About Us

Artificial intelligence should not be a black box. Fraunhofer HHI is a pioneer in explainable, reliable, and efficient AI, combining fundamental machine-learning research with practical applications. Techniques developed at the institute, such as Layer-wise Relevance Propagation and Concept Relevance Propagation, reveal how neural networks reach their decisions — not only which parts of an input mattered, but which human-understandable concepts a model relied on. These methods have been published in leading journals including Nature Machine Intelligence and help validate AI systems in areas where trust is essential, from medicine to industrial applications.

Transparency is only part of the picture. Fraunhofer HHI also researches neural network compression, which shrinks AI models so they can run efficiently on everyday devices, and has contributed to international standardization in this field. Its work on federated learning allows AI models to be trained collaboratively without sharing sensitive raw data. Together, these efforts make AI not only more transparent, but also more efficient and privacy-friendly.

Whether on a smartphone, a smart TV, or a streaming platform, high-quality video reaches you thanks to compression standards that Fraunhofer HHI helped create. Researchers at the institute have played central roles in developing the international video coding standards H.264/AVC, H.265/HEVC, and H.266/VVC. The first two run on billions of devices worldwide, while H.266/VVC delivers substantially better compression for the next generation of video services.

Beyond compression, Fraunhofer HHI develops algorithms for video transport, storage, and processing, along with 2D/3D analysis and synthesis and immersive media applications, connecting cutting-edge signal processing research with global media standards. Its computer vision research also reaches far beyond entertainment, developing AI methods for visual scene understanding, 3D reconstruction, digital scene representations, and intelligent image analysis. These methods provide the foundation for applications such as progress monitoring and digital twins for construction sites, automated quality inspection in industrial production, and medical imaging and image-guided interventions.

Fraunhofer HHI has been pushing the limits of optical communication for almost five decades. In 1977, the institute achieved the world's first optical fiber transmission at 1.12 Gbit/s. Since then, it has repeatedly set world records in optical fiber transmission, reaching data rates of several terabits per second. Today, its optical components touch almost every second bit transported on the internet.

The institute is now extending this expertise into communication in the terahertz range: in a recent world record, Fraunhofer HHI researchers transmitted data wirelessly at 221.5 Gbit/s over 500 meters through urban Berlin. Such "wireless fiber" links could one day connect mobile and optical networks in future 6G systems.

For more than 20 years, Fraunhofer HHI has helped define how mobile networks work, from 4G/LTE and 5G to the emerging 6G standard. Its contributions span the full arc from fundamental research in communication and information theory to standardization, field trials, and hardware prototypes. Scientific achievements include advances in MIMO theory, radio channel measurements up to sub-terahertz frequencies, and the QuaDRiGa channel model, developed at Fraunhofer HHI and used by researchers and industry worldwide.

The institute is also at the forefront of AI for communications, using machine learning to make networks faster, more reliable, and more energy-efficient — from AI-based signal processing to self-optimizing network management, complemented by research on open radio access networks (O-RAN) and network digital twins. Through major initiatives such as 6G-RIC, CampusOS, xG-RIC, and 6G Platform Germany, Fraunhofer HHI is laying the scientific and technical foundations of next-generation mobile communications.

Light is one of the most powerful tools of the digital age, and Fraunhofer HHI masters it at every scale. The institute develops photonic integrated circuits, lasers, modulators, and detectors, as well as hybrid and heterogenous integration technologies.

Its integrated photonic and terahertz sensors enable precise, non-contact measurements for spectroscopy, material analysis, quality assurance, and non-destructive testing in industry. HHI's photonic platforms also power emerging quantum technologies, from single-photon sources and detectors to complete miniaturized quantum-optical systems. This research covers the entire chain, from scientific modeling and component fabrication to integrated systems, prototypes, and field tests.

Since 2017, Fraunhofer HHI has been part of the Research Fab Microelectronics Germany, one of Europe's largest cross-location alliances for micro- and nanoelectronics research. As a one-stop shop, the alliance combines the technologies, infrastructure, and systems expertise of its member institutes into customized solutions for research and industry.