Qiu Hongsong, Kurihara Takayuki, Harada Hirofumi, Kato Kosaku, Takano Keisuke, Suemoto Tohru, Tani Masahiko, Sarukura Nobuhiko, Yoshimura Masashi, Nakajima Makoto
Opt Lett. 2018 Apr 15;43(8):1658-1661. doi: 10.1364/OL.43.001658.
Substantial enhancement of terahertz magnetic near field achieved by the combination of a tapered metallic waveguide and a micro-split-ring resonator is demonstrated. The magnetic near field is probed directly via the magneto-optic sampling with a TbGaO crystal. The incident terahertz wave with a half-cycle waveform is generated by using the pulse-front tilting method. The magnetic near field at the resonant frequency is enhanced by more than 30 times through the combination of the waveguide and the resonator. The peak amplitude of the magnetic field with a damped oscillation waveform in the time domain is up to 0.4 T. The resonant frequency can be tuned by adopting different resonator designs. The mechanism of the enhancement is analyzed by performing calculations based on the finite element method. The strong terahertz magnetic near field enables the excitation of large-amplitude spin dynamics and can be utilized for an ultrafast spin control.
通过锥形金属波导和微裂环谐振器的组合实现了太赫兹磁近场的显著增强。利用TbGaO晶体通过磁光采样直接探测磁近场。采用脉冲前沿倾斜法产生具有半周期波形的入射太赫兹波。通过波导和谐振器的组合，谐振频率处的磁近场增强了30倍以上。时域中具有阻尼振荡波形的磁场峰值幅度高达0.4 T。通过采用不同的谐振器设计可以调节谐振频率。基于有限元方法进行计算来分析增强机制。强太赫兹磁近场能够激发大幅度的自旋动力学，可用于超快自旋控制。
