Mid-infrared biomimetic moth-eye-shaped polarization-maintaining and angle-insensitive metalens

Abstract

Metalenses can potentially reduce the size and complexity of existing cameras, displays, and other optical devices, owing to their capability of flexible manipulation of the polarization, amplitude, and phase of light. However, metalenses capable of maintaining polarization and broadband wavefront shaping under arbitrarily polarized excitation have not been studied. In this study, we present the first demonstration of a biomimetic moth-eye-shaped metalens for polarization-maintaining, broadband and angle-insensitive focusing under an arbitrarily polarized excitation in the mid-infrared waveband (3.1–8.0 µm). Modulation and focusing efficiencies of 92% and 90%, respectively, were achieved. Moreover, a bifocal moth-eye-shaped metalens operating at normal and oblique incidences was realized. Compared to previously reported metalenses, the one proposed in this study exhibited a better focusing under oblique incidence, ensuring light transmission as effectively as a traditional lens. This study paves the way for the development of polarization-maintaining, broadband, and angle-insensitive microscale optical devices and imaging systems.

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“…The focus on size, weight, power, price, and performance (SWaP3) optimization in LWIR thermal imaging systems is a key trend in research and development. Metalenses, capable of their subwavelength scale manipulation of wavefront information such as amplitude, phase, and polarization, mark a significant advancement in optical technology [4][5][6][7][8][9][10] . They offer the potential to replace or supplement traditional lenses in applications requiring high-precision imaging or in miniature optical systems, attracting significant attention recently.…”

Asymmetric Plasmonic Moth-Eye Nanoarrays with Side Opening for Broadband Incident-Angle-Insensitive Antireflection and Absorption

“…However, the single plasmonic MIM structures providing angle insensitivity can only work at a specific wavelength due to their narrow-band SPR [29]. Inspired by the cornea of moths, many sub-wavelength biomimetic quasi-moth-eye structures providing a gradient refractive index, such as nanopyramids, nanocones and nanonipples, are investigated as broadband antireflection structures [3,30,31]. Combining moth-eye nanostructures with the antireflective MIM nanostructures can integrate the gradient-refractive-index effect and SPR effect, which is promising to produce enhanced broadband and angle-insensitive antireflection and absorption performance.…”

Mid-Infrared Continuous Varifocal Metalens with Adjustable Intensity Based on Phase Change Materials

“…A metasurface, a man-made, two-dimensional material consisting of an array of subwavelength optical antennas of differently shaped structures, acts like a scalpel and can "prune" electromagnetic waves such as changing their phase, amplitude, and polarization [1][2][3][4]. In recent years, various ultra-thin optical devices such as focusing lenses [5][6][7][8][9][10][11], holographic plates [12,13], polarization converters [14][15][16], and vortex phase plates [17][18][19][20] have been realized based on metasurface wavefront shaping technology. A metalens, as a subclass of metasurfaces, is a planar optical device that converges and images by modulating the phase of incident electromagnetic waves.…”