Record-high 350-W average output power from an ultrafast laser

F. Saltarelli, I.J. Graumann, L. Lang, D. Bauer, C.R. Phillips, U. Keller: Download"Power scaling of ultrafast oscillators: 350-W average-power sub-picosecond thin-disk laser" (PDF, 1.7 MB)vertical_align_bottom. ‎Opt. Express 27, 31465–31474 (2019).
doi: external page10.1364/OE.27.031465call_made

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Photonics Spectra October 2019:
C. R. Phillips, U. Keller, external page“Advances in Ultrafast Multi-100-W Average-Power Thin-Disk Lasers”call_made, DownloadDownload (PDF, 2.2 MB)vertical_align_bottom

In the last 20 years, the combination of Yb-doped gain materials with gain geometries optimized for heat extraction enabled a revolution in ultrafast high-power laser sources. A compelling route to high power is to directly power scale modelocked laser oscillators, bypassing the complicated chain of amplifiers traditionally used [1]. In this way the laser output is obtained directly from a simple, high-performance, and potentially cost-effective source. Moreover, oscillators offer low-noise, exceptional temporal pulse shape, diffraction limited beam quality, and high repetition rates.
Here we set a new benchmark for the average power of ultrafast oscillators. We demonstrate a SESAM-modelocked thin-disk oscillator delivering 350‑W output power [2], which improves the previous long-standing record of 275 W obtained in 2012 [3]. SESAM have been improved for high-power operation [4-6]
The first step in power scaling requires a larger pump spot on the thin disk. However, larger pump spots and higher intracavity powers lead to excessive thermal lensing effects. Counterintuitively, we found the solution to involve an active multi-pass cavity architecture, incorporating several passes of the intracavity beam on the thin disk. Such multi-pass approaches are expected to increase the sensitivity to thermal lensing, and were therefore avoided in previous record results, despite the major advantage they offer in terms of reduced intracavity power via larger output coupling rates. Here, we leverage our earlier discovery of the thin-disk gas-lensing effect [7] to achieve a laser which combines a very large pump spot, multiple passes on the disk gain medium, and vacuum operation. Novel concepts enable even 200-W operation in air [8]. These new record-level average power results reveal the path to even further power scaling in the near future.

References:

[1] C. J. Saraceno, F. Emaury, C. Schriber, A. Diebold, M. Hoffmann, M. Golling, T. Südmeyer, U. Keller, Download“Toward millijoule-level high-power ultrafast thin-disk oscillators” (PDF, 1.3 MB)vertical_align_bottom – Invited Paper, IEEE J. Selected Topics in Quantum Electronics (JSTQE), vol. 21 , No. 1, 1100318, 2015
doi: external page10.1109/JSTQE.2014.2341588call_made

[2] F. Saltarelli, I. J. Graumann, L. Lang, D. Bauer, C. R. Phillips, U. Keller,  Download“Power scaling of ultrafast oscillators: 350-W average-power sub-picosecond thin-disk laser” (PDF, 1.7 MB)vertical_align_bottom, Optics Express, vol. 27, No. 22, pp. 31465-31474, 2019
doi: external page10.1364/OE.27.031465call_made

[3] C. J. Saraceno, F. Emaury, O. H. Heckl, C. R. E. Baer, M. Hoffmann, C. Schriber, M. Golling, T. Südmeyer, U. Keller,  Download“275 W average output power from a femtosecond thin disk oscillator operated in a vaccum environment" (PDF, 1.3 MB)vertical_align_bottom, Optics Express, vol. 20, No. 21, pp. 23535-23541, 2012
doi: external page10.1364/OE.20.023535call_made

[4] C. G. E. Alfieri, A. Diebold, F. Emaury, E. Gini, C. J. Saraceno, U. Keller, Download“Improved SESAMs for femtosecond pulse generation approaching the kW average power regime” (PDF, 3.6 MB)vertical_align_bottom Optics Express, vol. 24, No. 24, pp. 27587-27599, 2016
doi: external page10.1364/OE.24.027587call_made

[5] A. Diebold, T. Zengerle, C. G. E. Alfieri, C. Schriber, F. Emaury, M. Mangold, M. Hoffmann, C. J. Saraceno, M. Golling, D. Follman, G. D. Cole, M. Aspelmeyer, T. Südmeyer, U. Keller, Download“Optimized SESAMs for kilowatt-level ultrafast lasers” (PDF, 5.5 MB)vertical_align_bottom, Optics Express, vol. 24, No. 10, pp. 10512-10526, 2016
doi: external page10.1364/OE.24.010512call_made

[6]  C. J. Saraceno, C. Schriber, M. Mangold, M. Hoffmann, O. H. Heckl, C. R. E. Baer, M. Golling, T. Südmeyer, U. Keller,  Download“SESAMs for high-power oscillators: design guidelines and damage thresholds” (PDF, 1.1 MB)vertical_align_bottom – Invited Paper, IEEE J. Selected Topics in Quantum Electronics (JSTQE), vol. 18, No. 1, pp. 29-41, 2012
doi: external page10.1109/JSTQE.2010.2092753call_made

[7] A. Diebold, F. Saltarelli, I. J. Graumann, C. J. Saraceno, C. R. Phillips, U. Keller, Download“Gas-lens effect in kW‑class thin-disk lasers” (PDF, 4 MB)vertical_align_bottom Optics Express, vol. 26, No. 10, pp. 12648-12659, 2018
doi: external page10.1364/OE.26.012648call_made

[8] F. Saltarelli, A. Diebold, I. J. Graumann, C. R. Phillips, U. Kelle,  Download“Self-phase modulation cancellation in a high-power ultrafast thin-disk laser oscillator” (PDF, 1.3 MB)vertical_align_bottom Optica, vol. 5, No. 12, pp. 1603-1606, 2018
doi: external page10.1364/OPTICA.5.001603call_made