Physical Review LettersInfrared Quantum Counter Action in Er-Doped Fluoride LatticesM. R. Brown, W. A. ShandPublished Mar 30, 1964• 51 citationsPublisherAbstractReceived 24 February 1964DOI:https://doi.org/10.1103/PhysRevLett.12.367©1964 American Physical SocietyDOI10.1103/physrevlett.12.367