Abstract

A new temperature performance record of 199.5 K for terahertz quantum cascade lasers is achieved by optimizing the lasing transition oscillator strength of the resonant phonon based three-well design. The optimum oscillator strength of 0.58 was found to be larger than that of the previous record (0.41) by Kumar et al. [Appl. Phys. Lett. 94, 131105 (2009)]. The choice of tunneling barrier thicknesses was determined with a simplified density matrix model, which converged towards higher tunneling coupling strengths than previously explored and nearly perfect alignment of the states across the injection and extraction barriers at the design electric field. At 8 K, the device showed a threshold current density of 1 kA/cm2, with a peak output power of ∼ 38 mW, and lasing frequency blue-shifting from 2.6 THz to 2.85 THz with increasing bias. The wavelength blue-shifted to 3.22 THz closer to the maximum operating temperature of 199.5 K, which corresponds to ∼ 1.28ħω/κB. The voltage dependence of laser frequency is related to the Stark effect of two intersubband transitions and is compared with the simulated gain spectra obtained by a Monte Carlo approach.

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  1. R. Kohler, A. Tredicucci, F. Beltram, H. E. Beere, E. H. Linfield, A. G. Davies, D. Ritchie, R. C. Iotti, and F. Rossi, “Terahertz semiconductor-heterostructure laser,” Nature 417, 156–159 (2002).
    [CrossRef] [PubMed]
  2. B. S. Williams, S. Kumar, Q. Hu, and J. L. Reno, “Operation of terahertz quantum-cascade lasers at 164 K in pulsed mode and at 117 K in continuous-wave mode,” Opt. Express 13, 3331–3339 (2005).
    [CrossRef] [PubMed]
  3. H. Luo, S. R. Laframboise, Z. R. Wasilewski, and H. C. Liu, “Terahertz quantum cascade lasers based on a three-well active module,” Appl. Phys. Lett. 90, 041112 (2007).
    [CrossRef]
  4. M. A. Belkin, J. A. Fan, S. Hormoz, F. Capasso, S. P. Khanna, M. Lachab, A. G. Davies, and E. H. Linfield, “Terahertz quantum cascade lasers with copper metal-metal waveguides operating up to 178 K,” Opt. Express 16, 3242–3248 (2008).
    [CrossRef] [PubMed]
  5. S. Kumar, Q. Hu, and J. L. Reno, “186 K operation of terahertz quantum cascade lasers based on a diagonal design,” Appl. Phys. Lett. 94, 131105 (2009).
    [CrossRef]
  6. S. Kumar, C. W. I. Chan, Q. Hu, and J. L. Reno, “A 1.8-THz quantum cascade laser operating significantly above the temperature of ħω/κB,” Nat. Phys. 7, 166–171 (2011).
    [CrossRef]
  7. R. W. Adams, K. Vijayraghavan, Q. J. Wang, J. Fan, F. Capasso, S. P. Khanna, A. G. Davies, E. H. Linfield, and M. A. Belkin, “GaAs/Al0.15Ga0.85As terahertz quantum cascade lasers with double-phonon resonant depopulation operating up to 172 K,” Appl. Phys. Lett. 97, 131111 (2010).
    [CrossRef]
  8. S. Kumar, C. W. I. Chan, Q. Hu, and J. L. Reno, “Two-well terahertz quantum-cascade laser with direct intrawellphonon depopulation,” Appl. Phys. Lett. 95, 141110 (2009).
    [CrossRef]
  9. G. Scalari, M. I. Amanti, C. Walther, R. Terazzi, M. Beck, and J. Faist, “Broadband THz lasing from a photon-phonon quantum cascade structure,” Opt. Express 8, 8043–8052 (2010).
    [CrossRef]
  10. A. Wacker, “Extraction-controlled quantum cascade lasers,” Appl. Phys. Lett. 97, 081105 (2010).
    [CrossRef]
  11. B. S. Williams, H. Callebaut, S. Kumar, Q. Hu, and J. L. Reno, “THz quantum cascade laser at λ ≈ 100 μm using metal waveguide for mode confinement,” Appl. Phys. Lett. 83, 2124–2126 (2003).
    [CrossRef]
  12. Q. Hu, B. S. Williams, S. Kumar, H. Callebaut, S. Kohen, and J. L. Reno, “Resonant-phonon-assisted THz quantum-cascade lasers with metal–metal waveguides,” Semicond. Sci. Technol. 20, S228–S236 (2005).
    [CrossRef]
  13. S. Fathololoumi, E. Dupont, S. G. Razavipour, S. R. Laframboise, G. Parent, Z. Wasilewski, H. C. Liu, and D. Ban, “On metal contacts of terahertz quantum-cascade lasers with a metal-metal waveguide,” Semicond. Sci. Technol. 26, 105021 (2011).
    [CrossRef]
  14. M. A. Belkin, Q. J. Wang, C. Pflügl, A. Belyanin, S. P. Khanna, A. G. Davies, E. H. Linfield, and F. Capasso, “High-temperature operation of terahertz quantum cascade laser sources,” IEEE Sel. Top. Quantum Electron. 15, 952–967 (2009).
    [CrossRef]
  15. R. Terrazi and J. Faist, “A density matrix model of transport and radiation in quantum cascade lasers,” New J. Phys. 12, 033045 (2010).
    [CrossRef]
  16. S. Kumar and Q. Hu, “Coherence of resonant-tunneling transport in terahertz quantum-cascade lasers,” Phys. Rev. B 80, 245316 (2009).
    [CrossRef]
  17. E. Dupont, S. Fathololoumi, and H. C. Liu, “Simplified density matrix model applied to three-well terahertz quantum cascade lsers,” Phys. Rev. B 81, 205311 (2010).
    [CrossRef]
  18. S. C. Lee and A. Wacker, “Nonequilibrium Greens function theory for transport and gain properties of quantum cascade structures,” Phys. Rev. B 66, 245314 (2002).
    [CrossRef]
  19. T. Kubis, C. Yeh, P. Vogl, A. Benz, G. Fasching, and C. Deutsch, “Theory of nonequilibrium quantum transport and energy dissipation in terahertz quantum cascade lasers,” Phys. Rev. B 79, 195323 (2009).
    [CrossRef]
  20. H. Callebaut, S. Kumar, B.S. Williams, Q. Hu, and J. L. Reno, “Analysis of transport properties of terahertz quantum cascade lasers,” Appl. Phys. Lett. 83, 207–209 (2003).
    [CrossRef]
  21. H. Callebaut and Q. Hu, “Importance of coherence for electron transport in terahertz quantum cascade lasers,” J. Appl. Phys. 98, 104505 (2005).
    [CrossRef]
  22. C. Jirauschek and P. Lugli, “Monte-Carlo-based spectral gain analysis for terahertz quantum cascade lasers,” J. Appl. Phys. 105, 123102 (2009).
    [CrossRef]
  23. A. Mátyás, M. A. Belkin, P. Lugli, and C. Jirauschek, “Temperature performance analysis of terahertz quantum cascade lasers: Vertical versus diagonal designs,” Appl. Phys. Lett. 96, 201110 (2010).
    [CrossRef]
  24. S. Fathololoumi, E. Dupont, S.R. Laframboise, Z. R. Wasilewski, D. Ban, and H. Liu, “Design of laser transition oscillator strength for THz quantum cascade lasers,” Presented at Conference on Lasers and Electro-Optics, Baltimore, MD (2011).
  25. H. Luo, S. R. Laframboise, Z. R. Wasilewski, and H. C. Liu, “Effects of injector barrier on performance of terahertz quantum-cascade lasers,” IEEE Electron. Lett. 43, 633–635 (2007).
    [CrossRef]
  26. H. Luo, S. R. Laframboise, Z. R. Wasilewski, H. C. Liu, and J. C. Cao, “Effects of extraction barrier width on performance of terahertz quantum-cascade lasers,” IEEE Electron. Lett. 44, 630–631 (2008).
    [CrossRef]
  27. For the density matrix calculations, the electron temperature was chosen 90 K higher than lattice. Pure dephasing time constants of tunneling τ* = 0.35 ps, and of optical intersubband transition τul*=1.1 ps were used. Intrawell intersubband scatterings by LO phonon, e-impurities and interface roughness were considered. The momentum dependance of scattering is averaged over the assumed Maxwell-Boltzmann distribution of carriers in the sub-bands.
  28. S. Fathololoumi, E. Dupont, Z. R. Wasilewski, S. R. Laframboise, D. Ban, and H. C. Liu, “Effect of intermediate resonance on the performance of resonant phonon based terahertz quantum cascade laser,” Presented at 11th International Conference on Intersubband Transitions in Quantum Wells, Badesi, Italy (2011).
  29. S. Fathololoumi, D. Ban, H. Luo, E. Dupont, S. R. Laframboise, A. Boucherif, and H. C. Liu, “Thermal behavior investigation of terahertz quantum-cascade lasers,” IEEE J. Quantum Electron. 44, 1139–1144 (2008).
    [CrossRef]
  30. S. Fathololoumi, E. Dupont, D. Ban, M. Graf, S. R. Laframboise, Z. Wasilewski, and H. C. Liu, “Time-resolved thermal quenching of THz quantum cascade lasers,” IEEE J. Quantum Electron 46, 396–404 (2010).
    [CrossRef]
  31. S. Kumar, “Development of terahertz quantum-cascade lasers,” Massachusetts Institute of Technology163–166 (2007).
  32. C. W. I. Chan, S. Fathololoumi, E. Dupont, Z. R. Wasilewski, S. R. Laframboise, D. Ban, Q. Hu, and H. C. Liu, “A terahertz quantum cascade laser operating up to 193 K,” Presented at 11th International Conference on Intersubband Transitions in Quantum Wells, Badesi, Italy (2011).
  33. The waveguide loss of 22.1 cm−1 was calculated for the Au-Au device without the top n+ layer (∼ 170 μm wide and 1.98 mm long). The estimated cavity loss is, therefore, reduced for ∼ 3 cm−1 (1.9 cm−1 from the waveguide loss and 1.1 cm−1 from the mirror loss), as compared to the estimated cavity loss of the Au-Au device with the top n+ layer (∼ 144 μm wide and 1 mm long), lasing up to 180 K. The MC simulations at 12.8 kV/cm and 3.22 THz showed a gain reduction of ∼ 4 cm−1.
  34. J. Faist, F. Capasso, A. L. Hutchinson, L. Pfeiffer, and K. W. West, “Suppression of optical absorption by electric-field-induced quantum interference in coupled potential wells,” Phys. Rev. Lett. 71, 3573–3576 (1993).
    [CrossRef] [PubMed]
  35. L. A. Dunbar, R. Houdré, G. Scalari, L. Sirigu, M. Giovannini, and J. Faist, “Small optical volume terahertz emitting microdisk quantum cascade lasers,” Appl. Phys. Lett. 90, 141114 (2007).
    [CrossRef]
  36. C. Weber, A. Wacker, and A. Knorr, “Density-matrix theory of the optical dynamics and transport in quantum cascade structures: the role of coherence,” Phys. Rev. B 79, 165322 (2007).
    [CrossRef]
  37. A. Mátyás, P. Lugli, and C. Jirauschek, “Photon-induced carrier transport in high efficiency midinfrared quantum cascade lasers,” J. Appl. Phys. 110, 013108 (2011).
    [CrossRef]
  38. A. Mátyás, T. Kubis, P. Lugli, and C. Jirauschek, “Comparison between semiclassical and full quantum transport analysis of THz quantum cascade lasers,” Physica E 42, 2628 (2010).
    [CrossRef]

2011 (3)

S. Kumar, C. W. I. Chan, Q. Hu, and J. L. Reno, “A 1.8-THz quantum cascade laser operating significantly above the temperature of ħω/κB,” Nat. Phys. 7, 166–171 (2011).
[CrossRef]

S. Fathololoumi, E. Dupont, S. G. Razavipour, S. R. Laframboise, G. Parent, Z. Wasilewski, H. C. Liu, and D. Ban, “On metal contacts of terahertz quantum-cascade lasers with a metal-metal waveguide,” Semicond. Sci. Technol. 26, 105021 (2011).
[CrossRef]

A. Mátyás, P. Lugli, and C. Jirauschek, “Photon-induced carrier transport in high efficiency midinfrared quantum cascade lasers,” J. Appl. Phys. 110, 013108 (2011).
[CrossRef]

2010 (8)

A. Mátyás, T. Kubis, P. Lugli, and C. Jirauschek, “Comparison between semiclassical and full quantum transport analysis of THz quantum cascade lasers,” Physica E 42, 2628 (2010).
[CrossRef]

A. Mátyás, M. A. Belkin, P. Lugli, and C. Jirauschek, “Temperature performance analysis of terahertz quantum cascade lasers: Vertical versus diagonal designs,” Appl. Phys. Lett. 96, 201110 (2010).
[CrossRef]

S. Fathololoumi, E. Dupont, D. Ban, M. Graf, S. R. Laframboise, Z. Wasilewski, and H. C. Liu, “Time-resolved thermal quenching of THz quantum cascade lasers,” IEEE J. Quantum Electron 46, 396–404 (2010).
[CrossRef]

R. W. Adams, K. Vijayraghavan, Q. J. Wang, J. Fan, F. Capasso, S. P. Khanna, A. G. Davies, E. H. Linfield, and M. A. Belkin, “GaAs/Al0.15Ga0.85As terahertz quantum cascade lasers with double-phonon resonant depopulation operating up to 172 K,” Appl. Phys. Lett. 97, 131111 (2010).
[CrossRef]

G. Scalari, M. I. Amanti, C. Walther, R. Terazzi, M. Beck, and J. Faist, “Broadband THz lasing from a photon-phonon quantum cascade structure,” Opt. Express 8, 8043–8052 (2010).
[CrossRef]

A. Wacker, “Extraction-controlled quantum cascade lasers,” Appl. Phys. Lett. 97, 081105 (2010).
[CrossRef]

R. Terrazi and J. Faist, “A density matrix model of transport and radiation in quantum cascade lasers,” New J. Phys. 12, 033045 (2010).
[CrossRef]

E. Dupont, S. Fathololoumi, and H. C. Liu, “Simplified density matrix model applied to three-well terahertz quantum cascade lsers,” Phys. Rev. B 81, 205311 (2010).
[CrossRef]

2009 (6)

S. Kumar and Q. Hu, “Coherence of resonant-tunneling transport in terahertz quantum-cascade lasers,” Phys. Rev. B 80, 245316 (2009).
[CrossRef]

T. Kubis, C. Yeh, P. Vogl, A. Benz, G. Fasching, and C. Deutsch, “Theory of nonequilibrium quantum transport and energy dissipation in terahertz quantum cascade lasers,” Phys. Rev. B 79, 195323 (2009).
[CrossRef]

C. Jirauschek and P. Lugli, “Monte-Carlo-based spectral gain analysis for terahertz quantum cascade lasers,” J. Appl. Phys. 105, 123102 (2009).
[CrossRef]

S. Kumar, C. W. I. Chan, Q. Hu, and J. L. Reno, “Two-well terahertz quantum-cascade laser with direct intrawellphonon depopulation,” Appl. Phys. Lett. 95, 141110 (2009).
[CrossRef]

M. A. Belkin, Q. J. Wang, C. Pflügl, A. Belyanin, S. P. Khanna, A. G. Davies, E. H. Linfield, and F. Capasso, “High-temperature operation of terahertz quantum cascade laser sources,” IEEE Sel. Top. Quantum Electron. 15, 952–967 (2009).
[CrossRef]

S. Kumar, Q. Hu, and J. L. Reno, “186 K operation of terahertz quantum cascade lasers based on a diagonal design,” Appl. Phys. Lett. 94, 131105 (2009).
[CrossRef]

2008 (3)

H. Luo, S. R. Laframboise, Z. R. Wasilewski, H. C. Liu, and J. C. Cao, “Effects of extraction barrier width on performance of terahertz quantum-cascade lasers,” IEEE Electron. Lett. 44, 630–631 (2008).
[CrossRef]

S. Fathololoumi, D. Ban, H. Luo, E. Dupont, S. R. Laframboise, A. Boucherif, and H. C. Liu, “Thermal behavior investigation of terahertz quantum-cascade lasers,” IEEE J. Quantum Electron. 44, 1139–1144 (2008).
[CrossRef]

M. A. Belkin, J. A. Fan, S. Hormoz, F. Capasso, S. P. Khanna, M. Lachab, A. G. Davies, and E. H. Linfield, “Terahertz quantum cascade lasers with copper metal-metal waveguides operating up to 178 K,” Opt. Express 16, 3242–3248 (2008).
[CrossRef] [PubMed]

2007 (4)

H. Luo, S. R. Laframboise, Z. R. Wasilewski, and H. C. Liu, “Terahertz quantum cascade lasers based on a three-well active module,” Appl. Phys. Lett. 90, 041112 (2007).
[CrossRef]

H. Luo, S. R. Laframboise, Z. R. Wasilewski, and H. C. Liu, “Effects of injector barrier on performance of terahertz quantum-cascade lasers,” IEEE Electron. Lett. 43, 633–635 (2007).
[CrossRef]

L. A. Dunbar, R. Houdré, G. Scalari, L. Sirigu, M. Giovannini, and J. Faist, “Small optical volume terahertz emitting microdisk quantum cascade lasers,” Appl. Phys. Lett. 90, 141114 (2007).
[CrossRef]

C. Weber, A. Wacker, and A. Knorr, “Density-matrix theory of the optical dynamics and transport in quantum cascade structures: the role of coherence,” Phys. Rev. B 79, 165322 (2007).
[CrossRef]

2005 (3)

B. S. Williams, S. Kumar, Q. Hu, and J. L. Reno, “Operation of terahertz quantum-cascade lasers at 164 K in pulsed mode and at 117 K in continuous-wave mode,” Opt. Express 13, 3331–3339 (2005).
[CrossRef] [PubMed]

Q. Hu, B. S. Williams, S. Kumar, H. Callebaut, S. Kohen, and J. L. Reno, “Resonant-phonon-assisted THz quantum-cascade lasers with metal–metal waveguides,” Semicond. Sci. Technol. 20, S228–S236 (2005).
[CrossRef]

H. Callebaut and Q. Hu, “Importance of coherence for electron transport in terahertz quantum cascade lasers,” J. Appl. Phys. 98, 104505 (2005).
[CrossRef]

2003 (2)

H. Callebaut, S. Kumar, B.S. Williams, Q. Hu, and J. L. Reno, “Analysis of transport properties of terahertz quantum cascade lasers,” Appl. Phys. Lett. 83, 207–209 (2003).
[CrossRef]

B. S. Williams, H. Callebaut, S. Kumar, Q. Hu, and J. L. Reno, “THz quantum cascade laser at λ ≈ 100 μm using metal waveguide for mode confinement,” Appl. Phys. Lett. 83, 2124–2126 (2003).
[CrossRef]

2002 (2)

S. C. Lee and A. Wacker, “Nonequilibrium Greens function theory for transport and gain properties of quantum cascade structures,” Phys. Rev. B 66, 245314 (2002).
[CrossRef]

R. Kohler, A. Tredicucci, F. Beltram, H. E. Beere, E. H. Linfield, A. G. Davies, D. Ritchie, R. C. Iotti, and F. Rossi, “Terahertz semiconductor-heterostructure laser,” Nature 417, 156–159 (2002).
[CrossRef] [PubMed]

1993 (1)

J. Faist, F. Capasso, A. L. Hutchinson, L. Pfeiffer, and K. W. West, “Suppression of optical absorption by electric-field-induced quantum interference in coupled potential wells,” Phys. Rev. Lett. 71, 3573–3576 (1993).
[CrossRef] [PubMed]

Adams, R. W.

R. W. Adams, K. Vijayraghavan, Q. J. Wang, J. Fan, F. Capasso, S. P. Khanna, A. G. Davies, E. H. Linfield, and M. A. Belkin, “GaAs/Al0.15Ga0.85As terahertz quantum cascade lasers with double-phonon resonant depopulation operating up to 172 K,” Appl. Phys. Lett. 97, 131111 (2010).
[CrossRef]

Amanti, M. I.

G. Scalari, M. I. Amanti, C. Walther, R. Terazzi, M. Beck, and J. Faist, “Broadband THz lasing from a photon-phonon quantum cascade structure,” Opt. Express 8, 8043–8052 (2010).
[CrossRef]

Ban, D.

S. Fathololoumi, E. Dupont, S. G. Razavipour, S. R. Laframboise, G. Parent, Z. Wasilewski, H. C. Liu, and D. Ban, “On metal contacts of terahertz quantum-cascade lasers with a metal-metal waveguide,” Semicond. Sci. Technol. 26, 105021 (2011).
[CrossRef]

S. Fathololoumi, E. Dupont, D. Ban, M. Graf, S. R. Laframboise, Z. Wasilewski, and H. C. Liu, “Time-resolved thermal quenching of THz quantum cascade lasers,” IEEE J. Quantum Electron 46, 396–404 (2010).
[CrossRef]

S. Fathololoumi, D. Ban, H. Luo, E. Dupont, S. R. Laframboise, A. Boucherif, and H. C. Liu, “Thermal behavior investigation of terahertz quantum-cascade lasers,” IEEE J. Quantum Electron. 44, 1139–1144 (2008).
[CrossRef]

S. Fathololoumi, E. Dupont, Z. R. Wasilewski, S. R. Laframboise, D. Ban, and H. C. Liu, “Effect of intermediate resonance on the performance of resonant phonon based terahertz quantum cascade laser,” Presented at 11th International Conference on Intersubband Transitions in Quantum Wells, Badesi, Italy (2011).

S. Fathololoumi, E. Dupont, S.R. Laframboise, Z. R. Wasilewski, D. Ban, and H. Liu, “Design of laser transition oscillator strength for THz quantum cascade lasers,” Presented at Conference on Lasers and Electro-Optics, Baltimore, MD (2011).

C. W. I. Chan, S. Fathololoumi, E. Dupont, Z. R. Wasilewski, S. R. Laframboise, D. Ban, Q. Hu, and H. C. Liu, “A terahertz quantum cascade laser operating up to 193 K,” Presented at 11th International Conference on Intersubband Transitions in Quantum Wells, Badesi, Italy (2011).

Beck, M.

G. Scalari, M. I. Amanti, C. Walther, R. Terazzi, M. Beck, and J. Faist, “Broadband THz lasing from a photon-phonon quantum cascade structure,” Opt. Express 8, 8043–8052 (2010).
[CrossRef]

Beere, H. E.

R. Kohler, A. Tredicucci, F. Beltram, H. E. Beere, E. H. Linfield, A. G. Davies, D. Ritchie, R. C. Iotti, and F. Rossi, “Terahertz semiconductor-heterostructure laser,” Nature 417, 156–159 (2002).
[CrossRef] [PubMed]

Belkin, M. A.

R. W. Adams, K. Vijayraghavan, Q. J. Wang, J. Fan, F. Capasso, S. P. Khanna, A. G. Davies, E. H. Linfield, and M. A. Belkin, “GaAs/Al0.15Ga0.85As terahertz quantum cascade lasers with double-phonon resonant depopulation operating up to 172 K,” Appl. Phys. Lett. 97, 131111 (2010).
[CrossRef]

A. Mátyás, M. A. Belkin, P. Lugli, and C. Jirauschek, “Temperature performance analysis of terahertz quantum cascade lasers: Vertical versus diagonal designs,” Appl. Phys. Lett. 96, 201110 (2010).
[CrossRef]

M. A. Belkin, Q. J. Wang, C. Pflügl, A. Belyanin, S. P. Khanna, A. G. Davies, E. H. Linfield, and F. Capasso, “High-temperature operation of terahertz quantum cascade laser sources,” IEEE Sel. Top. Quantum Electron. 15, 952–967 (2009).
[CrossRef]

M. A. Belkin, J. A. Fan, S. Hormoz, F. Capasso, S. P. Khanna, M. Lachab, A. G. Davies, and E. H. Linfield, “Terahertz quantum cascade lasers with copper metal-metal waveguides operating up to 178 K,” Opt. Express 16, 3242–3248 (2008).
[CrossRef] [PubMed]

Beltram, F.

R. Kohler, A. Tredicucci, F. Beltram, H. E. Beere, E. H. Linfield, A. G. Davies, D. Ritchie, R. C. Iotti, and F. Rossi, “Terahertz semiconductor-heterostructure laser,” Nature 417, 156–159 (2002).
[CrossRef] [PubMed]

Belyanin, A.

M. A. Belkin, Q. J. Wang, C. Pflügl, A. Belyanin, S. P. Khanna, A. G. Davies, E. H. Linfield, and F. Capasso, “High-temperature operation of terahertz quantum cascade laser sources,” IEEE Sel. Top. Quantum Electron. 15, 952–967 (2009).
[CrossRef]

Benz, A.

T. Kubis, C. Yeh, P. Vogl, A. Benz, G. Fasching, and C. Deutsch, “Theory of nonequilibrium quantum transport and energy dissipation in terahertz quantum cascade lasers,” Phys. Rev. B 79, 195323 (2009).
[CrossRef]

Boucherif, A.

S. Fathololoumi, D. Ban, H. Luo, E. Dupont, S. R. Laframboise, A. Boucherif, and H. C. Liu, “Thermal behavior investigation of terahertz quantum-cascade lasers,” IEEE J. Quantum Electron. 44, 1139–1144 (2008).
[CrossRef]

Callebaut, H.

H. Callebaut and Q. Hu, “Importance of coherence for electron transport in terahertz quantum cascade lasers,” J. Appl. Phys. 98, 104505 (2005).
[CrossRef]

Q. Hu, B. S. Williams, S. Kumar, H. Callebaut, S. Kohen, and J. L. Reno, “Resonant-phonon-assisted THz quantum-cascade lasers with metal–metal waveguides,” Semicond. Sci. Technol. 20, S228–S236 (2005).
[CrossRef]

H. Callebaut, S. Kumar, B.S. Williams, Q. Hu, and J. L. Reno, “Analysis of transport properties of terahertz quantum cascade lasers,” Appl. Phys. Lett. 83, 207–209 (2003).
[CrossRef]

B. S. Williams, H. Callebaut, S. Kumar, Q. Hu, and J. L. Reno, “THz quantum cascade laser at λ ≈ 100 μm using metal waveguide for mode confinement,” Appl. Phys. Lett. 83, 2124–2126 (2003).
[CrossRef]

Cao, J. C.

H. Luo, S. R. Laframboise, Z. R. Wasilewski, H. C. Liu, and J. C. Cao, “Effects of extraction barrier width on performance of terahertz quantum-cascade lasers,” IEEE Electron. Lett. 44, 630–631 (2008).
[CrossRef]

Capasso, F.

R. W. Adams, K. Vijayraghavan, Q. J. Wang, J. Fan, F. Capasso, S. P. Khanna, A. G. Davies, E. H. Linfield, and M. A. Belkin, “GaAs/Al0.15Ga0.85As terahertz quantum cascade lasers with double-phonon resonant depopulation operating up to 172 K,” Appl. Phys. Lett. 97, 131111 (2010).
[CrossRef]

M. A. Belkin, Q. J. Wang, C. Pflügl, A. Belyanin, S. P. Khanna, A. G. Davies, E. H. Linfield, and F. Capasso, “High-temperature operation of terahertz quantum cascade laser sources,” IEEE Sel. Top. Quantum Electron. 15, 952–967 (2009).
[CrossRef]

M. A. Belkin, J. A. Fan, S. Hormoz, F. Capasso, S. P. Khanna, M. Lachab, A. G. Davies, and E. H. Linfield, “Terahertz quantum cascade lasers with copper metal-metal waveguides operating up to 178 K,” Opt. Express 16, 3242–3248 (2008).
[CrossRef] [PubMed]

J. Faist, F. Capasso, A. L. Hutchinson, L. Pfeiffer, and K. W. West, “Suppression of optical absorption by electric-field-induced quantum interference in coupled potential wells,” Phys. Rev. Lett. 71, 3573–3576 (1993).
[CrossRef] [PubMed]

Chan, C. W. I.

S. Kumar, C. W. I. Chan, Q. Hu, and J. L. Reno, “A 1.8-THz quantum cascade laser operating significantly above the temperature of ħω/κB,” Nat. Phys. 7, 166–171 (2011).
[CrossRef]

S. Kumar, C. W. I. Chan, Q. Hu, and J. L. Reno, “Two-well terahertz quantum-cascade laser with direct intrawellphonon depopulation,” Appl. Phys. Lett. 95, 141110 (2009).
[CrossRef]

C. W. I. Chan, S. Fathololoumi, E. Dupont, Z. R. Wasilewski, S. R. Laframboise, D. Ban, Q. Hu, and H. C. Liu, “A terahertz quantum cascade laser operating up to 193 K,” Presented at 11th International Conference on Intersubband Transitions in Quantum Wells, Badesi, Italy (2011).

Davies, A. G.

R. W. Adams, K. Vijayraghavan, Q. J. Wang, J. Fan, F. Capasso, S. P. Khanna, A. G. Davies, E. H. Linfield, and M. A. Belkin, “GaAs/Al0.15Ga0.85As terahertz quantum cascade lasers with double-phonon resonant depopulation operating up to 172 K,” Appl. Phys. Lett. 97, 131111 (2010).
[CrossRef]

M. A. Belkin, Q. J. Wang, C. Pflügl, A. Belyanin, S. P. Khanna, A. G. Davies, E. H. Linfield, and F. Capasso, “High-temperature operation of terahertz quantum cascade laser sources,” IEEE Sel. Top. Quantum Electron. 15, 952–967 (2009).
[CrossRef]

M. A. Belkin, J. A. Fan, S. Hormoz, F. Capasso, S. P. Khanna, M. Lachab, A. G. Davies, and E. H. Linfield, “Terahertz quantum cascade lasers with copper metal-metal waveguides operating up to 178 K,” Opt. Express 16, 3242–3248 (2008).
[CrossRef] [PubMed]

R. Kohler, A. Tredicucci, F. Beltram, H. E. Beere, E. H. Linfield, A. G. Davies, D. Ritchie, R. C. Iotti, and F. Rossi, “Terahertz semiconductor-heterostructure laser,” Nature 417, 156–159 (2002).
[CrossRef] [PubMed]

Deutsch, C.

T. Kubis, C. Yeh, P. Vogl, A. Benz, G. Fasching, and C. Deutsch, “Theory of nonequilibrium quantum transport and energy dissipation in terahertz quantum cascade lasers,” Phys. Rev. B 79, 195323 (2009).
[CrossRef]

Dunbar, L. A.

L. A. Dunbar, R. Houdré, G. Scalari, L. Sirigu, M. Giovannini, and J. Faist, “Small optical volume terahertz emitting microdisk quantum cascade lasers,” Appl. Phys. Lett. 90, 141114 (2007).
[CrossRef]

Dupont, E.

S. Fathololoumi, E. Dupont, S. G. Razavipour, S. R. Laframboise, G. Parent, Z. Wasilewski, H. C. Liu, and D. Ban, “On metal contacts of terahertz quantum-cascade lasers with a metal-metal waveguide,” Semicond. Sci. Technol. 26, 105021 (2011).
[CrossRef]

E. Dupont, S. Fathololoumi, and H. C. Liu, “Simplified density matrix model applied to three-well terahertz quantum cascade lsers,” Phys. Rev. B 81, 205311 (2010).
[CrossRef]

S. Fathololoumi, E. Dupont, D. Ban, M. Graf, S. R. Laframboise, Z. Wasilewski, and H. C. Liu, “Time-resolved thermal quenching of THz quantum cascade lasers,” IEEE J. Quantum Electron 46, 396–404 (2010).
[CrossRef]

S. Fathololoumi, D. Ban, H. Luo, E. Dupont, S. R. Laframboise, A. Boucherif, and H. C. Liu, “Thermal behavior investigation of terahertz quantum-cascade lasers,” IEEE J. Quantum Electron. 44, 1139–1144 (2008).
[CrossRef]

C. W. I. Chan, S. Fathololoumi, E. Dupont, Z. R. Wasilewski, S. R. Laframboise, D. Ban, Q. Hu, and H. C. Liu, “A terahertz quantum cascade laser operating up to 193 K,” Presented at 11th International Conference on Intersubband Transitions in Quantum Wells, Badesi, Italy (2011).

S. Fathololoumi, E. Dupont, S.R. Laframboise, Z. R. Wasilewski, D. Ban, and H. Liu, “Design of laser transition oscillator strength for THz quantum cascade lasers,” Presented at Conference on Lasers and Electro-Optics, Baltimore, MD (2011).

S. Fathololoumi, E. Dupont, Z. R. Wasilewski, S. R. Laframboise, D. Ban, and H. C. Liu, “Effect of intermediate resonance on the performance of resonant phonon based terahertz quantum cascade laser,” Presented at 11th International Conference on Intersubband Transitions in Quantum Wells, Badesi, Italy (2011).

Faist, J.

R. Terrazi and J. Faist, “A density matrix model of transport and radiation in quantum cascade lasers,” New J. Phys. 12, 033045 (2010).
[CrossRef]

G. Scalari, M. I. Amanti, C. Walther, R. Terazzi, M. Beck, and J. Faist, “Broadband THz lasing from a photon-phonon quantum cascade structure,” Opt. Express 8, 8043–8052 (2010).
[CrossRef]

L. A. Dunbar, R. Houdré, G. Scalari, L. Sirigu, M. Giovannini, and J. Faist, “Small optical volume terahertz emitting microdisk quantum cascade lasers,” Appl. Phys. Lett. 90, 141114 (2007).
[CrossRef]

J. Faist, F. Capasso, A. L. Hutchinson, L. Pfeiffer, and K. W. West, “Suppression of optical absorption by electric-field-induced quantum interference in coupled potential wells,” Phys. Rev. Lett. 71, 3573–3576 (1993).
[CrossRef] [PubMed]

Fan, J.

R. W. Adams, K. Vijayraghavan, Q. J. Wang, J. Fan, F. Capasso, S. P. Khanna, A. G. Davies, E. H. Linfield, and M. A. Belkin, “GaAs/Al0.15Ga0.85As terahertz quantum cascade lasers with double-phonon resonant depopulation operating up to 172 K,” Appl. Phys. Lett. 97, 131111 (2010).
[CrossRef]

Fan, J. A.

Fasching, G.

T. Kubis, C. Yeh, P. Vogl, A. Benz, G. Fasching, and C. Deutsch, “Theory of nonequilibrium quantum transport and energy dissipation in terahertz quantum cascade lasers,” Phys. Rev. B 79, 195323 (2009).
[CrossRef]

Fathololoumi, S.

S. Fathololoumi, E. Dupont, S. G. Razavipour, S. R. Laframboise, G. Parent, Z. Wasilewski, H. C. Liu, and D. Ban, “On metal contacts of terahertz quantum-cascade lasers with a metal-metal waveguide,” Semicond. Sci. Technol. 26, 105021 (2011).
[CrossRef]

E. Dupont, S. Fathololoumi, and H. C. Liu, “Simplified density matrix model applied to three-well terahertz quantum cascade lsers,” Phys. Rev. B 81, 205311 (2010).
[CrossRef]

S. Fathololoumi, E. Dupont, D. Ban, M. Graf, S. R. Laframboise, Z. Wasilewski, and H. C. Liu, “Time-resolved thermal quenching of THz quantum cascade lasers,” IEEE J. Quantum Electron 46, 396–404 (2010).
[CrossRef]

S. Fathololoumi, D. Ban, H. Luo, E. Dupont, S. R. Laframboise, A. Boucherif, and H. C. Liu, “Thermal behavior investigation of terahertz quantum-cascade lasers,” IEEE J. Quantum Electron. 44, 1139–1144 (2008).
[CrossRef]

S. Fathololoumi, E. Dupont, Z. R. Wasilewski, S. R. Laframboise, D. Ban, and H. C. Liu, “Effect of intermediate resonance on the performance of resonant phonon based terahertz quantum cascade laser,” Presented at 11th International Conference on Intersubband Transitions in Quantum Wells, Badesi, Italy (2011).

S. Fathololoumi, E. Dupont, S.R. Laframboise, Z. R. Wasilewski, D. Ban, and H. Liu, “Design of laser transition oscillator strength for THz quantum cascade lasers,” Presented at Conference on Lasers and Electro-Optics, Baltimore, MD (2011).

C. W. I. Chan, S. Fathololoumi, E. Dupont, Z. R. Wasilewski, S. R. Laframboise, D. Ban, Q. Hu, and H. C. Liu, “A terahertz quantum cascade laser operating up to 193 K,” Presented at 11th International Conference on Intersubband Transitions in Quantum Wells, Badesi, Italy (2011).

Giovannini, M.

L. A. Dunbar, R. Houdré, G. Scalari, L. Sirigu, M. Giovannini, and J. Faist, “Small optical volume terahertz emitting microdisk quantum cascade lasers,” Appl. Phys. Lett. 90, 141114 (2007).
[CrossRef]

Graf, M.

S. Fathololoumi, E. Dupont, D. Ban, M. Graf, S. R. Laframboise, Z. Wasilewski, and H. C. Liu, “Time-resolved thermal quenching of THz quantum cascade lasers,” IEEE J. Quantum Electron 46, 396–404 (2010).
[CrossRef]

Hormoz, S.

Houdré, R.

L. A. Dunbar, R. Houdré, G. Scalari, L. Sirigu, M. Giovannini, and J. Faist, “Small optical volume terahertz emitting microdisk quantum cascade lasers,” Appl. Phys. Lett. 90, 141114 (2007).
[CrossRef]

Hu, Q.

S. Kumar, C. W. I. Chan, Q. Hu, and J. L. Reno, “A 1.8-THz quantum cascade laser operating significantly above the temperature of ħω/κB,” Nat. Phys. 7, 166–171 (2011).
[CrossRef]

S. Kumar, Q. Hu, and J. L. Reno, “186 K operation of terahertz quantum cascade lasers based on a diagonal design,” Appl. Phys. Lett. 94, 131105 (2009).
[CrossRef]

S. Kumar, C. W. I. Chan, Q. Hu, and J. L. Reno, “Two-well terahertz quantum-cascade laser with direct intrawellphonon depopulation,” Appl. Phys. Lett. 95, 141110 (2009).
[CrossRef]

S. Kumar and Q. Hu, “Coherence of resonant-tunneling transport in terahertz quantum-cascade lasers,” Phys. Rev. B 80, 245316 (2009).
[CrossRef]

Q. Hu, B. S. Williams, S. Kumar, H. Callebaut, S. Kohen, and J. L. Reno, “Resonant-phonon-assisted THz quantum-cascade lasers with metal–metal waveguides,” Semicond. Sci. Technol. 20, S228–S236 (2005).
[CrossRef]

H. Callebaut and Q. Hu, “Importance of coherence for electron transport in terahertz quantum cascade lasers,” J. Appl. Phys. 98, 104505 (2005).
[CrossRef]

B. S. Williams, S. Kumar, Q. Hu, and J. L. Reno, “Operation of terahertz quantum-cascade lasers at 164 K in pulsed mode and at 117 K in continuous-wave mode,” Opt. Express 13, 3331–3339 (2005).
[CrossRef] [PubMed]

H. Callebaut, S. Kumar, B.S. Williams, Q. Hu, and J. L. Reno, “Analysis of transport properties of terahertz quantum cascade lasers,” Appl. Phys. Lett. 83, 207–209 (2003).
[CrossRef]

B. S. Williams, H. Callebaut, S. Kumar, Q. Hu, and J. L. Reno, “THz quantum cascade laser at λ ≈ 100 μm using metal waveguide for mode confinement,” Appl. Phys. Lett. 83, 2124–2126 (2003).
[CrossRef]

C. W. I. Chan, S. Fathololoumi, E. Dupont, Z. R. Wasilewski, S. R. Laframboise, D. Ban, Q. Hu, and H. C. Liu, “A terahertz quantum cascade laser operating up to 193 K,” Presented at 11th International Conference on Intersubband Transitions in Quantum Wells, Badesi, Italy (2011).

Hutchinson, A. L.

J. Faist, F. Capasso, A. L. Hutchinson, L. Pfeiffer, and K. W. West, “Suppression of optical absorption by electric-field-induced quantum interference in coupled potential wells,” Phys. Rev. Lett. 71, 3573–3576 (1993).
[CrossRef] [PubMed]

Iotti, R. C.

R. Kohler, A. Tredicucci, F. Beltram, H. E. Beere, E. H. Linfield, A. G. Davies, D. Ritchie, R. C. Iotti, and F. Rossi, “Terahertz semiconductor-heterostructure laser,” Nature 417, 156–159 (2002).
[CrossRef] [PubMed]

Jirauschek, C.

A. Mátyás, P. Lugli, and C. Jirauschek, “Photon-induced carrier transport in high efficiency midinfrared quantum cascade lasers,” J. Appl. Phys. 110, 013108 (2011).
[CrossRef]

A. Mátyás, T. Kubis, P. Lugli, and C. Jirauschek, “Comparison between semiclassical and full quantum transport analysis of THz quantum cascade lasers,” Physica E 42, 2628 (2010).
[CrossRef]

A. Mátyás, M. A. Belkin, P. Lugli, and C. Jirauschek, “Temperature performance analysis of terahertz quantum cascade lasers: Vertical versus diagonal designs,” Appl. Phys. Lett. 96, 201110 (2010).
[CrossRef]

C. Jirauschek and P. Lugli, “Monte-Carlo-based spectral gain analysis for terahertz quantum cascade lasers,” J. Appl. Phys. 105, 123102 (2009).
[CrossRef]

Khanna, S. P.

R. W. Adams, K. Vijayraghavan, Q. J. Wang, J. Fan, F. Capasso, S. P. Khanna, A. G. Davies, E. H. Linfield, and M. A. Belkin, “GaAs/Al0.15Ga0.85As terahertz quantum cascade lasers with double-phonon resonant depopulation operating up to 172 K,” Appl. Phys. Lett. 97, 131111 (2010).
[CrossRef]

M. A. Belkin, Q. J. Wang, C. Pflügl, A. Belyanin, S. P. Khanna, A. G. Davies, E. H. Linfield, and F. Capasso, “High-temperature operation of terahertz quantum cascade laser sources,” IEEE Sel. Top. Quantum Electron. 15, 952–967 (2009).
[CrossRef]

M. A. Belkin, J. A. Fan, S. Hormoz, F. Capasso, S. P. Khanna, M. Lachab, A. G. Davies, and E. H. Linfield, “Terahertz quantum cascade lasers with copper metal-metal waveguides operating up to 178 K,” Opt. Express 16, 3242–3248 (2008).
[CrossRef] [PubMed]

Knorr, A.

C. Weber, A. Wacker, and A. Knorr, “Density-matrix theory of the optical dynamics and transport in quantum cascade structures: the role of coherence,” Phys. Rev. B 79, 165322 (2007).
[CrossRef]

Kohen, S.

Q. Hu, B. S. Williams, S. Kumar, H. Callebaut, S. Kohen, and J. L. Reno, “Resonant-phonon-assisted THz quantum-cascade lasers with metal–metal waveguides,” Semicond. Sci. Technol. 20, S228–S236 (2005).
[CrossRef]

Kohler, R.

R. Kohler, A. Tredicucci, F. Beltram, H. E. Beere, E. H. Linfield, A. G. Davies, D. Ritchie, R. C. Iotti, and F. Rossi, “Terahertz semiconductor-heterostructure laser,” Nature 417, 156–159 (2002).
[CrossRef] [PubMed]

Kubis, T.

A. Mátyás, T. Kubis, P. Lugli, and C. Jirauschek, “Comparison between semiclassical and full quantum transport analysis of THz quantum cascade lasers,” Physica E 42, 2628 (2010).
[CrossRef]

T. Kubis, C. Yeh, P. Vogl, A. Benz, G. Fasching, and C. Deutsch, “Theory of nonequilibrium quantum transport and energy dissipation in terahertz quantum cascade lasers,” Phys. Rev. B 79, 195323 (2009).
[CrossRef]

Kumar, S.

S. Kumar, C. W. I. Chan, Q. Hu, and J. L. Reno, “A 1.8-THz quantum cascade laser operating significantly above the temperature of ħω/κB,” Nat. Phys. 7, 166–171 (2011).
[CrossRef]

S. Kumar, Q. Hu, and J. L. Reno, “186 K operation of terahertz quantum cascade lasers based on a diagonal design,” Appl. Phys. Lett. 94, 131105 (2009).
[CrossRef]

S. Kumar, C. W. I. Chan, Q. Hu, and J. L. Reno, “Two-well terahertz quantum-cascade laser with direct intrawellphonon depopulation,” Appl. Phys. Lett. 95, 141110 (2009).
[CrossRef]

S. Kumar and Q. Hu, “Coherence of resonant-tunneling transport in terahertz quantum-cascade lasers,” Phys. Rev. B 80, 245316 (2009).
[CrossRef]

Q. Hu, B. S. Williams, S. Kumar, H. Callebaut, S. Kohen, and J. L. Reno, “Resonant-phonon-assisted THz quantum-cascade lasers with metal–metal waveguides,” Semicond. Sci. Technol. 20, S228–S236 (2005).
[CrossRef]

B. S. Williams, S. Kumar, Q. Hu, and J. L. Reno, “Operation of terahertz quantum-cascade lasers at 164 K in pulsed mode and at 117 K in continuous-wave mode,” Opt. Express 13, 3331–3339 (2005).
[CrossRef] [PubMed]

H. Callebaut, S. Kumar, B.S. Williams, Q. Hu, and J. L. Reno, “Analysis of transport properties of terahertz quantum cascade lasers,” Appl. Phys. Lett. 83, 207–209 (2003).
[CrossRef]

B. S. Williams, H. Callebaut, S. Kumar, Q. Hu, and J. L. Reno, “THz quantum cascade laser at λ ≈ 100 μm using metal waveguide for mode confinement,” Appl. Phys. Lett. 83, 2124–2126 (2003).
[CrossRef]

S. Kumar, “Development of terahertz quantum-cascade lasers,” Massachusetts Institute of Technology163–166 (2007).

Lachab, M.

Laframboise, S. R.

S. Fathololoumi, E. Dupont, S. G. Razavipour, S. R. Laframboise, G. Parent, Z. Wasilewski, H. C. Liu, and D. Ban, “On metal contacts of terahertz quantum-cascade lasers with a metal-metal waveguide,” Semicond. Sci. Technol. 26, 105021 (2011).
[CrossRef]

S. Fathololoumi, E. Dupont, D. Ban, M. Graf, S. R. Laframboise, Z. Wasilewski, and H. C. Liu, “Time-resolved thermal quenching of THz quantum cascade lasers,” IEEE J. Quantum Electron 46, 396–404 (2010).
[CrossRef]

S. Fathololoumi, D. Ban, H. Luo, E. Dupont, S. R. Laframboise, A. Boucherif, and H. C. Liu, “Thermal behavior investigation of terahertz quantum-cascade lasers,” IEEE J. Quantum Electron. 44, 1139–1144 (2008).
[CrossRef]

H. Luo, S. R. Laframboise, Z. R. Wasilewski, H. C. Liu, and J. C. Cao, “Effects of extraction barrier width on performance of terahertz quantum-cascade lasers,” IEEE Electron. Lett. 44, 630–631 (2008).
[CrossRef]

H. Luo, S. R. Laframboise, Z. R. Wasilewski, and H. C. Liu, “Effects of injector barrier on performance of terahertz quantum-cascade lasers,” IEEE Electron. Lett. 43, 633–635 (2007).
[CrossRef]

H. Luo, S. R. Laframboise, Z. R. Wasilewski, and H. C. Liu, “Terahertz quantum cascade lasers based on a three-well active module,” Appl. Phys. Lett. 90, 041112 (2007).
[CrossRef]

S. Fathololoumi, E. Dupont, Z. R. Wasilewski, S. R. Laframboise, D. Ban, and H. C. Liu, “Effect of intermediate resonance on the performance of resonant phonon based terahertz quantum cascade laser,” Presented at 11th International Conference on Intersubband Transitions in Quantum Wells, Badesi, Italy (2011).

C. W. I. Chan, S. Fathololoumi, E. Dupont, Z. R. Wasilewski, S. R. Laframboise, D. Ban, Q. Hu, and H. C. Liu, “A terahertz quantum cascade laser operating up to 193 K,” Presented at 11th International Conference on Intersubband Transitions in Quantum Wells, Badesi, Italy (2011).

Laframboise, S.R.

S. Fathololoumi, E. Dupont, S.R. Laframboise, Z. R. Wasilewski, D. Ban, and H. Liu, “Design of laser transition oscillator strength for THz quantum cascade lasers,” Presented at Conference on Lasers and Electro-Optics, Baltimore, MD (2011).

Lee, S. C.

S. C. Lee and A. Wacker, “Nonequilibrium Greens function theory for transport and gain properties of quantum cascade structures,” Phys. Rev. B 66, 245314 (2002).
[CrossRef]

Linfield, E. H.

R. W. Adams, K. Vijayraghavan, Q. J. Wang, J. Fan, F. Capasso, S. P. Khanna, A. G. Davies, E. H. Linfield, and M. A. Belkin, “GaAs/Al0.15Ga0.85As terahertz quantum cascade lasers with double-phonon resonant depopulation operating up to 172 K,” Appl. Phys. Lett. 97, 131111 (2010).
[CrossRef]

M. A. Belkin, Q. J. Wang, C. Pflügl, A. Belyanin, S. P. Khanna, A. G. Davies, E. H. Linfield, and F. Capasso, “High-temperature operation of terahertz quantum cascade laser sources,” IEEE Sel. Top. Quantum Electron. 15, 952–967 (2009).
[CrossRef]

M. A. Belkin, J. A. Fan, S. Hormoz, F. Capasso, S. P. Khanna, M. Lachab, A. G. Davies, and E. H. Linfield, “Terahertz quantum cascade lasers with copper metal-metal waveguides operating up to 178 K,” Opt. Express 16, 3242–3248 (2008).
[CrossRef] [PubMed]

R. Kohler, A. Tredicucci, F. Beltram, H. E. Beere, E. H. Linfield, A. G. Davies, D. Ritchie, R. C. Iotti, and F. Rossi, “Terahertz semiconductor-heterostructure laser,” Nature 417, 156–159 (2002).
[CrossRef] [PubMed]

Liu, H.

S. Fathololoumi, E. Dupont, S.R. Laframboise, Z. R. Wasilewski, D. Ban, and H. Liu, “Design of laser transition oscillator strength for THz quantum cascade lasers,” Presented at Conference on Lasers and Electro-Optics, Baltimore, MD (2011).

Liu, H. C.

S. Fathololoumi, E. Dupont, S. G. Razavipour, S. R. Laframboise, G. Parent, Z. Wasilewski, H. C. Liu, and D. Ban, “On metal contacts of terahertz quantum-cascade lasers with a metal-metal waveguide,” Semicond. Sci. Technol. 26, 105021 (2011).
[CrossRef]

E. Dupont, S. Fathololoumi, and H. C. Liu, “Simplified density matrix model applied to three-well terahertz quantum cascade lsers,” Phys. Rev. B 81, 205311 (2010).
[CrossRef]

S. Fathololoumi, E. Dupont, D. Ban, M. Graf, S. R. Laframboise, Z. Wasilewski, and H. C. Liu, “Time-resolved thermal quenching of THz quantum cascade lasers,” IEEE J. Quantum Electron 46, 396–404 (2010).
[CrossRef]

S. Fathololoumi, D. Ban, H. Luo, E. Dupont, S. R. Laframboise, A. Boucherif, and H. C. Liu, “Thermal behavior investigation of terahertz quantum-cascade lasers,” IEEE J. Quantum Electron. 44, 1139–1144 (2008).
[CrossRef]

H. Luo, S. R. Laframboise, Z. R. Wasilewski, H. C. Liu, and J. C. Cao, “Effects of extraction barrier width on performance of terahertz quantum-cascade lasers,” IEEE Electron. Lett. 44, 630–631 (2008).
[CrossRef]

H. Luo, S. R. Laframboise, Z. R. Wasilewski, and H. C. Liu, “Effects of injector barrier on performance of terahertz quantum-cascade lasers,” IEEE Electron. Lett. 43, 633–635 (2007).
[CrossRef]

H. Luo, S. R. Laframboise, Z. R. Wasilewski, and H. C. Liu, “Terahertz quantum cascade lasers based on a three-well active module,” Appl. Phys. Lett. 90, 041112 (2007).
[CrossRef]

S. Fathololoumi, E. Dupont, Z. R. Wasilewski, S. R. Laframboise, D. Ban, and H. C. Liu, “Effect of intermediate resonance on the performance of resonant phonon based terahertz quantum cascade laser,” Presented at 11th International Conference on Intersubband Transitions in Quantum Wells, Badesi, Italy (2011).

C. W. I. Chan, S. Fathololoumi, E. Dupont, Z. R. Wasilewski, S. R. Laframboise, D. Ban, Q. Hu, and H. C. Liu, “A terahertz quantum cascade laser operating up to 193 K,” Presented at 11th International Conference on Intersubband Transitions in Quantum Wells, Badesi, Italy (2011).

Lugli, P.

A. Mátyás, P. Lugli, and C. Jirauschek, “Photon-induced carrier transport in high efficiency midinfrared quantum cascade lasers,” J. Appl. Phys. 110, 013108 (2011).
[CrossRef]

A. Mátyás, T. Kubis, P. Lugli, and C. Jirauschek, “Comparison between semiclassical and full quantum transport analysis of THz quantum cascade lasers,” Physica E 42, 2628 (2010).
[CrossRef]

A. Mátyás, M. A. Belkin, P. Lugli, and C. Jirauschek, “Temperature performance analysis of terahertz quantum cascade lasers: Vertical versus diagonal designs,” Appl. Phys. Lett. 96, 201110 (2010).
[CrossRef]

C. Jirauschek and P. Lugli, “Monte-Carlo-based spectral gain analysis for terahertz quantum cascade lasers,” J. Appl. Phys. 105, 123102 (2009).
[CrossRef]

Luo, H.

S. Fathololoumi, D. Ban, H. Luo, E. Dupont, S. R. Laframboise, A. Boucherif, and H. C. Liu, “Thermal behavior investigation of terahertz quantum-cascade lasers,” IEEE J. Quantum Electron. 44, 1139–1144 (2008).
[CrossRef]

H. Luo, S. R. Laframboise, Z. R. Wasilewski, H. C. Liu, and J. C. Cao, “Effects of extraction barrier width on performance of terahertz quantum-cascade lasers,” IEEE Electron. Lett. 44, 630–631 (2008).
[CrossRef]

H. Luo, S. R. Laframboise, Z. R. Wasilewski, and H. C. Liu, “Effects of injector barrier on performance of terahertz quantum-cascade lasers,” IEEE Electron. Lett. 43, 633–635 (2007).
[CrossRef]

H. Luo, S. R. Laframboise, Z. R. Wasilewski, and H. C. Liu, “Terahertz quantum cascade lasers based on a three-well active module,” Appl. Phys. Lett. 90, 041112 (2007).
[CrossRef]

Mátyás, A.

A. Mátyás, P. Lugli, and C. Jirauschek, “Photon-induced carrier transport in high efficiency midinfrared quantum cascade lasers,” J. Appl. Phys. 110, 013108 (2011).
[CrossRef]

A. Mátyás, T. Kubis, P. Lugli, and C. Jirauschek, “Comparison between semiclassical and full quantum transport analysis of THz quantum cascade lasers,” Physica E 42, 2628 (2010).
[CrossRef]

A. Mátyás, M. A. Belkin, P. Lugli, and C. Jirauschek, “Temperature performance analysis of terahertz quantum cascade lasers: Vertical versus diagonal designs,” Appl. Phys. Lett. 96, 201110 (2010).
[CrossRef]

Parent, G.

S. Fathololoumi, E. Dupont, S. G. Razavipour, S. R. Laframboise, G. Parent, Z. Wasilewski, H. C. Liu, and D. Ban, “On metal contacts of terahertz quantum-cascade lasers with a metal-metal waveguide,” Semicond. Sci. Technol. 26, 105021 (2011).
[CrossRef]

Pfeiffer, L.

J. Faist, F. Capasso, A. L. Hutchinson, L. Pfeiffer, and K. W. West, “Suppression of optical absorption by electric-field-induced quantum interference in coupled potential wells,” Phys. Rev. Lett. 71, 3573–3576 (1993).
[CrossRef] [PubMed]

Pflügl, C.

M. A. Belkin, Q. J. Wang, C. Pflügl, A. Belyanin, S. P. Khanna, A. G. Davies, E. H. Linfield, and F. Capasso, “High-temperature operation of terahertz quantum cascade laser sources,” IEEE Sel. Top. Quantum Electron. 15, 952–967 (2009).
[CrossRef]

Razavipour, S. G.

S. Fathololoumi, E. Dupont, S. G. Razavipour, S. R. Laframboise, G. Parent, Z. Wasilewski, H. C. Liu, and D. Ban, “On metal contacts of terahertz quantum-cascade lasers with a metal-metal waveguide,” Semicond. Sci. Technol. 26, 105021 (2011).
[CrossRef]

Reno, J. L.

S. Kumar, C. W. I. Chan, Q. Hu, and J. L. Reno, “A 1.8-THz quantum cascade laser operating significantly above the temperature of ħω/κB,” Nat. Phys. 7, 166–171 (2011).
[CrossRef]

S. Kumar, Q. Hu, and J. L. Reno, “186 K operation of terahertz quantum cascade lasers based on a diagonal design,” Appl. Phys. Lett. 94, 131105 (2009).
[CrossRef]

S. Kumar, C. W. I. Chan, Q. Hu, and J. L. Reno, “Two-well terahertz quantum-cascade laser with direct intrawellphonon depopulation,” Appl. Phys. Lett. 95, 141110 (2009).
[CrossRef]

Q. Hu, B. S. Williams, S. Kumar, H. Callebaut, S. Kohen, and J. L. Reno, “Resonant-phonon-assisted THz quantum-cascade lasers with metal–metal waveguides,” Semicond. Sci. Technol. 20, S228–S236 (2005).
[CrossRef]

B. S. Williams, S. Kumar, Q. Hu, and J. L. Reno, “Operation of terahertz quantum-cascade lasers at 164 K in pulsed mode and at 117 K in continuous-wave mode,” Opt. Express 13, 3331–3339 (2005).
[CrossRef] [PubMed]

B. S. Williams, H. Callebaut, S. Kumar, Q. Hu, and J. L. Reno, “THz quantum cascade laser at λ ≈ 100 μm using metal waveguide for mode confinement,” Appl. Phys. Lett. 83, 2124–2126 (2003).
[CrossRef]

H. Callebaut, S. Kumar, B.S. Williams, Q. Hu, and J. L. Reno, “Analysis of transport properties of terahertz quantum cascade lasers,” Appl. Phys. Lett. 83, 207–209 (2003).
[CrossRef]

Ritchie, D.

R. Kohler, A. Tredicucci, F. Beltram, H. E. Beere, E. H. Linfield, A. G. Davies, D. Ritchie, R. C. Iotti, and F. Rossi, “Terahertz semiconductor-heterostructure laser,” Nature 417, 156–159 (2002).
[CrossRef] [PubMed]

Rossi, F.

R. Kohler, A. Tredicucci, F. Beltram, H. E. Beere, E. H. Linfield, A. G. Davies, D. Ritchie, R. C. Iotti, and F. Rossi, “Terahertz semiconductor-heterostructure laser,” Nature 417, 156–159 (2002).
[CrossRef] [PubMed]

Scalari, G.

G. Scalari, M. I. Amanti, C. Walther, R. Terazzi, M. Beck, and J. Faist, “Broadband THz lasing from a photon-phonon quantum cascade structure,” Opt. Express 8, 8043–8052 (2010).
[CrossRef]

L. A. Dunbar, R. Houdré, G. Scalari, L. Sirigu, M. Giovannini, and J. Faist, “Small optical volume terahertz emitting microdisk quantum cascade lasers,” Appl. Phys. Lett. 90, 141114 (2007).
[CrossRef]

Sirigu, L.

L. A. Dunbar, R. Houdré, G. Scalari, L. Sirigu, M. Giovannini, and J. Faist, “Small optical volume terahertz emitting microdisk quantum cascade lasers,” Appl. Phys. Lett. 90, 141114 (2007).
[CrossRef]

Terazzi, R.

G. Scalari, M. I. Amanti, C. Walther, R. Terazzi, M. Beck, and J. Faist, “Broadband THz lasing from a photon-phonon quantum cascade structure,” Opt. Express 8, 8043–8052 (2010).
[CrossRef]

Terrazi, R.

R. Terrazi and J. Faist, “A density matrix model of transport and radiation in quantum cascade lasers,” New J. Phys. 12, 033045 (2010).
[CrossRef]

Tredicucci, A.

R. Kohler, A. Tredicucci, F. Beltram, H. E. Beere, E. H. Linfield, A. G. Davies, D. Ritchie, R. C. Iotti, and F. Rossi, “Terahertz semiconductor-heterostructure laser,” Nature 417, 156–159 (2002).
[CrossRef] [PubMed]

Vijayraghavan, K.

R. W. Adams, K. Vijayraghavan, Q. J. Wang, J. Fan, F. Capasso, S. P. Khanna, A. G. Davies, E. H. Linfield, and M. A. Belkin, “GaAs/Al0.15Ga0.85As terahertz quantum cascade lasers with double-phonon resonant depopulation operating up to 172 K,” Appl. Phys. Lett. 97, 131111 (2010).
[CrossRef]

Vogl, P.

T. Kubis, C. Yeh, P. Vogl, A. Benz, G. Fasching, and C. Deutsch, “Theory of nonequilibrium quantum transport and energy dissipation in terahertz quantum cascade lasers,” Phys. Rev. B 79, 195323 (2009).
[CrossRef]

Wacker, A.

A. Wacker, “Extraction-controlled quantum cascade lasers,” Appl. Phys. Lett. 97, 081105 (2010).
[CrossRef]

C. Weber, A. Wacker, and A. Knorr, “Density-matrix theory of the optical dynamics and transport in quantum cascade structures: the role of coherence,” Phys. Rev. B 79, 165322 (2007).
[CrossRef]

S. C. Lee and A. Wacker, “Nonequilibrium Greens function theory for transport and gain properties of quantum cascade structures,” Phys. Rev. B 66, 245314 (2002).
[CrossRef]

Walther, C.

G. Scalari, M. I. Amanti, C. Walther, R. Terazzi, M. Beck, and J. Faist, “Broadband THz lasing from a photon-phonon quantum cascade structure,” Opt. Express 8, 8043–8052 (2010).
[CrossRef]

Wang, Q. J.

R. W. Adams, K. Vijayraghavan, Q. J. Wang, J. Fan, F. Capasso, S. P. Khanna, A. G. Davies, E. H. Linfield, and M. A. Belkin, “GaAs/Al0.15Ga0.85As terahertz quantum cascade lasers with double-phonon resonant depopulation operating up to 172 K,” Appl. Phys. Lett. 97, 131111 (2010).
[CrossRef]

M. A. Belkin, Q. J. Wang, C. Pflügl, A. Belyanin, S. P. Khanna, A. G. Davies, E. H. Linfield, and F. Capasso, “High-temperature operation of terahertz quantum cascade laser sources,” IEEE Sel. Top. Quantum Electron. 15, 952–967 (2009).
[CrossRef]

Wasilewski, Z.

S. Fathololoumi, E. Dupont, S. G. Razavipour, S. R. Laframboise, G. Parent, Z. Wasilewski, H. C. Liu, and D. Ban, “On metal contacts of terahertz quantum-cascade lasers with a metal-metal waveguide,” Semicond. Sci. Technol. 26, 105021 (2011).
[CrossRef]

S. Fathololoumi, E. Dupont, D. Ban, M. Graf, S. R. Laframboise, Z. Wasilewski, and H. C. Liu, “Time-resolved thermal quenching of THz quantum cascade lasers,” IEEE J. Quantum Electron 46, 396–404 (2010).
[CrossRef]

Wasilewski, Z. R.

H. Luo, S. R. Laframboise, Z. R. Wasilewski, H. C. Liu, and J. C. Cao, “Effects of extraction barrier width on performance of terahertz quantum-cascade lasers,” IEEE Electron. Lett. 44, 630–631 (2008).
[CrossRef]

H. Luo, S. R. Laframboise, Z. R. Wasilewski, and H. C. Liu, “Effects of injector barrier on performance of terahertz quantum-cascade lasers,” IEEE Electron. Lett. 43, 633–635 (2007).
[CrossRef]

H. Luo, S. R. Laframboise, Z. R. Wasilewski, and H. C. Liu, “Terahertz quantum cascade lasers based on a three-well active module,” Appl. Phys. Lett. 90, 041112 (2007).
[CrossRef]

S. Fathololoumi, E. Dupont, S.R. Laframboise, Z. R. Wasilewski, D. Ban, and H. Liu, “Design of laser transition oscillator strength for THz quantum cascade lasers,” Presented at Conference on Lasers and Electro-Optics, Baltimore, MD (2011).

S. Fathololoumi, E. Dupont, Z. R. Wasilewski, S. R. Laframboise, D. Ban, and H. C. Liu, “Effect of intermediate resonance on the performance of resonant phonon based terahertz quantum cascade laser,” Presented at 11th International Conference on Intersubband Transitions in Quantum Wells, Badesi, Italy (2011).

C. W. I. Chan, S. Fathololoumi, E. Dupont, Z. R. Wasilewski, S. R. Laframboise, D. Ban, Q. Hu, and H. C. Liu, “A terahertz quantum cascade laser operating up to 193 K,” Presented at 11th International Conference on Intersubband Transitions in Quantum Wells, Badesi, Italy (2011).

Weber, C.

C. Weber, A. Wacker, and A. Knorr, “Density-matrix theory of the optical dynamics and transport in quantum cascade structures: the role of coherence,” Phys. Rev. B 79, 165322 (2007).
[CrossRef]

West, K. W.

J. Faist, F. Capasso, A. L. Hutchinson, L. Pfeiffer, and K. W. West, “Suppression of optical absorption by electric-field-induced quantum interference in coupled potential wells,” Phys. Rev. Lett. 71, 3573–3576 (1993).
[CrossRef] [PubMed]

Williams, B. S.

Q. Hu, B. S. Williams, S. Kumar, H. Callebaut, S. Kohen, and J. L. Reno, “Resonant-phonon-assisted THz quantum-cascade lasers with metal–metal waveguides,” Semicond. Sci. Technol. 20, S228–S236 (2005).
[CrossRef]

B. S. Williams, S. Kumar, Q. Hu, and J. L. Reno, “Operation of terahertz quantum-cascade lasers at 164 K in pulsed mode and at 117 K in continuous-wave mode,” Opt. Express 13, 3331–3339 (2005).
[CrossRef] [PubMed]

B. S. Williams, H. Callebaut, S. Kumar, Q. Hu, and J. L. Reno, “THz quantum cascade laser at λ ≈ 100 μm using metal waveguide for mode confinement,” Appl. Phys. Lett. 83, 2124–2126 (2003).
[CrossRef]

Williams, B.S.

H. Callebaut, S. Kumar, B.S. Williams, Q. Hu, and J. L. Reno, “Analysis of transport properties of terahertz quantum cascade lasers,” Appl. Phys. Lett. 83, 207–209 (2003).
[CrossRef]

Yeh, C.

T. Kubis, C. Yeh, P. Vogl, A. Benz, G. Fasching, and C. Deutsch, “Theory of nonequilibrium quantum transport and energy dissipation in terahertz quantum cascade lasers,” Phys. Rev. B 79, 195323 (2009).
[CrossRef]

Appl. Phys. Lett. (9)

H. Luo, S. R. Laframboise, Z. R. Wasilewski, and H. C. Liu, “Terahertz quantum cascade lasers based on a three-well active module,” Appl. Phys. Lett. 90, 041112 (2007).
[CrossRef]

S. Kumar, Q. Hu, and J. L. Reno, “186 K operation of terahertz quantum cascade lasers based on a diagonal design,” Appl. Phys. Lett. 94, 131105 (2009).
[CrossRef]

R. W. Adams, K. Vijayraghavan, Q. J. Wang, J. Fan, F. Capasso, S. P. Khanna, A. G. Davies, E. H. Linfield, and M. A. Belkin, “GaAs/Al0.15Ga0.85As terahertz quantum cascade lasers with double-phonon resonant depopulation operating up to 172 K,” Appl. Phys. Lett. 97, 131111 (2010).
[CrossRef]

S. Kumar, C. W. I. Chan, Q. Hu, and J. L. Reno, “Two-well terahertz quantum-cascade laser with direct intrawellphonon depopulation,” Appl. Phys. Lett. 95, 141110 (2009).
[CrossRef]

A. Wacker, “Extraction-controlled quantum cascade lasers,” Appl. Phys. Lett. 97, 081105 (2010).
[CrossRef]

B. S. Williams, H. Callebaut, S. Kumar, Q. Hu, and J. L. Reno, “THz quantum cascade laser at λ ≈ 100 μm using metal waveguide for mode confinement,” Appl. Phys. Lett. 83, 2124–2126 (2003).
[CrossRef]

H. Callebaut, S. Kumar, B.S. Williams, Q. Hu, and J. L. Reno, “Analysis of transport properties of terahertz quantum cascade lasers,” Appl. Phys. Lett. 83, 207–209 (2003).
[CrossRef]

A. Mátyás, M. A. Belkin, P. Lugli, and C. Jirauschek, “Temperature performance analysis of terahertz quantum cascade lasers: Vertical versus diagonal designs,” Appl. Phys. Lett. 96, 201110 (2010).
[CrossRef]

L. A. Dunbar, R. Houdré, G. Scalari, L. Sirigu, M. Giovannini, and J. Faist, “Small optical volume terahertz emitting microdisk quantum cascade lasers,” Appl. Phys. Lett. 90, 141114 (2007).
[CrossRef]

IEEE Electron. Lett. (2)

H. Luo, S. R. Laframboise, Z. R. Wasilewski, and H. C. Liu, “Effects of injector barrier on performance of terahertz quantum-cascade lasers,” IEEE Electron. Lett. 43, 633–635 (2007).
[CrossRef]

H. Luo, S. R. Laframboise, Z. R. Wasilewski, H. C. Liu, and J. C. Cao, “Effects of extraction barrier width on performance of terahertz quantum-cascade lasers,” IEEE Electron. Lett. 44, 630–631 (2008).
[CrossRef]

IEEE J. Quantum Electron (1)

S. Fathololoumi, E. Dupont, D. Ban, M. Graf, S. R. Laframboise, Z. Wasilewski, and H. C. Liu, “Time-resolved thermal quenching of THz quantum cascade lasers,” IEEE J. Quantum Electron 46, 396–404 (2010).
[CrossRef]

IEEE J. Quantum Electron. (1)

S. Fathololoumi, D. Ban, H. Luo, E. Dupont, S. R. Laframboise, A. Boucherif, and H. C. Liu, “Thermal behavior investigation of terahertz quantum-cascade lasers,” IEEE J. Quantum Electron. 44, 1139–1144 (2008).
[CrossRef]

IEEE Sel. Top. Quantum Electron. (1)

M. A. Belkin, Q. J. Wang, C. Pflügl, A. Belyanin, S. P. Khanna, A. G. Davies, E. H. Linfield, and F. Capasso, “High-temperature operation of terahertz quantum cascade laser sources,” IEEE Sel. Top. Quantum Electron. 15, 952–967 (2009).
[CrossRef]

J. Appl. Phys. (3)

H. Callebaut and Q. Hu, “Importance of coherence for electron transport in terahertz quantum cascade lasers,” J. Appl. Phys. 98, 104505 (2005).
[CrossRef]

C. Jirauschek and P. Lugli, “Monte-Carlo-based spectral gain analysis for terahertz quantum cascade lasers,” J. Appl. Phys. 105, 123102 (2009).
[CrossRef]

A. Mátyás, P. Lugli, and C. Jirauschek, “Photon-induced carrier transport in high efficiency midinfrared quantum cascade lasers,” J. Appl. Phys. 110, 013108 (2011).
[CrossRef]

Nat. Phys. (1)

S. Kumar, C. W. I. Chan, Q. Hu, and J. L. Reno, “A 1.8-THz quantum cascade laser operating significantly above the temperature of ħω/κB,” Nat. Phys. 7, 166–171 (2011).
[CrossRef]

Nature (1)

R. Kohler, A. Tredicucci, F. Beltram, H. E. Beere, E. H. Linfield, A. G. Davies, D. Ritchie, R. C. Iotti, and F. Rossi, “Terahertz semiconductor-heterostructure laser,” Nature 417, 156–159 (2002).
[CrossRef] [PubMed]

New J. Phys. (1)

R. Terrazi and J. Faist, “A density matrix model of transport and radiation in quantum cascade lasers,” New J. Phys. 12, 033045 (2010).
[CrossRef]

Opt. Express (3)

Phys. Rev. B (5)

S. Kumar and Q. Hu, “Coherence of resonant-tunneling transport in terahertz quantum-cascade lasers,” Phys. Rev. B 80, 245316 (2009).
[CrossRef]

E. Dupont, S. Fathololoumi, and H. C. Liu, “Simplified density matrix model applied to three-well terahertz quantum cascade lsers,” Phys. Rev. B 81, 205311 (2010).
[CrossRef]

S. C. Lee and A. Wacker, “Nonequilibrium Greens function theory for transport and gain properties of quantum cascade structures,” Phys. Rev. B 66, 245314 (2002).
[CrossRef]

T. Kubis, C. Yeh, P. Vogl, A. Benz, G. Fasching, and C. Deutsch, “Theory of nonequilibrium quantum transport and energy dissipation in terahertz quantum cascade lasers,” Phys. Rev. B 79, 195323 (2009).
[CrossRef]

C. Weber, A. Wacker, and A. Knorr, “Density-matrix theory of the optical dynamics and transport in quantum cascade structures: the role of coherence,” Phys. Rev. B 79, 165322 (2007).
[CrossRef]

Phys. Rev. Lett. (1)

J. Faist, F. Capasso, A. L. Hutchinson, L. Pfeiffer, and K. W. West, “Suppression of optical absorption by electric-field-induced quantum interference in coupled potential wells,” Phys. Rev. Lett. 71, 3573–3576 (1993).
[CrossRef] [PubMed]

Physica E (1)

A. Mátyás, T. Kubis, P. Lugli, and C. Jirauschek, “Comparison between semiclassical and full quantum transport analysis of THz quantum cascade lasers,” Physica E 42, 2628 (2010).
[CrossRef]

Semicond. Sci. Technol. (2)

Q. Hu, B. S. Williams, S. Kumar, H. Callebaut, S. Kohen, and J. L. Reno, “Resonant-phonon-assisted THz quantum-cascade lasers with metal–metal waveguides,” Semicond. Sci. Technol. 20, S228–S236 (2005).
[CrossRef]

S. Fathololoumi, E. Dupont, S. G. Razavipour, S. R. Laframboise, G. Parent, Z. Wasilewski, H. C. Liu, and D. Ban, “On metal contacts of terahertz quantum-cascade lasers with a metal-metal waveguide,” Semicond. Sci. Technol. 26, 105021 (2011).
[CrossRef]

Other (6)

S. Kumar, “Development of terahertz quantum-cascade lasers,” Massachusetts Institute of Technology163–166 (2007).

C. W. I. Chan, S. Fathololoumi, E. Dupont, Z. R. Wasilewski, S. R. Laframboise, D. Ban, Q. Hu, and H. C. Liu, “A terahertz quantum cascade laser operating up to 193 K,” Presented at 11th International Conference on Intersubband Transitions in Quantum Wells, Badesi, Italy (2011).

The waveguide loss of 22.1 cm−1 was calculated for the Au-Au device without the top n+ layer (∼ 170 μm wide and 1.98 mm long). The estimated cavity loss is, therefore, reduced for ∼ 3 cm−1 (1.9 cm−1 from the waveguide loss and 1.1 cm−1 from the mirror loss), as compared to the estimated cavity loss of the Au-Au device with the top n+ layer (∼ 144 μm wide and 1 mm long), lasing up to 180 K. The MC simulations at 12.8 kV/cm and 3.22 THz showed a gain reduction of ∼ 4 cm−1.

S. Fathololoumi, E. Dupont, S.R. Laframboise, Z. R. Wasilewski, D. Ban, and H. Liu, “Design of laser transition oscillator strength for THz quantum cascade lasers,” Presented at Conference on Lasers and Electro-Optics, Baltimore, MD (2011).

For the density matrix calculations, the electron temperature was chosen 90 K higher than lattice. Pure dephasing time constants of tunneling τ* = 0.35 ps, and of optical intersubband transition τul*=1.1 ps were used. Intrawell intersubband scatterings by LO phonon, e-impurities and interface roughness were considered. The momentum dependance of scattering is averaged over the assumed Maxwell-Boltzmann distribution of carriers in the sub-bands.

S. Fathololoumi, E. Dupont, Z. R. Wasilewski, S. R. Laframboise, D. Ban, and H. C. Liu, “Effect of intermediate resonance on the performance of resonant phonon based terahertz quantum cascade laser,” Presented at 11th International Conference on Intersubband Transitions in Quantum Wells, Badesi, Italy (2011).

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Figures (5)

Fig. 1
Fig. 1

a) Conduction band diagram of the designed THz QCL with ful = 0.475, in isolated-well picture at 12.2 kV/cm, b) Contour plot of gain spectra (unit of cm−1) for different electric fields at a lattice temperature of 10 K. The line with crosses represents the energy difference between upper (g) and lower (l) lasing states as a function of electric field. Doping level is 3 × 1010 cm−2.

Fig. 2
Fig. 2

Conduction band diagram and squared moduli of wavefunctions of the optimized ful = 0.475 THz QCL at the design electric field of 12.2 kV/cm. It consists of three wells and three barriers with the layer thicknesses of 43/89/24.6/81.5/41/160 Å starting from injector barrier - the barriers are indicated in bold fonts.

Fig. 3
Fig. 3

Collected THz light (optical output power) versus current density at different heat sink temperatures, for the THz QCL with ful = 0.475. For comparison, the thicker and thinner lines are the LI curves of the Cu-Cu (lased up to 199.5 K, 170 × 1800 μm2 in dimension) and Au-Au (lased up to 180 K, 144 × 1000 μm2 in dimension) devices, respectively. Since the two devices are not measured in the same optical setup, the waveguide loss difference can not be estimated from the external differential efficiencies. The curves with a horizontal left arrow are the voltage-current density characteristics of the Cu-Cu based laser without (w/o) the top n+ layer at 8 K and of the Au-Au-based laser with (w/) this layer at 9 K and 180 K. The insets show the spectra of the Cu-Cu based lasing device, at 8 K and 199.5 K, and the threshold current density versus temperature for two devices.

Fig. 4
Fig. 4

Energy spacing between various extended wavefunctions in the designed THz QCL. The width of each curve at each point represents the corresponding oscillator strengths.

Fig. 5
Fig. 5

Spectra of the lasing device at various current densities at 10 K (a to d), 150 K (e and f), and 199.5 K (g), along with the comparison with the calculated gain spectra using MC simulation. The corresponding measured current density along with the simulated bias values are indicated within each plot, assuming 0.8 V Schottky voltage drop across the top contact. Plots (a) to (f) show the laser spectra for the Au-Au device with the top n+ GaAs contact layer (Tmax = 180 K); plot (g) shows the laser spectra for the Cu-Cu device (Tmax = 199.5 K). The vertical scales for all plots are the same.

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