A coherent, compact and robust light source with coverage from the ultraviolet to the infrared is desirable for heterodyne super-resolution imaging1, broadband infrared microscopy2, protein structure determination3 and standoff trace-gas detection4. To address these demanding problems, frequency combs5 combine absolute frequency accuracy with sub-femtosecond timing and waveform control to enable high-resolution, high-speed and broadband spectroscopy6,7,8,9. Here we demonstrate a scalable source of near-single-cycle pulses from robust and low-noise erbium fibre (Er:fibre) technology. With a peak power of 0.56 MW we generate a comb spanning six octaves, from the ultraviolet (350 nm) to the mid-infrared (22,500 nm), achieving a resolving power of 1010 across 0.86 PHz of bandwidth. Second-order nonlinearities in LiNbO3, GaSe and CdSiP2 provide phase-stable infrared ultrashort pulses with simultaneous brightness exceeding a synchrotron10, while cascaded nonlinearities in LiNbO3 yield four octaves simultaneously (0.350–5.6 μm). We anticipate that these advances will be enabling for basic and applied spectroscopy, microscopy and phase-sensitive nonlinear optics.
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The data supporting the findings of this study are available from D.M.B.L. upon reasonable request.
Nonlinear Schrödinger equation code is available from citations in the Supplementary Information as well as from D.M.B.L. upon reasonable request.
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The mention of specific companies, products or tradenames does not constitute an endorsement by the National Institute of Standards and Technology (NIST). We thank T. Schibli for his contributions and P. Schunemann and K. Zawilski at BAE for providing the CSP crystal, as well as I. Coddington, D. Carlson and M. Hummon for their manuscript feedback. D.M.B.L. and A.K. acknowledge award 70NANB18H006 from NIST. This research was supported by the Defense Advanced Research Projects Agency SCOUT Program, the Air Force Office of Scientific Research (FA9550-16-1-0016) and NIST.
The authors declare no competing interests.
Peer review information Nature Photonics thanks the anonymous reviewers for their contribution to the peer review of this work.
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Lesko, D.M.B., Timmers, H., Xing, S. et al. A six-octave optical frequency comb from a scalable few-cycle erbium fibre laser. Nat. Photonics 15, 281–286 (2021). https://doi.org/10.1038/s41566-021-00778-y
Nature Photonics (2021)
Nature Photonics (2021)