3D-patterned inverse-designed mid-infrared metaoptics

Abstract

Modern imaging systems can be enhanced in efficiency, compactness, and application through the introduction of multilayer nanopatterned structures for manipulation of light based on its fundamental properties. High transmission multispectral imaging is elusive due to the commonplace use of filter arrays which discard most of the incident light. Further, given the challenges of miniaturizing optical systems, most cameras do not leverage the wealth of information in polarization and spatial degrees of freedom. Optical metamaterials can respond to these electromagnetic properties but have been explored primarily in single-layer geometries, limiting their performance and multifunctional capacity. Here we use advanced two-photon lithography to realize multilayer scattering structures that achieve highly nontrivial optical transformations intended to process light just before it reaches a focal plane array. Computationally optimized multispectral and polarimetric sorting devices are fabricated with submicron feature sizes and experimentally validated in the mid-infrared. A final structure shown in simulation redirects light based on its angular momentum. These devices demonstrate that with precise 3-dimensional nanopatterning, one can directly modify the scattering properties of a sensor array to create advanced imaging systems.

Two-photon polymerization lithography for imaging optics

“…For instance, a broader selection of available printing materials offers diverse Abbe number options, facilitating the design of broadband optical devices. Beyond the wellexplored visible band, TPL can achieve precise wavefront control in the x-ray [213][214][215] band and larger wavelength bands, such as NIR and mid-infrared bands [212]. A promising candidate is a hybrid organically modified silicate-based photoresist called SZ2080™, known for its high transparency, low absorption in the UV, visible, and infrared spectra [216], and a high laser-induced damage threshold for the fabrication process [217].…”

“…Drawing inspiration from color routing concepts, Roberts et al embarked on the inverse design of 3D patterned midinfrared metadevices. Employing optimization algorithms, they achieved the experimental validation of devices fabricated via TPL, showcasing the capabilities of multispectral and linear polarization sorting, OAM sorting, and Stokes polarimetry (depicted in figure 17(k)) [212]. The incorporation of intricate, multilayered nanophotonic structures marks a pivotal advancement in enhancing imaging system performance and multifunctionality.…”

Roadmap for Optical Metasurfaces

“…These systems have similar design flexibility as multilayer meta-optics but can potentially achieve that functionality in a more compact footprint. For instance, it has been demonstrated that 3D meta-optics can achieve high efficiency spectral and polarization sorting using one, continuously structured, optical component . This functionality is not possible in single layer metasurfaces that are invariant along the optical axis without introducing reflection loss.…”

All-Glass 100 mm Diameter Visible Metalens for Imaging the Cosmos

“…Dielectric metasurfaces, which consist of subwavelength-spaced nanostructures with micron-scale thickness, have the potential to serve as ultralight and thin transmissive optics if they can be fabricated at scale over large areas. Although many early demonstrations of metasurfaces and binary subwavelength diffractive optics utilized electron-beam (e-beam) lithography − or other serial point-by-point fabrication techniques, such as two-photon optical lithography, − which led to skepticism about their practical scalability, metasurfaces are now produced at larger scales using modern semiconductor foundry photolithography − and nanoimprinting techniques, − alleviating such scaling concerns.…”