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APS » Journals » Phys. Rev. Lett. » Volume 82 » Issue 9
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Phys. Rev. Lett. 82, 1963–1966 (1999)

Stimulated Emission and Amplification in Josephson Junction Arrays

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P. Barbara, A. B. Cawthorne, S. V. Shitov*, and C. J. Lobb
Center for Superconductivity Research, Department of Physics, University of Maryland, College Park, Maryland 20742-4111

Received 22 September 1998; published in the issue dated 1 March 1999

See accompanying Physics Focus

We report measurements of mm-wavelength radiation from two-dimensional arrays of underdamped Josephson junctions. All of our samples emit coherently in a novel synchronized state, which is triggered by a resonance in the array structure. Measurements of the detected power as a function of the number N of active junctions show a threshold, suggesting population inversion. Above threshold, the power scales with N2 up to an array size bigger than the free-space radiation wavelength. The highest measured conversion efficiency from dc to ac power is about 17%. Our data are consistent with stimulated emission causing coherence and cannot be explained by existing classical coupling mechanisms.

© 1999 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevLett.82.1963
DOI:
10.1103/PhysRevLett.82.1963
PACS:
78.45.+h, 42.25.Kb, 85.25.Cp

*Permanent address: Institute of Radio Engineering and Electronics, Russia Academy of Sciences, Mokhovaya 11, 103907 Moscow, Russia.

 
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