Mid-infrared Ultrashort Pulse: Comparison
Please note this is a comparison between versions V2 by Conner Chen and V1 by Xinyang Su.

Mid-infrared (MIR) ultrashort laser pulses, with wavebands ranging from 2 to 20 µm, have a wide range of applications in the fields of environmental monitoring, laser medicine, food quality control, strong-field physics, attosecond science, and some other aspects. There are various technologies for MIR ultrashort pulse generation towards different wavebands.

  • mid-infrared
  • ultrashort pulse
  • laser technology
  • molecular fingerprint region
  • quantum cascade lasers
  • difference frequency generation
  • supercontinuum
  • optical parametric oscillation
  • optical parametric amplification
  • THz generation

1. Motivations for the Research of Mid-Infrared Ultrashort Pulse Generation

The mid-infrared (MIR) spectral region is known as the “molecular fingerprint region”, and almost every kind of gas molecule shows a unique and strong absorption characteristic within that region, as shown in Figure 1a [1,2,3,4,5,6,7][1][2][3][4][5][6][7]. The MIR ultrashort pulsed lasers can be widely used in gas detection [7,8][7][8], cancer diagnosis [9,10,11][9][10][11], pollutant monitoring [12[12][13][14][15][16],13,14,15,16], food quality control [17[17][18][19][20][21][22][23],18,19,20,21,22,23], and other aspects [24[24][25][26][27][28],25,26,27,28], since they own much broader spectral ranges than ultrafast lasers in visible and near-infrared region. In addition, they also play essential roles in strong-field physics [29[29][30][31][32][33][34],30,31,32,33,34], laser surgery [35,36[35][36][37][38][39][40][41],37,38,39,40,41], attosecond science [42[42][43],43], and molecule dynamics [44,45,46][44][45][46] (as shown in Figure 1b), as they feature the ultrashort time domain and have the potential to achieve peak powers. Therefore, there is an essential and broad application value in MIR ultrashort pulse generation research.
Figure 1.
a) Absorption spectra of gas molecules in the MIR region. Reprinted with permission from Ref. [7]. 2019, MDPI. (
) Absorption spectra of gas molecules in the MIR region. (
) Application fields of ultrafast MIR sources.

2. Methods for Mid-Infrared Ultrashort Pulse Generation Technology

MIR application is driven by the development of laser technology in related wavelengths. For example, the emergence of MIR laser frequency combs has facilitated the research process of highly sensitive (up to the order of several parts per billion (ppb)) molecular spectroscopy detection techniques [2]. Therefore, the timely promotion of the research on MIR coherent light sources is crucial to the development of science, technology, national defense, industry, medicine, and other applications. In the last decade, continuous breakthroughs and improvements have been made in the performance of MIR laser technology with regard to power, efficiency, wavelength range, time/frequency domain, beam quality, and stability [1,2,3,4,5][1][2][3][4][5]. The designs of the lasers have become increasingly compact, practical, portable, and miniature. However, due to the lack of suitable gain materials, the output of conventional solid-state lasers and fiber lasers cannot cover most of the MIR region, especially the long-wavelength MIR band of 8–20 µm. The application and development of spectroscopy in this band have been limited by the low laser power, narrow tunable wavelength range, and unstable operation [1,2,3,4,5][1][2][3][4][5]. At present, the main technologies for long-wavelength MIR laser generation include stimulated radiation methods (e.g., free-electron lasers, lead-salt semiconductor lasers, and quantum cascade lasers (QCLs)), and the nonlinear frequency conversion methods. Free-electron lasers are large, expensive, and usually used for X-ray pulse generation [47,48][47][48]. Lead-salt semiconductor lasers have low output power (about 0.1 mW), and require low-temperature cooling to achieve regular state operation, which are exceptionally sensitive to changes in temperature [8]. Due to the limited wavelength-tunable ranges of QCLs, it is usually required to use several QCLs with different working wavelengths, which is inconvenient and has high costs. Furthermore, mode-locking is hard to be realized in QCLs due to their picosecond-level gain recovery time. The picosecond-level laser pulse at 8 µm was only recently, in 2020, achieved in QCLs [49], and femtosecond pulses around 8 µm were generated via spectral filtering, gain modulation-induced spectral broadening, and external pulse compression in 2021 [50].
The nonlinear frequency conversion methods, including optical parametric oscillation (OPO), optical parametric amplification (OPA), difference frequency generation (DFG), and supercontinuum generation (SCG), have become the primary techniques to build up MIR ultrafast lasers above 8 µm. The principles of OPO, OPA, and DFG are shown in Figure 2 [51]. The OPO setup consists of a nonlinear crystal and a resonant cavity, which allows the signal or idler light or both of them to oscillate in the cavity to obtain the desired wavelength. In nonlinear crystals, the pump, signal and idler lights are overlapped, and the interaction between them leads to the corresponding gain obtained by the signal and idler light. The physical processes of DFG and OPA are basically the same and both require two beams of light (pump and signal lights) to interact in the nonlinear crystal. OPA aims to amplify the original signal light or to obtain high-energy idler light, while DFG aims to obtain high-average-power idler light. DFG is suitable for both continuous-wave and pulsed operation, while OPA is only suitable for pulsed operation. In addition, the signal light in the general OPA process is very weak compared to the pump light in power, while the signal light in the DFG process is stronger.
Figure 2. The principle of (a) OPO, (b) DFG, and (c) OPA. Reprinted by permission from Springer Nature Customer Service Centre GmbH: Springer Nature, A new generation of high-powerwaveform controlledfew-cycle light sources, by Seidel, M., COPYRIGHT 2019. T The OPO setup consists of a nonlinear crystal and a resonant cavity, allowing the signal or idler light or both of them to oscillate in the cavity to obtain the desired wavelength. The physical processes of DFG and OPA are basically the same and both require two beams of light (pump and signal lights) to interact in the nonlinear crystal [51].
SCG is another effective nonlinear frequency conversion method for MIR generation. A supercontinuum is mainly generated from high-nonlinearity fibers, waveguides, or bulk crystals. In SCG, several nonlinear physical processes usually work together, such as self-phase/cross-phase modulation (SPM/XPM), parametric four-wave mixing, Raman scattering, soliton generation, soliton fission, soliton self-frequency shift, dispersive wave, and so on [5]. The current commercial product has already been available in the 2–5 µm of the MIR region [52]. However, the spanning range of supercontinuum greatly depends on the nonlinear material especially for MIR wavelengths longer than 5 µm or even 8 µm. Silicate glass is one of the most common and typical materials for SCG shorter than 2.5 µm. ZrF4-BaF2-LaF3-AlF3-NaF (ZBLAN) glass can extend the SCG wavelength to 10 µm. Chalcogenide glass, such as sulfur (S), selenium (Se), and tellurium (Te), is considered to be the most potential material for longer wavelength MIR generation [5,52,53][5][52][53].
The main drawback of OPO is the additional complexity brought by the resonant cavity and the relatively limited oscillation spectral range. It usually works in the region of 3–5 µm. Recent efforts show that the OPO-based MIR source could span over 8 µm by employing nonlinear crystals such as orientation-patterned gallium phosphide (OP-GaP) and silver gallium sulfide (AGS), owing to their long-wavelength transparency [54,55,56][54][55][56]. OPA usually works at a low repetition rate (from one to several hundreds of kHz level) but with high pulse energy (from one to several hundreds of μJ level), aiming to pursue high peak power or pulse energy in the MIR region [57,58,59,60,61,62,63,64,65,66,67,68,69,70,71][57][58][59][60][61][62][63][64][65][66][67][68][69][70][71]. However, there is still not much work regarding OPA working under an MHz repetition rate of over 10 μm because of the thermal effects. Many research efforts have shown that wavelengths generated by SCG could span over 8 µm or even 10 µm with the power of tens of milliwatts under well-engineered material structure [72,73,74,75,76,77,78,79,80,81,82,83,84,85,86,87,88,89,90,91,92,93,94][72][73][74][75][76][77][78][79][80][81][82][83][84][85][86][87][88][89][90][91][92][93][94]. However, long-wavelength (ranging from 2 to 9 µm) femtosecond pump sources with relatively high power (at least hundreds of milliwatts) and high-nonlinearity material are necessary for long-wavelength MIR generation by SCG, regardless of the pumping scheme (direct pumping or cascaded pumping). This makes the whole process more complicated since all the components mentioned above are not commercially available.
Nowadays, DFG is one of the most important techniques to achieve high average power MIR with a high repetition rate and has become an effective tool to generate optical frequency combs [51]. When the repetition rate is locked, the pump and signal pulse sequences come from the same oscillator and share the same carrier-envelope offset (CEO). This offset is automatically eliminated during the DFG process, resulting in a stable optical frequency comb. DFG has not only been applied to MIR but also to THz generation as the two wavelengths participating in the process are controllable. Thus, there is no doubt that DFG is still the mainstream method for generating MIR pulses. 


  1. Ebrahim-Zadeh, M.; Sorokina, I.T. Mid-Infrared Coherent Sources and Applications: Preface; Springer Science & Business Media: Berlin/Heidelberg, Germany, 2008; ISBN 9781402064395.
  2. Schliesser, A.; Picqué, N.; Hänsch, T.W. Mid-infrared frequency combs. Nat. Photonics 2012, 6, 440–449.
  3. Pires, H.; Baudisch, M.; Sanchez, D.; Hemmer, M.; Biegert, J. Ultrashort pulse generation in the mid-IR. Prog. Quantum Electron. 2015, 43, 1–30.
  4. Petrov, V. Frequency down-conversion of solid-state laser sources to the mid-infrared spectral range using non-oxide nonlinear crystals. Prog. Quantum Electron. 2015, 42, 1–106.
  5. Vodopyanov, K.L. Laser-Based Mid-Infrared Sources and Applications; John Wiley & Sons: Hoboken, NJ, USA, 2020.
  6. Haas, J.; Mizaikoff, B. Advances in Mid-Infrared Spectroscopy for Chemical Analysis. Annu. Rev. Anal. Chem. 2016, 9, 45–68.
  7. Popa, D.; Udrea, F. Towards integrated mid-infrared gas sensors. Sensors 2019, 19, 2076.
  8. Du, Z.; Zhang, S.; Li, J.; Gao, N.; Tong, K. Mid-infrared tunable laser-based broadband fingerprint absorption spectroscopy for trace gas sensing: A review. Appl. Sci. 2019, 9, 338.
  9. Seddon, A.B. Mid-infrared (IR)—A hot topic: The potential for using mid-IR light for non-invasive early detection of skin cancer in vivo. Phys. Status Solidi Basic Res. 2013, 250, 1020–1027.
  10. Tseng, Y.-P.; Bouzy, P.; Pedersen, C.; Stone, N.; Tidemand-Lichtenberg, P. Upconversion raster scanning microscope for long-wavelength infrared imaging of breast cancer microcalcifications. Biomed. Opt. Express 2018, 9, 4979–4987.
  11. Ma, P.; Li, J.; Chen, Y.; Zhou Montano, B.A.; Luo, H.; Zhang, D.; Zheng, H.; Liu, Y.; Lin, H.; Zhu, W.; et al. Non-invasive exhaled breath diagnostic and monitoring technologies. Microw. Opt. Technol. Lett. 2021, 1–14.
  12. Pejcic, B.; Myers, M.; Ross, A. Mid-infrared sensing of organic pollutants in aqueous environments. Sensors 2009, 9, 6232–6253.
  13. Siciliani de Cumis, M.; Viciani, S.; Borri, S.; Patimisco, P.; Sampaolo, A.; Scamarcio, G.; De Natale, P.; D’Amato, F.; Spagnolo, V. Widely-tunable mid-infrared fiber-coupled quartz-enhanced photoacoustic sensor for environmental monitoring. Opt. Express 2014, 22, 28222–28231.
  14. Baudet, E.; Gutierrez-Arroyo, A.; Němec, P.; Bodiou, L.; Lemaitre, J.; De Sagazan, O.; Lhermitte, H.; Rinnert, E.; Michel, K.; Bureau, B.; et al. Selenide sputtered films development for MIR environmental sensor. Opt. Mater. Express 2016, 6, 2616–2627.
  15. Dong, X.; Jochmann, M.A.; Elsner, M.; Meyer, A.H.; Bäcker, L.E.; Rahmatullah, M.; Schunk, D.; Lens, G.; Meckenstock, R.U. Monitoring Microbial Mineralization Using Reverse Stable Isotope Labeling Analysis by Mid-Infrared Laser Spectroscopy. Environ. Sci. Technol. 2017, 51, 11876–11883.
  16. Schulte, S.M.; Köster, D.; Jochmann, M.A.; Meckenstock, R.U. Applying reverse stable isotope labeling analysis by mid-infrared laser spectroscopy to monitor BDOC in recycled wastewater. Sci. Total Environ. 2019, 665, 1064–1072.
  17. Wang, T.; Rodriguez-Saona, L.E. Rapid Determination of Sugar Level in Snack Products Using Infrared Spectroscopy. J. Food Sci. 2012, 77, C874–C879.
  18. Maurice-Van Eijndhoven, M.H.T.; Soyeurt, H.; Dehareng, F.; Calus, M.P.L. Validation of fatty acid predictions in milk using mid-infrared spectrometry across cattle breeds. Animal 2013, 7, 348–354.
  19. Li, X.; Huo, G.; Wang, Y.; Sun, H.; Kong, Q. Research on rapid detection method of protein and fat in raw milk based on mid-infrared spectrum. Int. J. Multimed. Ubiquitous Eng. 2016, 11, 131–142.
  20. Ferreira, D.S.; Galão, O.F.; Pallone, J.A.L.; Poppi, R.J. Comparison and application of near-infrared (NIR) and mid-infrared (MIR) spectroscopy for determination of quality parameters in soybean samples. Food Control 2014, 35, 227–232.
  21. Cocchi, M.; Foca, G.; Lucisano, M.; Marchetti, A.; Pagani, M.A.; Tassi, L.; Ulrici, A. Classification of Cereal Flours by Chemometric Analysis of MIR Spectra. J. Agric. Food Chem. 2004, 52, 1062–1067.
  22. López-Lorente, Á.I.; Mizaikoff, B. Mid-infrared spectroscopy for protein analysis: Potential and challenges. Anal. Bioanal. Chem. 2016, 408, 2875–2889.
  23. Dabrowska, A.; David, M.; Freitag, S.; Andrews, A.M.; Strasser, G.; Hinkov, B.; Schwaighofer, A.; Lendl, B. Broadband laser-based mid-infrared spectroscopy employing a quantum cascade detector for milk protein analysis. Sens. Actuators B Chem. 2022, 350, 130873.
  24. Borri, S.; Santambrogio, G. Laser spectroscopy of cold molecules. Adv. Phys. X 2016, 1, 368–386.
  25. Kowligy, A.S.; Timmers, H.; Lind, A.J.; Elu, U.; Cruz, F.C.; Schunemann, P.G.; Biegert, J.; Diddams, S.A. Infrared electric field sampled frequency comb spectroscopy. Sci. Adv. 2019, 5, 36–38.
  26. Etezadi, D.; Warner, J.B.; Ruggeri, F.S.; Dietler, G.; Lashuel, H.A.; Altug, H. Nanoplasmonic mid-infrared biosensor for in vitro protein secondary structure detection. Light Sci. Appl. 2017, 6, e17029.
  27. Rodrigo, D.; Limaj, O.; Janner, D.; Etezadi, D.; García De Abajo, F.J.; Pruneri, V.; Altug, H. Mid-infrared plasmonic biosensing with graphene. Science 2015, 349, 165–168.
  28. Akin, B.; Linford, M.R.; Ahmadivand, A.; Altindal, S. All-Dielectric Fabry–Pérot Cavity Design for Spectrally Selective Mid-Infrared Absorption. Phys. Status Solidi Basic Res. 2021, 2100464, 1–7.
  29. Sheehy, B.; Martin, J.D.D.; Di Mauro, L.F.; Agostini, P.; Schafer, K.J.; Gaarde, M.B.; Kulander, K.C. High harmonic generation at long wavelengths. Phys. Rev. Lett. 1999, 83, 5270–5273.
  30. Günter, G.; Anappara, A.A.; Hees, J.; Sell, A.; Biasiol, G.; Sorba, L.; De Liberato, S.; Ciuti, C.; Tredicucci, A.; Leitenstorfer, A.; et al. Sub-cycle switch-on of ultrastrong light-matter interaction. Nature 2009, 458, 178–181.
  31. Dura, J.; Camus, N.; Thai, A.; Britz, A.; Hemmer, M.; Baudisch, M.; Senftleben, A.; Schröter, C.D.; Ullrich, J.; Moshammer, R.; et al. Ionization with low-frequency fields in the tunneling regime. Sci. Rep. 2013, 3, 2675.
  32. Wolter, B.; Pullen, M.G.; Baudisch, M.; Sclafani, M.; Hemmer, M.; Senftleben, A.; Schröter, C.D.; Ullrich, J.; Moshammer, R.; Biegert, J. Strong-field physics with Mid-IR fields. Phys. Rev. X 2015, 5, 021034.
  33. Panagiotopoulos, P.; Whalen, P.; Kolesik, M.; Moloney, J.V. Super high power mid-infrared femtosecond light bullet. Nat. Photonics 2015, 9, 543–548.
  34. Woodbury, D.; Feder, L.; Shumakova, V.; Gollner, C.; Miao, B.; Schwartz, R.; Pugžlys, A.; Baltuška, A.; Milchberg, H.M. Laser wakefield acceleration with mid-IR laser pulses. Opt. InfoBase Conf. Pap. 2017, 43, 1131–1134.
  35. Xiao, Y.; Guo, M.; Parker, K.; Hutson, M.S. Wavelength-dependent collagen fragmentation during Mid-IR laser ablation. Biophys. J. 2006, 91, 1424–1432.
  36. Zavalin, A.; Hachey, D.L.; Sundaramoorthy, M.; Banerjee, S.; Morgan, S.; Feldman, L.; Tolk, N.; Piston, D.W. Kinetics of a collagen-like polypeptide fragmentation after mid-IR free-electron laser ablation. Biophys. J. 2008, 95, 1371–1381.
  37. Edwards, G.S. Mechanisms for soft-tissue ablation and the development of alternative medical lasers based on investigations with mid-infrared free-electron lasers. Laser Photonics Rev. 2009, 3, 545–555.
  38. Serebryakov, V.S.; Bo, É.V.; Kalintsev, A.G.; Kornev, A.F.; Narivonchik, A.S. Mid-IR laser for high-precision surgery. J. Opt. Technol. 2015, 82, 781–788.
  39. Serebryakov, V.A.; Narivonchik, A.S.; Kalintseva, N.A.; Skvortsov, D.V.; Doroganov, S.V. Repetitively-pulsed mid-IR laser for precise microsurgery. Proc.-Int. Conf. Laser Opt. 2018, 788, 479.
  40. Toor, F.; Jackson, S.; Shang, X.; Arafin, S.; Yang, H. Mid-infrared Lasers for Medical Applications: Introduction to the feature issue. Biomed. Opt. Express 2018, 9, 6255–6257.
  41. Larson, E.; Hines, M.; Tanas, M.; Miller, B.; Coleman, M.; Toor, F. Mid-infrared absorption by soft tissue sarcoma and cell ablation utilizing a mid-infrared interband cascade laser. J. Biomed. Opt. 2021, 26, 043012.
  42. Popmintchev, T.; Chen, M.C.; Popmintchev, D.; Arpin, P.; Brown, S.; Ališauskas, S.; Andriukaitis, G.; Balčiunas, T.; Mücke, O.D.; Pugzlys, A.; et al. Bright coherent ultrahigh harmonics in the kev x-ray regime from mid-infrared femtosecond lasers. Science 2012, 336, 1287–1291.
  43. Chini, M.; Zhao, K.; Chang, Z. The generation, characterization and applications of broadband isolated attosecond pulses. Nat. Photonics 2014, 8, 178–186.
  44. Wagner, M.; Fei, Z.; McLeod, A.S.; Rodin, A.S.; Bao, W.; Iwinski, E.G.; Zhao, Z.; Goldflam, M.; Liu, M.; Dominguez, G.; et al. Ultrafast and nanoscale plasmonic phenomena in exfoliated graphene revealed by infrared pump-probe nanoscopy. Nano Lett. 2014, 14, 894–900.
  45. Weichman, M.L.; Changala, P.B.; Ye, J.; Chen, Z.; Yan, M.; Picqué, N. Broadband molecular spectroscopy with optical frequency combs. J. Mol. Spectrosc. 2019, 355, 66–78.
  46. Aerts, A.; Kockaert, P.; Gorza, S.-P.; Brown, A.; Vander Auwera, J.; Vaeck, N. Laser control of a dark vibrational state of acetylene in the gas phase—Fourier transform pulse shaping constraints and effects of decoherence. J. Chem. Phys. 2022, 156, 084302.
  47. Shea, P.G.O.; Freund, H.P. Free-Electron Lasers: Status and Applications. Science 2001, 292, 1853–1859.
  48. Barletta, W.A.; Bisognano, J.; Corlett, J.N.; Emma, P.; Huang, Z.; Kim, K.J.; Lindberg, R.; Murphy, J.B.; Neil, G.R.; Nguyen, D.C.; et al. Free electron lasers: Present status and future challenges. Nucl. Instrum. Methods Phys. Res. Sect. A Accel. Spectrometers Detect. Assoc. Equip. 2010, 618, 69–96.
  49. Hillbrand, J.; Opačak, N.; Piccardo, M.; Schneider, H.; Strasser, G.; Capasso, F.; Schwarz, B. Mode-locked short pulses from an 8 μm wavelength semiconductor laser. Nat. Commun. 2020, 11, 5788.
  50. Täschler, P.; Bertrand, M.; Schneider, B.; Singleton, M.; Jouy, P.; Kapsalidis, F.; Beck, M.; Faist, J. Femtosecond pulses from a mid-infrared quantum cascade laser. Nat. Photonics 2021, 15, 919–924.
  51. Seidel, M. A New Generation of High-Power, Waveform Controlled, Few-Cycle Light Sources; Springer: Berlin/Heidelberg, Germany, 2019.
  52. Sylvestre, T.; Genier, E.; Ghosh, A.N.; Bowen, P.; Genty, G.; Troles, J.; Mussot, A.; Peacock, A.C.; Klimczak, M.; Heidt, A.M.; et al. Recent advances in supercontinuum generation in specialty optical fibers . J. Opt. Soc. Am. B 2021, 38, F90–F103.
  53. Saini, T.S.; Sinha, R.K. Mid-infrared supercontinuum generation in soft-glass specialty optical fibers: A review. Prog. Quantum Electron. 2021, 78, 100342.
  54. Maidment, L.; Schunemann, P.G.; Reid, D.T. Molecular fingerprint-region spectroscopy from 5 to 12 μm using an orientation-patterned gallium phosphide optical parametric oscillator. Opt. Lett. 2016, 41, 4261–4264.
  55. Iwakuni, K.; Porat, G.; Bui, T.Q.; Bjork, B.J.; Schoun, S.B.; Heckl, O.H.; Fermann, M.E.; Ye, J. Phase-stabilized 100 mW frequency comb near 10 μm. Appl. Phys. B Lasers Opt. 2018, 124, 128.
  56. Maidment, L.; Kara, O.; Schunemann, P.G.; Piper, J.; McEwan, K.; Reid, D.T. Long-wave infrared generation from femtosecond and picosecond optical parametric oscillators based on orientation-patterned gallium phosphide. Appl. Phys. B Lasers Opt. 2018, 124, 143.
  57. Junginger, F.; Sell, A.; Schubert, O.; Mayer, B.; Brida, D.; Marangoni, M.; Cerullo, G.; Leitenstorfer, A.; Huber, R. Single-cycle multiterahertz transients with peak fields above 10 MV/cm. Opt. Lett. 2010, 35, 2645–2647.
  58. Krauth, J.; Steinmann, A.; Hegenbarth, R.; Conforti, M.; Giessen, H. Broadly tunable femtosecond near- and mid-IR source by direct pumping of an OPA with a 417 MHz Yb:KGW oscillator. Opt. Express 2013, 21, 11516–11522.
  59. Namboodiri, M.; Golz, T.; Bus, J.H.; Schulz, M.; Riedel, R.; Laarmann, T.; Prandolini, M.J. Review of thermal parameters of Li-based nonlinear crystals for high power 8 µm sources. In Proceedings of the Conference on Lasers and Electro-Optics Science and Innovations 2021, San Jose, CA, USA, 9–14 May 2021; pp. 8–9.
  60. Heiner, Z.; Petrov, V.; Panyutin, V.L.; Badikov, V.V.; Kato, K.; Miyata, K.; Mero, M. Efficient generation of few-cycle pulses beyond 10 μm from an optical parametric amplifier pumped by a 1-µm laser system. Sci. Rep. 2022, 12, 5082.
  61. Sanchez, D.; Hemmer, M.; Baudisch, M.; Cousin, S.L.; Zawilski, K.; Schunemann, P.; Chalus, O.; Simon-Boisson, C.; Biegert, J. 7 μm, ultrafast, sub-millijoule-level mid-infrared optical parametric chirped pulse amplifier pumped at 2 μm. Optica 2016, 3, 147–150.
  62. Qu, S.; Liang, H.; Liu, K.; Zou, X.; Li, W.; Wang, Q.J.; Zhang, Y. 9 μm few-cycle optical parametric chirped-pulse amplifier based on LiGaS2. Opt. Lett. 2019, 44, 2422–2425.
  63. Elu, U.; Steinle, T.; Sánchez, D.; Maidment, L.; Zawilski, K.; Schunemann, P.; Zeitner, U.D.; Simon-Boisson, C.; Biegert, J. Table-top high-energy 7 μm OPCPA and 260 mJ Ho:YLF pump laser. Opt. Lett. 2019, 44, 3194–3197.
  64. Liang, H.; Krogen, P.; Wang, Z.; Park, H.; Kroh, T.; Zawilski, K.; Schunemann, P.; Moses, J.; Dimauro, L.F.; Kärtner, F.X.; et al. High-energy mid-infrared sub-cycle pulse synthesis from a parametric amplifier. Nat. Commun. 2017, 8, 141.
  65. Seidel, M.; Xiao, X.; Hussain, S.A.; Arisholm, G.; Hartung, A.; Zawilski, K.T.; Schunemann, P.G.; Habel, F.; Trubetskov, M.; Pervak, V.; et al. Multi-watt, multi-octave, mid-infrared femtosecond source. Sci. Adv. 2018, 4, eaaq1526.
  66. Penwell, S.B.; Whaley-Mayda, L.; Tokmakoff, A. Single-stage MHz mid-IR OPA using LiGaS2 and a fiber laser pump source. Opt. Lett. 2018, 43, 1363–1366.
  67. Liu, K.; Liang, H.; Wang, L.; Qu, S.; Lang, T.; Li, H.; Wang, Q.J.; Zhang, Y. Multimicrojoule GaSe-based midinfrared optical parametric amplifier with an ultrabroad idler spectrum covering 4.2–16 μm. Opt. Lett. 2019, 44, 1003–1006.
  68. Jakob, M.A.; Namboodiri, M.; Prandolini, M.J.; Laarmann, T. Generation and characterization of tailored MIR waveforms for steering molecular dynamics. Opt. Express 2019, 27, 26979–26987.
  69. Chen, B.-H.; Wittmann, E.; Morimoto, Y.; Baum, P.; Riedle, E. Octave-spanning single-cycle middle-infrared generation through optical parametric amplification in LiGaS2. Opt. Express 2019, 27, 21306–21316.
  70. Heiner, Z.; Petrov, V.; Mero, M. Efficient, sub-4-cycle, 1-µm-pumped optical parametric amplifier at 10 µm based on BaGa4S7. Opt. Lett. 2020, 45, 5692–5695.
  71. Budriūnas, R.; Jurkus, K.; Varanavičius, A. Yb-laser-based sub-60 fs mid-infrared source tunable from 2.5 μm to 10 μm. Opt. InfoBase Conf. Pap. 2021, 202, 10233.
  72. Petersen, C.R.; Møller, U.; Kubat, I.; Zhou, B.; Dupont, S.; Ramsay, J.; Benson, T.; Sujecki, S.; Abdel-Moneim, N.; Tang, Z.; et al. Mid-infrared supercontinuum covering the 1.4–13.3 μm molecular fingerprint region using ultra-high NA chalcogenide step-index fibre. Nat. Photonics 2014, 8, 830–834.
  73. Yu, Y.; Zhang, B.; Gai, X.; Zhai, C.; Qi, S.; Guo, W.; Yang, Z.; Wang, R.; Choi, D.-Y.; Madden, S.; et al. 1.8–10 μm Mid-Infrared Supercontinuum Generated in a Step-Index Chalcogenide Fiber Using Low Peak Pump Power. Opt. Lett. 2015, 40, 1081–1084.
  74. Guo, K.; Martinez, R.A.; Plant, G.; Maksymiuk, L.; Janiszewski, B.; Freeman, M.J.; Maynard, R.L.; Islam, M.N.; Terry, F.L.; Bedford, R.; et al. Generation of near-diffraction-limited, high-power supercontinuum from 1.57 μm to 12 μm with cascaded fluoride and chalcogenide fibers. Appl. Opt. 2018, 57, 2519–2532.
  75. Martinez, R.A.; Plant, G.; Guo, K.; Janiszewski, B.; Freeman, M.J.; Maynard, R.L.; Islam, M.N.; Terry, F.L.; Alvarez, O.; Chenard, F.; et al. Mid-infrared supercontinuum generation from 1.6 to >11 μm using concatenated step-index fluoride and chalcogenide fibers. Opt. Lett. 2018, 43, 296–299.
  76. Wu, Z.; Yang, L.; Xu, Y.; Zhang, P.; Nie, Q.; Wang, X. 1.8–13 μm supercontinuum generation by pumping at normal dispersion regime of As–Se–Te glass fiber. J. Am. Ceram. Soc. 2019, 102, 5025–5032.
  77. Butler, T.P.; Lilienfein, N.; Xu, J.; Nagl, N.; Hofer, C.; Gerz, D.; Mak, K.F.; Gaida, C.; Heuermann, T.; Gebhardt, M.; et al. Multi-octave spanning, Watt-level ultrafast mid-infrared source. J. Phys. Photonics 2019, 1, 044006.
  78. Li, G.; Peng, X.; Dai, S.; Wang, Y.; Xie, M.; Yang, L.; Yang, C.; Wei, W.; Zhang, P. Highly coherent 1.5–8.3 μm broadband supercontinuum generation in tapered As—S chalcogenide fibers. J. Lightwave Technol. 2019, 37, 1847–1852.
  79. Lemière, A.; Désévédavy, F.; Mathey, P.; Froidevaux, P.; Gadret, G.; Jules, J.-C.; Aquilina, C.; Kibler, B.; Béjot, P.; Billard, F.; et al. Mid-infrared supercontinuum generation from 2 to 14 μm in arsenic- and antimony-free chalcogenide glass fibers. J. Opt. Soc. Am. B 2019, 36, A183–A192.
  80. Jiao, K.; Yao, J.; Wang, X.; Wang, X.; Zhao, Z.; Zhang, B.; Si, N.; Liu, J.; Shen, X.; Zhang, P.; et al. 1.2–15.2 μm Supercontinuum Generation in a Low-Loss Chalcohalide Fiber Pumped At a Deep Anomalous-Dispersion Region. Opt. Lett. 2019, 44, 5545–5548.
  81. Jiao, K.; Yao, J.; Zhao, Z.; Wang, X.; Si, N.; Wang, X.; Chen, P.; Xue, Z.; Tian, Y.; Zhang, B.; et al. Mid-infrared flattened supercontinuum generation in all-normal dispersion tellurium chalcogenide fiber. Opt. Express 2019, 27, 2036–2043.
  82. Montesinos-Ballester, M.; Lafforgue, C.; Frigerio, J.; Ballabio, A.; Vakarin, V.; Liu, Q.; Ramirez, J.M.; Roux, X.L.; Bouville, D.; Barzaghi, A.; et al. On-Chip Mid-Infrared Supercontinuum Generation from 3 to 13 μm Wavelength. ACS Photonics 2020, 7, 3423–3429.
  83. Qu, S.; Chaudhary Nagar, G.; Li, W.; Liu, K.; Zou, X.; Hon Luen, S.; Dempsey, D.; Hong, K.-H.; Jie Wang, Q.; Zhang, Y.; et al. Long-wavelength-infrared laser filamentation in solids in the near-single-cycle regime. Opt. Lett. 2020, 45, 2175–2178.
  84. Zhang, B.; Yu, Y.; Zhai, C.; Qi, S.; Wang, Y.; Yang, A.; Gai, X.; Wang, R.; Yang, Z.; Luther-Davies, B.; et al. High Brightness 2.2–12 μm Mid-Infrared Supercontinuum Generation in a Nontoxic Chalcogenide Step-Index Fiber. J. Am. Ceram. Soc. 2016, 99, 2565–2568.
  85. Venck, S.; St-Hilaire, F.; Brilland, L.; Ghosh, A.N.; Chahal, R.; Caillaud, C.; Meneghetti, M.; Troles, J.; Joulain, F.; Cozic, S.; et al. 2–10 µm Mid-Infrared Fiber-Based Supercontinuum Laser Source: Experiment and Simulation. Laser Photonics Rev. 2020, 14, 2000011.
  86. Lemière, A.; Bizot, R.; Désévédavy, F.; Gadret, G.; Jules, J.C.; Mathey, P.; Aquilina, C.; Béjot, P.; Billard, F.; Faucher, O.; et al. 1.7–18 µm mid-infrared supercontinuum generation in a dispersion-engineered step-index chalcogenide fiber. Results Phys. 2021, 26, 104397.
  87. Woyessa, G.; Kwarkye, K.; Dasa, M.K.; Petersen, C.R.; Sidharthan, R.; Chen, S.; Yoo, S.; Bang, O. Power stable 1.5–10.5 µm cascaded mid-infrared supercontinuum laser without thulium amplifier. Opt. Lett. 2021, 46, 1129–1132.
  88. Yu, Y.; Gai, X.; Ma, P.; Vu, K.; Yang, Z.; Wang, R.; Choi, D.-Y.; Madden, S.; Luther-Davies, B. Experimental demonstration of linearly polarized 2–10 μm supercontinuum generation in a chalcogenide rib waveguide. Opt. Lett. 2016, 41, 958–961.
  89. Cheng, T.; Nagasaka, K.; Tuan, T.H.; Xue, X.; Matsumoto, M.; Tezuka, H.; Suzuki, T.; Ohishi, Y. Mid-infrared supercontinuum generation spanning 2.0 to 15.1 μm in a chalcogenide step-index fiber. Opt. Lett. 2016, 41, 2117–2120.
  90. Zhao, Z.; Wang, X.; Dai, S.; Pan, Z.; Liu, S.; Sun, L.; Zhang, P.; Liu, Z.; Nie, Q.; Shen, X.; et al. 1.5–14 μm midinfrared supercontinuum generation in a low-loss Te-based chalcogenide step-index fiber. Opt. Lett. 2016, 41, 5222–5225.
  91. Zhao, Z.; Wu, B.; Wang, X.; Pan, Z.; Liu, Z.; Zhang, P.; Shen, X.; Nie, Q.; Dai, S.; Wang, R. Mid-infrared supercontinuum covering 2.0–16 μm in a low-loss telluride single-mode fiber. Laser Photonics Rev. 2017, 11, 2–6.
  92. Stingel, A.M.; Vanselous, H.; Petersen, P.B. Covering the vibrational spectrum with microjoule mid-infrared supercontinuum pulses in nonlinear optical applications. J. Opt. Soc. Am. B 2017, 34, 1163–1169.
  93. Hudson, D.D.; Antipov, S.; Li, L.; Alamgir, I.; Hu, T.; Amraoui, M.E.; Messaddeq, Y.; Rochette, M.; Jackson, S.D.; Fuerbach, A. Toward all-fiber supercontinuum spanning the mid-infrared. Optica 2017, 4, 1163–1166.
  94. Wang, Y.; Dai, S.; Han, X.; Zhang, P.; Liu, Y.; Wang, X.; Sun, S. Broadband mid-infrared supercontinuum generation in novel As2Se3-As2Se2S step-index fibers. Opt. Commun. 2018, 410, 410–415.