Leonardo DRS has a consistent track record of extending the boundaries of electro-optical infrared imaging, both enabling advanced capabilities and making them accessible through scalable production techniques. From a retrospective of innovations, this talk will extend to active development and discuss the outlook for future advancement at Leonardo DRS.

Space-qualified midwave infrared (MWIR) camera systems have been high in cost and proprietary to large aerospace companies. To achieve high frame rates, the power consumption is also high. The smaller pixels used in larger arrays have low charge handling capacity that results in poor signal to noise performance. This is a significant obstacle for many small satellite missions.

This paper presents a novel, low SWAP-C, commercially available high-end MWIR camera technology that is fully space-qualified for LEO missions. The design uses high-end commercial infrared detectors and coolers combined with custom circuitry for smart power management of cryo-coolers and latch-up protection of the detectors.

We describe the performance of long-wavelength MCT operating at 4.2K as a fast photoconductive detector for far-infrared nanospectroscopy. The technique employs scattering from the tip of an atomic force microscope (AFM) engaged with a sample surface while in "tapping mode" at a frequency f, with the scattered infrared sensed at a higher harmonic, e.g. 2f, 3f or even 4f to improve spatial discrimination. With typical tapping frequencies >100 kHz, the infrared detector requires a bandwidth of 1 MHz or higher, for which thermal-type IR detectors are not sufficiently fast. MCT detectors are usually limited to wavelengths shorter than 25µm when operating at T=77K, but this can be overcome by cooling to 4.2K, in which case the detection threshold wavelength extends to beyond 50 microns. An additional benefit is an overall 5X improvement in S/N.

*This work supported by the U.S. Department of Energy under contract DE-SC0012704 at NSLS-II and BNL. See ACS Photonics, 10, 4329-4339 (2023), (https://doi.org/10.1021/acsphotonics.3c01148)

Polycrystalline lead selenide thin film has now emerged as a promising choice for low-cost and uncooled MWIR detectors and arrays operating at room temperature within the 3~5 µm wavelength range. LCDG (Laser Components Detector Groups) has successfully fabricated a new version of PbSe thin films using the chemical bath deposition (CBD) method on quartz substrates, enabling the development of infrared detectors and arrays with robust and high production yield. To achieve efficient activation of the PbSe thin film, LCDG investigates PbSe material from chemical reaction of the bath deposition to final packaging to meet various customer specifications and establishes PbSe detectors based on nano- and micro-particles embedded PbSe thin film, resulting in exceptional MWIR photoconductive response at room temperature. The characterization of PbSe thin film reveals the presence of various nanostructures, such as nano- and micro-particles as well as Pb-oxide phases and Pb-iodine phase carrier transporting channels. This paper reports the MWIR performance of the uncooled LCDG’s PbSe detector, focusing on responsivity, EQE, 1/f noise and FTIR spectral response (77K-340K), and D*.

New nano- or micro-patterned metal nonlinear metasurfaces, robust against temperature and more sustainable than current IR materials, could respond across the LWIR-to-SWIR spectrum (no band gap) for long-distance data/power transfer, thermal management, sensing, navigation, and detection. In this presentation, we discuss our recent discovery of longitudinal and transverse optical rectification (OR) in an asymmetric plasmonic grating that is inherently linear. A periodic Au stripe array breaks inversion symmetry perpendicular to the stripes, so that direct (zero frequency) electronic, rectified current, due to selective excitation of only one SPP mode, flows with incident photons polarized perpendicular to the stripes. We also measured the influence of the photon helicity on the OR current, from coupling of the spin of propagating surface plasmon-polaritons (SPPs) to their linear momentum and to the angular momentum of incident photons. It is interesting that bosonic SPPs generate this electrical current. Simple ‘photon drag’ and other models of electronic current do not completely explain the experiment. We discuss scientific advances to better understand these phenomena.

The emissivity, reflection, or transmittance of media in the infrared can be measured using a filter spectrometer, which typically consists of an incandescent light source, filters, and one or more detectors. In the case of a focal-plane array of detectors, this configuration can be a multispectral or hyperspectral camera. We demonstrate that the spectral resolution of this simple system can be significantly improved when the temperature of the incandescent source is varied and tracked, i.e. via “Planck enhancement”.

This talk shows the recent development of linear and Geiger-mode pseudo-planar Ge-on-Si avalanche photodiodes (APDs) in the short-wave infrared region. We demonstrate a 26 µm-diameter Ge-on-Si Geiger-mode APD with an extremely low noise-equivalent-power of 7.7 × 10−17 WHz−½ and a jitter value of 134 ± 10 ps at 1310 nm wavelength and at 100 K operating temperature. We demonstrate that a linear array of Ge-on-Si linear mode APDs comprising of 10 pixels shows high responsivity, highly uniform avalanche breakdown voltage and avalanche gain at 1550 nm wavelength and at room temperature.

Infrared photodetection at ambient temperature is a challenge that classical photodetectors have not been able to fulfill yet. New materials, like the 2D materials family, and plasmonic nanostructures, are currently explored to address this challenge. We will show how the combination of carefully design coupled Fabry-Perot nanoresonnators and graphene can be used has an ambient infrared photodetector.

Electroluminescence in mid-IR of hBN-encapsulated graphene under large bias was recently put into evidence through spectroscopy and noise thermometry. We demonstrate in this presentation that hyperbolic phonon polariton electroluminescence is responsible for efficient out-of-plane energy transfer through hBN. We then show that this energy transfer can be engineered using hBN with various turbidity, exhibiting for the first time that far-field energy transfer in turbid media remains valid in the case of energy transfer by confined hyperbolic rays.