分类: 光学 >> 量子光学 提交时间: 2023-02-19
摘要: The imaginary Poynting momentum (IPM) of light has been captivated an unusual origin of optomechanical effects on dipolar magnetoelectric particles, but yet observed in experiments. Here, we report, for the very first time, a whole family of high-order IPM forces for not only magnetoelectric but also generic Mie particles, assisted with their excited higher multipoles within. Such optomechanical phenomena derive from a nonlinear contribution of the IPM to the optical force, and can be remarkable even when the incident IPM is small. We observe the high-order optomechanics in a structured light beam with vortex-like IPM streamlines, which allows the low-order dipolar contribution to be suppressed. Our results provide the first unambiguous evidence of the ponderomotive nature of the IPM, expand the classification of optical forces and open new possibilities for optical forces and micromanipulations.
分类: 光学 >> 量子光学 提交时间: 2023-02-19
摘要: Metasurfaces, artificial 2D structures, have been widely used for the design of various functionalities in optics. Jones matrix, a 2*2 matrix with eight parameters, provides the most complete characterization of the metasurface structures in linear optics, and the number of free parameters (i.e., degrees of freedom, DOFs) in the Jones matrix determines the limit to what functionalities we can realize. Great efforts have been made to continuously expand the number of DOFs, and a maximal number of six has been achieved recently. However, the realization of 'holy grail' goal with eight DOFs (full free parameters) has been proven as a great challenge so far. Here, we show that by cascading two layer metasurfaces and utilizing the gradient descent optimization algorithm, a spatially varying Jones matrix with eight DOFs is constructed and verified numerically and experimentally in optical frequencies. Such ultimate control unlocks new opportunities to design optical functionalities that are unattainable with previously known methodologies and may find wide potential applications in optical fields.
分类: 光学 >> 量子光学 提交时间: 2023-02-19
摘要: The delivery of optical signals from an external light source to a nanoscale waveguide is highly important for the development of nanophotonic circuits. However, the efficient coupling of external light energy into nanophotonic components is difficult and still remains a challenge. Herein, we use an external silica nanofiber to light up an organic-inorganic hybrid nano-waveguide, namely a system composed of a polymer filament doped with MoS$_{2}$ quantum dots. Nanofiber-excited nano-waveguides in a crossed geometry are found to asymmetrically couple excitation signals along two opposite directions, with different energy dissipation resulting in different colors of the light emitted by MoS$_{2}$ quantum dots and collected from the waveguide terminals. Interestingly, rainbow-like light in the hybrid waveguide is achieved by three-in-one mixing of red, green, and blue components. This hetero-dimensional system of dots-in-waveguide represents a significant advance towards all-optical routing and full-color display in integrated nanophotonic devices.