Geometric phase for multidimensional manipulation of photonics spin Hall effect and helicity-dependent imaging

Abstract

<jats:title>Abstract</jats:title><jats:p>The spin Hall effect of light, associated with spin-orbit interactions, describes a transport phenomenon with optical spin-dependent splitting, leading to a plethora of applications such as sensing, imaging, and spin-controlled nanophotonics. Although geometric meatsurfaces can mimic photonic spin Hall effect by spatially splitting left-hand circularly polarized and right-hand circularly polarized states of electromagnetic waves with anomalous refraction or reflection angles, the geometric phase generated by metasurfaces hinders metalenses to realize simultaneous focusing of different spin states, limiting further applications. Here, we propose and experimentally demonstrate an approach to realizing a spin Hall metalens that can focus terahertz waves with different spin states and flexibly manipulate spin-dependent focal points in multiple spatial dimensions based on a pure geometric phase. A dielectric metasurface consisting of micropillars with identical shape and different in-plane orientations is designed to realize the multidimensional manipulation of photonics spin Hall effect in terahertz region. Furthermore, helicity-dependent imaging is demonstrated by the terahertz spin Hall metalens. The uniqueness and robust approach for manipulating spin photons may have a significant impact on designing ultra-compact and multifunctional devices and spin photonics devices.</jats:p>

Multi‐Channel Image Encryption Based on an All‐Dielectric Metasurface Incorporating Near‐Field Nanoprinting and Far‐Field Holography

“…As 2D artificial metamaterials, metasurfaces, which have the advantages of being ultrathin and ultracompact, have shown flexibility in regulating the polarization, amplitude, and phase of light on the subwavelength scale. [7][8][9][10][11] By appropriately designing the distribution of scattered nanounit structures, metasurfaces can be used for optical elements with various functions, such as orbital angular momentum, [12][13][14][15][16][17] optical switching, [18][19][20] spin Hall effect, [21][22][23][24] beam focusing, [17,[25][26][27] nanoprinting, [28][29][30][31][32][33] and holographic imaging. [4,[34][35][36][37][38][39][40][41] Recently, metasurfaces have exhibited significant potential in miniaturized and high-security information encryption devices owing to their small size, high resolution, and low manufacturing cost.…”

Active multiband varifocal metalenses based on orbital angular momentum division multiplexing

“…Moreover, the modulation of light field based on Pancharatnam Berry (PB) phase is a simple and effective means, which has developed into a mature and effective coding methods. Combined with the PB phase modulation ability of symmetry-breaking antennas 47 , 49 , 50 , the metalenses can discretionarily realize selective modulation of vortex beams with OAMs. The orthogonal relation between each vortices ensures less crosstalk between the functions, greatly boosting the effective and reliable selection of the channels, which also promises an effective guarantee for the multiplexing 47 , 51 .…”

Structural Optimization and Performance Analysis of a Tunable Ultra‐Broadband Terahertz Absorber

“…In these terahertz devices, wave absorbers play a very important role. Electromagnetic metamaterial absorbers respond in a wide terahertz frequency range or a single‐terahertz frequency by adjusting the geometric size and the period size of their structural units, so they can be used in different fields such as transmitters, [ 11 ] stealth technology, [ 12 ] photovoltaic cells, [ 13 ] imaging, [ 14 ] and so on.…”