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Terahertz quantum-cascade-laser source based on intracavity difference-frequency generation

Nature Photonics volume 1, pages 288–292 (2007)Cite this article

Abstract

The terahertz spectral range (λ = 30–300 µm) has long been devoid of compact, electrically pumped, room-temperature semiconductor sources1,2,3,4. Despite recent progress with terahertz quantum cascade lasers2,3,4, existing devices still require cryogenic cooling. An alternative way to produce terahertz radiation is frequency down-conversion in a nonlinear optical crystal using infrared or visible pump lasers5,6,7. This approach offers broad spectral tunability and does work at room temperature; however, it requires powerful laser pumps and a more complicated optical set-up, resulting in bulky and unwieldy sources. Here we demonstrate a monolithically integrated device designed to combine the advantages of electrically pumped semiconductor lasers and nonlinear optical sources. Our device is a dual-wavelength quantum cascade laser8 with the active region engineered to possess giant second-order nonlinear susceptibility associated with intersubband transitions in coupled quantum wells. The laser operates at λ1 = 7.6 µm and λ2 = 8.7 µm, and produces terahertz output at λ = 60 µm through intracavity difference-frequency generation.

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Figure 1: Band-structure design and THz-DFG process.
Figure 2: Waveguide design and the laser modes.
Figure 3: Light output versus current (L–I ), red and blue lines, and current versus voltage (I–V ), black line, characteristics obtained at 10 K in pulsed mode (60-ns pulses at 200 kHz) with a 20-µm-wide, 2-mm-long ridge device with a high-reflection coating on a back facet.
Figure 4: Spectral characteristics and power dependence of THz DFG.
Figure 5: Dependence of THz-DFG spectra on mid-infrared emission spectra (inset).

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References

  1. Brundermann, E. et al. High duty cycle and continuous terahertz emission from germanium. Appl. Phys. Lett. 76, 2991–2993 (2000).

    Article  ADS  Google Scholar 

  2. Köhler, R. et al. Terahertz semiconductor-heterostructure laser. Nature 417, 156–159 (2002).

    Article  ADS  Google Scholar 

  3. Rochat, M. et al. Low-threshold terahertz quantum-cascade lasers. Appl. Phys. Lett. 81, 1381–1383 (2002).

    Article  ADS  Google Scholar 

  4. Williams, B. S. et al. 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).

    Article  ADS  Google Scholar 

  5. Shen, Y. R. The Principles of Nonlinear Optics (John Wiley & Sons, New York, 1984).

    Google Scholar 

  6. Tanabe, T. et al. Frequency-tunable terahertz wave generation via excitation of phonon-polaritons in GaP. J. Phys. D 36, 953–957 (2003).

    Article  ADS  Google Scholar 

  7. Vodopyanov, K. L. et al. Terahertz-wave generation in quasi-phase-matched GaAs. Appl. Phys. Lett. 89, 141119 (2006).

    Article  ADS  Google Scholar 

  8. Faist, J. et al. Quantum cascade laser. Science 264, 553–556 (1994).

    Article  ADS  Google Scholar 

  9. Diehl, L. et al. High-power quantum cascade lasers grown by low-pressure metal organic vapor-phase epitaxy operating in continuous wave above 400 K. Appl. Phys. Lett. 88, 201115 (2006).

    Article  ADS  Google Scholar 

  10. Butcher, P. N. & Cotter, D. The Elements of Nonlinear Optics (Cambridge Univ. Press, Cambridge, 1990).

    Book  Google Scholar 

  11. Boyd, R. W. Nonlinear Optics (Academic Press, New York, 2003).

    Google Scholar 

  12. Hoffmann, S. et al. Four-wave mixing and direct terahertz emission with two-color semiconductor lasers. Appl. Phys. Lett. 84, 3585–3587 (2004).

    Article  ADS  Google Scholar 

  13. Hoffmann, S. et al. Two-colour diode lasers for generation of THz radiation. Semicond. Sci. Technol. 20, S205–S210 (2005).

    Article  Google Scholar 

  14. Hoffmann, S. et al. Bandwidth limitations of two-colour diode lasers for direct terahertz emission. Electron. Lett. 42, 696–697 (2006).

    Article  Google Scholar 

  15. Fejer, M. M. et al. Observation of extremely large quadratic susceptibility at 9.6–10.8 µm in electric field biased AlGaAs/GaAs quantum wells. Phys. Rev. Lett. 62, 1041–1044 (1989).

    Article  ADS  Google Scholar 

  16. Capasso, F. et al. Coupled quantum well semiconductors with giant electric field tunable nonlinear optical properties in the infrared. IEEE J. Quant. Electron. 30, 1313–1326 (1994).

    Article  ADS  Google Scholar 

  17. Rosencher, E. et al. Quantum engineering of optical nonlinearities. Science 271, 168–173 (1996).

    Article  ADS  Google Scholar 

  18. Sirtori, C. et al. Far-infrared generation by doubly resonant difference frequency mixing in a coupled quantum well two-dimensional electron gas system. Appl. Phys. Lett. 65, 445–447 (1994).

    Article  ADS  Google Scholar 

  19. Dupont, E. et al. Terahertz emission in asymmetric quantum wells by frequency mixing of midinfrared waves. IEEE J. Quant. Electron. 42, 1157–1174 (2006).

    Article  ADS  Google Scholar 

  20. Owschimikow, N. et al. Resonant second-order nonlinear optical processes in quantum cascade lasers. Phys. Rev. Lett. 90, 043902 (2003).

    Article  ADS  Google Scholar 

  21. Gmachl, C. et al. Optimized second-harmonic generation in quantum cascade lasers. IEEE J. Quant. Electron. 39, 1345–1355 (2003).

    Article  ADS  Google Scholar 

  22. Malis, O. et al. Milliwatt second harmonic generation in quantum cascade lasers with modal phase matching. Electron. Lett. 40, 1586–1587 (2004).

    Article  Google Scholar 

  23. Faist, J. et al. Bound-to-continuum and two-phonon resonance quantum-cascade lasers for high duty cycle, high-temperature operation. IEEE J. Quant. Electron. 38, 533–546 (2002).

    Article  ADS  Google Scholar 

  24. Kohen, S. et al. Electromagnetic modeling of terahertz quantum cascade laser waveguides and resonators. J. Appl. Phys. 97, 053106 (2005).

    Article  ADS  Google Scholar 

  25. Fan, J. A. et al. Surface emitting terahertz quantum cascade laser with a double-metal waveguide. Opt. Express 14, 11672–11680 (2006).

    Article  ADS  Google Scholar 

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Acknowledgements

This work was supported by Air Force Office of Scientific Research under Contract No. FA9550-05-1-0435. A.B. acknowledges partial support from National Science Foundation through grants ECS-0547019, EEC-0540832 and OISE 0530220. Fabrication was carried out in the Center for Nanoscale Systems at Harvard University. Harvard-CNS is a member of the National Nanotechnology Infrastructure Network.

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Authors and Affiliations

  1. Harvard School of Engineering and Applied Sciences, Harvard University, Cambridge, 02138, Massachusetts, USA

    Mikhail A. Belkin & Federico Capasso

  2. Department of Physics, Texas A&M University, College Station, 77843, Texas, USA

    Alexey Belyanin

  3. Bell Laboratories, Lucent Technologies, Murray Hill, 07974, New Jersey, USA

    Deborah L. Sivco & Alfred Y. Cho

  4. Lincoln Laboratory, Massachusetts Institute of Technology, Lexington, 02420, Massachusetts, USA

    Douglas C. Oakley, Christopher J. Vineis & George W. Turner

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  1. Mikhail A. Belkin
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Correspondence to Mikhail A. Belkin.

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Belkin, M., Capasso, F., Belyanin, A. et al. Terahertz quantum-cascade-laser source based on intracavity difference-frequency generation. Nature Photon 1, 288–292 (2007). https://doi.org/10.1038/nphoton.2007.70

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