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Breakthroughs brought about by two‐dimensional (2D) materials in the field of photodetection have opened up new possibilities in infrared imaging. However, challenges still exist in fabricating high‐density detector arrays using such materials, which are essential for traditional imaging systems. In this study, we present a state‐of‐the‐art computing imaging system that utilizes a MoTe2/Si self‐powered photodetector coupled with flexible Hadamard modulation algorithms. This system demonstrates remarkable capability to produce high‐quality images in the shortwave infrared (SWIR) band, surpassing the capabilities of devices based on alternative material systems. The exceptional infrared imaging capability primarily stems from the MoTe2/Si photodetector's inherent features, including an ultra‐wide spectral range (265–1550 nm) and extremely high sensitivity (linear dynamic range (LDR) up to 123 dB, responsivity (R) up to 0.33 A W–1, external quantum efficiency (EQE) up to 43% and a specific detectivity (D*) exceeding 2.9 × 1011 Jones). Moreover, the imaging system demonstrates the ability to achieve high‐quality edge imaging of objects in the SWIR band (1550 nm), even in strong scattering environments and under low sampling rate conditions (sampling rate of 25%). We believe that this work will effectively advance the application scope of 2D materials in the field of computational imaging in SWIR bands. [ABSTRACT FROM AUTHOR]

Variable‐angle spectroscopic ellipsometry is used to determine the room temperature complex refractive index (n˜=n+ik)$\left(\right. \overset{˜}{n} = n + i k \left.\right)$ of molecular beam epitaxy grown GaSb1−xBix films with x ≤ 4.25% over a spectral range of 0.47–6.2 eV. By correlating to critical points in the extinction coefficient k, the energies of several interband transitions are extracted as functions of Bi content. The observed change in the fundamental bandgap energy (E0, −36.5 meV per %Bi) agrees well with previously published values; however, the samples examined here show a much more rapid increase in the spin‐orbit splitting energy (Δ0, +30.1 meV per Bi) than previous calculations have predicted. As in the related GaAsBi, the energy of transitions involving the top of the valence band are observed to have a much stronger dependence on Bi content than those that do not, suggesting the valence band maximum is most sensitive to Bi alloying. Finally, the effects of surface droplets on both the complex refractive index and the critical point energies are examined. [ABSTRACT FROM AUTHOR]

Abstract Breakthroughs brought about by two‐dimensional (2D) materials in the field of photodetection have opened up new possibilities in infrared imaging. However, challenges still exist in fabricating high‐density detector arrays using such materials, which are essential for traditional imaging systems. In this study, we present a state‐of‐the‐art computing imaging system that utilizes a MoTe2/Si self‐powered photodetector coupled with flexible Hadamard modulation algorithms. This system demonstrates remarkable capability to produce high‐quality images in the shortwave infrared (SWIR) band, surpassing the capabilities of devices based on alternative material systems. The exceptional infrared imaging capability primarily stems from the MoTe2/Si photodetector's inherent features, including an ultra‐wide spectral range (265–1550 nm) and extremely high sensitivity (linear dynamic range (LDR) up to 123 dB, responsivity (R) up to 0.33 A W–1, external quantum efficiency (EQE) up to 43% and a specific detectivity (D*) exceeding 2.9 × 1011 Jones). Moreover, the imaging system demonstrates the ability to achieve high‐quality edge imaging of objects in the SWIR band (1550 nm), even in strong scattering environments and under low sampling rate conditions (sampling rate of 25%). We believe that this work will effectively advance the application scope of 2D materials in the field of computational imaging in SWIR bands.

We report on the design and experimental verification of angle and polarization insensitive mid-infrared filters based on dense arrays of dielectric resonators embedded into a metallic film. We experimentally show filters with 60% peak transmission for angles from 0 to 60 degrees for perpendicular polarization states. We also study the surface plasmonic mode excited due to the periodicity of the micro-resonators in the array. Simulations support the experimental results for both the primary resonance and the plasmonic mode. Integrating these filters with IR detectors offers multispectral imaging and improved search and track capability.

Atomic layer deposition (ALD) has emerged as a promising technology for the development of the next generation of low-power semiconductor electronics. The wafer-scaled growth of two-dimensional (2D) crystalline nanostructures is a fundamental step toward the development of advanced nanofabrication technologies. Ga2O3 is an ultra-wide bandgap metal oxide semiconductor for application in electronic devices. The polymorphous Ga2O3 with its unique electronic characteristics and doping capabilities is a functional option for heterointerface engineering at metal-semiconductor 2D heterojunctions for application in nanofabrication technology. Plasma-enhanced atomic layer deposition (PE-ALD) enabled the deposition of ultra-thin nanostructures at low-growth temperatures. The present study used the PE-ALD process for the deposition of atomically thin crystalline ß-Ga2O3 films for heterointerface engineering at 2D metal-semiconductor heterojunctions. Via the control of plasma gas composition and ALD temperature, the wafer-scaled deposition of ~5.0 nm thick crystalline ß-Ga2O3 at Au/Ga2O3-TiO2 heterointerfaces was achieved. Material characterization techniques showed the effects of plasma composition and ALD temperature on the properties and structure of Ga2O3 films. The following study on the electronic characteristics of Au/Ga2O3-TiO2 2D heterojunctions confirmed the tunability of this metal/semiconductor polarized junction, which works as functional electron channel layer developed based on tunable p-n junctions at 2D metal/semiconductor interfaces. [ABSTRACT FROM AUTHOR]

Control over the radiative and non-radiative channels of the IR-emitting quantum dots (QDs) is crucially important to improve performance of related devices. Here, we study spontaneous photoluminescence (PL) enhancement of mercury telluride QDs coupled to plasmonic nanoantenna arrays supporting collective plasmon mode spectrally matching QD's PL spectrum. Our systematic studies revealed how PL enhancement varies with QDs layer thicknesses as well as laser excitation and emission collection conditions, providing deeper insight into the QD/plasmonic arrays interaction. We demonstrated that careful adjustment of excitation and emission collection parameters leads to more than an order of magnitude enhancement of spontaneous emission of HgTe QDs coupled with periodical plasmonic arrays with resonances spectrally matched to QDs absorption and emission bands. The region of QDs layer thickness, wherein plasmon-related quenching and dot-to-dot resonance energy transfer have the minimal impact and, hence the PL enhancement has the maximal factor, had been determined. [ABSTRACT FROM AUTHOR]

Infrared radiation serves as a cooling channel when an emitting surface is directly exposed to the atmosphere. However, the cooling performance is restricted, or it might be transitioned to heating mode in an enclosure. In this study, we develop a design strategy to modify the surface emissivity to mitigate radiative heating in an enclosure comprising of two (i.e., a floor and a cover) gray bodies. Indoor heating experiments were performed on a copper enclosure with a view factor of 0.67, and it was demonstrated that rationally designed surfaces lowered the floor and cover temperatures by 11 °C and 2 °C when they were heated at 115 °C and 48 °C, respectively. Heat transfer simulations verified the experimental results, further indicating that the heat dissipation capability was improved with an increase in the view factor from floor to cover and the in-plane thermal conductivity of a cover. This study will provide useful guidelines for the development of passive cooling structures in an enclosure such as buildings, automobiles, electronic devices, and batteries.

• The study of optimized and controllable thermal radiation sources could lead to mass production of low-cost miniaturized and integrable devices operating in the mid-infrared (mid-IR) ranging from IR sensing to biomedical diagnostics and target detecting. • Our calculations, based on a complete Stokes parameters analysis of emitted radiation, show that it is possible to obtain circularly polarized thermal radiation in the mid-IR with a twisted bilayer system having about two microns of total thickness. • Our approach takes advantage of the strong anisotropy of low-symmetry materials such as β-Ga2O3 and α-MoO3. • We numerically report narrow-band, high degree of circular polarization (over 0.85), thermal radiation at two typical emission frequencies related to the excitation of β-Ga2O3 optical phonons. • Our simple but effective scheme could set the basis for a new class of lithography-free thermal sources for IR bio-sensing. We investigate a bi-layer scheme for circularly polarized infrared thermal radiation. Our approach takes advantage of the strong anisotropy of low-symmetry materials such as β-Ga 2 O 3 and α-MoO 3. We numerically report narrow-band, high degree of circular polarization (over 0.85), thermal radiation at two typical emission frequencies related to the excitation of β-Ga 2 O 3 optical phonons. Optimization of the degree of circular polarization is achieved by a proper relative tilt of the crystal axes between the two layers. Our simple but effective scheme could set the basis for a new class of lithography-free thermal sources for IR bio-sensing. [ABSTRACT FROM AUTHOR]

Heavily doped semiconductors have emerged as low-loss and tunable materials for plasmonics at mid-infrared frequencies. We analyze the nonlinear optical response of free electrons and show how nonlinear optical phenomena associated with high electron concentration are influenced by the intrinsic properties of semiconductors, namely background permittivity and effective mass. We apply our recently developed hydrodynamic description that takes into account nonlinear contributions up to the third order, usually negligible for noble metals, to compare third-harmonic generation from InP, Ge, GaAs, Si, ITO and InSb. We show how free electron nonlinearities may be enhanced with a proper choice of the semiconductor. [ABSTRACT FROM AUTHOR]

We report a study on the infrared optical emission of Er3+ inserted on ZnO hosts. The doping process was carried out during the growth of thin films by spray pyrolysis. The precursor solutions consisted of zinc acetate and erbium chloride proportionally diluted in distilled water, producing films in a clean and cost-effective process. The different molarity conditions employed here, M=10−3 and M=10−1, provided the growth of high textured c-axis, optical transparent ZnO, and white powder-like ZnO films, respectively. The infrared emissions at 0.8 eV (1.5 μm) are affected by the level manifolds due to the Stark effect, which is found to be strongly dependent on synthesis parameters. Lower crystallinity implies mitigation of the strong electric field in c-direction, reducing the intensity of the splitting caused by Stark effect. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Thermal radiation from an unpatterned object is similar to that of a gray body. The thermal emission is insensitive to polarization, shows only Lambertian angular dependence, and is well modeled as the product of the blackbody distribution and a scalar emissivity over large frequency bands. Here, we design, fabricate and experimentally characterize the spectral, polarization, angular and temperature dependence of a microstructured SiC dual band thermal infrared source; achieving independent control of the frequency and polarization of thermal radiation in two spectral bands. The measured emission of the device in the Reststrahlen band (10.3–12.7 µm) selectively approaches that of a blackbody, peaking at an emissivity of 0.85 at λ x = 11.75 μ m and 0.81 at λ y = 12.25 μ m. This effect arises due to the thermally excited phonon polaritons in silicon carbide. The control of thermal emission properties exhibited by the design is well suited for applications requiring infrared sources, gas or temperature sensors and nanoscale heat transfer. Our work paves the way for future silicon carbide based thermal metasurfaces. [ABSTRACT FROM AUTHOR]

We report here single-layer ultracompact Fano-resonance photonic crystal membrane reflectors (MRs) at mid-infrared (IR) and far-IR (FIR) bands, based on single layer crystalline Si membranes. High-performance reflectors were designed for surface-normal incidence illumination with center operation wavelengths up to the 75-μm FIR spectral band. Large-area patterned MRs were also fabricated and transferred onto glass substrates based on membrane transfer processes. Close to 100% reflection was obtained at the ~ 76-μm spectral band, with a single-layer Si membrane thickness of 18 μm. Such Fano-resonance-based membranes reflectors offer great opportunities for high-performance ultracompact dielectric reflectors at IR and THz regions.