Terahertz Oscillating Devices Based Upon the Intrinsic Josephson Junctions in a High Temperature Superconductor
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Terahertz Oscillating Devices Based Upon the Intrinsic Josephson Junctions in a High Temperature Superconductor Kaveh Delfanazari · Hidehiro Asai · Manabu Tsujimoto · Takanari Kashiwagi · Takeo Kitamura · Kazuya Ishida · Chiharu Watanabe · Shunsuke Sekimoto · Takashi Yamamoto · Hidetoshi Minami · Masashi Tachiki · Richard A. Klemm · Toshiaki Hattori · Kazuo Kadowaki Received: 7 May 2013 / Accepted: 18 September 2013 / Published online: 30 October 2013 © Springer Science+Business Media New York 2013
Abstract Recent developments of coherent terahertz (THz) oscillators based on the intrinsic Josephson junctions (IJJs) in mesas of the high temperature superconductor Bi2 Sr2 CaCu2 O8+δ are reviewed. Experimental and theoretical studies of the emission from equilateral, right-angled isosceles, and acute isosceles triangular mesas are compared with those obtained from rectangular, square, and disk mesas, in order to determine the role of the mesa geometry. The superconducting properties and emission frequency f spectra are presented for a variety of triangular mesa geometries.
K. Delfanazari () · M. Tsujimoto · T. Kashiwagi · T. Kitamura · K. Ishida · C. Watanabe · S. Sekimoto · H. Minami · K. Kadowaki · M. Tachiki · T. Hattori Graduate School of Pure and Aplied Sciences, University of Tsukuba, CREST-JST, WPI-MANA, 1-1-1, Tennodai, Tsukuba, Ibaraki 305-8573, Japan e-mail: [email protected] H. Asai Electronics and Photonics Research Institute, The National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki 305-8568, Japan T. Yamamoto Semiconductor Analysis and Radiation Effects Group, Japan Atomic Energy Agency, Gunma 370-1292, Japan R. A. Klemm Department of Physics, University of Central Florida, 4000 Central Florida Blvd., Orlando, FL 32816-2385, USA Present Address: K. Delfanazari Optoelectronics Research Centre, University of Southampton, Highfield, Southampton, UK
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J Infrared Milli Terahz Waves (2014) 35:131–146
Analytic and finite difference time domain numerical calculations of the emissions from the internal electromagnetic (EM) cavity modes of triangular mesas are compared with experiment. The experimental f always satisfies the ac Josephson relation, and its narrow linewidth arises from the synchronized emissions from many IJJs. For some mesa geometries, f also strongly locks onto an EM cavity mode frequency, enhancing the emission’s stability and output power. For other geometries, such cavity mode locking is weak, and f is highly tunable. Keywords Superconductor · Intrinsic Josephson junctions · Ac-Josephson effect · Terahertz wave · Cavity resonance
1 Introduction The frequency f ranging between 0.1 to 10 terahertz (THz) is often called the THz band [1, 2] or “THz gap” [3]. To date, sources of artificial THz waves include a gyrotron, backward wave oscillator (BWO), far infrared laser (FIR-laser), quantum cascade laser (QCL), free electron laser (FEL), synchrotron light, photomixer, photoconductor, surface field, photo-Dember, optical rectifier, and a resonant tunnel
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