Researchers Cut the Size, Bolster the Efficiency with Short-Pulse Laser System Design
STUTTGART, Germany, Nov. 28, 2025 — Researchers at the University of Stuttgart, in collaboration with Stuttgart Instruments, have developed a compact and efficient short-pulse laser system. Typical schemes for lasers that emit extremely short light pulses require a lot of space. On top of that, they're expensive. These lasers are typically used within manufacturing, medical applications, and research.
The new approach boasts double the efficiency of previous systems, a high level of versatility, and a greatly reduced footprint. According to the researchers, the device is small enough to fit in the palm of a hand.
Multipass optical parametric amplifier with laser beam: The new system demonstrates the development of highly efficient and compact short-pulse lasers. Courtesy of the University of Stuttgart.
Further, the team's experimentation showed that 80% efficiency is fundamentally possible.
“For comparison: current technologies achieve only about 35%, which means they lose much of their efficiency and are correspondingly expensive,” said professor Harald Giessen, head of the 4th Physics Institute at the University of Stuttgart.
Short-pulse lasers generate light pulses that last just nano-, pico-, or femtoseconds, allowing them to concentrate a large amount of energy on a small area within an extremely short time. A pump laser and the laser that emits the short pulses work together. The pump laser supplies a special crystal with light energy. This crystal is the core of the process and transfers the energy from the pump laser to the ultrashort signal pulse. This converts the incoming light particles into infrared light, which makes it possible to carry out experiments, measurements, or production processes that are not possible with visible light.
“In order to generate short pulses, we need to amplify the incoming light beam and cover a wide range of wavelengths. Until now, it has not been possible to combine both properties simultaneously in a small and compact optical system,” said Tobias Steinle, lead author of the study.
Laser amplifiers with a wide bandwidth require special crystals that are particularly short and thin, while efficient amplifiers require especially long crystals. Connecting several short crystals in series is one possible way to combine both. It is already being pursued in research. The key is to ensure that the pulses from the pump laser and the signal laser remain synchronized.
The team used an alternative route to solve this problem: a new multipass procedure. Instead of using a single long crystal or many short crystals, they use a single short crystal and repeatedly run the light pulses through this crystal in their optical parametric amplifier. The separated pulses are precisely realigned so that they remain synchronized. The system can generate pulses shorter than 50 fs, occupies only a few square centimeters, and consists of just five components.
“Our multipass system demonstrates that extremely high efficiencies need not to come at the expense of bandwidth,” said Steinle. “It can replace large and expensive laser systems with high power losses, which were previously required to amplify ultrashort pulses.”
The new system is highly versatile and beyond infrared light, as well as to different crystal systems and pulse durations. With this concept, the researchers aim to build small, lightweight, compact, portable, and tunable lasers capable of precisely adjusting wavelengths. They see potential areas of application in medicine, analytics, gas sensor technology, and environmental research.
This research was published in Nature (www.doi.org/10.1038/s41586-025-09665-w).
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