Temperature and Field Dependence of the Emission of Terahertz Waves from Intrinsic Josephson Junctions*

We have recently succeeded in extracting coherent cw THz-radiation from intrinsic Josephson junctions in BSCCO [Science 318, 1291, (2007)]. An electromagnetic cavity resonance inside the sample generates a coherent state in which a large number of junctions are synchronized to oscillate in phase resulting in emission powers of up to 5 $\mu $W at frequencies up to 0.85 THz. The emission displays a non-monotonic temperature dependence with a sample dependent sharp maximum in the range of 25 to 45 K which we attribute to the interplay of self-heating effects and re-trapping of intrinsic junctions. Application of magnetic fields of less than 100 Oe parallel to the CuO$_{2}$ planes as well as perpendicular leads to the rapid suppression of the emission.