Ultrashort laser pulses are indispensable tools for sensing and measurement, but it is challenging to generate them at high powers. Quantum mechanics dictates that the more localized a laser pulse is in time, the wider the range of frequencies of its photons — ultrashort laser pulses are said to be ‘broadband’ because of their wide frequency range. The power of ultrashort laser pulses can be increased through amplification, but efficiently amplifying these pulses is difficult. However, in a paper in Nature, Nägele et al.1 report a method that efficiently amplifies a weak, ultrashort laser pulse by overlapping it with a high-power laser pulse. The authors achieved this by bouncing the two pulses back and forth between two mirrors such that they repeatedly passed through a crystal. The mirrors were designed to reduce unwanted mismatch between the pulses, and the researchers demonstrate that this set-up transfers energy to the weaker pulse with high efficiency.
Nature 647, 45-46 (2025)
doi: https://doi.org/10.1038/d41586-025-03449-y
References Nägele, J. H., Steinle, T., Thannheimer, J., Flad, P. & Giessen, H. Nature 647, 74–79 (2025). Fattahi, H. et al. Optica 1, 45–63 (2014). Viotti, A.-L. et al. Optica 9, 197–216 (2022). Kovalenko, N., Hariton, V., Fritsch, K. & Pronin, O. Opt. Lett. 48, 6220–6223 (2023). Download references
Competing Interests C.H. is applying for a national research grant together with Harald Giessen and Tobias Steinle (two co-authors of Nägele et al. Nature 2025; ref. 1) that builds on the work described in ref. 1 and in this News & Views article.
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