Researchers from ETH Zurich have developed a laser that produces the strongest ultra-short pulses to date, setting a new world record in laser technology.
Led by Professor Ursula Keller from the Institute for Quantum Electronics, the team created pulses with an average power of 550 watts, surpassing the previous record by over 50%.
These laser pulses last less than a picosecond—just a millionth of a millionth of a second—and are fired at a rate of five million pulses per second.
These ultra-short and powerful laser pulses can be used for various scientific and industrial applications, such as machining materials and observing ultra-fast processes in the attosecond range (a billionth of a billionth of a second).
The laser pulses reach peak power of 100 megawatts, which is equivalent to powering 100,000 vacuum cleaners for a brief moment.
Keller’s team has been working on improving short pulsed disk lasers for over 25 years.
These lasers use a crystal disk, only 100 micrometers thick, containing ytterbium atoms.
Along the way, they faced many challenges, such as parts of the laser breaking during experiments, but each challenge led to new insights and more reliable lasers for industry.
The team achieved this breakthrough using two key innovations.
First, they developed a special arrangement of mirrors that allow the laser light to pass through the disk multiple times, greatly amplifying the light without destabilizing the laser.
Second, they used a unique mirror called SESAM (Semiconductor Saturable Absorber Mirror), which was invented by Keller 30 years ago.
SESAM reflects light more effectively when the light is strong, helping the laser create short pulses rather than a continuous beam.
Previously, achieving such powerful pulses required amplifying weaker pulses outside the laser, but this method added noise and caused problems for precision measurements.
Keller’s team managed to generate high power directly within the laser, offering a cleaner, more efficient system.
This advancement in laser technology could lead to applications like more accurate clocks and testing materials using terahertz radiation. Keller also believes the laser could be used to study natural constants and even create new measurement techniques.
All in all, this breakthrough shows that laser oscillators can be a powerful alternative to traditional amplifier-based laser systems.
