Highly efficient broadband spin-multiplexed metadevices for futuristic imaging applications

Achieving broadband and multifunctional response through a single optical device is a highly sought-after capability for various applications like microscopy and optical imaging, which provide detailed morphological information of a targeted object. Traditional optical systems require a chain of elements to achieve such functionality, resulting in bulky systems hindering integration with modern photonics devices. Metasurfaces are exquisitely designed and exhibit unprecedented light-manipulation capability at the nanoscale, thus creating easy-to-integrate miniaturized photonic devices. Recently, broadband multifunctional metasurfaces with polarization's degree of freedom have attracted considerable interest due to their exceptional ability of wavefront shaping, which may find their applications in imaging and data communication. However, realizing single-cell driven, highly efficient multifunctional metasurfaces operating over broadband wavelengths remains challenging. This study presents a unique helicity-dependent broadband multifunctional metasurface platform to manipulate visible light for futuristic imaging applications. The proposed platform can integrate multiple optical phenomena into a single-layered metadevice to generate several uncorrelated, spin-dependent responses across the targeted visible spectrum (470–650 nm). For proof of concept, we demonstrated several all-dielectric transmissive metadevices carrying various spin-multiplexed phase profiles, efficiently generating diffraction-limited focusing and structured light beams with different characteristics. Each designed metasurface was studied under selected visible wavelengths, and the diffracted light exhibited excellent and stable broadband performance. With the advantages of broadband multifunctional platform and miniaturized metadevices, the presented strategy may open new vistas for various applications, including biomedical imaging, optical interconnects, and microscopy.