enabling even more applications in the future.
The team plans to continue working by creating phased terahertz chip arrays. These arrays could steer and focus terahertz beams, further expanding their capabilities for real-world uses.
