This talk will cover DARPA research programs that have made important strides in metasurfaces for imaging applications. The EXTREME program developed broadband achromatic metasurfaces and hybrid meta-optics for visible imaging applications, as well as actively tunable and hemispherical FOV metalenses in the infrared. The Enabling Night Vision in Eyeglass form factors (ENVision) program is leveraging these advances to develop planar night vision goggle systems based on meta-optics that are achromatic across two full IR bands and have enhanced FOV compared to state-of-the-art devices, all through a single common aperture.

Beam steering devices can be used for various applications such as light detection and ranging and free space optical communication. The conventional methods for the beam steering are based on the mechanical rotation of mirrors and cause bulk form-factor and limited operation speed. The metasurfaces are arrays of dielectric or metallic antennas that can tailor the optical properties such as amplitude and phase at the deep subwavelength range. Here, we present the all-dielectric metasurface that can modulate the reflection phase >270° with high reflectivity >60% as a function of the individually applied voltage in the near infrared regime.

Phase change material (PCM)-based actively tunable mid-wave IR filters have broad imaging and sensing applications—from probing molecular vibrations in chemical species to detecting radiant thermal signatures. We introduce the Phase-change actively tunable filter (P-ACTIVE) project lead by NASA Langley Research Center with collaborators MIT and the University of Cambridge. It covers background science, experimental and theoretical device performance, as well as recent results obtained from a MISSE-14 mission for space qualification of active metasurface optics and constituent PCM. We conclude with a prospective view of the technology and discuss the potential for these filters to serve multiple NASA missions.

Modern imaging systems can be enhanced in efficiency, compactness, and range of applications through introduction of multilayer nanopatterned structures for manipulation of light based on its fundamental properties. Metaoptical components can be tailored to respond to these varying electromagnetic properties, but have been mostly explored in single-layer, ultrathin geometries, which limits their capacity for multifunctional behavior. Here we show the design of several pixel-sized scattering structures which sort light efficiently based on its wavelength, polarization state, and spatial mode. The multispectral and polarimetry devices are further fabricated via two-photon lithography and experimentally validated in the mid-infrared.

A new hybrid Material platform for dynamically reconfigurable metaphotonic devices with control over amplitude, phase, polarization, and spectral properties of an optical wavefront will be demonstrated. The integration of dielectric, plasmonic, and phase-change materials in this platform enables the engineering of the electromagnetic modes in different states of the device with a wide range of properties for realization of reconfigurable metaphotonic devices. Design, fabrication, and application of these platforms for state-of-the-art applications will be covered.

I will discuss opportunities for new regimes of quantum-limited imaging and detection that are enabled by recent advances at the confluence of materials innovation, the development of functional metamaterials, and foundational concepts of quantum metrology. Together, these advances allow for a redefinition of fundamental limits to imaging or detection by enabling new modalities, enhancing light-matter interactions at the nanoscale or creating new opportunities for applications ranging from nanoscale biochemistry to space-based remote sensing. Using ongoing DARPA efforts such as OpTIm (Optomechanical Thermal Imaging) and SAVaNT (Science of Atomic Vapors for New Technologies) as exemplars, I will also discuss various approaches to transitioning novel laboratory-scale proofs-of-concept to deployable technologies.

Phase change materials (PCM) provide unique optical characteristics such as a dramatic change in optical refractive index greater than 1, not obtainable from conventional semiconductor optical materials such as Si and InP. Thus, the PCM is being explored to program and reconfigure optical devices to adapt to the sensing needs per environment. Also, the non-volatile nature of PCM devices offers its system integration without disturbing the sensing. Here, we report on a new solid-state optical modulator device with SbTe PCM operating in the infrared range and at cryogenic temperatures with excellent switching cycle reliability for the programming of PCM-based optical devices.

We have developed a spectral image sensor based on CMOS image sensor for smartphone. The spectral image sensor consists of optical bandpass filter array integrated on top of image sensor pixels. Each filter has a different transmission wavelength peaks so spectral information is directly retrieved by intensity map of the image sensor. We applied the spectral sensor technology to 1) Raman spectroscopy for drug identification, 2) Freshness detection of vegetables and 3) hyperspectral imaging applications for color enhancement, food inspection and skincare.

Optical metasurfaces are planar subwavelength nanoantenna arrays engineered to provide on-demand manipulation of light, thereby enabling ultra-compact flat optics with high performance, small form-factor and new functionalities. When integrated with active elements, the pixelated, thin device architecture further facilitates dynamic tuning of local and global optical responses. Leveraging advanced materials, designs and architectures, we develop novel active and passive meta-optics capable of transforming a variety of optical systems that are traditionally bulky and complicated.

Flat optics with micro-nano-structures fabricated on a thin film has shown strong power in light manipulation and is promising for integrated optoelectronics for its compactness and compatibility for large volume manufacturing. In this talk, I will introduce flat lenses to break the diffraction limit and their applications in medical imaging and high density data storage. By engaging the strong excitonic absorption in 2D materials, ultra-thin flat lenses in MoS2 is demonstrated for sub-diffraction limit imaging. Furthermore, high electrical tunability in refractive index is achieved in monolayer WS2 in an optical cavity for potentially tunable ultra-thin flat lenses.

Heavily-doped III-V semiconductors have been shown to be good plasmonic materials in the mid- to far-infrared. A superlattice comprising alternating doped and undoped layers can act as a hyperbolic metamaterial (HMM). HMMs have an open, hyperbolic isofrequency surface enabling the propagation of light with large wavevectors, called volume plasmonic polaritons (VPPs). In this presentation, I will focus on semiconductor-based HMMs, explaining how material choice impacts HMM performance, showing far-field thermal emission properties, and demonstrating strong coupling between the HMM VPP modes and epitaxially embedded quantum wells.

We demonstrate meta-optic based accelerators that can off-load computationally expensive operations into high-speed and low-power optics. The key to these architectures are the new freedoms afforded by metasurfaces such as optical edge isolation, polarization discrimination, and the ability to spatially multiplex, and demultiplex, information channels. I will discuss how these freedoms can be utilized for accelerating optical segmentation networks and objection classifiers, both based on incoherent illumination. This approach could enable compact, high-speed, and low-power image and information processing systems for a wide range of applications in machine-vision and artificial intelligence.

Herein, we evaluate Yb3+ doped CsPbCl3 as a bright ceramic scintillator material and investigate different doping amounts to elucidate its bright luminescence enabled by quantum cutting. We demonstrate that the host CsPbCl3 perovskite structure is maintained up to 7% mole Yb3+, which produces a light yield of 102,000 photons/MeV. We show that these polycrystalline perovskite scintillators can be pressed into a ceramic pellet and used for x-ray imaging with a resolution of approximately 0.1 mm. The combination of high light yield and the simple, inexpensive synthesis reported in this work demonstrates the great potential of Yb3+:CsPbCl3 for scintillation applications.