Ahmed Aftab, Gelfand Rachel, Storm S David, Lee Anna, Klinkova Anna, Guest Jeffrey R, Pelton Matthew
Department of Electrical Engineering, California State University, Long Beach, California 90840, United States.
Department of Physics, University of Maryland, Baltimore County, Baltimore, Maryland 21250, United States.
Nano Lett. 2022 Jul 13;22(13):5365-5371. doi: 10.1021/acs.nanolett.2c01339. Epub 2022 Jun 14.
Time-resolved optical measurements of vibrating metal nanoparticles have been used extensively to probe the ultrafast mechanical properties of the nanoparticles and of the surrounding liquid, but nearly all investigations so far have been limited to the linear regime. Here, we report the observation of a low-frequency oscillating signal in transient-absorption measurements of nanoparticles with octahedral gold cores and cubic silver shells; the signal appears at the difference of two mechanical vibrational frequencies in the particles, suggesting a nonlinear mixing process. We tentatively attribute this proposed mixing to a nonlinear coupling between a vibrational mode of the nanoparticle and its optical-frequency plasmon resonance. The optimization of this nonlinear transduction may enable high-efficiency opto-mechanical frequency mixing in the GHz-THz frequency regime.
时间分辨光学测量振动金属纳米颗粒已被广泛用于探测纳米颗粒及其周围液体的超快力学性质，但迄今为止几乎所有研究都局限于线性区域。在此，我们报告在具有八面体金核和立方银壳的纳米颗粒的瞬态吸收测量中观察到低频振荡信号；该信号出现在颗粒中两个机械振动频率的差值处，表明存在非线性混合过程。我们初步将这种提出的混合归因于纳米颗粒的振动模式与其光频等离子体共振之间的非线性耦合。这种非线性转导的优化可能实现GHz-THz频率范围内的高效光机械频率混合。
