Copyright Interesting Engineering
A laser that fits in the palm of your hand has just beaten the efficiency of room-sized short-pulse systems by more than double, and could redefine how industry, medicine, and quantum research use ultrafast light. Researchers at the University of Stuttgart, working with Stuttgart Instruments GmbH, have developed a compact short-pulse laser system that pushes efficiency above 80 percent, a level previously considered nearly impossible for such devices. For decades, short-pulse lasers have required bulky setups, expensive components, and large cooling systems. Their efficiency hovered around 30–35 percent, making them powerful but wasteful tools used mostly in specialized labs. The new system compresses that capability into a device spanning just a few square centimeters, without sacrificing power, pulse duration, or bandwidth. Breaking old limits “With our new system, we can achieve levels of efficiency that were previously almost unattainable,” says Prof. Harald Giessen, who led the work. The team showed that an 80 percent conversion efficiency is fundamentally possible, meaning almost all incoming power is translated into useful laser output rather than being lost as heat. “For comparison: current technologies achieve only about 35%,” Giessen explains. Short-pulse lasers fire bursts lasting femtoseconds — quadrillionths of a second — packing huge energy into extremely tight time windows. These are the tools behind precision micromachining, delicate medical procedures, molecular imaging in quantum science, and semiconductor fabrication. But designing systems that are both compact and efficient has always been a major engineering challenge. New multipass magic “In order to generate short pulses, we need to amplify the incoming light beam and cover a wide range of wavelengths,” says lead author Dr. Tobias Steinle. “Until now, it has not been possible to combine both properties simultaneously in a small and compact optical system.” Typically, wide-bandwidth amplifiers rely on thin, short crystals, while high-efficiency systems need long crystals. Some research groups have tried linking several short crystals in sequence so each crystal handles part of the amplification. The idea worked on paper, but in practice, the alignment was extremely delicate, and the overall setup became unstable and hard to scale. The Stuttgart team solved the problem entirely differently. They used a single short crystal, but sent the light pulses through it multiple times, realigning and resynchronizing the split beams between each pass. This “multipass optical parametric amplification” preserves bandwidth while supercharging efficiency. The finished device generates pulses below 50 femtoseconds, uses only five components, and occupies just a few square centimeters. Small tool, big future “Our multipass system demonstrates that extremely high efficiencies need not to come at the expense of bandwidth,” Steinle says. Because the system is compact, tunable, and adaptable to various wavelengths, it could open the door to portable ultrafast lasers for medicine, gas sensing, environmental monitoring, and advanced analytics. The team imagines small, lightweight, battery-friendly tools that can do what today’s refrigerator-sized systems accomplish ranging from precision surgery to molecular diagnostics. With efficiency doubled, size slashed, and complexity reduced, this palm-sized laser may reshape how ultrafast optical tools move from the lab into the real world. The study appears in the journal Nature.
