Thermal broadening of the power spectra of laser-trapped particles in vacuum
Thermal broadening of the power spectra of laser-trapped particles in vacuum
复制标题
真空中激光捕获粒子的功率谱的热展宽
DOI：
10.1088/1361-6455/aa95ab
复制
发表时间：
2017
期刊：
影响因子：
--
通讯作者：
K. Aikawa
中科院分区：
文献类型：
--
作者：
M. Yoneda;K. Aikawa
我们发现，在低压下，激光捕获粒子的功率谱的谱宽几乎与压力无关，并且由于陷阱的非线性，反映了粒子的热分布。在实验中的纳米粒子被困在一个光学晶格，我们确定了两个不同的功能的宽度。首先，沿光学晶格的宽度沿着比沿其它方向的宽度宽得多。其次，对于较大的纳米颗粒，光谱宽度较窄。我们开发了一个理论的热加宽，并表明，由质心运动的频率归一化的光谱宽度直接揭示了热能的陷阱深度的比率。所提出的模型提供了一个很好的理解所观察到的功能。我们的模型也适用于更小的粒子，如原子和分子，并可以很容易地扩展到一般情况下的单光束光阱。
We show that, at low pressures, the spectral widths of the power spectra of laser-trapped particles are nearly independent from pressures and, due to the nonlinearities of the trap, reflect the thermal distribution of particles. In experiments with nanoparticles trapped in an optical lattice, we identify two distinct features of the widths. First, the widths along an optical lattice are much broader than those in the other directions. Second, the spectral widths are narrower for larger nanoparticles. We develop a theory of thermal broadening and show that the spectral widths normalized by the frequencies of the center-of-mass motion directly reveal the ratio of the thermal energy to the trap depth. The presented model provides a good understanding of the observed features. Our model holds also for smaller particles such as atoms and molecules and can be readily extended to the general case with a single-beam optical trap.