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Theoretical study on optimization of THz-wave emission device using Josephson junction of high-temperature superconductors

高温超导约瑟夫森结太赫兹波发射装置优化的理论研究

基本信息

批准号：
20510121
负责人：
NONOMURA Yoshihiko
金额：
$ 2.91万
依托单位：
National Institute for Materials Science
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2008
资助国家：
日本
起止时间：
2008 至 2010
项目状态：
已结题

项目摘要

Electromagnetic wave with frequency around 1 THz is expected to have a wide range of applications in biological and medical fields. Although it has been difficult to generate such stable electromagnetic wave with conventional electric or optical devices, stable emission of such wave became possible recently using intrinsic Josephson junctions of high-Tc superconductors. I investigated emission properties of such devices by large-scale numerical simulations of an established theoretical model and found that the surface impedance Z is crucial. Without magnetic fields emission becomes maximum when the bias current corresponding to the cavity resonance is applied, and the optimal emission is obtained around Z=50 for the fundamental mode. When magnetic fields along junctions are applied, emission intensity takes a maximum value at zero field and monotonically decreases as the field increases for Z>50, while it takes a maximum value for a small but finite magnetic field for Z<50.

频率在1THz左右的电磁波在生物和医学领域有着广泛的应用前景。虽然用传统的电或光器件很难产生这种稳定的电磁波，但最近使用高Tc超导体的本征约瑟夫森结，这种波的稳定发射成为可能。我研究了这种设备的发射性能的大规模数值模拟建立的理论模型，发现表面阻抗Z是至关重要的。无磁场时，当施加与腔谐振相对应的偏置电流时，发射达到最大值，基模在Z=50附近获得最佳发射。当沿结沿着施加磁场时，发射强度在零场处取最大值，并且当Z>50时随着场的增加而单调减小，而当Z<50时，发射强度在小但有限的磁场下取最大值。