Terahertz radiation, occupying a spectral region between microwaves and infrared light, holds immense promise for revolutionizing fields ranging from high-speed communication to advanced sensing technologies. This segment of the electromagnetic spectrum, characterized by frequencies from several hundred gigahertz to a few terahertz, possesses unique advantages owing to its short wavelengths. These allow terahertz waves to carry vast amounts of data rapidly, yet harnessing and integrating these signals seamlessly with existing optical and microwave platforms has posed a formidable challenge until now.
In a groundbreaking development, scientists at EPFL’s Laboratory of Hybrid Photonics have engineered an ultra-thin photonic chip composed of lithium niobate that not only generates terahertz radiation tunable to precise specifications but also detects incoming terahertz waves by converting them into optical signals. This feat represents a significant leap in bridging the long-standing gap between terahertz and optical technologies within a single, miniaturized device.
The team’s innovation centers on the integration of micron-scale transmission lines onto the lithium niobate chip. These transmission lines, akin to miniature radio cables etched onto the chip, guide terahertz waves across the platform with remarkable efficiency. Positioned adjacent to these are complementary structures dedicated to channeling optical waves. The proximity of these two guiding elements greatly enhances the interaction and conversion efficiency between terahertz and optical signals, minimizing energy loss and maximizing signal fidelity.
By achieving bi-directional conversion—both generation and detection—of terahertz waves on a unified platform, researchers have unlocked unprecedented potential for compact, power-efficient devices capable of multifunctional roles in future technologies. This breakthrough paves the way for innovations in communication, sensing, spectroscopy, and even quantum information processing, heralding a new era of integrated terahertz photonics.
Notably, the lithium niobate chip produced terahertz electric fields more than 100 times stronger than previous benchmarks and expanded the operational bandwidth from roughly 680 GHz to an impressive 3.5 THz. This dramatic enhancement in both power and bandwidth is crucial for applications requiring high resolution and rapid data rates, such as ultra-precise distance measurement and high-throughput wireless communication.
The ramifications for next-generation communication systems, particularly the emerging 6G networks, are profound. Terahertz signals have the potential to enable high-speed wireless links with vastly increased data capacity while simultaneously incorporating sensing capabilities into the communication framework. This dual functionality could revolutionize how devices interact with their environment, seamlessly integrating data transmission with real-time spatial awareness.
From a technological standpoint, the chip’s compatibility with extant photonic components—including lasers, modulators, and detectors—facilitates its integration into current optical infrastructures. This compatibility is vital, ensuring that the transition to terahertz-enhanced systems can build upon the well-established optical communication technologies already in widespread use.
Beyond communications, the novel device found promising applications in terahertz-based radar systems. The chip’s ability to generate ultrashort terahertz pulses with fine temporal precision means it can determine object distances with sub-millimeter accuracy. Such precision ranging capabilities are especially pertinent to autonomous driving technologies, where spatial resolution and rapid signal processing are paramount for safe navigation.
The researchers’ architectural innovation hinges on a clever photonic circuit design that tightly confines both terahertz and optical waves while facilitating their interaction. This design achieves an unprecedented bandwidth for on-chip terahertz transmission lines, pushing the performance envelope further than previous integrated photonic devices.
Crucially, the chip leverages the exceptional electro-optic properties of thin-film lithium niobate. This material exhibits strong nonlinear optical effects and low optical losses, making it ideal for converting signals across disparate frequency regimes. Its use in this context underscores the increasing importance of material science advances in driving photonics research forward.
The study’s successful demonstration signals a promising shift toward miniaturized terahertz systems that could be seamlessly embedded in everyday technologies. By drastically reducing the size and power requirements of terahertz generation and detection, these integrated circuits might soon underpin innovations in wireless communications, medical imaging, chemical sensing, and even quantum computing.
Looking ahead, the EPFL team is focused on further miniaturizing the chip and refining its integration with existing photonic components. This next stage is key to translating laboratory successes into practical devices that can be deployed in smartphones, autonomous vehicles, and industrial sensing platforms, where size, power efficiency, and multifunctionality are critical.
The interdisciplinary collaboration driving this research exemplifies how advances in photonics, materials science, and electrical engineering converge to open new horizons. The convergence of optical and terahertz technologies into a unified chip platform could redefine what is achievable in wireless communication and sensing technologies, heralding a new technological paradigm.
As 6G communication standards and next-generation sensing technologies begin taking shape, the foundational work by the EPFL team provides a blueprint for integrating terahertz functionalities with existing photonic infrastructure. Harnessing terahertz bandwidths combined with optical signal processing could unlock data rates and sensing capabilities that were previously unattainable, positioning this technology at the forefront of future connectivity and sensing landscapes.
Subject of Research: Integrated photonic circuits for terahertz wave generation and detection on a single lithium niobate chip.
Article Title: Photonics-integrated terahertz transmission lines
News Publication Date: 30-Jul-2025
Web References:
https://actu.epfl.ch/news/integrated-photonic-circuits-could-help-close-the-/
DOI: 10.1038/s41467-025-62267-y
References:
Lampert, Y., Shams-Ansari, A., Gaier, A. et al. Photonics-integrated terahertz transmission lines. Nat Commun 16, 7004 (2025).
Image Credits: 2025 EPFL/Alain Herzog CC BY SA 4.0
Keywords: Applied optics, Communications, Remote sensing
