Ultrashort Electromagnetic Pulse Radiation from YBCO Thin Films Excited by Femtosecond Optical Pulse
Ultrashort Electromagnetic Pulse Radiation from YBCO Thin Films Excited by Femtosecond Optical Pulse
复制标题
飞秒光脉冲激发 YBCO 薄膜的超短电磁脉冲辐射
DOI：
10.1143/jjap.35.2624
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发表时间：
1996
影响因子：
1.5
通讯作者：
S. Nakashima
中科院分区：
文献类型：
--
作者：
M. Tonouchi;M. Tani;Zhen Wang;K. Sakai;Seiji Tomozawa;M. Hangyo;Y. Murakami;S. Nakashima
我们在YBa2Cu3O7-δ薄膜偶极子天线上观测到了超短电磁脉冲辐射。利用飞秒激光脉冲将超载流子激发成准粒子，产生超电流瞬态，并对自由传播的电磁脉冲进行了测量和表征。得到了全宽0.5 ps的脉冲，其频率分量高达2.0 THz。光谱的飞秒时间分辨特性表明，它们强烈依赖于激发条件，准粒子复合时间随着激发强度的增加而变长。在弱激发区，辐射功率与偏置电流和激光功率的平方成正比地增大，这与基于双流体模型的经典理论一致。在强激发区域，观测到与经典理论的偏差。
We have observed ultrashort electromagnetic pulse radiation from YBa2Cu3O7-δ thin-film dipole antennas. The supercurrent transient is created by the excitation of the supercarriers into quasiparticles with a femtosecond laser pulse, and freely propagated electromagnetic pulses are measured and characterized. A pulse with 0.5 ps full width at half-maximum was obtained, containing frequency components up to 2.0 THz. A femtosecond time-resolved characterization of the spectra revealed that they strongly depend on the excitation conditions, and the quasiparticle recombination time becomes longer with increase in the excitation intensity. It is also observed that the radiation power increases in proportion to the square of both the bias current and the laser power in the region of weak excitation, which is consistent with the classical theory based on a two-fluid model. In the region of strong excitation, deviation from the classical theory was observed.