A new study led by the Aerospace Information Research Institute of the Chinese Academy of Sciences, along with their collaborators, has demonstrated that high pressure can significantly enhance and precisely tune terahertz (THz) radiation from the two-dimensional semiconductor gallium telluride (GaTe). Using a diamond anvil cell, the research team achieved a 13-fold increase in THz emission and directly mapped the sequence of ultrafast processes that produce THz waves.

Their findings were recently published in Laser & Photonics Reviews.

Terahertz radiation is widely used in spectroscopy, imaging, and materials research. It is typicallygenerated when ultrafast laser pulses strike a material, triggering rapid movements of electrons and the crystal lattice. However, different THz emission mechanisms, such as optical rectification and ultrafast transient currents, often occur simultaneously, making them difficult to separate.

To address this challenge, the team used high pressure as a "clean, powerful tuning tool" to manipulate GaTe's crystal and electronic structure. Their experiments not only amplified THz output but also revealed a critical time-domain signature: a phase shift of more than 150 femtoseconds indicated that the transient current process precedes optical rectification—a sequence that became directly observable only under high pressure.

Complementary simulations and first-principles calculations further showed that pressure alters GaTe's intrinsic resonant frequency and initial charge distribution. These changes, the researchers explained, determine the amplitude, frequency, and phase of emitted THz waves, providing a unified framework to understand how different ultrafast mechanisms interact.

"This work proves that pressure is a versatile tool for controlling terahertz emission dynamics," said Prof. WANG Tianwu, a corresponding author of the study. "It also offers guidance for designing new THz-active materials, including those modified through chemical-pressure-based doping."

The studysuggests hydrostatic pressure could be used to probe and enhance a broad range of emerging THz emitters, such as topological materials, spintronic materials, and heterostructures. By improving these materials' bandwidth, efficiency, and tunability, the study opens new avenues for developing next-generation THz sources for both scientific research and technological applications.