Transfer of resonance radiation in a narrow spectral line

M. B. Gornyi, D. L. Markman, Boris G. Matisov

C. O. Alley

Sergey G. Rautian

Abdul-Wahab Kadir Ali

Grzegorz Jung, Janusz Konopka, Stefano Vitale

Spectral properties of rf radiation from intrinsic Josephson junctions in high Tc Y-Ba-Cu-O thin film have been measured in the frequency range up to 1.5 GHz. Narrow emission lines with the 3 dB bandwidth of the order of 20 MHz were detected indicating that Josephson clusters radiate coherently. Synchronization conditions are determined by dc current and external magnetic field bias. Frequency locking of radiation to external resonant circuit was also observed. Spectral line narrowing due to resonant lock was distinguished from the coherence-induced narrowing by different tuning properties of the emission line. Noncoherent Josephson radiation manifests itself as a broadband background noise increase. A pronounced 1/f-like tail sensitive to dc bias and magnetic field was observed in a low frequency part of the spectrum.

Peter M. Selzer, William M. Yen

The first direct observation of radiative spectral transfer within an inhomogeneously broadened line (the R(1) line of ruby) is reported. As opposed to nonradiative transfer, the temperature dependence of the radiative process is consistent with exponential, in agreement with recent predictions. A temperature-independent, resonant process is also directly observed. The implication of these results for the concept of microscopic strain broadening is discussed.