All-dielectric bifocal isotropic metalens for a single-shot hologram generation device

Abstract

Planar metalenses are regarded as promising functional nanodevices because of their lightweight, nano-resolution properties, and, therefore, they can serve as versatile platforms for imaging and Fourier transforming. Here, we demonstrate a meta-device that functions as an isotropic bifocal all-dielectric Huygens' metalens to realize nanoscale real-time coaxial digital hologram generation. We design an isotropic bifocal metalens for micro/nano hologram recording, and the metalens utilizes the complete region compared to a previously reported interleaved multifocal metalens scheme. In addition, the hologram generation does not depend on complex polarization conversion, thereby improving the practical efficiency. For high-fidelity reconstruction, compressive reconstruction is utilized to remove twin-image and zero-order items and to suppress noise. Such concept would be extended to white-light achromatic meta-holography and three-dimensional micro/nano in vivo incoherent super-resolution imaging under subwavelength modulation.

Dielectric metalens for miniaturized imaging systems: progress and challenges

“…In addition to the applications that have been introduced in this review, there are multifunctional metalenses for nanotracking 167 , hologram 168 , optical analog computing 169 , and phase measurement 170 , 171 applications. However, multifunctional metalenses usually involve multiple focal spots, so several sets of sub-unit are usually interleaved to achieve the multiple functions within a shared aperture.…”

Roadmap on Recent Progress in FINCH Technology

“…To solve the above challenges, a simple FINCH setup based on bifocal metalens has been proposed and demonstrated [37]. The metalens is an ultra-thin two-dimensional flat device composed of cylinder nanofins designed based on Huygens' principle.…”

“…In this study, the beam modulator was randomly multiplexed Fresnel zone lenses fabricated using electron beam lithography [14,36]. In 2020, FINCH was demonstrated for the first time using flat bifocal metalens by Zhou et al [37].…”

Digital Incoherent Compressive Holography Using a Geometric Phase Metalens

“…Besides using the phase-only SLM [ 22 , 23 ], the liquid crystal GRIN lens [ 24 ] or the birefringent crystal lens [ 25 , 26 ] were utilized as active-type wavefront modulating devices. The binary diffractive Fresnel zone lens [ 27 ], ring-shaped bifocal lens [ 28 ], bifocal metasurface lens [ 29 ], or the liquid crystal polymer-based polarization directed flat lens were implemented as passive-type wavefront modulating optics, giving rise to the simplicity of the system setup [ 30 ]. Most of the reported systems are described with the terms of self-interference incoherent digital holography (SIDH) or Fresnel incoherent correlation holography (FINCH).…”

“…Through compressive holography, we can acquire the sectional images of the 3D target scene, excluding out-of-focus information on the other plane [ 37 , 38 ]. Recently, the compressive sensing (CS) algorithm was used to eliminate the twin and DC noise in the coaxial holographic system with a bifocal metalens [ 29 ]. The metalenses feature broadband -phase modulation and can be made to have a high numerical aperture (NA) in the visible wavelength band.…”