title: Emission of coherent THz radiation from superconductors.
abstract: Compact solid-state sources of terahertz (THz) radiation are being sought for sensing, imaging, and spectroscopy applications across the physical and biological sciences. We demonstrate that coherent continuous-wave THz radiation of sizable power can be extracted from intrinsic Josephson junctions in the layered high-temperature superconductor Bi2Sr2CaCu2O8. In analogy to a laser cavity, the excitation of an electromagnetic cavity resonance inside the sample generates a macroscopic coherent state in which a large number of junctions are synchronized to oscillate in phase. The emission power is found to increase as the square of the number of junctions reaching values of 0.5 microwatt at frequencies up to 0.85 THz, and persists up to approximately 50 kelvin. These results should stimulate the development of superconducting compact sources of THz radiation.
authors.affiliation: Department of Physics, Izmir Institute of Technology, TR-35430 Izmir, Turkey.
authors.forename: L
authors.initials: L
authors.lastname: Ozyuzer
authors.forename: A E
authors.initials: AE
authors.lastname: Koshelev
authors.forename: C
authors.initials: C
authors.lastname: Kurter
authors.forename: N
authors.initials: N
authors.lastname: Gopalsami
authors.forename: Q
authors.initials: Q
authors.lastname: Li
authors.forename: M
authors.initials: M
authors.lastname: Tachiki
authors.forename: K
authors.initials: K
authors.lastname: Kadowaki
authors.forename: T
authors.initials: T
authors.lastname: Yamamoto
authors.forename: H
authors.initials: H
authors.lastname: Minami
authors.forename: H
authors.initials: H
authors.lastname: Yamaguchi
authors.forename: T
authors.initials: T
authors.lastname: Tachiki
authors.forename: K E
authors.initials: KE
authors.lastname: Gray
authors.forename: W-K
authors.initials: WK
authors.lastname: Kwok
authors.forename: U
authors.initials: U
authors.lastname: Welp