Optical tunability is demonstrated with multi-metal hyperbolic metamaterial (HMM) structures on varying substrate surfaces. A systematic uniaxial modeling methodology is adapted from classical approaches to extract the anisotropic permittivity of the films to identify epsilon-near-zero (ENZ) behavior over a wide range of metal volume fractions (φ). The anisotropic model accuracy is quantified by a mean squared error (MSE) with the presented modeling routine resulting in a MSE < 35 for all samples. The optical model thicknesses were verified with transmission electron microscopy (TEM) imaging and measurements. This study also demonstrates the ability to tune the optical responses in the visible-to-infrared frequencies with surface microtexturing and applied strain with HMM coatings on flexible Kapton substrates. Furthermore, the structured films and modeling procedure lay the groundwork for future studies on coupling the anisotropic optical and thermal properties for control over advanced multifunctional thin-film coatings.

Metasurfaces, optics made from subwavelength-scale nanostructures, have been limited to millimeter-sizes by the scaling challenge of producing vast numbers of precisely engineered elements over a large area. In this study, we demonstrate an all-glass 100 mm diameter metasurface lens (metalens) comprising 18.7 billion nanostructures that operates in the visible spectrum with a fast f-number (f/1.5, NA = 0.32) using deep-ultraviolet (DUV) projection lithography. Our work overcomes the exposure area constraints of lithography tools and demonstrates that large metasurfaces are commercially feasible. Additionally, we investigate the impact of various fabrication errors on the imaging quality of the metalens, several of which are specific to such large area metasurfaces. We demonstrate direct astronomical imaging of the Sun, the Moon, and emission nebulae at visible wavelengths and validate the robustness of such metasurfaces under extreme environmental thermal swings for space applications.

Quasi-3D plasmonic nanostructures are in high demand for their ability to manipulate and enhance light-matter interactions at subwavelength scales, making them promising building blocks for diverse nanophotonic devices. Despite their potential, the integration of these nanostructures with optical sensors and imaging systems on a large scale poses challenges. Here, a robust technique for the rapid, scalable, and seamless replication of quasi-3D plasmonic nanostructures is presented straight from their production wafers using a microbubble process. This approach not only simplifies the integration of quasi-3D plasmonic nanostructures into a wide range of standard and custom optical imaging devices and sensors but also significantly enhances their imaging and sensing performance beyond the limits of conventional methods. This study encompasses experimental, computational, and theoretical investigations, and it fully elucidates the operational mechanism. Additionally, it explores a versatile set of options for outfitting nanophotonic devices with custom-designed plasmonic nanostructures, thereby fulfilling specific operational criteria.

Linear gratings polarizers provide remarkable potential to customize the polarization properties and tailor device functionality via dimensional tuning of configurations. Here, we extensively investigate the polarization properties of single- and double-layer linear grating, mainly focusing on self-aligned bilayer linear grating (SABLG), serving as a wire grid polarizer in the mid-wavelength infrared (MWIR) region. Computational analyses revealed the polarization properties of SABLG, highlighting enhancement in TM transmission and reduction in TE transmission compared to single-layer linear gratings (SLG) due to optical cavity effects. As a result, the extinction ratio is enhanced by approximately 2724-fold in wavelength 3–6 μm. Furthermore, integrating the specially designed SABLG with an MWIR InAs/GaSb Type-II Superlattice (T2SL) photodetector yields a significantly enhanced spectral responsivity. The TM-spectral responsivity of SABLG is enhanced by around twofold than the bare device. The simulation methodology and analytical analysis presented herein provide a versatile route for designing optimized polarimetric structures integrated into infrared imaging devices, offering superior capabilities to resolve linear polarization signatures.

Metasurfaces offer flexibility for expanding functionality and reducing the size of optical systems by providing optical functionality from a flat surface. Previous work has demonstrated a rapid fabrication and testing process for wafers containing multiple 1- centimeter diameter metalenses that can be applied towards mass manufacturing. However, quality feedback was limited to analyzing imaging performance parameters such as the modulation transfer function and focal length. These techniques do not give direct feedback about specific manufacturing errors. Currently, getting this feedback still requires expensive, time-intensive processes such as scanning electron microscope (SEM) measurements or local area interferometry, which tend to have a small field of view. Theoretical investigation suggests that phase errors in the metasurface phase profile result in a shift in diffraction efficiency away from the first order and into the other diffraction orders, zero order, second, third, etc. We exploit this concept to comprehensively characterize metalens performance, including the analysis of standard image quality parameters and extending the study to multiple diffraction orders. An extensive set of measurements of the relative efficiency of the diffraction orders is presented for a set of fabricated metalenses alongside SEM measurements to cross-validate the presence of manufacturing defects. This will establish the extent to which current conventional CMOS processing and manufacturing techniques can be applied to metasurface optics by indicating uniformity and yield characteristics across positions and wafers.

Infrared imaging systems are an essential part of many fields of study, typically used for military and airborne surveillance, manufacturing, security, night vision, threat detection, medical imaging, and inspection, to name a few. One of the best-performing systems in the midwave infrared is the type-II strained layer superlattice (SLS) photodetectors. They require external subzero cooling at very low temperatures. While technically capable of operating at higher temperatures, this reduces their sensitivity while increasing their noise-to-signal ratio (NSR). Additionally, previous research showed that detector sensitivity could be improved by integrating a microsphere lens into the photodetector. Still, the microsphere-lens-enhanced photodetector Fourier transform infrared response (FTIR) shows that this microsphere lens also introduces material absorption. New signal processing, analysis, and computational methods are needed to automatically detect and remove material absorption, aberrations, and to improve their performance. This article proposes hybrid methods using experimental data and computational models to smooth, detect, characterize, and reduce material absorption and noise from FTIR data collected from microsphere-lens-enhanced MWIR SLS detectors. Using the percent area lost performance metric of photodetectors with and without microsphere lens enhancement. We propose a novel combination method for improving the overall FTIR signal performance based on piecewise polynomial fit and a Hilbert-transform-based algorithm. Our results show that for different types/sizes of microsphere-lens material and detector sizes, these algorithms can quantify the increase in sensitivity of MWIR SLS detectors while automatically finding and quantifying microsphere-lens material-based absorption and reducing their adverse effects on the SLS detector across the MWIR spectral band.

Thin-film LC based geo-phase optics have previously been demonstrated to drastically reduce size, weight, and power requirements for large-aperture optical systems while providing non-mechanical functionality for discrete values - for example, digital switching of the beam steering angle. In this work, we present a series of geo-phase Alvarez-Lohmann lens systems capable of analog tuning of focal length through lateral translation or azimuthal rotation. For circularly polarized inputs, diffraction efficiencies greater than 90% were observed over the visible spectrum with some wavelengths exceeding 99% for lateral embodiments. Both cylindrical and spherical Alvarez-Lohman systems were fabricated with focal lengths varying from infinity to 110 mm with increasing lateral displacement. These LC-based geo-phase optical systems could enable a new generation of low-cost, high-performance, and ruggedized dynamic optical components.

An overview of a research program to screen material candidates for more durable windows that operate over a broad temperature and wavelength range is presented. The hardness, high melting points, and oxidation resistance of cubic oxides make them logical material choices to screen. Empirical and density functional theory modeling along with extensive datamining of literature and on-line databases are used to screen materials for window relevant properties. Promising materials are processed and characterized for optical transparency at room and high temperature by high-throughput methods to validate predicted properties. Potential window materials identified by these methods are presented and discussed.

This work demonstrates the utility of a design, fabrication, and testing loop on 10 mm diameter metalenses to accelerate large-scale production of flat optics. By enabling rapid measurement and analysis of metalenses, it is possible to identify differences between designed performance and as-built performance quickly and correlate those to process characteristics. This accelerated feedback between the design, fabrication, and testing is expected to enable higher yields of better-performing metalenses.

Fluorite structure oxides include cubic-stabilized ZrO2, HfO2, ThO2, UO2, and some rare-earth compositions. Many rare-earth oxides also form cubic bixbyite (Ln2O3) structures. These materials are some of the most refractory oxides known. The optical and thermomechanical properties of fluorite structured oxides and rare-earth bixbyites are reviewed. Existing data on transmittance in the visible and infrared is summarized and compared with theoretical predictions from density functional theory and other physics-based models. Properties such as thermal conductivity, thermal expansion, melting point, modulus, hardness, refractive index, dielectric constant, thermochemical stability, and the trade-offs between these properties and optical properties are also discussed. New results for optical and thermomechanical properties for selected bixbyite and fluorite compositions will be presented, compared with existing data, and with model predictions.

Photonic upconversion from the infrared regime to the visible spectrum can occur through sum-frequency generation (SFG). A second-order nonlinear optical response, such as SFG, can be produced from a nonlinear material, in this case an ABC nanolaminate. Optimization of a metamaterial consisting of a plasmonic nanolaminate device can maximize the SFG from incident wavelengths. Utilization of a deep learning framework removes the need for traditional guess and check methods and creates new possibilities for plasmonic geometries. Applications of this research include low-cost night vision or low light imaging systems for defense, autonomous vehicles, and other commercial uses.

Combining planar optics such as metalenses or metacorrectors with conventional lenses can drastically improve the optical performance of imaging systems with additional benefits such as cost, size and weight improvements. However, incorporating metacorrectors into conventional lens design requires multiscale simulations to account for the different length scale interactions. Namely, full wave scattering and geometric optics analysis is needed for the metacorrector and hybrid lens design, respectively. Multiscale inverse optimization using Sandia National Laboratories’ MIRaGE along with different wave propagation techniques and commercial-off-the-shelf GO tools are considered to accurately predict hybrid design optical performance.

Within optics, the Pancharatnam–Berry phase enables the design and creation of various flat special optical elements such as top-hat converters. We present a study on engineering efficient vectorial top-hat converters inscribed in glass by high-power femtosecond laser pulses. We phase-encode a top-hat converter and demonstrate how its quality is influenced by various parameters. We investigate theoretically the generation of the top-hat beam under imperfect conditions such as the mismatch of the incident beam width or the misalignment of the center of the converter. Experimental verification of the concept is also presented.

The conventional process for developing an optimal design for nonlinear optical responses is based on a trial-and-error approach that is largely inefficient and does not necessarily lead to an ideal result. Deep learning can automate this process and widen the realm of nonlinear geometries and devices. This research illustrates a deep learning framework used to create an optimal plasmonic design for a nonlinear metamaterial. The algorithm produces a plasmonic pattern that can maximize the second-order nonlinear effect of a nonlinear metamaterial. A nanolaminate metamaterial is used as a nonlinear material, and plasmonic patterns are fabricated on the prepared nanolaminate to demonstrate the validity and efficacy of the deep learning algorithm. The optimal pattern produced yielded second-harmonic generation from the nanolaminate with normal incident fundamental light. The deep learning architecture applied in this research can be expanded to other optical responses and light-matter interaction processes.

Inverse‐vulcanized polymeric sulfur has received considerable attention for application in waste‐based infrared (IR) polarizers with high polarization sensitivities, owing to its high transmittance in the IR region and thermal processability. However, there have been few reports on highly sensitive polymeric sulfur‐based polarizers by replication of pre‐simulated dimensions to achieve a high transmission of the transverse magnetic field (TTM) and extinction ratio (ER). Herein, a 400‐nanometer‐pitch mid‐wavelength infrared bilayer linear polarizer with self‐aligned metal gratings is introduced on polymeric sulfur gratings integrated with a spacer layer (SM‐polarizer). The dimensions of the SM‐polarizer can be closely replicated using pre‐simulated dimensions via a systematic investigation of thermal nanoimprinting conditions. Spacer thickness is tailored from 40 to 5100 nm by adjusting the concentration of polymeric sulfur solution during spin‐coating. A tailored spacer thickness can maximize TTM in the broadband MWIR region by satisfying Fabry–Pérot resonance. The SM‐polarizer yields TTM of 0.65, 0.59, and 0.43 and ER of 3.12 × 103, 5.19 × 103, and 5.81 × 103 at 4 µm for spacer thicknesses of 90, 338, and 572 nm, respectively. This demonstration of a highly sensitive and cost‐effective SM‐polarizer opens up exciting avenues for infrared polarimetric imaging and for applications in polarization manipulation.

Chain-like magnetic self-organizations have been documented for micron/submicron-scale magnetic particles. However, the positions of the particles are not stationary in a sustaining fluid owing to Brownian translational motion, resulting in irregular magnetic self-assembly. Toward the development of a programmable and reversible magnetic self-assembly, we report a stepwise collective magnetic self-assembly with periodic polymeric micropillar arrays containing magnetic particles. Under an external magnetic field, the individual micropillar acts as a micromagnet; magnetic polarities of embedded ferromagnetic particles are arranged in the same direction. The nearest pillar tops undergo a pairwise assembly owing to the anisotropic quadrupolar interaction, whereas the pillar bases remain stationary because of the presence of a magnetically inert substrate. By increasing the magnetic flux density, a collective quad-body assembly of vicinal paired micropillars is accomplished, finally leading to long-range connectivity of the pillar tops. Simple evaporation of the polymeric solution yields shape-fixation of the connected micropillar architectures even after magnetic fields are removed. We investigate geometric effects on this stepwise collective magnetic self-assembly using rectangular, square, and circular micropillars. Also, we demonstrate spatially selective magnetic self-assembly (e.g., arbitrary letters) using a masking technique. Finally, we demonstrate on-demand programming of bidirectional liquid spreading through long-range ordered magnetic self-assembly.

Traditional processes for the design of metamaterial structures are often computational heavy, time-consuming, and occasionally does not lead to the desired optical response. Deep learning can quickly optimize structures through inverse design, and create new geometries for devices. This research uses a deep learning framework for the inverse design of an optimal plasmonic structure to maximize the second-order nonlinear response from a nonlinear metamaterial. The thinfilm nonlinear metamaterial employed is a nanolaminate, and the optimal plasmonic structure is fabricated to establish the validity of the deep learning algorithm.

We put forward a co-axial pump(optical)-probe(X-rays) experimental concept and show performance of the optical component. A Bessel beam generator with a central 100 micrometers-diameter hole (on the optical axis) was fabricated using femtosecond (fs) laser structuring inside a silica plate. This flat-axicon optical element produces a needle-like axial intensity distribution which can be used for the optical pump pulse. The fs-X-ray free electron laser (X-FEL) beam of sub-1 micrometer diameter can be introduced through the central hole along the optical axis onto a target as a probe. Different realisations of optical pump are discussed. Such optical elements facilitate alignment of ultra-short fs-pulses in space and time and can be used in light-matter interaction experiments at extreme energy densities on the surface and in the volume of targets. Full advantage of ultra-short 10 fs X-FEL probe pulses with fs-pump(optical) opens an unexplored temporal dimension of phase transitions and the fastest laser-induced rates of material heating and quenching. A wider field of applications of fs-laser-enabled structuring of materials and design of specific optical elements for astrophotonics is presented.

The authors demonstrate the ability to create an ultrafast hyperbolic momentum state using metallic InAsSb alloys embedded within dielectric GaSb and explore the possibility of transient modification of metamaterials to control the optical properties of photon emission. Properly engineered quantum well structures were grown by molecular beam epitaxy and Si-doped in order to convert the InAsSb layers from dielectric to metallic at infrared frequencies. The carrier excitation scheme of the engineered hyperbolic stacks was investigated in a variety of excitation levels using pump–probe measurements. The photo-excited carriers in the structure with a metal fraction of ∼0.5 showed a polarization dependent reflectivity change, which indicates a transient hyperbolic metamaterial state in the heterostructure induced by the pump laser.

We perform numerical and initial experimental study of temperature-dependent phase profile of metasurfaces. Berry phase-based structures are found more stable with respect to refractive index variation and thermal expansion, compared to propagation phase- based geometries.