Abstract

Quantum cascade laser (QCL) frequency combs are a promising candidate for chemical sensing and biomedical diagnostics1,2,3,4. They are electrically pumped and compact, making them an ideal platform for on-chip integration5. Until now, optical feedback is fatal for frequency comb generation in QCLs6. This property limits the potential for integration. Here, we demonstrate coherent electrical injection locking of the repetition frequency to a stabilized radio-frequency oscillator. We prove that the injection-locked QCL spectrum can be phase-locked, resulting in the generation of a frequency comb. We show that injection locking is not only a versatile tool for all-electrical frequency stabilization, but also mitigates the fatal effect of optical feedback. A prototype self-detected dual-comb set-up consisting only of an injection-locked dual-comb chip, a lens and a mirror demonstrates the enormous potential for on-chip dual-comb spectroscopy. These results pave the way to miniaturized and all-solid-state mid-infrared spectrometers.

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The data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.

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References

  1. 1.

    Faist, J. et al. Quantum cascade laser. Science 264, 553–556 (1994).

  2. 2.

    Hugi, A., Villares, G., Blaser, S., Liu, H. C. & Faist, J. Mid-infrared frequency comb based on a quantum cascade laser. Nature 492, 229–233 (2012).

  3. 3.

    Geiser, M. et al. Single-shot microsecond-resolved spectroscopy of the bacteriorhodopsin photocycle with quantum cascade laser frequency combs. Biophys. J. 114, 173a (2018).

  4. 4.

    Villares, G., Hugi, A., Blaser, S. & Faist, J. Dual-comb spectroscopy based on quantum-cascade-laser frequency combs. Nat. Commun. 5, 5192 (2014).

  5. 5.

    Villares, G. et al. On-chip dual-comb based on quantum cascade laser frequency combs. Appl. Phys. Lett. 107, 251104 (2015).

  6. 6.

    Jouy, P. et al. Dual comb operation of λ ~ 8.2 μm quantum cascade laser frequency comb with 1 W optical power. Appl. Phys. Lett. 111, 141102 (2017).

  7. 7.

    Udem, T., Holzwarth, R. & Hänsch, T. W. Optical frequency metrology. Nature 416, 233–237 (2002).

  8. 8.

    Udem, T., Reichert, J., Holzwarth, R. & Hänsch, T. W. Absolute optical frequency measurement of the Cesium D 1 line with a mode-locked laser. Phys. Rev. Lett. 82, 3568–3571 (1999).

  9. 9.

    Holzwarth, R. et al. Optical frequency synthesizer for precision spectroscopy. Phys. Rev. Lett. 85, 2264–2267 (2000).

  10. 10.

    Bernhardt, B. et al. Cavity-enhanced dual-comb spectroscopy. Nat. Photon. 4, 55–57 (2009).

  11. 11.

    Haas, J. & Mizaikoff, B. Advances in mid-infrared spectroscopy for chemical analysis. Annu. Rev. Anal. Chem. 9, 45–68 (2016).

  12. 12.

    Waclawek, J. P. et al. Quartz-enhanced photoacoustic spectroscopy-based sensor system for sulfur dioxide detection using a CW DFB-QCL. Appl. Phys. B 117, 113–120 (2014).

  13. 13.

    Friedli, P. et al. Four-wave mixing in a quantum cascade laser amplifier. Appl. Phys. Lett. 102, 222104 (2013).

  14. 14.

    Faist, J. et al. Quantum cascade laser frequency combs. Nanophotonics 5, 272–291 (2016).

  15. 15.

    Razavi, B. A study of injection locking and pulling in oscillators. IEEE J. Solid-State Circuit 39, 1415–1424 (2004).

  16. 16.

    Gellie, P. et al. Injection-locking of terahertz quantum cascade lasers up to 35 GHz using RF amplitude modulation. Opt. Express 18, 20799–20816 (2010).

  17. 17.

    Barbieri, S. et al. Coherent sampling of active mode-locked terahertz quantum cascade lasers and frequency synthesis. Nat. Photon. 5, 306–313 (2011).

  18. 18.

    St-Jean, M. R. et al. Injection locking of mid-infrared quantum cascade laser at 14 GHz, by direct microwave modulation. Laser Photon. Rev. 8, 443–449 (2014).

  19. 19.

    Piccardo, M. et al. Time-dependent population inversion gratings in laser frequency combs. Optica 5, 475–478 (2018).

  20. 20.

    Kane, D. & Trebino, R. Characterization of arbitrary femtosecond pulses using frequency-resolved optical gating. IEEE J. Quantum Electron. 29, 571–579 (1993).

  21. 21.

    Iaconis, C. & Walmsley, I. A. Spectral phase interferometry for direct electric-field reconstruction of ultrashort optical pulses. Opt. Lett. 23, 792–794 (1998).

  22. 22.

    Burghoff, D. et al. Terahertz laser frequency combs. Nat. Photon. 8, 462–467 (2014).

  23. 23.

    Burghoff, D. et al. Evaluating the coherence and time-domain profile of quantum cascade laser frequency combs. Opt. Express 23, 1190–1202 (2015).

  24. 24.

    Khurgin, J. B., Dikmelik, Y., Hugi, A. & Faist, J. Coherent frequency combs produced by self frequency modulation in quantum cascade lasers. Appl. Phys. Lett. 104, 081118 (2014).

  25. 25.

    Mansuripur, T. S. et al. Single-mode instability in standing-wave lasers: the quantum cascade laser as a self-pumped parametric oscillator. Phys. Rev. A 94, 063807 (2016).

  26. 26.

    Singleton, M., Jouy, P., Beck, M. & Faist, J. Evidence of linear chirp in mid-infrared quantum cascade lasers. Optica 5, 948–953 (2018).

  27. 27.

    Burghoff, D., Yang, Y. & Hu, Q. Computational multiheterodyne spectroscopy. Sci. Adv. 2, e1601227 (2016).

  28. 28.

    Schwarz, B. et al. Monolithically integrated mid-infrared lab-on-a-chip using plasmonics and quantum cascade structures. Nat. Commun. 5, 4085 (2014).

  29. 29.

    Schneider, H. & Liu, H. C. Quantum Well Infrared Photodetectors (Springer-Verlag, Berlin Heidelberg, 2006).

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Acknowledgements

This work was supported by the Austrian Science Fund (FWF) in the framework of ‘Building Solids for Function’ (Project W1243), the projects ‘NanoPlas’ (P28914-N27) and ‘NextLite’ (F4909-N23). H.D. acknowledges support by the ESF under project CZ.02.2.69/0.0/0.0/16_027/0008371. A.M.A was supported by projects COMTERA—FFG 849614 and AFOSR FA9550-17-1-0340.

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Affiliations

  1. Institute of Solid State Electronics, TU Wien, Vienna, Austria

    • Johannes Hillbrand
    • , Aaron Maxwell Andrews
    • , Hermann Detz
    • , Gottfried Strasser
    •  & Benedikt Schwarz
  2. Center for Micro- and Nanostructures, TU Wien, Vienna, Austria

    • Aaron Maxwell Andrews
    •  & Gottfried Strasser
  3. CEITEC, Brno University of Technology, Brno, Czech Republic

    • Hermann Detz

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Contributions

J.H. and B.S. built up the SWIFTS set-up. J.H. carried out the experiments and wrote the manuscript, with B.S. and A.M.A. providing editorial input. H.D., A.M.A. and G.S. were responsible for MBE growth. B.S. developed the algorithm for the SWIFTS data processing and supervised this work. All authors contributed to analysing the results and commented on the paper.

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The authors declare no competing interests.

Corresponding author

Correspondence to Benedikt Schwarz.

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DOI

https://doi.org/10.1038/s41566-018-0320-3