Abstract-Study on terahertz emission and optical/terahertz pulse responses with superconductors

Iwao Kawayama¹, Caihong Zhang¹, Huabing Wang² and Masayoshi Tonouchi¹
http://iopscience.iop.org/0953-2048/26/9/093002;jsessionid=F87B757F752FE819355A675537AF0596.c2

tonouchi@ile.osaka-u.ac.jp
¹ Institute of Laser Engineering, Osaka University, Osaka 565-0871, Japan
² National Institute for Materials Science, Tsukuba 305-0047, Japan

Recent progress in terahertz technology has enabled precise investigation of the ultrafast dynamics of excited carriers, nonequilibrium state and nonlinear response of superconductors, resulting in the proposal of novel optoelectronic device applications based on such ultrafast perturbation of supercarriers in the terahertz frequency region. In this paper, we focus on exploratory research in the field of superconductor terahertz science and technology, and present a review of superconducting terahertz sources and the response of superconductors excited by ultrashort electromagnetic pulses, including optical pulses and high-intensity THz pulses.

Abstract-Superconducting emitters of THz radiation

                                                           The layered crystal structure of Bi₂Sr₂CaCu₂O_8+δ consists
                                                            of superconducting CuO₂ bilayers and intervening insulating
                                                            Bi–Sr–O layers, forming a stack of IJJs. The shaded background
                                                            represents the magnitude of the superconducting order

Ulrich Welp,¹ Kazuo Kadowaki², Reinhold Kleiner³
http://www.nature.com/nphoton/journal/v7/n9/full/nphoton.2013.216.html

Layered superconductors such as the copper-oxide high-temperature superconductor Bi₂Sr₂CaCu₂O_8+δ are emerging as compact sources of coherent continuous-wave electromagnetic radiation in the subterahertz and terahertz frequency ranges. The basis of their operation is the Josephson effect, which intrinsically occurs between the superconducting layers. The Josephson effect naturally converts a direct-current voltage into a high-frequency electric current. Therefore, a unique property of the devices reviewed here is the wide tunability of their frequency by varying the bias voltage. Recently, emission powers of free-space radiation of several hundreds of microwatts and emission linewidths as low as 6 MHz at 600 GHz have been achieved. These devices are promising for new applications in imaging, medical diagnostics, spectroscopy and security

Abstract-Enhanced transmission of terahertz radiation through a periodically modulated slab of layered superconductor

http://iopscience.iop.org/1367-2630/15/2/023040

D V Kadygrob, N M Makarov, F Pérez-Rodríguez, T M Slipchenko and V A Yampol'skii

We predict the enhanced transparency of a modulated slab of layered superconductor for terahertz radiation due to the diffraction of an incident wave and the resonance excitation of eigenmodes. The electromagnetic field is transferred from the irradiated side of the slab to the other by excited waveguide modes (WGMs) which do not decay in layered superconductors, in contrast to metals, where the enhanced light transmission is caused by the excitation of evanescent surface waves. We show that a series of resonance peaks can be observed in the dependence of transmittance on the incidence angle when the dispersion curve of the diffracted wave crosses successive dispersion curves for the WGMs.