[1] Köhler R, Tredicucci A, Beltram F et al. Terahertz semiconductor-heterostructure laser[J]. Nature, 417, 156-159(2002).

[2] Chan W L, Deibel J, Mittleman D M et al. Imaging with terahertz radiation[J]. Rep. Progr. Phys, 70, 1325-1379(2007).

[3] Kim S M, Hatami F, Harris, J S et al. Biomedical terahertz imaging with a quantum cascade laser[J]. Appl. Phys. Lett, 88, 81-83(2006).

[4] Nguyen K L, Johns M L, Gladden L F et al. Three-dimensional imaging with a terahertz quantum cascade laser[J]. Opt. Express, 14, 2123-2129(2006).

[5] Lee Alan W M, Qin Q, Kumar S et al. Real-time terahertz imaging over a standoff distance (>25meters)[J]. Appl. Phys. Lett, 89, 4-7(2006).

[6] Hu Q. Terahertz quantum cascade lasers and video-rate THz imaging[J]. IEEE Trans. Terahertz Sci. Technol, 2, 120-130(2009).

[7] Mittleman D M, Jacobsen R H, Neelamani R et al. Gas sensing using terahertz time-domain spectroscopy[J]. Appl. Phys. B Lasers Opt, 67, 379-390(1998).

[8] Federici J F, Schulkin B, Huang F et al. THz imaging and sensing for security applications—Explosives, weapons and drugs. Semicond[J]. Sci. Technol, 20, S266-S280(2005).

[9] Ren Y, Hovenier J N, Higgins R et al. High-resolution heterodyne spectroscopy using a tunable quantum cascade laser around3.5 THz[J]. Appl. Phys. Lett, 98, 231109(2011).

[10] Koenig S, Lopez-Diaz D, Antes J et al. Wireless sub-THz communication system with high data rate[J]. Nature Photon, 7, 977-981(2013).

[11] Kleine-Ostmann T, Nagatsuma T. A review on terahertz communications research[J]. Infrared. Millim. THz Waves, 32, 143-171(2011).

[12] Chen Z, Tan Z Y, Ha Y J et al. Wireless communication demonstration at4.1 THz using quantum cascade laser and quantum well photodetector[J]. Electron. Lett, 47, 1002-1004(2011).

[13] Ren Y, Hovenier J N, Higgins R et al. Terahertz heterodyne spectrometer using a quantum cascade laser[J]. Appl. Phys. Lett, 97, 10-13(2010).

[14] Kloosterman J L, Hayton D J, Ren Y et al. Hot electron bolometer heterodyne receiver with a4.7-THz quantum cascade laser as a local oscillator[J]. Appl. Phys. Lett, 102, 011123(2013).

[15] Hayton D J, Kloosterman J L, Ren Y et al. A 4.7 THz heterodyne receiver for a balloon borne telescope[C], 9153, 91531R(2014).

[16] Nguyen DT, Simoens F, Ouvrier-Buffet J L et al. Broadband THz Uncooled Antenna-Coupled Microbolometer Array—Electromagnetic Design, Simulations and Measurements[J]. IEEE Trans. Terahertz Sci. Technol, 2, 299-305(2012).

[17] Richter H, Wienold M, Schrottke L et al. 4.7-THz Local Oscillator for the GREAT Heterodyne Spectrometer on SOFIA[J]. IEEE Trans. Terahertz Sci. Technol, 5, 539-545(2015).

[18] Williams B S. Terahertz quantum-cascade lasers[J]. Nature Photon, 1, 517-525(2007).

[19] Faist J, Beck M, Aellen T et al. Quantum-cascade lasers based on a bound-to-continuum transition[J]. Appl. Phys. Lett, 78, 147-149(2001).

[20] Scalari G, Ajili L, Faist J et al. (λ Far-infrared87μm) bound-to-continuum quantum-cascade lasers operating up to 90 K[J]. Appl. Phys. Lett, 82, 3165-3167(2003).

[21] Xu B, Hu Q, Melloch M R. Electrically pumped tunable terahertz emitter based on intersubband transition[J]. Appl. Phys. Lett, 71, 440-442(1997).

[22] Williams B S, Xu B, Hu Q et al. Narrow-linewidth terahertz intersubband emission from three-level systems[J]. Appl. Phys. Lett, 75, 2927-2929(1999).

[23] Fathololoumi S, Dupont E, Chan C W I et al. Terahertz quantum cascade lasers operating up to similar to200K with optimized oscillator strength and improved injection tunneling[J]. Opt. Express, 20, 3866-3876(2012).

[24] Ali Khalatpour, Paulsen A K, Deimert C et al. High-power portable terahertz laser systems[J]. Nature Photon, 15, 16(2020).

[25] Williams B S, Kumar S, Hu Q et al. Operation of terahertz quantum-cascade lasers at164K in pulsed mode and at 117 K in continuous-wave mode[J]. Opt. Express, 13, 3331-3339(2005).

[26] Williams B S, Kumar S, Hu Q et al. High-power terahertz quantum cascade lasers[J]. Electron. Lett, 42, 89-91(2006).

[27] Scalari G, Hoyler N, Giovannini M et al. Terahertz bound-to-continuum quantum cascade lasers based on optical-phonon scattering extraction[J]. Appl. Phys. Lett, 86, 181101(2005).

[28] Kohen S, Williams B S, Hu Q. Electromagnetic modeling of terahertz quantum cascade laser waveguides and resonators[J]. Appl. Phys, 97, 053106(2005).

[29] Amanti M I, Fischer M, Scalari G et al. Low-divergence single-mode terahertz quantum cascade laser[J]. Nature Photon, 3, 586-590(2009).

[30] Ali Khalatpour, Reno J L, Kherani N P et al. Unidirectional photonic wire laser[J]. Nature Photon, 11, 555(2017).

[31] Ali Khalatpour, Reno J L, Hu Q et al. Phase-locked photonic wire lasers by π coupling[J]. Nature Photon, 13, 47(2019).

[32] Biasco S, Garrasi K, Castellano F et al. Continuous-wave highly-efficient low-divergence terahertz wire lasers[J]. Nat. Commun, 9, 1122(2018).

[33] Xu G Y, Colombelli R, Khanna S et al. Efficient power extraction in surface-emitting semiconductor lasers using graded photonic heterostructures[J]. Nat. Commun, 3, 952(2012).

[34] Xu G Y, Li L H, Isac N et al. Surface-emitting terahertz quantum cascade lasers with continuous-wave power in the tens of milliwatt range[J]. Appl. Phys. Lett, 104, 091112(2014).

[35] Wenzel H, Schwertfeger S, Klehr A et al. High peak power optical pulses generated with a monolithic master-oscillator power amplifier[J]. Opt. Lett, 37, 1826(2012).

[36] O’Brien, Welch D F, Parke R et al. Operating characteristics of a high-power monolithically integrated flared amplifier master oscillator power amplifier[J]. IEEE J. Quantum Electron, 29, 2052(1993).

[37] Troccoli M, Gmachl C, Capasso F et al. (λ≈ Mid-infrared7.4 μm) quantum cascade laser amplifier for high power single-mode emission and improved beam quality[J]. Appl. Phys. Lett, 80, 4103(2002).

[38] Rauter P, Menzel S, Goyal A K et al. Master-oscillator power-amplifier quantum cascade laser array[J]. Appl. Phys. Lett, 101, 261117(2012).

[39] Hinkov B, Beck M, Gini E et al. Quantum cascade laser in a master oscillator power amplifier configuration with Watt-level optical output power[J]. Opt. Express, 21, 19180(2013).

[40] Zhu H, Wang F F, Yan Q et al. Terahertz master-oscillator power-amplifier quantum cascade lasers[J]. Appl. Phys. Lett, 109, 231105(2016).

[41] Yu C R, Zhu H, Wang F F et al. Highly efficient power extraction in terahertz quantum cascade laser via a grating coupler[J]. Appl. Phys. Lett, 113, 121114(2018).

[42] Zhu H, Zhu H Q, Wang F F et al. Terahertz master-oscillator power-amplifier quantum cascade laser with a grating coupler of extremely low reflectivity[J]. Opt. Express, 26, 1942-1953(2018).

[43] Zhu H Q, Zhu H, Yu C R et al. Modeling and improving the output power of terahertz master-oscillator power-amplifier quantum cascade lasers[J]. Opt. Express, 28, 23239-23250(2020).

[44] Jin Y, Gao L, Chen J et al. High power surface emitting terahertz laser with hybrid second- and fourth-order Bragg gratings[J]. Nat. Cummon, 9, 1407(2018).

[45] Jin Y, Reno J L, Kumar S et al. Phase-locked terahertz plasmonic laser array with2W output power in a single spectral mode[J]. Optica, 7, 708-715(2020).

[46] Zhou R J, Ibarra-Escamilla B, Haus J W et al. Fiber laser generating switchable radially and azimuthally polarized beams with140mW output power at 1.6 μm wavelength[J]. Appl. Phys. Lett, 95, 191111(2009).

[47] Grady N K, Heyes J E, Chowdhury D R et al. Terahertz metamaterials for linear polarization conversion and anomalous refraction[J]. Science, 340, 1304-1307(2013).

[48] Cheng Y Z, Withayachumnankul W, Upadhyay A et al. Ultrabroadband reflective polarization convertor for terahertz waves[J]. Appl. Phys. Lett, 105, 181111(2014).

[49] Fan R H, Zhou Y, Ren X P et al. Freely tunable broadband polarization rotator for terahertz waves[J]. Adv. Mater, 27, 1201-1206(2015).

[50] Lin J, Mueller J P B, Wang Q et al. Polarization-controlled tunable directional coupling of surface plasmon polaritons[J]. Science, 340, 331-334(2013).

[51] Rauter P, Lin J, Genevet P et al. Electrically pumped semiconductor laser with monolithic control of circular polarization[J]. PNAS, 111, E5623-E5632(2014).

[52] Xu L Y, Chen D G, Curwen C A et al. Metasurface quantum-cascade laser with electrically switchable polarization[J]. Optica, 4, 468-475(2017).

[53] Liang G Z, Zeng Y Q, Hu X N et al. Monolithic Semiconductor Lasers with Dynamically Tunable Linear-to-Circular Polarization[J]. ACS Photonics, 4, 517-524(2017).

[54] Zhu H Q, Zhu H, Wang K et al. Terahertz master-oscillator power-amplifier quantum Cascade laser with controllable polarization[J]. Appl. Phys. Lett, 117, 021103(2020).

[55] Mahler L, Tredicucci A, Beltram F et al. Tuning a distributed feedback laser with a coupled microcavity[J]. Opt. Express, 18, 19185-19191(2010).

[56] Qin Q, Williams B S, Kumar S et al. Tuning a terahertz wire laser[J]. Nature Photon, 3, 732-737(2009).

[57] Curwen C A, Reno J L, Williams B S et al. Broadband continuous single-mode tuning of a short-cavity quantum-cascade VECSEL[J]. Nature Photon, 13, 855(2019).

[58] Mittal S, Waks E. Quantum cascade laser lives on the edge[J]. Nature, 578, 219-220(2020).

[59] Yang Y H, Yamagami Y, Yu X B et al. Terahertz topological photonics for on-chip communication[J]. Nature Photon, 14, 446(2020).

[60] Brandstetter M, Liertzer M, Deutsch C et al. Reversing the pump dependence of a laser at an exceptional point[J]. Nat. Commun, 5, 4034(2014).

[61] Yang Y, Burghoff D, Hayton D J et al. Terahertz multiheterodyne spectroscopy using laser frequency combs[J]. Optica, 3, 499-502(2016).

[62] Rosch M, Scalari G, Villares G et al. On-chip, self-detected terahertz dual-comb source[J]. Appl. Phys. Lett, 108, 171104(2016).

[63] Zhao Y R, Li Z P, Zhou K et al. Active Stabilization of Terahertz Semiconductor Dual-Comb Laser Sources Employing a Phase Locking Technique[J]. Laser Photonics Rev, 15, 2000498(2021).

[64] Li H, Yan M, Wan W J et al. Graphene-Coupled Terahertz Semiconductor Lasers for Enhanced Passive Frequency Comb Operation[J]. Adv. Sci, 6, 1900460(2019).

[65] Li H, Li Z P, Wan W J et al. Toward Compact and Real-Time Terahertz Dual-Comb Spectroscopy Employing a Self-Detection Scheme[J]. ACS Photonics, 7, 49-56(2020).