UCLA engineers shrink terahertz systems onto single chip
Terahertz waves have major potential in high-speed comms, imaging, security screening and sensing, but are still underused due to complex and bulky systems.
Now, using quantum well (QW) semiconductor structures, UCLA researchers have integrated laboratory-sized terahertz systems onto one semiconductor chip, opening the door to compact, scalable devices.
In a prototype fabricated on a GaAs/AlGaAs QW PIC substrate, they demonstrated frequency-tuneable terahertz generation and detection across the 100–500 GHz range, achieving both higher terahertz generation efficiency and improved terahertz detection sensitivity compared to the state-of-the-art.
The breakthrough 'Terahertz generation and detection through gain-enhanced interband photomixing in quantum well structures' was published in Nature Communications in May 2026.
“Terahertz optoelectronic systems have been bulky, expensive, power-hungry and difficult to scale for widespread use,” said study leader Mona Jarrahi , a professor of electrical and computer engineering and holder of UCLA Samueli’s Northrop Grumman Chair in Electrical Engineering. “By demonstrating that many of these functions can be integrated onto a single chip using proven industry-standard fabrication platforms, our study opens the door to practical, scalable terahertz technologies for real-world applications.”
Earlier approaches to single-chip optoelectronic terahertz systems primarily relied on specialised materials and fabrication techniques incompatible with standard photonic chip technology. The team’s breakthrough focused instead on QW PIN photodiodes tailored to simultaneously generate, detect, modulate and amplify terahertz signals on a single shared chip platform.
QWs embedded in PIN photodiodes (key elements of commercially available PICs) enable monolithic integration of lasers, semiconductor optical amplifiers, modulators, filters, demultiplexers, and other passive optical components.
The researchers’ key innovation was demonstrating that these structures could also support terahertz signal generation and detection through a process called gain-enhanced interband photomixing, in which two laser beams combine to generate signals at a desired wavelength.
The team says the work positions terahertz technology for widespread use, facilitating practical applications across remote sensing, communications, and medical diagnostics within portable devices.
