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Name (Title):
Shizeng Lin (NIMS Junior Researcher) and Xiao Hu (Principal Investigator)
Affiliation:
WPI Center for Materials Nanoarchitectonics, National Institute for
Materials Science
Address:
WPI Center for Materials Nanoarchitectonics, National Institute for
Materials Science, Tsukuba 305-0047, Japan
Email: lin.shizeng@nims.go.jp
Home Page: http://www.nims.go.jp/cmsc/scm/index_en.html
Presentation Title:
Radiation of Terahertz Electromagnetic Wave from High-Tc Superconductors
Abstract:
The electromagnetic wave in the
terahertz region (0.1THz~10THz) has
potential for wide applications, such as
cancer detection, security check and so on.
However, THz wave is hard to generate
either by conventional electronics or by
photonics. Thus it is demanding to
develop compact, solid-state and cheap
generators.
There are many different techniques to
generate THz wave, for instance,
quantum cascade laser. Among them, the generator based on intrinsic Josephson junctions in
layered high-Tc superconductors is quite promising since a Josephson junction naturally forms a
voltage to frequency converter. The proposed device based on Josephson junctions is sketched in
Fig. 1, where a stack of Josephson junctions made of Bi2Sr2CaCu2O8+δ single crystal is
sandwiched by two gold electrodes and is fed by a dc voltage.
In 2007, a great breakthrough has been achieved by the joint experimental group from
Argonne National Lab and University of Tsukuba, in which continuous and coherent terahertz
radiation from BSCCO was clearly observed [1]. It inspired many experimental [2] as well as
theoretical efforts [3, 4, 5] to understand and improve the radiation. Using large-scale computer
simulations, we found a new dynamic state in layered high-Tc superconductors, which supports
strong terahertz radiation. In this state, large amount of the input dc power is pumped into the
plasma oscillation and furthermore, the plasma oscillation is coherent in different junctions. As a
result, we have superradiation, which means that the radiation power is proportional to N
squared, with N being the number of junctions. The maximum radiation power is about 10mW
and the frequency is about 1THz according to our theoretical calculations.
References:
[1] L. Ozyuzer et al., Science 318, 1291 (2007).
[2] K. Kadowaki et al., Physca C 468, 634 (2008).
[3] S.-Z. Lin and X. Hu, Phys. Rev. Lett. 100, 247006 (2008).
[4] X. Hu and S. -Z. Lin, Phys. Rev. B 78, 134510 (2008).
[5] S.-Z. Lin and X. Hu, arXiv.0809.5169.
80
Poster Session PS-10
Fig. 1. Schematic view of terahertz wave generator based on
high-Tc superconductors