Forskare gjorde vanlig industrilaser hundra gånger skarpare

Inom forskning, medicin och industrin har olika typer av lasrar blivit ett allt viktigare verktyg. Särskilt stor efterfrågan finns på lasrar med väldigt hög precision, vilket uppnås med korta pulser. Men ju kortare pulser, ju dyrare laser, med följd att dessa ”superlasrar” inte är så vanliga. Nu har ett internationellt forskarteam hittat ett sätt att komprimera pulserna från vanliga industrilasrar – till en hundradel!

– Publicerad den 22 May 2020

Bild: Cord Arnold.

Metoden kan bidra till att dagens mer exklusiva laserteknik på sikt kan komma användas betydligt bredare än idag.

Cord Arnold, laserfysiker vid LTH, är en av författarna till studien som publiceras i Optics Letters. Här berättar han om upptäckten.

"A team of researchers from Germany (Deutsches Elektronen Synchrotron - DESY, Hamburg), France (École Polytechnique, Paris) and Sweden (Lund University), has achieved record high temporal compression of laser pulses from picosecond duration (one trillionths of a second) to the few femtosecond regime (quadrillionths of a second).

Taking into account that light travels to the moon in little more a second, those pulses only travel a tenth of the thickness of a human hair within their duration. The obtained compression is also remarkable because such short pulses have before only been generated with elaborate scientific ultrashort pulse laser technology that is both complicated and expensive.

The presented work opens up for achieving equally short pulses from compact, industrial grade, picosecond lasers that can deliver hundred times higher average power at significantly lower costs. Femtosecond laser pulses are highly appreciable for challenging applications where precision and speed are key requirements.

They are already today enabling tools in many areas of research and technology, such as fundamental science in physics, chemistry and biology, industrial applications like precision drilling and structuring as well as in medical diagnostics and treatment. The presented work will contribute to reducing the costs and further spreading the technology.

The scientists achieved the temporal compression in a two-stage process. The pulses were sent subsequently into two mirror tubes filled with krypton gas. The interaction with the krypton gas slightly broadens the color spectrum of the initially almost monochromatic infrared laser light each time it passes through the tube.

After 44 and 12 round trips in the first and second tube, respectively, the massive broadening of the color spectrum was the key for being able to push together the pulses to much shorter duration, in total achieving a new record compression factor of 90.

The Lund researchers Ivan Sytcevich, Chen Guo, Anne-Lise Viotti, Anne L’Huillier and Cord L. Arnold contributed to the achievements with their expertise in the characterization of ultrashort laser pulses with the patented dispersion-scan technique and by developing simulation tools. The work is presented in the journal Optics Letters."

 

Reference:

Post-compression of picosecond pulses into the few-cycle regime; Prannay Balla et al.; Optics Letters, 2020; DOI: 10.1364/OL.388665