Abstract

We report on quantum cascade lasers employing waveguides based on a predominant air confinement mechanism in which the active region is located immediately at the device top surface. The lasers employ ridge-waveguide resonators with narrow lateral electrical contacts only, with a large, central top region not covered by metallization layers. Devices based on this principle have been reported in the past; however, they employed a thick, doped top-cladding layer in order to allow for uniform current injection. We find that the in-plane conductivity of the active region - when the material used is of high quality - provides adequate electrical injection. As a consequence, the devices demonstrated in this work are thinner, and most importantly they can simultaneously support air-guided and surface-plasmon waveguide modes. When the lateral contacts are narrow, the optical mode is mostly located below the air-semiconductor interface. The mode is predominantly air-guided and it leaks from the top surface into the surrounding environment, suggesting that these lasers could be employed for surface-sensing applications. These laser modes are found to operate up to room temperature under pulsed injection, with an emission spectrum centered around λ ≈ 7:66 μm.

© 2007 Optical Society of America

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  1. J. Faist, F. Capasso, D. L. Sivco, C. Sirtori, A. L. Hutchinson, A. Y. Cho, "Quantum cascade laser," Science 264, 553 (1994).
    [CrossRef] [PubMed]
  2. C. Gmachl, F. Capasso, D. L. Sivco, and A. Y. Cho, "Recent progress in quantum cascade lasers and applications," Rep. Progr. in Physics 64, 1533 (2001).
    [CrossRef]
  3. J. Faist and C. Sirtori, in ’Long wavelength infrared semiconductor lasers’ (J. Wiley and Sons, Hoboken, NJ, USA, 2004).
  4. M. Beck, D. Hofstetter, T. Allen, J. Faist, U. Oesterle, M. Ilegems, E. Gini, H. Melchior, "Continuous Wave Operation of a Mid-Infrared Semiconductor Laser at Room Temperature," Science 295, 301 (2002).
    [CrossRef] [PubMed]
  5. J. S. Yu, S. Slivken, A. Evans, L. Doris, and M. Razeghi, "High-power continuous-wave operation of a 6 µm quantum-cascade laser at room temperature," Appl. Phys. Lett. 83, 2503 (2003).
    [CrossRef]
  6. M. Troccoli, D. Bour, S. Corzine, G. Hofler, A. Tandon, D. Mars, D. J. Smith, L. Diehl, and F. Capasso, "Lowthreshold continuous-wave operation of quantum-cascade lasers grown by metalorganic vapor phase epitaxy," Appl. Phys. Lett. 85, 5842 (2004).
    [CrossRef]
  7. G. Wysocki, M. McCurdy, S. So, D. Weidmann, C. Roller, R. F. Curl, and F.K. Tittel, "Pulsed Quantum-Cascade Laser-Based Sensor for Trace-Gas Detection of Carbonyl Sulfide," App. Opt. 43, 6040 (2004).
    [CrossRef]
  8. A. A. Kosterev and F. K. Tittel, "Chemical sensors based on quantum cascade lasers," IEEE J. Quantum Elec. 38, 582 (2002).
    [CrossRef]
  9. D. Erickson, T. Rockwood, T. Emery, A. Scherer, and Demetri Psaltis, "Nanofluidic tuning of photonic crystal circuits," Proc. SPIE 6475, 647513 (2007).
    [CrossRef]
  10. B. Maune, M. Loncar, J. Witzens, M. Hochberg, T. Baehr-Jones, D. Psaltis, A. Scherer, and Y. Qiu, "Liquidcrystal electric tuning of a photonic crystal laser," Appl. Phys. Lett. 85, 360 (2004).
    [CrossRef]
  11. M. Loncar, A. Scherer, and Y. Qiu, "Photonic crystal laser sources for chemical detection," Appl. Phys. Lett. 82, 4648 (2003).
    [CrossRef]
  12. C. Monat, P. Domachuk, and B. J. Eggleton, "Integrated optofluidics: A new river of light," Nature Photon. 1, 106 (2007).
    [CrossRef]
  13. D. Psaltis, S. R. Quake, and C. Yang, "Developing optofluidic technology through the fusion of microfluidics and optics," Nature 442, 381 (2006).
    [CrossRef] [PubMed]
  14. M. Schaden, A. Doninguez-Vidal, and B. Lendl, "Simultaneous measurement of two compounds in aqueous solution with dual quantum cascade laser absorption spectroscopy," Appl. Phys. B 83, 135 (2006).
    [CrossRef]
  15. M. Loncar, B. G. Lee, L. Diehl, M. A. Belkin, F. Capasso, M. Giovannini, J. Faist, and E. Gini, "Design and fabrication of photonic crystal quantum cascade lasers for optofluidics," Opt. Express 15, 4499 (2007).
    [CrossRef] [PubMed]
  16. J. Chen, Z. Liu, C. F. Gmachl, and D. L. Sivco, "Silver halide fiber-based evanescent-wave liquid droplet sensing with room tempreature mid-infrared quantum cascade lasers," Opt. Express 13, 5953 (2005).
    [CrossRef] [PubMed]
  17. C. Charlton, A. Katzir, and B. Mizaikoff, "Infrared Evanescent Field Sensing with Quantum Cascade Lasers and Planar Silver Halide Waveguides," Anal. Chem. 77, 4398 (2005).
    [CrossRef] [PubMed]
  18. R. Perahia, K. Srinivasan, O. Painter, V. Moreau, M. Bahriz, R. Colombelli, F. Capasso, "Quantum cascade photonic crystal lasers: design, fabrication, and applications," CLEO 2006 (CTuAA5), Long Beach CA, May 2006.
  19. R. Perahia, O. Painter, M. Bahriz, V. Moreau, R. Colombelli, "Design of quantum cascade lasers for intra-cavity sensing in the mid infrared," manuscript in preparation.
  20. R. Perahia, O. Painter, V. Moreau, M. Bahriz, R. Colombelli, L.R. Wilson, A.B. Krysa, "Quantum Cascade Microdisk Lasers for Mid Infrared Intra-Cavity Sensing," CLEO 2007 (CTuE5), Baltimore (MA), May 2007.
  21. L. Diehl, B.G. Lee, P. Behroozi, M. Loncar, M.A. Belkin, F. Capasso, T. Aellen, D. Hofstetter, M. Beck, and J. Faist, "Microfluidic tuning of distributed feedback quantum cascade lasers," Opt. Express 14, 11660 (2006).
    [CrossRef] [PubMed]
  22. R. Colombelli, K. Srinivasan, M. Troccoli, O. Painter, C.F. Gmachl, D. M. Tennant, A. M. Sergent, D. L. Sivco, A. Y. Cho, F. Capasso, "Quantum Cascade Surface-Emitting Photonic Crystal Laser," Science 302, 1374 (2003).
    [CrossRef] [PubMed]
  23. D. Hofstetter, T. Aellen, M. Beck, and J. Faist, "High average power first-order distributed feedback quantum cascade lasers," IEEE Photon. Technol. Lett. 12, 1610 (2000).
    [CrossRef]
  24. W. Schrenk and N. Finger and S. Gianordoli and L. Hvozdara and G. Strasser and E. Gornik, "Surface-emitting distributed feedback quantum-cascade lasers," Appl. Phys. Lett. 77, 2086 (2000).
    [CrossRef]
  25. C. Sirtori and C. Gmachl and F. Capasso and J. Faist and D. L. Sivco and A. L. Hutchinson and A. Y. Cho, "Longwavelength (l ¼ 8¡11:5 µm) semiconductor lasers with waveguides based on surface plasmons," Opt. Lett. 23, 1366 (1998).
    [CrossRef]
  26. M. Bahriz, V. Moreau, J. Palomo, R. Colombelli, D.A. Austin, J.W. Cockburn, L.R. Wilson, A.B. Krysa, J.S. Roberts, "Room temperature operation of l ¼ 7:5 µm surface-plasmon quantum cascade lasers," Appl. Phys. Lett. 88, 181103 (2006).
    [CrossRef]
  27. M.A. Ordal, L.L. Long, R.J. Bell, S. E. Bell, R. R. Bell, R.W. Alexander, and C. A. Ward, "Optical properties of the metals Al, Co, Cu, Au, Fe, Pb, Ni, Pd, Pt, Ag, Ti, and W in the infrared and far infrared," App. Opt. 22, 1099 (1983).
    [CrossRef]
  28. V. Moreau, M. Bahriz, J. Palomo, L.R. Wilson, A.B. Krysa, C. Sirtori, D.A. Austin, J.W. Cockburn, J.S. Roberts, R. Colombelli, "Optical Mode Control of Surface-Plasmon Quantum Cascade Lasers," Photon. Technol. Lett. 18, 2499 (2006).
    [CrossRef]
  29. A.B. Krysa, J.S. Roberts, R.P. Green, L.R. Wilson, H. Page, M. Garcia, and J.W. Cockburn, "MOVPE-grown quantum cascade lasers operating at ¼ 9 µm wavelength," J. Cryst. Growth,  272, 682 (2004).
    [CrossRef]
  30. R. P. Green, L. R. Wilson, E. A. Zibik, D. G. Revin, J. W. Cockburn, C. Pfl¨ugl, W. Schrenk, G. Strasser, A. B. Krysa, J. S. Roberts, C. M. Tey, and A. G. Cullis, "High-performance distributed feedback quantum cascade lasers grown by metalorganic vapor phase epitaxy," Appl. Phys. Lett. 85, 5529 (2004).
    [CrossRef]
  31. The commercial software Comsol Multiphysics was used.
  32. Z. Yin, and F. W. Smith, "Optical dielectric function and infrared absorption of hydrogenated amorphous silicon nitride films: Experimental results and effective-medium-approximation analysis," Phys. Rev. B 42, 3666 (1990).
    [CrossRef]
  33. L. A. Coldren, S. W. Corzine, "Diode Lasers and Photonic Integrated Circuits," Wiley-Interscience (1995).
  34. V. Moreau, M. Bahriz, R. Colombelli. P.-A Lemoine, Y. DeWilde, L.R.Wilson, and A.B. Krysa, "Direct imaging of a laser mode via midinfrared near-field microscopy," Appl. Phys. Lett. 90, 201114 (2007).
    [CrossRef]

2007 (4)

D. Erickson, T. Rockwood, T. Emery, A. Scherer, and Demetri Psaltis, "Nanofluidic tuning of photonic crystal circuits," Proc. SPIE 6475, 647513 (2007).
[CrossRef]

C. Monat, P. Domachuk, and B. J. Eggleton, "Integrated optofluidics: A new river of light," Nature Photon. 1, 106 (2007).
[CrossRef]

V. Moreau, M. Bahriz, R. Colombelli. P.-A Lemoine, Y. DeWilde, L.R.Wilson, and A.B. Krysa, "Direct imaging of a laser mode via midinfrared near-field microscopy," Appl. Phys. Lett. 90, 201114 (2007).
[CrossRef]

M. Loncar, B. G. Lee, L. Diehl, M. A. Belkin, F. Capasso, M. Giovannini, J. Faist, and E. Gini, "Design and fabrication of photonic crystal quantum cascade lasers for optofluidics," Opt. Express 15, 4499 (2007).
[CrossRef] [PubMed]

2006 (5)

L. Diehl, B.G. Lee, P. Behroozi, M. Loncar, M.A. Belkin, F. Capasso, T. Aellen, D. Hofstetter, M. Beck, and J. Faist, "Microfluidic tuning of distributed feedback quantum cascade lasers," Opt. Express 14, 11660 (2006).
[CrossRef] [PubMed]

M. Bahriz, V. Moreau, J. Palomo, R. Colombelli, D.A. Austin, J.W. Cockburn, L.R. Wilson, A.B. Krysa, J.S. Roberts, "Room temperature operation of l ¼ 7:5 µm surface-plasmon quantum cascade lasers," Appl. Phys. Lett. 88, 181103 (2006).
[CrossRef]

D. Psaltis, S. R. Quake, and C. Yang, "Developing optofluidic technology through the fusion of microfluidics and optics," Nature 442, 381 (2006).
[CrossRef] [PubMed]

M. Schaden, A. Doninguez-Vidal, and B. Lendl, "Simultaneous measurement of two compounds in aqueous solution with dual quantum cascade laser absorption spectroscopy," Appl. Phys. B 83, 135 (2006).
[CrossRef]

V. Moreau, M. Bahriz, J. Palomo, L.R. Wilson, A.B. Krysa, C. Sirtori, D.A. Austin, J.W. Cockburn, J.S. Roberts, R. Colombelli, "Optical Mode Control of Surface-Plasmon Quantum Cascade Lasers," Photon. Technol. Lett. 18, 2499 (2006).
[CrossRef]

2005 (2)

C. Charlton, A. Katzir, and B. Mizaikoff, "Infrared Evanescent Field Sensing with Quantum Cascade Lasers and Planar Silver Halide Waveguides," Anal. Chem. 77, 4398 (2005).
[CrossRef] [PubMed]

J. Chen, Z. Liu, C. F. Gmachl, and D. L. Sivco, "Silver halide fiber-based evanescent-wave liquid droplet sensing with room tempreature mid-infrared quantum cascade lasers," Opt. Express 13, 5953 (2005).
[CrossRef] [PubMed]

2004 (5)

A.B. Krysa, J.S. Roberts, R.P. Green, L.R. Wilson, H. Page, M. Garcia, and J.W. Cockburn, "MOVPE-grown quantum cascade lasers operating at ¼ 9 µm wavelength," J. Cryst. Growth,  272, 682 (2004).
[CrossRef]

R. P. Green, L. R. Wilson, E. A. Zibik, D. G. Revin, J. W. Cockburn, C. Pfl¨ugl, W. Schrenk, G. Strasser, A. B. Krysa, J. S. Roberts, C. M. Tey, and A. G. Cullis, "High-performance distributed feedback quantum cascade lasers grown by metalorganic vapor phase epitaxy," Appl. Phys. Lett. 85, 5529 (2004).
[CrossRef]

B. Maune, M. Loncar, J. Witzens, M. Hochberg, T. Baehr-Jones, D. Psaltis, A. Scherer, and Y. Qiu, "Liquidcrystal electric tuning of a photonic crystal laser," Appl. Phys. Lett. 85, 360 (2004).
[CrossRef]

M. Troccoli, D. Bour, S. Corzine, G. Hofler, A. Tandon, D. Mars, D. J. Smith, L. Diehl, and F. Capasso, "Lowthreshold continuous-wave operation of quantum-cascade lasers grown by metalorganic vapor phase epitaxy," Appl. Phys. Lett. 85, 5842 (2004).
[CrossRef]

G. Wysocki, M. McCurdy, S. So, D. Weidmann, C. Roller, R. F. Curl, and F.K. Tittel, "Pulsed Quantum-Cascade Laser-Based Sensor for Trace-Gas Detection of Carbonyl Sulfide," App. Opt. 43, 6040 (2004).
[CrossRef]

2003 (3)

M. Loncar, A. Scherer, and Y. Qiu, "Photonic crystal laser sources for chemical detection," Appl. Phys. Lett. 82, 4648 (2003).
[CrossRef]

J. S. Yu, S. Slivken, A. Evans, L. Doris, and M. Razeghi, "High-power continuous-wave operation of a 6 µm quantum-cascade laser at room temperature," Appl. Phys. Lett. 83, 2503 (2003).
[CrossRef]

R. Colombelli, K. Srinivasan, M. Troccoli, O. Painter, C.F. Gmachl, D. M. Tennant, A. M. Sergent, D. L. Sivco, A. Y. Cho, F. Capasso, "Quantum Cascade Surface-Emitting Photonic Crystal Laser," Science 302, 1374 (2003).
[CrossRef] [PubMed]

2002 (2)

M. Beck, D. Hofstetter, T. Allen, J. Faist, U. Oesterle, M. Ilegems, E. Gini, H. Melchior, "Continuous Wave Operation of a Mid-Infrared Semiconductor Laser at Room Temperature," Science 295, 301 (2002).
[CrossRef] [PubMed]

A. A. Kosterev and F. K. Tittel, "Chemical sensors based on quantum cascade lasers," IEEE J. Quantum Elec. 38, 582 (2002).
[CrossRef]

2001 (1)

C. Gmachl, F. Capasso, D. L. Sivco, and A. Y. Cho, "Recent progress in quantum cascade lasers and applications," Rep. Progr. in Physics 64, 1533 (2001).
[CrossRef]

2000 (2)

D. Hofstetter, T. Aellen, M. Beck, and J. Faist, "High average power first-order distributed feedback quantum cascade lasers," IEEE Photon. Technol. Lett. 12, 1610 (2000).
[CrossRef]

W. Schrenk and N. Finger and S. Gianordoli and L. Hvozdara and G. Strasser and E. Gornik, "Surface-emitting distributed feedback quantum-cascade lasers," Appl. Phys. Lett. 77, 2086 (2000).
[CrossRef]

1998 (1)

1994 (1)

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

1990 (1)

Z. Yin, and F. W. Smith, "Optical dielectric function and infrared absorption of hydrogenated amorphous silicon nitride films: Experimental results and effective-medium-approximation analysis," Phys. Rev. B 42, 3666 (1990).
[CrossRef]

1983 (1)

M.A. Ordal, L.L. Long, R.J. Bell, S. E. Bell, R. R. Bell, R.W. Alexander, and C. A. Ward, "Optical properties of the metals Al, Co, Cu, Au, Fe, Pb, Ni, Pd, Pt, Ag, Ti, and W in the infrared and far infrared," App. Opt. 22, 1099 (1983).
[CrossRef]

Anal. Chem. (1)

C. Charlton, A. Katzir, and B. Mizaikoff, "Infrared Evanescent Field Sensing with Quantum Cascade Lasers and Planar Silver Halide Waveguides," Anal. Chem. 77, 4398 (2005).
[CrossRef] [PubMed]

App. Opt. (2)

G. Wysocki, M. McCurdy, S. So, D. Weidmann, C. Roller, R. F. Curl, and F.K. Tittel, "Pulsed Quantum-Cascade Laser-Based Sensor for Trace-Gas Detection of Carbonyl Sulfide," App. Opt. 43, 6040 (2004).
[CrossRef]

M.A. Ordal, L.L. Long, R.J. Bell, S. E. Bell, R. R. Bell, R.W. Alexander, and C. A. Ward, "Optical properties of the metals Al, Co, Cu, Au, Fe, Pb, Ni, Pd, Pt, Ag, Ti, and W in the infrared and far infrared," App. Opt. 22, 1099 (1983).
[CrossRef]

Appl. Phys. B (1)

M. Schaden, A. Doninguez-Vidal, and B. Lendl, "Simultaneous measurement of two compounds in aqueous solution with dual quantum cascade laser absorption spectroscopy," Appl. Phys. B 83, 135 (2006).
[CrossRef]

Appl. Phys. Lett. (8)

B. Maune, M. Loncar, J. Witzens, M. Hochberg, T. Baehr-Jones, D. Psaltis, A. Scherer, and Y. Qiu, "Liquidcrystal electric tuning of a photonic crystal laser," Appl. Phys. Lett. 85, 360 (2004).
[CrossRef]

M. Loncar, A. Scherer, and Y. Qiu, "Photonic crystal laser sources for chemical detection," Appl. Phys. Lett. 82, 4648 (2003).
[CrossRef]

J. S. Yu, S. Slivken, A. Evans, L. Doris, and M. Razeghi, "High-power continuous-wave operation of a 6 µm quantum-cascade laser at room temperature," Appl. Phys. Lett. 83, 2503 (2003).
[CrossRef]

M. Troccoli, D. Bour, S. Corzine, G. Hofler, A. Tandon, D. Mars, D. J. Smith, L. Diehl, and F. Capasso, "Lowthreshold continuous-wave operation of quantum-cascade lasers grown by metalorganic vapor phase epitaxy," Appl. Phys. Lett. 85, 5842 (2004).
[CrossRef]

R. P. Green, L. R. Wilson, E. A. Zibik, D. G. Revin, J. W. Cockburn, C. Pfl¨ugl, W. Schrenk, G. Strasser, A. B. Krysa, J. S. Roberts, C. M. Tey, and A. G. Cullis, "High-performance distributed feedback quantum cascade lasers grown by metalorganic vapor phase epitaxy," Appl. Phys. Lett. 85, 5529 (2004).
[CrossRef]

W. Schrenk and N. Finger and S. Gianordoli and L. Hvozdara and G. Strasser and E. Gornik, "Surface-emitting distributed feedback quantum-cascade lasers," Appl. Phys. Lett. 77, 2086 (2000).
[CrossRef]

M. Bahriz, V. Moreau, J. Palomo, R. Colombelli, D.A. Austin, J.W. Cockburn, L.R. Wilson, A.B. Krysa, J.S. Roberts, "Room temperature operation of l ¼ 7:5 µm surface-plasmon quantum cascade lasers," Appl. Phys. Lett. 88, 181103 (2006).
[CrossRef]

V. Moreau, M. Bahriz, R. Colombelli. P.-A Lemoine, Y. DeWilde, L.R.Wilson, and A.B. Krysa, "Direct imaging of a laser mode via midinfrared near-field microscopy," Appl. Phys. Lett. 90, 201114 (2007).
[CrossRef]

IEEE J. Quantum Elec. (1)

A. A. Kosterev and F. K. Tittel, "Chemical sensors based on quantum cascade lasers," IEEE J. Quantum Elec. 38, 582 (2002).
[CrossRef]

IEEE Photon. Technol. Lett. (1)

D. Hofstetter, T. Aellen, M. Beck, and J. Faist, "High average power first-order distributed feedback quantum cascade lasers," IEEE Photon. Technol. Lett. 12, 1610 (2000).
[CrossRef]

J. Cryst. Growth (1)

A.B. Krysa, J.S. Roberts, R.P. Green, L.R. Wilson, H. Page, M. Garcia, and J.W. Cockburn, "MOVPE-grown quantum cascade lasers operating at ¼ 9 µm wavelength," J. Cryst. Growth,  272, 682 (2004).
[CrossRef]

Nature (1)

D. Psaltis, S. R. Quake, and C. Yang, "Developing optofluidic technology through the fusion of microfluidics and optics," Nature 442, 381 (2006).
[CrossRef] [PubMed]

Nature Photon. (1)

C. Monat, P. Domachuk, and B. J. Eggleton, "Integrated optofluidics: A new river of light," Nature Photon. 1, 106 (2007).
[CrossRef]

Opt. Express (3)

Opt. Lett. (1)

Photon. Technol. Lett. (1)

V. Moreau, M. Bahriz, J. Palomo, L.R. Wilson, A.B. Krysa, C. Sirtori, D.A. Austin, J.W. Cockburn, J.S. Roberts, R. Colombelli, "Optical Mode Control of Surface-Plasmon Quantum Cascade Lasers," Photon. Technol. Lett. 18, 2499 (2006).
[CrossRef]

Phys. Rev. B (1)

Z. Yin, and F. W. Smith, "Optical dielectric function and infrared absorption of hydrogenated amorphous silicon nitride films: Experimental results and effective-medium-approximation analysis," Phys. Rev. B 42, 3666 (1990).
[CrossRef]

Proc. SPIE (1)

D. Erickson, T. Rockwood, T. Emery, A. Scherer, and Demetri Psaltis, "Nanofluidic tuning of photonic crystal circuits," Proc. SPIE 6475, 647513 (2007).
[CrossRef]

Rep. Progr. in Physics (1)

C. Gmachl, F. Capasso, D. L. Sivco, and A. Y. Cho, "Recent progress in quantum cascade lasers and applications," Rep. Progr. in Physics 64, 1533 (2001).
[CrossRef]

Science (3)

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

M. Beck, D. Hofstetter, T. Allen, J. Faist, U. Oesterle, M. Ilegems, E. Gini, H. Melchior, "Continuous Wave Operation of a Mid-Infrared Semiconductor Laser at Room Temperature," Science 295, 301 (2002).
[CrossRef] [PubMed]

R. Colombelli, K. Srinivasan, M. Troccoli, O. Painter, C.F. Gmachl, D. M. Tennant, A. M. Sergent, D. L. Sivco, A. Y. Cho, F. Capasso, "Quantum Cascade Surface-Emitting Photonic Crystal Laser," Science 302, 1374 (2003).
[CrossRef] [PubMed]

Other (6)

The commercial software Comsol Multiphysics was used.

L. A. Coldren, S. W. Corzine, "Diode Lasers and Photonic Integrated Circuits," Wiley-Interscience (1995).

J. Faist and C. Sirtori, in ’Long wavelength infrared semiconductor lasers’ (J. Wiley and Sons, Hoboken, NJ, USA, 2004).

R. Perahia, K. Srinivasan, O. Painter, V. Moreau, M. Bahriz, R. Colombelli, F. Capasso, "Quantum cascade photonic crystal lasers: design, fabrication, and applications," CLEO 2006 (CTuAA5), Long Beach CA, May 2006.

R. Perahia, O. Painter, M. Bahriz, V. Moreau, R. Colombelli, "Design of quantum cascade lasers for intra-cavity sensing in the mid infrared," manuscript in preparation.

R. Perahia, O. Painter, V. Moreau, M. Bahriz, R. Colombelli, L.R. Wilson, A.B. Krysa, "Quantum Cascade Microdisk Lasers for Mid Infrared Intra-Cavity Sensing," CLEO 2007 (CTuE5), Baltimore (MA), May 2007.

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Figures (6)

Fig. 1.
Fig. 1.

Waveguide calculations, performed in a 1D transfer matrix approach, for two different waveguide geometries applied to the same heterostructure. Dark blue-line: surface-plasmon waveguide mode with a gold plasmon-carrying layer (Γ = 90%, α = 48 cm-1). Light blue-line: air-confinement waveguide with removal of the top n+-layers (Γ = 72%, α = 3 cm-1). The grey areas correspond to the laser active region. The surface is located at x = 0 and the red area is the portion of the mode that leaks evanescently above the surface. Its “confining” factor Γ air is ≈ 0:9%.

Fig. 2.
Fig. 2.

(a) Schematic layout of the fabricated devices. The contacts are deposited laterally on the edge of the ridge waveguide. Most of the ridge surface is left exposed to the air. The sidewalls in the real-devices are slanted, not vertical, since a wet chemical etch (HBr:HNO3:H2O) has been used. (b) A wet etch, or an aggressive oxygen plasma followed by a dip in HCl can remove the thin top n+ layer. (c) SEM image of a typical final device.

Fig. 3.
Fig. 3.

(a) Current-voltage (IV) characteristics at a temperature of 78K for a typical device (100 ns pulse width at 5 kHz repetition rate). The device dimensions are 1500 μm X 36 μm. Inset: Fabry-Perot spectrum of a typical device at 78 K. (b) Emission spectra at different temperatures for a typical device (50 ns pulse width at 84 kHz repetition rate). The spectra were acquired with a Fourier Transform Infrared Spectrometer (FTIR) operated in rapidscan mode and with a resolution of 0.125 cm-1. The signal was detected with a DTGS (deuterated triglycine sulfate) detector.

Fig. 4.
Fig. 4.

Light-current (LI) characteristics of a typical device at different temperatures (100ns pulse width at 1 kHz repetition rate). The device dimensions are 1500 μm X 36 μm. The power was measured with a fast MCT (Mercury-Cadmium-Telluride) detector that had been calibrated with a thermopile.

Fig. 5.
Fig. 5.

(a) Schematic geometry of the measured device. (b) High-loss waveguide mode (Ez component) localised below one of the metal bands. We calculate α ≈ 52 cm-1 for this mode. An identical mode exists and it is localised below the other metal band. (c) Low-loss, air-guided modes (Ez component) for a laser device with ridge width of 36 μm. The geometry corresponds to panel (a). We calculate α ≈ 9 cm-1 for this mode.

Fig. 6.
Fig. 6.

(a) Cross-section schematic of the end-facet of the laser ridge. The ridge width is 36 μm. (b) 2D color-plot of the calculated far field for the ridge in panel (a). (c) 2D surface-plot of the calculated far field intensity. (d) Calculated far field as a function of θx (see panel a), for θy = 0 (e) Experimental far field, measured by scanning a liquid-nitrogen-cooled MCT detector in front of the device at a fixed distance. The agreement with the calculated far field is excellent.

Tables (1)

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Table 1. QCL Epitaxy

Equations (1)

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E far ( θ x , θ y , R ) 2 = cos 2 ( θ x ) cos 2 ( θ y ) λ 2 R 2 ( sin 2 ( θ x ) sin 2 ( θ y ) ) E ( x , y ) e + ikx sin ( θ x ) e + iky sin ( θ y ) dxdy | 2 ,

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