Ultrawide bandgap AlN metasurfaces for ultraviolet focusing and routing

Abstract

All-dielectric metasurfaces offer a promising way to control amplitude, polarization, and phase of light. However, ultraviolet (UV) component metasurfaces are rarely reported due to significant absorption loss for most dielectric materials and the required smaller footprint or feature size. Here, we demonstrate broadband UV focusing and routing in both transmission and reflection modes in simulations by adopting aluminum nitride (AlN) with ultrawide bandgap and a waveplate metasurface structure. As for experiments, the on-axis, off-axis focusing characteristics in transmission mode have been investigated at representative UVA (375 nm) wavelength for the first time, to the best of our knowledge. Furthermore, we fabricated a UV transmission router for monowavelength, guiding UV light to the designated different spatial positions of the same or different focal planes. Our work is meaningful for the development of UV photonics components and devices and would facilitate the integration and miniaturization of UV nanophotonics.

Spectral imaging and spectral LIDAR systems: moving toward compact nanophotonics-based sensing

“…The monolithic fabrication process can be developed based on the mature CMOS fabrication technology. More functional optical components using the materials on the existing CMOS-compatible fabrication line, including Si [51,176], SiO 2 [177], SiN [178] and AlN [179,180], are expected to be demonstrated. More large-area metasurface-based optical components are expected to be realized by deep UV photolithography for mass manufacturing [113].…”

Revisiting Optical Material Platforms for Efficient Linear and Nonlinear Dielectric Metasurfaces in the Ultraviolet, Visible, and Infrared

“…AlN has been used for metalenses operating at λ = 375, 308, and 244 nm (Figure c.iv). They have a recorded measured focusing efficiency of 33.3% at λ = 375 nm; the calculated focusing efficiencies are 82.3%, 90%, and 91% at λ = 375, 308, and 244 nm, respectively. In the case of HfO 2 , the highest efficiencies in metasurfaces have been achieved with near-zero k (at λ > 220 nm) and high n (at λ < 400 nm) (Figure c.v).…”

Spin-isolated ultraviolet-visible dynamic meta-holographic displays with liquid crystal modulators

“…10,45,47–49 But a few groups have reported metasurfaces at ultraviolet (UV) wavelengths suffering from low efficiency, and the need to contend with costly and complex fabrication procedures. 50–59 For example, a broadband dielectric metasurface comprising silicon (Si) meta-atoms designed at UV wavelengths has been reported to exhibit an efficiency of ∼30%, attributed to the high extinction coefficient in the UV regime. 50…”

“…10,45,[47][48][49] But a few groups have reported metasurfaces at ultraviolet (UV) wavelengths suffering from low efficiency, and the need to contend with costly and complex fabrication procedures. [50][51][52][53][54][55][56][57][58][59] For example, a broadband dielectric metasurface comprising silicon (Si) meta-atoms designed at UV wavelengths has been reported to exhibit an efficiency of B30%, attributed to the high extinction coefficient in the UV regime. 50 To overcome this low efficiency, researchers have developed aluminum nitride (Al 2 N 3 )-based, 52 niobium pentoxide (Nb 2 O 5 )based, 54 and hafnium dioxide (HfO 2 )-based 55 metasurfaces in the UV regime.…”