Abstract

We demonstrate an In0.635Al0.356As/In0.678Ga0.322As strain compensated quantum cascade laser that employs heterogeneous injector regions for low voltage defect operation. The active core consists of interdigitated undoped and doped injectors followed by nominally identical wavelength optical transitions. The undoped injector regions are designed with reduced voltage defect while the doped injectors are of a more conventional design. The measured average voltage defect is less than 79 meV. At 80 K, a 2.3 mm long, back facet high reflectance coated laser has an emission wavelength of 4.7 µm and outputs 2.3 W pulsed power with a peak wall-plug efficiency of 19%.

© 2007 Optical Society of America

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  1. J. Faist, F. Capasso, D.L. Sivco, C. Sirtori, A.L. Hutchinson, and A.Y. Cho, "Quantum cascade laser," Science 264, 553 - 556 (1994).
    [CrossRef] [PubMed]
  2. M. Beck, D. Hofstetter, T. Aellen, J. Faist, U. Oesterle, M. Ilegems, E. Gini, and H. Melchior, "Continuous wave operation of a midinfrared semiconductor laser at room temperature," Science 295, 301 - 305 (2002).
    [CrossRef] [PubMed]
  3. C. Gmachl, D.L. Sivco, R. Colombelli, F. Capasso, and A.Y. Cho, "Ultra-broadband semiconductor laser," Nature 415, 883 - 887 (2002).
    [CrossRef] [PubMed]
  4. A. Tredicucci, C. Gmachl, F. Capasso, D.L. Sivco, A.L. Hutchinson, and A.Y. Cho, "A multiwavelength semiconductor laser," Nature 396, 350-353 (1998).
    [CrossRef]
  5. C. Gmachl, D.L. Sivco, J.N. Baillargeon, A.L. Hutchinson, F. Capasso, and A.Y. Cho, "Quantum cascade lasers with a heterogeneous cascade: Two-wavelength operation," Appl. Phys. Lett. 79, 572 - 574 (2001).
    [CrossRef]
  6. A. Straub, T.S. Mosely, C. Gmachl, R. Colombelli, M. Troccoli, F. Capasso, D.L. Sivco, and A.Y. Cho, "Threshold reduction in quantum cascade lasers with partially undoped, dual-wavelength interdigitated cascades," Appl. Phys. Lett. 80, 2845 -2847 (2002).
    [CrossRef]
  7. I. Vurgaftman and J.R. Meyer, "Analysis of limitations to wallplug efficiency and output power from quantum cascade lasers," J. Appl. Phys. 99, 123108 (2006).
    [CrossRef]
  8. J. Faist, "Wallplug efficiency of quantum cascade lasers: Critical parameters and fundamental limits," Appl. Phys. Lett. 90, 253512 (2007).
    [CrossRef]
  9. Z. Liu, Princeton University, Department of Electrical Engineering, Princeton, NJ 08544, and C. Gmachl, L. Cheng, F. Choa, F.J. Towner, X. Wang, and J. Fan have submitted a manuscript called "Temperature dependence of optical gain and loss in λ ≈ 8.2 - 10.2 μm quantum cascade lasers," to IEEE J. Quantum Elect.
  10. J. Nguyen, J.S. Yu, A. Evans, S. Slivken, and M. Razeghi, "Optical coatings by ion-beam sputtering deposition for long-wave infrared quantum cascade lasers," Appl. Phys. Lett. 89, 111113 (2006).
    [CrossRef]
  11. A. Tsekoun, R. Go, M. Pushkarsky, M. Razeghi, and C.K.N. Patel, "Improved performance of quantum cascade lasers through a scalable, manufacturable epitaxial-side-down mountin process," PNAS 103, 4831 - 4835 (2006).
    [CrossRef] [PubMed]
  12. A. Evans, S.R. Darvish, S. Slivken, J. Nguyen, Y. Bai, and M. Razeghi, "Buried heterostructure quantum cascade lasers with high continuous-wave wall plug efficiency," Appl. Phys. Lett. 91, 071101 (2007).
    [CrossRef]
  13. J.S. Yu, S.R. Darvish, A. Evans, J. Nguyen, S. Slivken, and M. Razeghi, "Room-temperature continuous-wave operation of quantum-cascade lasers at λ ~ 4 μm " Appl. Phys. Lett. 88, 041111 (2006).
    [CrossRef]
  14. A. Evans, J.S. Yu, J. David, L. Doris, K. Mi, S. Slivken, and M. Razeghi, "High-temperature, high-power, continuous-wave operation of buried heterostructure quantum-cascade lasers," Appl. Phys. Lett. 84, 314 - 316 (2004).
    [CrossRef]
  15. A. Evans, J.S. Yu, S. Slivken, and M. Razeghi, "Continuous-wave operation of λ ~ 4.8 μm quantum-cascade lasers at room temperature," Appl. Phys. Lett. 85, 2166 -2168 (2004).
    [CrossRef]

2007

J. Faist, "Wallplug efficiency of quantum cascade lasers: Critical parameters and fundamental limits," Appl. Phys. Lett. 90, 253512 (2007).
[CrossRef]

A. Evans, S.R. Darvish, S. Slivken, J. Nguyen, Y. Bai, and M. Razeghi, "Buried heterostructure quantum cascade lasers with high continuous-wave wall plug efficiency," Appl. Phys. Lett. 91, 071101 (2007).
[CrossRef]

2006

J.S. Yu, S.R. Darvish, A. Evans, J. Nguyen, S. Slivken, and M. Razeghi, "Room-temperature continuous-wave operation of quantum-cascade lasers at λ ~ 4 μm " Appl. Phys. Lett. 88, 041111 (2006).
[CrossRef]

J. Nguyen, J.S. Yu, A. Evans, S. Slivken, and M. Razeghi, "Optical coatings by ion-beam sputtering deposition for long-wave infrared quantum cascade lasers," Appl. Phys. Lett. 89, 111113 (2006).
[CrossRef]

A. Tsekoun, R. Go, M. Pushkarsky, M. Razeghi, and C.K.N. Patel, "Improved performance of quantum cascade lasers through a scalable, manufacturable epitaxial-side-down mountin process," PNAS 103, 4831 - 4835 (2006).
[CrossRef] [PubMed]

I. Vurgaftman and J.R. Meyer, "Analysis of limitations to wallplug efficiency and output power from quantum cascade lasers," J. Appl. Phys. 99, 123108 (2006).
[CrossRef]

2004

A. Evans, J.S. Yu, J. David, L. Doris, K. Mi, S. Slivken, and M. Razeghi, "High-temperature, high-power, continuous-wave operation of buried heterostructure quantum-cascade lasers," Appl. Phys. Lett. 84, 314 - 316 (2004).
[CrossRef]

A. Evans, J.S. Yu, S. Slivken, and M. Razeghi, "Continuous-wave operation of λ ~ 4.8 μm quantum-cascade lasers at room temperature," Appl. Phys. Lett. 85, 2166 -2168 (2004).
[CrossRef]

2002

A. Straub, T.S. Mosely, C. Gmachl, R. Colombelli, M. Troccoli, F. Capasso, D.L. Sivco, and A.Y. Cho, "Threshold reduction in quantum cascade lasers with partially undoped, dual-wavelength interdigitated cascades," Appl. Phys. Lett. 80, 2845 -2847 (2002).
[CrossRef]

M. Beck, D. Hofstetter, T. Aellen, J. Faist, U. Oesterle, M. Ilegems, E. Gini, and H. Melchior, "Continuous wave operation of a midinfrared semiconductor laser at room temperature," Science 295, 301 - 305 (2002).
[CrossRef] [PubMed]

C. Gmachl, D.L. Sivco, R. Colombelli, F. Capasso, and A.Y. Cho, "Ultra-broadband semiconductor laser," Nature 415, 883 - 887 (2002).
[CrossRef] [PubMed]

2001

C. Gmachl, D.L. Sivco, J.N. Baillargeon, A.L. Hutchinson, F. Capasso, and A.Y. Cho, "Quantum cascade lasers with a heterogeneous cascade: Two-wavelength operation," Appl. Phys. Lett. 79, 572 - 574 (2001).
[CrossRef]

1998

A. Tredicucci, C. Gmachl, F. Capasso, D.L. Sivco, A.L. Hutchinson, and A.Y. Cho, "A multiwavelength semiconductor laser," Nature 396, 350-353 (1998).
[CrossRef]

1994

J. Faist, F. Capasso, D.L. Sivco, C. Sirtori, A.L. Hutchinson, and A.Y. Cho, "Quantum cascade laser," Science 264, 553 - 556 (1994).
[CrossRef] [PubMed]

Appl. Phys. Lett.

C. Gmachl, D.L. Sivco, J.N. Baillargeon, A.L. Hutchinson, F. Capasso, and A.Y. Cho, "Quantum cascade lasers with a heterogeneous cascade: Two-wavelength operation," Appl. Phys. Lett. 79, 572 - 574 (2001).
[CrossRef]

A. Straub, T.S. Mosely, C. Gmachl, R. Colombelli, M. Troccoli, F. Capasso, D.L. Sivco, and A.Y. Cho, "Threshold reduction in quantum cascade lasers with partially undoped, dual-wavelength interdigitated cascades," Appl. Phys. Lett. 80, 2845 -2847 (2002).
[CrossRef]

J. Faist, "Wallplug efficiency of quantum cascade lasers: Critical parameters and fundamental limits," Appl. Phys. Lett. 90, 253512 (2007).
[CrossRef]

A. Evans, S.R. Darvish, S. Slivken, J. Nguyen, Y. Bai, and M. Razeghi, "Buried heterostructure quantum cascade lasers with high continuous-wave wall plug efficiency," Appl. Phys. Lett. 91, 071101 (2007).
[CrossRef]

J.S. Yu, S.R. Darvish, A. Evans, J. Nguyen, S. Slivken, and M. Razeghi, "Room-temperature continuous-wave operation of quantum-cascade lasers at λ ~ 4 μm " Appl. Phys. Lett. 88, 041111 (2006).
[CrossRef]

A. Evans, J.S. Yu, J. David, L. Doris, K. Mi, S. Slivken, and M. Razeghi, "High-temperature, high-power, continuous-wave operation of buried heterostructure quantum-cascade lasers," Appl. Phys. Lett. 84, 314 - 316 (2004).
[CrossRef]

A. Evans, J.S. Yu, S. Slivken, and M. Razeghi, "Continuous-wave operation of λ ~ 4.8 μm quantum-cascade lasers at room temperature," Appl. Phys. Lett. 85, 2166 -2168 (2004).
[CrossRef]

J. Nguyen, J.S. Yu, A. Evans, S. Slivken, and M. Razeghi, "Optical coatings by ion-beam sputtering deposition for long-wave infrared quantum cascade lasers," Appl. Phys. Lett. 89, 111113 (2006).
[CrossRef]

J. Appl. Phys.

I. Vurgaftman and J.R. Meyer, "Analysis of limitations to wallplug efficiency and output power from quantum cascade lasers," J. Appl. Phys. 99, 123108 (2006).
[CrossRef]

Nature

C. Gmachl, D.L. Sivco, R. Colombelli, F. Capasso, and A.Y. Cho, "Ultra-broadband semiconductor laser," Nature 415, 883 - 887 (2002).
[CrossRef] [PubMed]

A. Tredicucci, C. Gmachl, F. Capasso, D.L. Sivco, A.L. Hutchinson, and A.Y. Cho, "A multiwavelength semiconductor laser," Nature 396, 350-353 (1998).
[CrossRef]

PNAS

A. Tsekoun, R. Go, M. Pushkarsky, M. Razeghi, and C.K.N. Patel, "Improved performance of quantum cascade lasers through a scalable, manufacturable epitaxial-side-down mountin process," PNAS 103, 4831 - 4835 (2006).
[CrossRef] [PubMed]

Science

J. Faist, F. Capasso, D.L. Sivco, C. Sirtori, A.L. Hutchinson, and A.Y. Cho, "Quantum cascade laser," Science 264, 553 - 556 (1994).
[CrossRef] [PubMed]

M. Beck, D. Hofstetter, T. Aellen, J. Faist, U. Oesterle, M. Ilegems, E. Gini, and H. Melchior, "Continuous wave operation of a midinfrared semiconductor laser at room temperature," Science 295, 301 - 305 (2002).
[CrossRef] [PubMed]

Other

Z. Liu, Princeton University, Department of Electrical Engineering, Princeton, NJ 08544, and C. Gmachl, L. Cheng, F. Choa, F.J. Towner, X. Wang, and J. Fan have submitted a manuscript called "Temperature dependence of optical gain and loss in λ ≈ 8.2 - 10.2 μm quantum cascade lasers," to IEEE J. Quantum Elect.

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Figures (5)

Fig. 1.
Fig. 1.

A portion of the conduction band structure with the moduli squared of the relevant wavefunctions. The optical transitions with design energies of 283 meV are denoted by the vertical black arrows. The doped and undoped injector regions are marked by the letters A and B, respectively. The shaded green and blue regions in the band diagram show the voltage defect for the two injectors. The extraction barrier marked “*”, indicates the first barrier for the design sequence detailed in the main text. The calculation is for an applied electric field of 82 kV/cm.

Fig. 2.
Fig. 2.

(a). Pulsed EL spectra at 80 K from cleaved mesas as a function of current. Various pulse widths, 100 ns to 4 µs, at a repetition rate of 79.9 kHz were used for the measurements. The inset shows a current-voltage plot for the same device at 80 K. (b) Spectral peak position (squares) and full width at half maximum (circles) of the fit Lorentzians versus applied current. The red data points are attributed to optical transitions following the undoped injectors and the black data points are attributed to optical transitions following the conventional injectors. The inset shows a characteristic double-peak Lorentzian fit of an EL spectrum.

Fig. 3.
Fig. 3.

(a) Light-current measurements for a 15 µm wide, 1.23 mm long laser at different temperatures. The current-voltage curve for the laser at 80 K is also plotted. The inset shows the lasing spectrum of the device at room temperature and 1.1 times the threshold current. (b) Pulsed threshold current density, Jth , as a function of the heat sink temperature. The experimental data (squares), excluding 80 K, were fit with an exponential (dashed line), Jth=Jo exp(T/To), resulting in To =140 K.

Fig. 4.
Fig. 4.

(a) Peak power (dashed) and wall-plug efficiency (solid) for the best performing, as-cleaved laser (15 µm×1.44 mm). The device was operated with 90 ns pulses at a repetition rate of 5 kHz. The peak wall-plug efficiency (WPE) occurs at 5.6 kA/cm2 is 14 % with a power of 2.0 W. (b) Peak WPE (black squares), peak power (red triangles), and power at peak WPE (red circles) as a function of temperature for the laser presented in Fig. 3(a).

Fig. 5.
Fig. 5.

(a) Pulsed wall-plug efficiency collected from one facet for several lasers versus cavity length. The black squares are for uncoated lasers and the red squares are for select devices that were HR coated on the back facet after initial as-cleaved measurements (filled black squares). (b) Measured pulsed threshold current density versus reciprocal cavity length at 80 K (filled squares). The dashed line is the result of a linear least squares fit.

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