Infrared Research Articles

Oversampling for Enhanced Spatial Resolution of Zebrafish by Top-Hat IR-MALDESI-MSI.

Mass spectrometry imaging (MSI) has become a significant tool for measuring chemical species in biological tissues, where much of the impact of these platforms lies in their capability to report the spatial distribution of analytes for correlation to sample morphology. As a result, enhancement of spatial resolution has become a frontier of innovation in the field, and necessary developments are dependent on the ionization source. More particularly, laser-based imaging sources may require modifications to the optical train or alternative sampling techniques. These challenges are heightened for systems with infrared (IR) lasers, as their operating wavelength generates spot sizes that are inherently larger than their ultraviolet counterparts. Recently, the infrared matrix-assisted laser desorption electrospray ionization (IR-MALDESI) source has shown the utility of a diffractive optical element (DOE) to produce square ablation patterns, termed top-hat IR-MALDESI. If the DOE optic is combined with oversampling methods, smaller ablation volumes can be sampled to render higher spatial resolution imaging experiments. Further, this approach enables reproducible spot sizes and ablation volumes for better comparison between scans. Herein, we investigate the utility of oversampling with top-hat IR-MALDESI to enhance the spatial resolution of measured lipids localized within the head of sectioned zebrafish tissue. Four different spatial resolutions were evaluated for data quality (e.g., mass measurement accuracy, spectral accuracy) and quantity of annotations. Other experimental parameters to consider for high spatial resolution imaging are also discussed. Ultimately, 20 μm spatial resolution was achieved in this work and supports feasibility for use in future IR-MALDESI studies.

Acoustic phonon excitation in gold probed by time-resolved photoemission electron microscopy.

Electron-phonon coupling is an important energy transfer mechanism in solids after ultrafast laser excitation. In this study, we present an extreme ultraviolet (EUV) and infrared (IR) pump-probe photoemission experiment to investigate the electron-phonon coupling in nonequilibrium gold. The energy of IR-laser-emitted photoelectrons is shifted due to the EUV photoemission and oscillates with a ∼4THz frequency. Such oscillation is considered as the effective excitation of the longitudinal acoustic phonon mode in gold through the spectral-dependent electron-phonon coupling. Our study showcases the capability of time-resolved photoemission electron microscopy to monitor the non-equilibrium lattice vibrations with ultrahigh spatial and temporal resolution.

Experimental Study to Visualize a Methane Leak of 0.25 mL/min by Direct Absorption Spectroscopy and Mid-Infrared Imaging

Tunable laser spectroscopy (TLS) with infrared (IR) imaging is a powerful tool for gas leak detection. This study focuses on direct absorption spectroscopy (DAS) that utilizes wavelength modulation to extract gas information. A tunable interband cascade laser (ICL) with an optical power of 5 mW is periodically modulated by a sawtooth injection current at 10 Hz across the methane absorption around 3271 nm. A fast and sensitive thermal imaging camera for the mid-infrared range between 3 and 5.7 µm is operated at a frame rate of 470 Hz. Offline processing of image stacks is performed using different algorithms (DAS-F, DAS-f and DAS-2f) based on the Lambert–Beer law and the HITRAN database. These algorithms analyze various features of gas absorption, such as area (F), peak (f) and second derivative (2f) of the absorbance. The methane concentration in ppm*m is determined on a pixel-by-pixel analysis without calibration. Leak localization for methane leak rates as low as 0.25 mL/min is accurately displayed in a single concentration image with pixelwise sensitivities of approximately 1 ppm*m in a laboratory environment. Concentration image sequences represent the spatiotemporal dynamics of a gas plume with high contrast. The DAS-2f concept demonstrates promising characteristics, including accuracy, precision, 1/f noise rejection, simplicity and computational efficiency, expanding the applications of DAS.

Integrated Optical Diagnostics Of Cyclopentane Sprays To Characterize Transcritical Phase Transitions

This research investigates spray phase transitions under subcritical and transcritical conditions relevant to high-pressure combustion systems. Using advanced optical diagnostic techniques, including shadowgraphy (SH), Mie scattering (MS), and infrared radiation (IR) measurements, the study focuses on cyclopentane sprays in a high-pressure, high-temperature chamber filled with gaseous nitrogen. Three cases are studied to understand spray behavior under varying injection conditions. SH and MS analyses reveal significant differences across the cases. As the chamber temperature increases, the liquid core length shortens, indicating enhanced vaporization. This is particularly evident in the MS images, where step-like transitions in the axial distribution highlight abrupt phase changes from liquid to gas in subcritical conditions. Such transitions are absent under supercritical conditions, suggesting a smoother phase transition process. IR measurements provide additional insights into the spray dynamics, especially under transcritical conditions. The IR images display complex downstream (at x/D > 125) signal patterns with bimodal distributions. The application of inverse Abel deconvolution highlights negative intensities near the spray axis downstream, indicative of regions near the pseudo-critical temperature. This phenomenon, characterized by blocked background radiation due to critical opalescence, offers indirect evidence of the pseudo-critical temperature and the associated phase transition dynamics. Dynamic Mode Decomposition (DMD) analysis identifies dominant frequencies around 4.5 kHz, corresponding to injection pressure fluctuations. This correlation suggests that injection pressure variations significantly influence spray fluctuations. Differences in mode shapes among the cases are also observed; lateral fluctuations near the injector nozzle exit are present in Cases 1 and 2 but not in Case 3. Axial fluctuations beyond a certain length are consistent in all cases. The lateral fluctuations are related to the chamber pressure and the potential large-scale vortex formation or cavitation in the nozzle. The combined use of SH, MS, and IR methodologies provides a comprehensive understanding of transcritical spray dynamics, emphasizing the effectiveness of combining multiple optical diagnostic techniques. These findings will improve numerical simulations and contribute to the development of more efficient high-pressure combustion systems. The research underscores the complexity of phase transitions in sprays and the critical role of precise diagnostics in the advancement of combustion technology.

Gold Nanoclusters Whose Photoluminescent Properties are Dynamically Tunable by Modulating the Assembly Pathway Complexity.

Modulating the assembly pathway is an indispensable strategy for optimizing the performance of optical materials. However, implementing this strategy is nontrivial for metal nanocluster building blocks, due to the limited functional modification of nanoclusters and complexity of their emission mechanism. In this report, we demonstrate that a gold nanocluster modified by 4,6-diamino-2-pyrimidinethiol (DPT-AuNCs) self-assembles into two distinct aggregation structures in methanol (MeOH)/water mixed solvent, thus exhibiting pathway complexity. Kinetic studies show that DPT-AuNCs firstly assembles into non-luminescent nanofibers (kinetically controlled), which further transforms into strongly luminescent microflowers (thermodynamically controlled). In-depth analysis of the assembly mechanism reveals that the transformation of aggregation structures involves the disassembly of nanofibers and a subsequent nucleation-growth process. Temperature-dependent photoluminescence (PL) spectroscopy and infrared (IR) measurements reveal that inter-cluster hydrogen bonding bridged by solvent molecules and C-H⋅⋅⋅π interaction are the key factors for emission enhancement. The photoluminescent property of DPT-AuNCs can be controlled by varying the cosolvent in water, enabling DPT-AuNCs to distinguish different kind of alcohols, particularly the isomerism n-propanol (NPA) and isopropanol (IPA). Additionally, the addition of seeds effectively regulate the assembly kinetics of DPT-AuNCs. This study advances our understanding of assembly pathways and improves the luminescent performance of nanoclusters (NCs).

Optimization of Thermoelectric Nanoantenna for Massive High-Output-Voltage Arrays.

Thermoelectric nanoantennas have been extensively investigated due to their ability to directly convert infrared (IR) radiation into direct current without an additional rectification device. In this study, we introduce a thermoelectric nanoantenna geometry for maximum output voltage (Voc) and propose an optimal series array configuration with a finite number of antennas to enhance the Voc. A finite and open-ended SiO2 substrate, with a thickness of a quarter-effective wavelength at a frequency of 28.3 THz, is used to generate standing waves within the substrate. An array of antennas is then positioned optimally on the substrate to maximize the temperature difference (∆T) between hot and cold areas, thereby increasing the average Voc per antenna element. In numerical simulations, a linearly polarized incident wave with a power density of 1.42 W/cm2 is applied to the structure. The results show that a single antenna with the optimum geometry on a substrate measuring 35 µm × 35 µm generates a ∆T of 64.89 mK, corresponding to a Voc of 1.75 µV. Finally, a series array of 5 × 6 thermoelectric nanoantennas on a 150 µm × 75 µm substrate including measurement pads achieves an average ∆T of 49.60 mK with a total Voc of 40.18 µV, resulting in an average Voc of 1.34 µV per antenna element and a voltage responsivity (βv) of 0.77 V/W. This value, achieved solely by optimizing the antenna geometry and open-ended substrate, matches or exceeds the Voc and βv of approximately 1 µV and 0.66 V/W, respectively, from suspended thermoelectric antenna arrays over air cavities. Therefore, the proposed thermoelectric nanoantenna array device, characterized by high stability and ease of fabrication, is suitable for manufacturing massive nanoantenna arrays for high-output IR-DC energy harvesters.

Adsorption configuration, electronic structure and spectra of the harmful NH3, NO, and NO2 molecules on a bilayer boron cluster

Density functional theory (DFT) calculations were performed to investigate the adsorption configuration, electronic structure and spectra of a bilayer B48 cluster with NH3, NO, and NO2 adsorptions. The B48 shows a high affinity for NH3 and NO2 molecules and a medium adsorption ability for NO. The high binding strength of the B48 cluster for these gases originates from the direct B–N bonds corresponding to partially covalent characters. The energy gap changes are in the order of NO2 > NH3 > NO. The recovery time of the B48 for different gases can be adjusted to a reasonable range by increasing the temperature. Infrared (IR) and ultraviolet–visible (UV–vis) spectra were in detail analyzed before and after gas adsorptions for the identification of the adsorption structures in further experiments. Along with gas adsorption, the B48 cluster exhibits vastly different spectral characteristics. Our results indicate that the B48 shows promising sensor performance for studied gases, in particular for NO molecules, and can be considered as potential gas sensor candidates.

AAg2MS4 (A = Na, K, Rb; M = P, As) Nonlinear Optical Series with Unique Cation‐Regulated Highly Anisotropic [AgS4] Hypertetrahedral Layered Framework

AbstractCommercial infrared (IR) nonlinear optical (NLO) materials are mainly from chalcopyrite‐type AMQ2 (A = Ag, Zn, M = Ga, Ge, Q = S, Se, P) crystals such as AgGaS2 (AGS), AgGaSe2 (AGSe), and ZnGeP2 (ZGP), in which the basic NLO‐active groups are MQ4 tetrahedral units. However, the small anisotropic character of them critical for small birefringence hinders the practical applications in the available IR wavelength range. In this study, a novel strategy for modulating birefringence is proposed using a cation regulation‐driven compressed hypertetrahedral layer approach and a family of AAg2MS4 (A = Na, K, Rb; M = P, As) IR NLO crystals are successfully obtained. Remarkably, the title compounds increase the birefringence to 0.12–0.15, about three times larger than that of AGS (0.04), while they can maintain large bandgaps and strong NLO effects. In addition, they exhibit congruent‐melting properties, beneficial for bulk single crystal growth. The work offers a firsthand access for designing and fabricating high‐performance IR NLO materials.

Enhancing point cloud data fusion through 2D thermal infrared camera and 2D lidar scanning

Sensor data fusion from multiple sources plays a pivotal role in advancing our understanding of real-world phenomena. This paper focuses on the integration of a thermal imager and a lidar to simultaneously capture four-dimensional (XYZT) space coordinates and temperatures. The fusion of data relies on establishing correspondence between overlapping lines in the lidar’s 3D point cloud and the infrared (IR) camera’s 2D thermal map. The presented combination method offers several key advantages. Firstly, it simplifies the calibration process. Furthermore, it can achieve near real-time performance, enabling prompt data analysis. Moreover, the method demonstrates high accuracy in capturing spatial information and temperature measurements. The thermal IR camera used in the experiment features a 1280 × 1024 pixel cooled indium antimonide (InSb) detector, operating in the short wavelength infrared (MWIR) spectral range of 1.5 to 5.5 µm. It provides temperature readings with ± 1 K accuracy and sub-30 mK resolution. On the other hand, the lidar system delivers centimeter-level precision within a range of approximately 1 to 12 m, even in well-lit outdoor environments. The experimental results validate the effectiveness of our combined system, successfully generating high-quality four-dimensional (4D) point clouds. The integration of the thermal IR camera and profilometer presents an intriguing tool with significant potential in various industrial applications. For instance, it can be employed to accurately assess gas leaks, enhance metallurgical processes, and improve safety on construction sites.

Ag2GeS3: A Diamond‐Like Chalcogenide as an IR Nonlinear Optical Material with Outstanding Second‐Harmonic Generation Response

AbstractDiamond‐like (DL) metal chalcogenides have attracted significant attention in recent years because of their complex structural compositions and exceptional nonlinear optical (NLO) capabilities in the infrared (IR) range. Despite notable advancements in this field, there is still a lack of systematic research on high‐performance and simply composed IR‐NLO chalcogenides with DL structures. In this study, the insightful structural characteristics and IR‐NLO properties of a ternary Ag‐based chalcogenide Ag2GeS3 are investigated for the first time at both experimental and theoretical levels. The compound belongs to the non‐centrosymmetric Cmc21 space group (No.36) and displays a 3D DL structure comprising highly oriented [AgS4] and [GeS4] tetrahedra. Due to its distinct structure, the compound may produce significant second harmonic generation (SHG) response (5.6 × AgGaS2 at 2050 nm), the biggest value reported among Ag‐based IR‐NLO chalcogenides to date, and phase matchability in the IR range with a calculated birefringence of Δn = 0.09 at 2050 nm. According to theoretical calculations, the combined impacts of the distorted [AgS4] and [GeS4] NLO‐active motifs inside the 3D DL framework provide the SHG tensor d24 of Ag2GeS3 at 51.9 pm V−1 at 2050 nm. The prospective uses of Ag2GeS3 in the field of IR‐NLO are highlighted in this work.

LRS Bianchi type-I with Hubble’s horizon as IR cut-off in [formula omitted] gravity

we explored the holographic dark energy model using Hubble’s Horizon as the infrared (IR) cut-off in Locally Rotationally Symmetric (LRS) Bianchi type-I, considering the f(R) gravity framework in our analysis. In order to solve the field equations, we assume a relation F∝am and volumetric power law expansion (where m is constant). we have expressed various crucial cosmological parameters in terms of the redshift z and depicted them graphically to enhance our understanding of the expansion and evolution of the universe like holographic dark energy density (ρΛ), holographic dark energy pressure (pΛ), equation of state parameter (ω) , total energy density parameter (Ω) etc. Also, we analyzed the stability of the universe in our model through the squared speed of sound test and its validity by energy conditions. Ultimately, our model indicates that the universe is currently in an expanding phase, exhibiting an accelerating phase, closely approaching a flat geometry, and its behavior resembles that of a quintessence dark energy model.

Electrical, Optical and Thermal Properties of Ge-Si-Sn-O Thin Films.

This work evaluates the electrical, optical and thermal properties of Sn-doped GexSi1-xOy thin films for use as microbolometer sensing materials. The films were prepared using a combination of a radio frequency (RF) magnetron and direct current (DC) sputtering using a Kurt J Leskar Proline PVD-75 series sputtering machine. Thin films were deposited in an O2+Ar environment at a chamber pressure of 4 mTorr. The thicknesses of the thin films were varied between 300 nm-1.2 µm by varying the deposition time. The morphology and microstructure of thin films were investigated by atomic force microscope (AFM) imaging and X-ray diffraction (XRD), while the atomic composition was determined using the energy dispersive spectroscopy (EDS) function of a scanning electron microscope. The thin film with an atomic composition of Ge0.45Si0.05Sn0.15O0.35 was found to be amorphous. We used the Arrhenius relationship to determine the activation energy as well as temperature coefficient of resistance of the thin films, which were found to be 0.2529 eV and -3.26%/K, respectively. The noise voltage power spectral density (PSD) of the film was analyzed using a Primarius-9812DX noise analyzer using frequencies ranging from 2 Hz to 10 kHz. The noise voltage PSD of the film was found to be 1.76 × 10-11 V2/Hz and 2.78 × 10-14 V2/Hz at 2 Hz and 1KHz frequencies, respectively. The optical constants were determined using the ellipsometry reflection data of samples using an RC2 and infrared (IR) VASE Mark-II ellipsometer from J A Woollam. Absorption, transmission and reflection data for a wavelength range of 900 nm-5000 nm were also determined. We also determined the optical constant values such as the real and imaginary parts of refractive index (n and k, respectively) and real and imaginary part of permittivity (ε1 and ε2, respectively) for wavelength ranges between 193 nm to 35 µm. An optical band gap of 1.03 eV was determined from absorption data and using Tauc's equation. In addition, the thermal conductivity of the film was analyzed using a Linseis thin film analyzer employing the 3ω method. The thermal conductivity of a 780 nm thick film was found to be 0.38 Wm-1K-1 at 300 K. From the data, the Ge-Si-Sn-O alloy was found to be a promising material for use as a sensing material for microbolometers.

Structural investigation of lithium bismuth borate glasses through Raman and infrared spectroscopies

AbstractThe structure of lithium bismuth borate glasses in the compositional series xBi2O3–25Li2O–(75 − x) B2O3 was studied with the use of Raman and infrared (IR) spectroscopies. Transparent glasses formed between x = 0 and 55, whereas glass–ceramics formed between x = 60 and 75 mol% Bi2O3. Structural investigation on the borate network showed that the glasses were undermodified at high Bi2O3 compositions with metaborate, pyroborate, and orthoborate triangles and tetrahedra being present past the stoichiometric orthoborate compositions (O/B = 3). Bi2O3 was found to participate in the glass as both a network former and modifier, as observed in the Raman and IR spectra. Optical absorption spectra of the glasses show a redshift of the absorption edge with increased Bi2O3. Optical, thermal, and physical properties of the glasses were examined and correlated to the structural evolution.

Exploring the nonlinear optical characteristics of supersalt-decorated graphyne via DFT analysis: unveiling quantum insights into light-matter interaction

In this comprehensive study, we explore into the nonlinear optical (NLO) properties of graphyne (GRY) and its compounds decorated with a super salt (OLi3BeF3), namely GRY@SS1, and GRY@SS2) using the rB3LYP/6−31G(d,p) DFT method. Our findings reveal a substantial enhancement in the electron transfer properties of decorated compounds compared to the pristine GRY surface. This enhancement is evidence by the reduction in the bandgap energies (Eg) from 3.52 eV to 1.68 eV and remarkable boost in maximum absorption ( λmax) from 372.66 to 807.73 nm. Noteably, GRY@SS2 exhibits a significant increase in linear polarizability ( α0 ) (538.18 au), first hyperpolarizability ( β0 ) (3872.76 au), and second hyperpolarizability ( γ0 ) (1.00 × 106) due to reduced excitations energies compared to the GRY ( α0 = 448.61, β0 = 0.14 and γ0 = 5.97 × 105 au). NBO charges show that electrons are transferring from the dopant (supersalt) to the GRY sheet. Furthermore, Non-covalent interactions (NCl), iso-surface, infrared (IR), 1H NMR, and 13C NMR studies have been conducted to provide insights into the nature of interactions, vibrational frequencies, and structural-functional aspects of GRY and GRY@SS1, and GRY@SS2. According to TD-DFT calculations, all compounds demonstrate superior vertical ionization potential, UV–vis absorbance, HOMO–LUMO characteristics, as well as interaction energies. Our results underscore the potential of these compounds as valuable NLO materials, particularly highlighting the promising prospects of GRY@SS2.

Black bioceramic scaffolds with micro/nano surface structure inducing mild hyperthermal environment for regenerating osteochondral defects

The treatment of osteochondral defects remains a huge challenge in clinic. The thermotherapy in traditional Chinese medicine is widely used in treating joint disease because the mild heat stimulation can promote the nutrient circulation. Inspired by the function of thermotherapy, we design a new thermotherapy strategy by using black bioceramic scaffolds to build local mild hyperthermal environment for treating osteochondral defects. Herein, black akermanite (B-AKT) bioceramic scaffolds with micro/nano surface structure and excellent photothermal conversion property are successfully fabricated. The temperature of scaffolds can be precisely controlled by near infrared (NIR) irradiation to construct a mild hyperthermal environment (～41°C). The micro/nanostructure on the scaffolds surface well promoted the cell adhesion and nutrition absorption by activating integrins and focal adhesion kinase (FAK). Meanwhile, the mild hyperthermal environment constructed by B-AKT scaffolds can simultaneously induce the chondrogenesis and osteogenesis both in vitro and in vivo by activating the expression of cellular heat shock proteins (HSPs) and corresponding signaling pathways. Furthermore, in rabbit osteochondral defects, mild hyperthermal environment induced by B-AKT scaffolds exhibits stimulatory effects on the integrated regeneration of cartilage and bone. This study proposes a novel therapy strategy of constructing local mild hyperthermal environment by black bioceramic scaffolds to treat osteochondral defects and other joint diseases.

Characterization of acid sites on Hf-Beta zeolite by CD3CN IR-TPD

To identify Hf species and quantitatively evaluate their acid properties, combined measurement of infrared (IR) and temperature-programmed desorption (TPD) with deuterated acetonitrile (CD3CN) as probe molecule was performed on Hf-Beta and HfO2/Si-Beta. IR spectra of CD3CN adsorbed on Hf-Beta showed five types of Hf species including framework open and closed Hf sites, extra-framework HfO2, and two types of Hf species bearing hydroxy groups. IR measurement showed structural change in Hf-Beta upon exposing to water vapor with generation of the two types of Hf species bearing hydroxy groups. Integrated molar extinction coefficients for C N stretching vibration of CD3CN adsorbed on these Hf species were estimated and the number of each Hf acid site was calculated. Acid strength of these Hf species was estimated from CD3CN-TPD measurement in combination with IR; the acid strength of the open and closed Hf sites, extra-framework HfO2 species, and the other Hf species was found to be strong, moderate, and weak, respectively.

Effects of contact ultrasound coupled with infrared radiation on drying kinetics, water migration and physical properties of beef during hot air drying

Drying, as a critical step in the production of air-dried beef, has a direct impact on the quality of the final product. Innovatively, a composite system incorporating contact ultrasound (CU) and infrared radiation (IR) as auxiliary measures within a hot air drying (HAD) framework was built in this research, and the effects of these techniques on the drying kinetics, protein denaturation, and moisture transformation of air-dried beef were investigated. In comparison to HAD treatment, the integrated CU and IR (CU-IRD) system displayed marked enhancements in heat and moisture transport efficiency, thereby saving 36.84% of time expenditure and contributing favorably to the improved moisture distribution of the end-product. This was mainly ascribed to the denaturation of myosin induced by IR thermal effect and the micro-channel produced by CU sponge effect, thus increasing T2 relaxation time and the proportion of free water. In conclusion, the composite system solved the problem of surface hardening and reduces hardness and chewiness of air-dried beef by 40.42% and 45.25% respectively, but inevitably increased the energy burden by 41.60%.

Deciphering the Nd3+ environment and energy-transfer mechanisms in thermally stable novel calcium aluminate glasses: elucidation of broadband high-gain performance for laser applications

Rare-earth-doped barium calcium aluminate (BCA) glasses, having extended infrared (IR) transmission (6 μm), are attractive materials for near IR (NIR) photonic applications. Nd2O3-doped BCA glasses display broadband emission at 1.07 µm, but they are limited, with poor glass-forming ability (GFA) and low emission cross sections. In the present study, four different barium zinc calcium aluminate (BZCA) glasses are synthesized with varied ZnO concentrations (from 9.5 to 24.5 mol%) and doped with 0.5 mol% Nd2O3 to decipher the effect on GFA and spectroscopic properties. The addition of ZnO enhances the GFA, and the NdBZCA20 glass shows the maximum GFA. Ultraviolet (UV)–visible (Vis)–NIR absorption spectra reveal a decreasing trend in the nephelauxetic effect, while J–O parameters, emission, and gain properties lead to no significant alteration with increasing ZnO, and the structure–properties correlation is established accordingly. However, the emission cross sections for all ZnO concentrations are found ∼4.5 × 10−20 cm2 accompanied by broadband emission (Δλ eff ∼ 40 nm), which ensures the potentiality of these glasses for low-threshold high-gain laser applications as well as ultrashort pulse laser applications. Furthermore, a thorough analysis of 1.06 µm emission as a function of Nd concentration in the BZCA20 glass is reported here. The emission spectra and decay time indicate that 0.5 mol% is the optimized doping concentration. Inokuti–Hirayama and Burshtein equations are adopted to study the decay kinetics and energy-transfer mechanisms, which confirm that the energy-transfer process due to cross-relaxation is dominant up to 0.5 mol% concentration, whereas, beyond that concentration, excitation energy migration via the hopping mechanism supersedes.

Multi-band microbolometer in CMOS technology

Multi-spectral imaging enhances the information diversity of the object with complex, expensive, and low integrated components. Here, we demonstrated an antenna-coupled microbolometric detector in complementary metal-oxide-semiconductor (CMOS) technology, utilizing SiO2 absorption and L-shaped fractal antenna to achieve multi-band detection from infrared (IR) to terahertz (THz). Experimental results demonstrate that the detector can achieve high sensitivity detection in both THz and IR bands, with the maximum detectivity of 5 (108 cm·Hz1/2/W @305 GHz and 7 (108 cm·Hz1/2/W @8.55 µm, respectively. The presented multi-spectral detector is easily implementable in integrated circuit process, conducive to high-density, low-cost, and high-performance array imaging.

Adaptive infrared radiation modulator using reversible metal electrodeposition with silicon carbide-based fabry-perot cavity

Conventional materials that statically modulate radiation in the infrared (IR) region of the electromagnetic spectrum underpin the performance of many entrenched technologies. The development of their adaptive variants, whereby the IR radiation properties dynamically change as a response to external stimuli, has emerged as an important unfulfilled scientific challenge. Here, by combining the silicon carbide (SiC)-based Fabry-Perot (FP) cavity effect with the traditional reversible metal electrodeposition device (RMED), where the FP cavity is used as a color filter to emit a particular wavelength and the RMED is used to reversibly modulate IR radiation, we develop an adaptive IR radiation modulator with large and uniform IR emissivity tunability (Δε ≥ 0.579) in the 3–14 µm region. A specific structural color which is a function of the SiC thickness can be simultaneously displayed when the modulator is in the low-emissivity mode. By varying the SiC thickness from 100 to 180 nm, a full gamut of colors spanning the entire visible spectrum can be achieved. Additionally, the modulator can exhibit fantastic patterns consisting of different structural colors with simple designs achieved. We believe that our findings may open opportunities for camouflage in multispectral detection and many technologies related to IR radiation management.