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Topological structure generates topological light
We discover optical properties that are solely dictated by the overall topology of structures, and at the same time are irrelevant to their material constituents or specific geometries! " The central idea of metamaterials is that structural geometry offers a broad extra dimension to explore for exotic functionalities. We show that structural topology can be a new dimension! " Science Advances 8, eabq0910 (2022) PDF |
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Optical manipulations by polarization singularities
How to spin a particle by using linearly polarized incident light? We show that a simple metal scatterer can generate circularly polarized near fields, i.e., C lines, which enable rich manipulations of small particles via the induced optical torque. Optics Express 30, 16489 (2022) PDF |
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Sensing chiral particle by a non-chiral sphere
Normal metal sphere excited by linearly polarized light - a completely non-chiral configuration- can be used for chiral discrimination! Physical Review A 105, 033513 (2022) PDF |
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Acoustic helical dichroism
We demonstrate differential absorption of acoustic vortices carrying opposite OAM in a 1D chiral lattice. This is the first time the so-called "helical dichroism" or "vortex dichroism" is demonstrated in acoustics. Physical Review B 105, 024111 (2022) PDF |
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Transverse sound
We show that airborne sound can be a transverse wave carrying both spin and orbital angular momentum. This spin-1 transverse sound has spin-orbit interactions same as light! Nature Communications 12, 6125 (2021) PDF Media Coverage: CityU Research Stories, EurekAlert!, Phys.org, Science Magazine, Science Daily ... 
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Robust exceptional point of arbitrary order
Coupled spinning resonators give rise to arbitrary-order exceptional point, without selective excitation! Optics Express 29, 29720 (2021) PDF |
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Subwavelength nonmagnetic optical isolator A particle (radius = 1/5 wavelength) can block light from one direction while allow transmission in the opposite direction. Physical Review B 103, 094105 (2021) PDF |
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Polarization singularities generated by small particles
Simple spherical particle can generate polarization singularity lines with interesting topological properties. Physical Review A 103, 023520 (2021) PDF |
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Optical forces in coupled chiral particles
Want to separate chiral particles using light induced forces? We need to understand the coupling between chiral particles. Physical Review A 102, 043526 (2020) PDF |
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Scale invariance results in optimal absorber
A metasurface (thickness = 5 mm) consisting of logarithmic spiral resonators can absorb >95% of incident microwave energy within 6 GHz–37 GHz, approaching the theoretical Rozanov limit. Scientific Report 9, 14078 (2019) PDF |
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Arbitrary order exceptional point
The locking between spin and linear momentum k induces unidirectional coupling, and thus exceptional point. Nature Communications 10, 832 (2019) PDF CityU Research Story: “Exceptional point achieved with photonic resonators Paves way for development of ultrasensitive optical sensors” Link |
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Acoustic spin-redirection geometric phase
Airborne sound does not carry spin, but it can have spin-redirection geometric phase deriving from orbital angular momentum. Science Advances 4, eaaq1475 (2018) PDF CityU Research Story: “Spin-redirection phase of sound wave demonstrated for the first time" Link |
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Does light push or pull a boundary?
If you shine a light beam to a material surface, does it push or pull? Check out our very counterintuitive discovery! Science Advances 2, e1501485 (2016) PDF (highlighted in Nature Photonics: "Momentum in metamaterials") Physical Review B 91, 235439 (2015) PDF |
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Light can separate chiral particles
Light can induce a lateral force on chiral particles, and the force points in opposite directions for opposite chiral particles-- an optomechanical spin-Hall effect! Nature Communications 5, 3307 (2014) PDF |
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Strong attractive force induced by light
Ever thought about climbing walls like a gecko? We found light can induce attractive force between metal plates. The force is 2-3 orders of magnitude larger than normal photon pressure! Physical Review B 84, 075114 (2011) PDF Physical Review Letters 106, 087401 (2011) PDF Physical Review B 86, 085446 (2012) PDF Journal of Physics D 46, 395104 (2013) PDF Physical Review Letters 112, 045504 (2014) PDF Physical Review Letters 121, 035502 (2018) PDF |
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Optical force enhanced by a three-layer substrate
The reflection singularity of a three-layer substrate can significantly amplify the scattering of small particles. Optics Express 24, 2235 (2016) PDF |
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Fast multipole boundary element method
We developed a fast multipole boundary element method for solving the three-dimensional vectorial Helmholtz equation that arises in electromagnetic scattering problems. International Journal of Computational Materials Science and Engineering 01, 1250038 (2012) PDF |