Parallel Polarization Illumination with a Multifocal Axicon Metalens for Improved Polarization Imaging

Abstract

Polarization imaging is an important branch of the microscopy technique that can provide additional information and enhanced contrast. The illumination system of a polarization microscope enables many different polarizations but makes the setup bulky, complicated, and slow. Here, we design and fabricate an ultrathin planar axicon metalens that also enables parallel illumination with different polarizations. Our results reveal a diffraction-limited size and high degree of linear polarization. To verify our approach, we accurately map the polarization angle of an aluminum grating, which is used as a polarizer. Furthermore, we demonstrate that elliptical polarization can be generated without additional design. A single metalens has the same capabilities as a conventional illumination module containing a polarizer, compensator, and rotation-stage/optical modulator. In addition, our device has the potential to enable rapid super-resolution polarization imaging. The new method could be useful in many applications and areas, including, e.g., materials research and biomedicine.

All‐Dielectric Fiber Meta‐Tip Enabling Vortex Generation and Beam Collimation for Optical Interconnect

“…[ 5 ] The FMT equipped the crystal fiber with unprecedented light‐manipulating capabilities; however, it was susceptible to intrinsic ohmic losses associated with metallic structures. [ 13,14 ] Miniaturized multifunctional MSs, which facilitate the completion of concurrent tasks, have also been the focus of studies on integrated photonic modules and systems owing to their potential in implementing multifocal metalenses, [ 15–17 ] holograms, [ 18–21 ] vortex beams, [ 22,23 ] and various beam manipulations. [ 24–29 ] By taking advantage of the simultaneous control of the linear polarization states of the incident and transmitted light, a highly efficient dielectric metalens that is able to render distinct triple foci has been proposed.…”

Recent Progress on Ultrathin Metalenses for Flat Optics

“…For the case of a transverse multifocal metalens, a planar metalens to enable parallel illumination for polarization imaging has been reported (Figure 5C) (Chen et al, 2020a). A unit cell composed of four nanopillars allows the metalens to manipulate states of polarization and phase independently by combining the PB phase and the propagation phase.…”

“…Scale bars, (left) 20 mm and (right) 200 nm. Reprinted with permission from(Chen et al, 2020a). Copyright 2020, American Chemical Society.…”

Metalens‐Assisted System for Underwater Imaging

“…[ 17 ] Optical metasurfaces, wavelength‐scale‐thickness planar nanophotonic devices, are composed of an array of dielectric or metallic nanoantennas of spatially varying in‐plane dimensions and rotations and can arbitrarily maneuver the amplitude, phase, or state of polarization of incident light. [ 18–25 ] With judicious design, a metasurface acting as a metalens has been utilized for both polarization‐insensitive [ 26–31 ] and polarization‐sensitive [ 31–45 ] imaging applications. Compared to conventional polarization imaging equipment, polarization‐sensitive metalenses are compact in size and can simultaneously image the incoming scene with orthogonal polarization states through a single aperture, thereby overcoming the 50% upper limit on operational efficiency of polarization‐filter‐based cameras.…”