In a groundbreaking achievement, a team of researchers at ETH Zurich has set a new record in the generation of ultra-short laser pulses, producing pulses that are not only exceptionally powerful but also extremely brief. This advancement has significant implications for fields such as precision measurement and materials processing.
The Breakthrough in Laser Technology
Led by Professor Ursula Keller at the Institute for Quantum Electronics, the team successfully generated laser pulses with an impressive power output of 550 watts, corresponding to an energy of 100 µJ (microjoules). This achievement surpasses the previous maximum by 50%, marking a monumental step in laser technology. The newly created pulses last for less than a picosecond and are emitted at a staggering rate of five million pulses per second.
The researchers indicate that these pulses can theoretically reach peak powers of up to 100 megawatts, a level of intensity that could, in theory, power up to 100,000 vacuum cleaners simultaneously.
Applications of Ultra-Short Laser Pulses
The potential applications for these ultra-short laser pulses are vast. Professor Keller suggests that they could significantly impact ultraviolet X-ray regimes, leading to advancements in precision instruments, including highly accurate clocks. These lasers could revolutionize the way we approach intricate tasks like precise cutting and laser ablation, enhancing both efficiency and accuracy in various industries.
A Long Journey of Innovation
The research team has been dedicated to enhancing short-pulsed disk lasers for the past 25 years. Throughout this journey, they faced numerous challenges, including technical obstacles and setbacks that tested their resolve. Reflecting on their efforts, Professor Keller stated, “This record is the result of a long and exciting journey with lots of interesting laser physics.”
The success of this project is attributed to two key innovations that have transformed the capabilities of laser oscillators.
Innovative Mirror Arrangement: The team designed a unique mirror configuration that allows light to reflect multiple times within the laser before exiting through an outcoupling mirror. This arrangement enables the amplification of light without compromising stability, a significant leap in laser design.
SESAM Technology: The second innovation involves the use of a Semiconductor Saturable Absorber Mirror (SESAM), a technology pioneered by Keller herself. SESAM’s reflectivity is contingent upon the intensity of incoming light, allowing researchers to redirect short pulses instead of maintaining a continuous beam. This method focuses the light energy into an extremely high-intensity pulse, effectively concentrating it over a very brief duration.
Advantages Over Traditional Systems
Traditionally, generating high-power laser pulses involved passing weaker laser beams through multiple amplifiers. This process often resulted in excessive noise, complicating applications. However, by integrating the SESAM mirror with a thin sapphire window, the ETH Zurich team successfully generated high power directly from the laser oscillator, eliminating the need for noisy amplification processes.
Future Prospects
The researchers anticipate further advancements in their laser technology, with plans to efficiently shorten the duration of the pulses to a few cycles. This development is crucial for creating attosecond pulses, which could open new frontiers in scientific research and technology.
Professor Keller expressed her gratitude for the support received from ETH Zurich and the Swiss National Fund, acknowledging that their backing has been instrumental in achieving this significant milestone. As the team continues its work, the future of ultra-short laser technology looks promising, with the potential to transform various scientific and industrial applications.
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