Optical manipulation with metamaterial structures

Abstract

Optical tweezers employing forces produced by light underpin important manipulation tools employed in numerous areas of applied and biological physics. Conventional optical tweezers are widely based on refractive optics, and they require excessive auxiliary optical elements to reshape both amplitude and phase, as well as wavevector and angular momentum of light, and thus impose limitations on the overall cost and integration of optical systems. Metamaterials can provide both electric and optically induced magnetic responses in subwavelength optical structures, and they are highly beneficial to achieve unprecedented control of light required for many applications and can open new opportunities for optical manipulation. Here, we review the recent advances in the field of optical manipulation employing the physics and concepts of metamaterials and demonstrate that metamaterial structures could not only help to advance classical operations such as trapping, transporting, and sorting of particles, but they can uncover exotic optical forces such as pulling and lateral forces. In addition, apart from optical manipulation of particles (that can also be called “meta-tweezers”), metamaterials can be powered dynamically by light to realize ingenious “meta-robots.” This review culminates with an outlook discussing future novel opportunities in this recently emerged field ranging from enhanced particle manipulation to meta-robot actuation.

Exploiting extraordinary topological optical forces at bound states in the continuum

“…To illustrate the BIC-induced topological force in momentum space for manipulating nanoparticles, we are calculating the net optical force on the nanosphere above PhCS as a function of the metastructure geometry. Rigorous calculation of optical forces on arbitrary sized and shaped particles can be obtained by integrating the flow of Maxwell stress tensor (MST) through a closed surface S containing the nanoparticle as follows ( 21 , 24 , 33 )boldF=∮S⟨boldTfalse↔⟩⋅boldn^dSwhere bold-italicnfalse^ is the unit vector normal to the surrounding surface S , and ⟨ · ⟩ is the time-average operator. The MST can be given in the form of electric field E and magnetic field H ,⟨Tij⟩=18πℜ[DiEj∗+BiHj∗−12(boldD⋅boldE∗+boldB⋅boldH∗)δij]…”

“…Besides the control of polarization state, amplitude, and phase of waves, PhCSs and metasurfaces have also been great candidates for exploiting optical forces, such as optical trapping, manipulation, and meta-vehicles (20)(21)(22)(23)(24)(25)(26)(27). By tailoring the scattering direction and structural chirality, optically pumped vehicles, light sails, and motors for transportation of nanoparticles and space exploration have been proposed recently (20,21,26,28).…”

Recent Progress on Optical Micro/Nanomanipulations: Structured Forces, Structured Particles, and Synergetic Applications

“…There are also other emerging manipulation platforms such as metasurfaces 87 and metamaterials, 88 which will be outlined later. As a summary of this section, we list concisely the main technical parameters of the representative platforms/works (Table 1), such as particle size, material, trap stiffness, heating, etc.…”

“…87,170−173 Therefore, we believe that the metasurface/two-dimensional material will be an important nanophotonic platform for future optical manipulations. 88 4.4. Interface-Based Optical Manipulation.…”

“…There are many other degrees of freedom to engineer light beams by designing functional metasurface and two-dimensional materials. They all can provide powerful handles or abilities for optical manipulation. ,− Therefore, we believe that the metasurface/two-dimensional material will be an important nanophotonic platform for future optical manipulations …”