Chip-Based System To Generate Terahertz Waves

MIT researchers have created a scalable, low-cost chip that generates high-power terahertz waves without requiring bulky silicon lenses.

Terahertz waves enable faster data transmission, precise medical imaging, and high-resolution radar, but generating them efficiently on a semiconductor chip is challenging. Many techniques require bulky silicon lenses to achieve enough radiating power, making integration into electronic devices difficult.

MIT researchers have developed a terahertz amplifier-multiplier system that boosts radiating power without silicon lenses. Adding a thin, patterned sheet to the back of the chip and using high-power Intel transistors created a scalable chip-based generator for applications like security scanners and environmental monitors.

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Making waves

The researchers took a different approach by applying an electromechanical theory called matching, which aims to balance the dielectric constants of silicon and air to reduce signal reflection at the boundary. They achieved this by attaching a thin sheet of material with a dielectric constant between that of silicon and air to the back of the chip, allowing most waves to transmit outward rather than being reflected.

A scalable approach

The researchers selected a low-cost, commercially available substrate with a dielectric constant close to the desired value for matching. To fine-tune its properties, they used a laser cutter to create tiny holes, adjusting the dielectric constant precisely. They also integrated Intel’s specialized transistors, which offer a higher maximum frequency and breakdown voltage than traditional CMOS transistors, enabling their chip to generate terahertz signals with a peak radiation power of 11.1 decibel-milliwatts—the highest among state-of-the-art techniques. Since the chip is inexpensive and scalable, it could be more easily integrated into real-world devices.

A key challenge in making the chip scalable was managing power and temperature during terahertz wave generation and developing a manufacturing-friendly method for installing the matching sheet. The researchers plan to demonstrate scalability by fabricating a phased array of CMOS terahertz sources, allowing them to steer and focus a powerful terahertz beam using a compact, low-cost device.