Enhancing Circularly Polarized Emission by a Planar Chiral Dielectric Metasurface

Abstract

Abstract Circularly polarized emission (CPE) has attracted great interest in optoelectronics, biosensing, etc. Here, a resonant planar chiral dielectric metasurface that can be constructed to provide a preferable way for CPE is demonstrated. The planar metasurface is easy to fabricate, and the corresponding far‐field circular polarization degree is extremely high and angle‐insensitive. The designed metasurface is made of a periodic array of in‐plane mirror‐asymmetric silicon pillar dimers and supports a low‐leakage chiral band‐edge mode. Experimentally, the photoluminescence of a thin film of PbS/CdS quantum dots coated on such a metasurface is enhanced by 57 times with the far‐field degree of circular polarization as high as 0.74. The planar platform provides a flexible and efficient way for manipulating CPE, in which other periodic coupling effects may also be adopted to enhance the light–matter interaction, such as quasi‐bound states in the continuum and lattice resonance.