High-performance circular polarization modulation using a dielectric metasurface

Abstract

We demonstrate a chiral metasurface that exhibits a giant chiroptical response as well as functions as an optical diode due to geometrical asymmetry for circularly polarized light (CPL). Engineering the Mie-type multipole radiation using geometrical features led to performance values in terms of near-unity transmission and circular dichroism (CD) efficiency (about 0.96) and an extinction ratio of ∼3.8×104 for 1550 nm wavelength. A continuous stopband of 1538–1556 nm is achieved for an unchosen component of CPL while keeping the transmission efficiency of the chosen CPL component larger than 0.9. Because of the high extinction ratio and CD efficiency, the proposed metasurface has the potential for chiroptical applications including high-contrast polarization imaging, precise Stokes parameters measurement, optical diodes, and polarization detection for CPL.

Maximal circular polarization isolation and asymmetric polarization conversion by chiral meta-structure

“…With their simple design methodologies and enhanced performance, dielectric structures can offer an efficient platform. From table 1, it is evident that the AT value reported by other chiral structures does not approach its maximum value even for other reported dielectric chiral metasurfaces [5,[9][10][11]15]. To the best of our knowledge, our AT value is the highest demonstrated so far.…”

“…Elliptical unit cells [10] produce narrowband AT of −0.83, −0.68, and 0.94 for 997 nm, 1042 nm, and 1055 nm wavelengths respectively. In the deformed Hshape [15], the maximum AT is about 0.92. Their full performance is hindered by reflection losses and the effect of the substrate in the propagation direction which alters the index contrast.…”

“…This is mostly attributed to the weak interaction between light and matter, which is caused by the large mismatch between the molecular feature size and the wavelength of the incident light. In recent years, metasurfaces [2][3][4][5][6][7][8][9][10][11][12][13][14][15], and metamaterials [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] have emerged as promising platforms to engineer optical chirality enabling unprecedented control over the electromagnetic behavior of light. Meta-structures have been employed to create spectrometer filters [32], lensing [33], structural colors [34], and holographic structures [35], owing to their ultrathin profile and flat optics.…”