Schawlow, A. L. & Townes, C. H. Infrared and optical masers. Phys. Rev. 112, 1940–1949 (1958).
Maiman, T. Stimulated optical radiation in ruby. Nature 187, 493–494 (1960).
Siegman, A. E. Lasers (University Science Books, 1986).
Ismail, N., Kores, C. C., Geskus, D. & Pollnau, M. Fabry–Pérot resonator: spectral line shapes, generic and related Airy distributions, linewidths, finesses, and performance at low or frequency-dependent reflectivity. Opt. Express 24, 16366–16389 (2016).
Faist, J. et al. Quantum cascade laser. Science 264, 553–556 (1994).
Köhler, R. et al. Terahertz semiconductor-heterostructure laser. Nature 417, 156–159 (2002).
Senica, U. et al. Planarized THz quantum cascade lasers for broadband coherent photonics. Light Sci. Appl. 11, 347 (2022).
Maineult, W. et al. Microwave modulation of terahertz quantum cascade lasers: a transmission-line approach. Appl. Phys. Lett. 96, 021108 (2010).
Jirauschek, C. Theory of hybrid microwave–photonic quantum devices. Laser Photonics Rev. 17, 2300461 (2023).
Kuizenga, D. & Siegman, A. FM and AM mode locking of the homogeneous laser-Part I: Theory. IEEE J. Quantum Electron. 6, 694–708 (1970).
Haus, H. A theory of forced mode locking. IEEE J. Quantum Electron. 11, 323–330 (1975).
Perego, A. M. et al. Coherent master equation for laser modelocking. Nat. Commun. 11, 311 (2020).
Bowers, J. E., Morton, P. A., Mar, A. & Corzine, S. W. Actively mode-locked semiconductor lasers. IEEE J. Quantum Electron. 25, 1426–1439 (2002).
Boyd, R. W. Slow and fast light: fundamentals and applications. J. Mod. Opt. 56, 1908–1915 (2009).
Udem, T., Holzwarth, R. & Hänsch, T. W. Optical frequency metrology. Nature 416, 233–237 (2002).
Diddams, S. A., Vahala, K. & Udem, T. Optical frequency combs: coherently uniting the electromagnetic spectrum. Science 369, 267 (2020).
Kärtner, F. X., Zumbühl, D. M. & Matuschek, N. Turbulence in mode-locked lasers. Phys. Rev. Lett. 82, 4428–4431 (1999).
Picqué, N. & Hänsch, T. W. Frequency comb spectroscopy. Nat. Photon. 13, 146 (2019).
Coddington, I., Newbury, N. & Swann, W. Dual-comb spectroscopy. Optica 3, 414–426 (2016).
Hugi, A., Villares, G., Blaser, S., Liu, H. & Faist, J. Mid-infrared frequency comb based on a quantum cascade laser. Nature 492, 229–233 (2012).
Burghoff, D. Unraveling the origin of frequency modulated combs using active cavity mean-field theory. Optica 7, 1781–1787 (2020).
Opačak, N. & Schwarz, B. Theory of frequency-modulated combs in lasers with spatial hole burning, dispersion, and Kerr nonlinearity. Phys. Rev. Lett. 123, 243902 (2019).
Senica, U. et al. Frequency-modulated combs via field-enhancing tapered waveguides. Laser Photonics Rev. 17, 2300472 (2023).
Becker, M., Kuizenga, D. & Siegman, A. Harmonic mode locking of the Nd:YAG laser. IEEE J. Quantum Electron. 8, 687–693 (1972).
Herr, T. et al. Temporal solitons in optical microresonators. Nat. Photon. 8, 145–152 (2014).
Guo, Q. et al. Ultrafast mode-locked laser in nanophotonic lithium niobate. Science 382, 708–713 (2023).
Forrer, A. et al. Photon-driven broadband emission and frequency comb RF injection locking in THz quantum cascade lasers. ACS Photonics 7, 784–791 (2020).
Yao, Y., Hoffman, A. J. & Gmachl, C. F. Mid-infrared quantum cascade lasers. Nat. Photon. 6, 432–439 (2012).
Burghoff, D. et al. Terahertz laser frequency combs. Nat. Photon. 8, 462–467 (2014).
Faist, J. et al. Quantum cascade laser frequency combs. Nanophotonics 5, 272–291 (2016).
Barbieri, S. et al. 13 GHz direct modulation of terahertz quantum cascade lasers. Appl. Phys. Lett. 91, 143510 (2007).
Marpaung, D., Yao, J. & Capmany, J. Integrated microwave photonics. Nat. Photon. 13, 80–90 (2019).
Han, Z., Ren, D. & Burghoff, D. Sensitivity of SWIFT spectroscopy. Opt. Express 28, 6002–6017 (2020).
Hillbrand, J., Andrews, A. M., Detz, H., Strasser, G. & Schwarz, B. Coherent injection locking of quantum cascade laser frequency combs. Nat. Photon. 13, 101–104 (2019).
Schneider, B. et al. Controlling quantum cascade laser optical frequency combs through microwave injection. Laser Photonics Rev. 15, 2100242 (2021).
Silvestri, C., Columbo, L. L., Brambilla, M. & Gioannini, M. Coherent multi-mode dynamics in a quantum cascade laser: amplitude-and frequency-modulated optical frequency combs. Opt. Express 28, 23846–23861 (2020).
Cappelli, F., Villares, G., Riedi, S. & Faist, J. Intrinsic linewidth of quantum cascade laser frequency combs. Optica 2, 836–840 (2015).
Consolino, L. et al. Fully phase-stabilized quantum cascade laser frequency comb. Nat. Commun. 10, 2938 (2019).
Heckelmann, I., Pinto, D., Schmitt, U., Beck, M. & Faist, J. Fast and compact time-resolved spectroscopy enabled by quantum walk combs. Preprint at https://arxiv.org/abs/2509.20112 (2025).
Mroziewicz, B. External cavity wavelength tunable semiconductor lasers-a review. Optoelectron. Rev. 16, 347–366 (2008).
Geng, Z. et al. Photonic integrated circuit implementation of a sub-GHz-selectivity frequency comb filter for optical clock multiplication. Opt. Express 25, 27635–27645 (2017).
Parriaux, A., Hammani, K. & Millot, G. Electro-optic frequency combs. Adv. Opt. Photonics 12, 223–287 (2020).
Haring, R. et al. High-power passively mode-locked semiconductor lasers. IEEE J. Quantum Electron. 38, 1268–1275 (2002).
Teng, C. C., Westberg, J. & Wysocki, G. Gapless tuning of quantum cascade laser frequency combs with external cavity optical feedback. Opt. Lett. 48, 363–366 (2023).
Kim, J. & Song, Y. Ultralow-noise mode-locked fiber lasers and frequency combs: principles, status, and applications. Adv. Opt. Photonics 8, 465–540 (2016).
Kippenberg, T. J., Holzwarth, R. & Diddams, S. A. Microresonator-based optical frequency combs. Science 332, 555–559 (2011).
Leindecker, N., Marandi, A., Byer, R. L. & Vodopyanov, K. L. Broadband degenerate OPO for mid-infrared frequency comb generation. Opt. Express 19, 6296–6302 (2011).
Wang, C. Y. et al. Mode-locked pulses from mid-infrared quantum cascade lasers. Opt. Express 17, 12929–12943 (2009).
Rafailov, E. U., Cataluna, M. A. & Sibbett, W. Mode-locked quantum-dot lasers. Nat. Photon. 1, 395–401 (2007).
Marzban, B. et al. A quantum walk comb source at telecommunication wavelengths. Nat. Photon. 20, 370–376 (2026).
Khalatpour, A. et al. Enhanced operating temperature in terahertz quantum cascade lasers based on direct phonon depopulation. Appl. Phys. Lett. 122, 161101 (2023).
Berthomieu, C. & Hienerwadel, R. Fourier transform infrared (FTIR) spectroscopy. Photosynth. Res. 101, 157–170 (2009).
Bozhkov, V. G. Semiconductor detectors, mixers, and frequency multipliers for the terahertz band. Radiophys. Quantum Electron. 46, 631–656 (2003).
Jirauschek, C., Riesch, M. & Tzenov, P. Optoelectronic device simulations based on macroscopic Maxwell–Bloch equations. Adv. Theory Simul. 2, 1900018 (2019).
Risken, H. & Nummedal, K. Self-pulsing in lasers. J. Appl. Phys. 39, 4662–4672 (1968).
Senica, U. et al. Plot datasets for “Continuously and widely tunable coherent pulse generation in semiconductor lasers”. figshare https://doi.org/10.6084/m9.figshare.30413005 (2026).

