To support the infrared radiance calibration needs in fields such as remote sensing, climate change monitoring, and aerospace, the National Institute of Metrology of China has built up an infrared spectral radiance measurement system (ISRMS) in the 2.0–14.0 µm wavelength range. In this study, two main improvements were implemented in the ISRMS. The first is the nonlinearity correction of the measurement system. A one-dimensional convolutional neural network (1D-CNN) method was employed to correct nonlinearity by modeling the relationship between the measured spectral response of a standard blackbody and its theoretical radiance derived from Planck’s law at each wavelength; validation results demonstrated that, compared to both piecewise linear interpolation and polynomial fitting methods, the 1D-CNN model achieved smaller deviations from the theoretical values, suggesting its effectiveness. The second is the suppression of the background stray radiation. A constant-temperature water-cooled plate was designed and installed at the entrance of the relay optics in the ISRMS, and results showed that the repeatability and reproducibility of the system were effectively improved. Furthermore, the measurement uncertainty of the ISRMS was evaluated. At a temperature of 798 K, the expanded measurement uncertainty (with a coverage factor k =2) was 2.74–1.26% in the 2.0–5.0 µm range, 1.26–0.54% in the 5.0–8.0 µm range, and 0.54–0.42% in the 8.0–14.0 µm range.

To address the drawbacks of existing Whispering Gallery Mode (WGM) optical microring cavities for high-precision temperature sensing-where mainstream schemes including asymmetric coupling and high-order mode manipulation demand complex heterogeneous integration and ultra-high-precision micro-nano fabrication, which easily induce increased mode loss and degraded sensing performance stability, and the single resonant peak structure features poor resistance to environmental interference, making it hard to balance temperature sensing performance with fabrication feasibility-this study proposes a novel high-precision temperature sensing scheme based on silicon-based SiNx WGM optical microring cavities. The scheme introduces a controllable additional phase via V-shaped waveguide coupling, thus constructing a uniquely distinguishable "main peak-secondary peak" optical fingerprint dual-extremum structure in the resonant spectrum. First, a theoretical model of waveguide-microring evanescent field coupling was established, the formulas for bending phase difference, transmittance and temperature-induced frequency shift were derived, and the physical mechanism of the dual-extremum structure induced by the additional phase was clarified. Subsequently, the optimal bending angle of the V-shaped waveguide (theta = 5 degrees) was obtained through COMSOL simulations in the 1520-1580 nm communication band. Silicon-based SiNx microring cavity devices were fabricated and subjected to performance tests in the 310-350 K temperature range. Validated by repeatability and reproducibility tests, the device exhibits excellent measurement stability: the repeatability standard deviation of key parameters is <= 0.0018 nm, and the maximum reproducibility deviation is <= 0.0014 nm after 5 heating-cooling cycles. This scheme dispenses with the preparation of special functional materials and complex heterogeneous integration processes, and is fully CMOS-compatible. It takes advantage of the synchronous redshift characteristic of the dual resonant peaks to automatically compensate for the common-mode noise caused by thermal expansion, thereby significantly improving the anti-interference capability and identification accuracy of temperature sensing.

Al-hyperdoped black silicon (Al-BSi) is prepared by femtosecond laser-assisted chemical etching, and the material surface was characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). The gas sensing performance of the Al-BSi sensor to NH3 at room temperature was systematically studied, and the sensor has the characteristics of high responsivity, fast response speed, good selectivity, and long-term durability. The NH3 gas sensing ability is effectively enhanced by the introduction of Al dopants, and the responsivity is more than 1.76 times higher than that without Al hyperdoping. In addition, the band structure of the Al-hyperdoped layer was calculated using first principles, and the potential mechanism of the enhanced responsivity of the Al-BSi sensor was proposed. These results are helpful for the development of high-precision and high-reliability gas sensors based on Al-BSi, opening up potential applications in different fields such as environmental monitoring and industrial safety.

To address the growing need for field calibration of the optical properties of pedestrian targets used in autonomous emergency braking (AEB) tests, a novel three-dimensional multi-faceted standard body (TDMFSB) was developed. A camera-based analytical algorithm was proposed to evaluate the bidirectional reflectance distribution function (BRDF) characteristics of pedestrian targets. Additionally, a field calibration method applied in AEB testing scenarios (CPFAO and CPLA protocols) on one new and one aged typical pedestrian target of the same type revealed a 21% decrease in the BRDF uniformity of the aged target compared to the new one, confirming optical degradation due to repeated “crash–scatter–reassembly” cycles. The surface wear of the aged target on the side facing the vehicle produced a smoother surface, increasing its BRDF magnitude by 25% compared to the new target and making it easily detectable by the vehicle’s perception system. This led to “reverse scoring,” a safety risk in performance evaluation, necessitating timely calibration of AEB pedestrian targets to ensure reliable test results. The findings provide valuable insights into the development of regulatory techniques, evaluation standards, and technical specifications for test targets and offer a practical path toward full-life-cycle traceability and quality control.

This study proposes a polarity regulation in two-dimensional InSe via substrate engineering. By selecting different substrates (h-BN and multilayer graphene (MLG)/SiO2), controllable doping of p-type and n-type regions on the same piece of two-dimensional InSe material is achieved. Utilizing this characteristic, a high-performance homogeneous PN junction is constructed. The rectification characteristics of this device can be dynamically regulated by the gate voltage and laser irradiation. The gate voltage can adjust the rectification ratio from 10 to more than 107, and the regulation range and performance are significantly superior to those of the reported devices of the same kind. The rectification ratio can be effectively regulated by a broadband laser with a wavelength range of 280-965 nm. When the device is irradiated by a laser with a wavelength of 365 nm at a power of 16.75 mW/cm2, the rectification effect of the device disappears completely. Additionally, an NMOS is constructed in the n-p-n region and a PMOS is constructed in the p-n-p region on InSe respectively, and their output transfer characteristics can also be cooperatively regulated by the gate voltage and laser. Compared with traditional field induced carriers, this doping method has the advantage of nonvolatility. The doping state will not disappear with the removal of the gate voltage, which avoids the problems related to the stability during the device operation and continuous power supply. It shows important application potential in the fields of optoelectronic integration and reconfigurable electronics.

Au-hyperdoped black silicon (Au-BSi) is prepared via femtosecond laser-assisted chemical etching in NF3 atmosphere and characterized using scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and Xray photoelectron spectroscopy (XPS). The room-temperature NH3 gas sensing performance of Au-BSi, both before and after thermal annealing, is systematically studied. The sensor demonstrates a more stable response under varying humidity levels, along with high response, fast response/recovery times, excellent selectivity, and acceptable long-term durability. Notably, the introduction of Au dopants induces a transition in the gas response type from n-type to p-type. Concurrently, the NH3 sensing capability is significantly enhanced, with a responsivity over 2.78 times higher than that of the black silicon without Au hyperdoping. Furthermore, annealing markedly improves the response speed of the Au-BSi sensor. The alteration in the surface structure of the Auhyperdoped layer is analyzed using First Principles calculations to elucidate the mechanism underlying the change in gas response type. Additionally, potential mechanisms for the enhanced responsivity of Au-BSi sensors, as well as the observed reduction in responsivity after annealing, are proposed. These findings advance the development of highly accurate and reliable gas sensors based on Au-BSi, paving up the way for potential applications in diverse fields such as environmental monitoring and industrial safety.

The realization of the super black level diffuse reflectance scale of the National Institute of Metrology (NIM, China) is presented. Two facilities were used to achieve the reflectance scale under 0 d condition covering 0.0001-1.0 (absolute value), the first one based on the supercontinuum light source was used to realize the diffuse scale in the wavelength range 500 nm-2000 nm, while the other one based on QCL was applied for the mid infrared range from 7.5 mu m to 10.6 mu m. The relative expanded uncertainty (k = 2) of the reflectance scale was evaluated to be from 2.3% to 8.4% varying with range and wavelength in visible band to near infrared band while the reflectance is down to 0.0001. In the mid infrared band, the uncertainty of the reflectance scale was up to 8.9% while reflectance is 0.001, and up to 42.6% while reflectance is down to 0.0001. This low reflectance level scale can meet the calibration requirement of super black material or system such as carbon nanotube or blackbody.

Infrared thermography for human skin temperature measurement, when calibrated with standard blackbodies, suffers from errors due to the mismatch in emissivity between a blackbody and human skin. This study introduces a novel calibration method utilizing a human skin-like gradient radiation source to enhance measurement accuracy. A custom radiation source with six temperature points and skin-like emissivity was developed. Thermal imagers were calibrated using this source, and their performance was compared against traditional blackbody calibration. The proposed method reduced the calibration error to 0.04 °C, a significant improvement over the 0.15 °C error obtained with blackbody calibration. Calibration with a skin-like radiation source proves superior to the blackbody method, enabling high-accuracy (less than 0.1 °C) human skin temperature measurement for improved fever screening.

On the basis of the vector diffraction theory, this article investigates the transverse energy flow distributions of azimuthally polarized Lorentz–Gaussian beams modulated by power order space-variant phase modulation. The findings of the study show that the distribution of transverse energy flow is significantly affected by variations in the power order of the space-variant phase n. We obtained circular distribution, two zone distribution, bullet-shaped distribution, and reverse Z-distribution. Furthermore, it can be observed that the variation of phase change parameter C will affect the transverse energy flow distributions, while the variation of topological charge m will lead to the diffusion of energy. These phenomena may assist in capturing specific particles.

Measuring the emissivity of an infrared radiant sample with high accuracy is important. Previous studies reported on the multi- or two-temperature calibration methods, which used a reference blackbody (or blackbodies) to eliminate the background radiation, and assumed that the background radiation was independent of temperature. However, in practical measurements, this assumption does not hold. To solve the above problems, this study proposes a modified two-temperature calibration method and facility. The two temperature points are set in a certain small interval based on the proposed calculation method; based on the indication of the approximation that the emissivities of the sample and the background radiations remain the same at these two temperatures, the emissivities can be calculated with measurement signals at these two temperatures, and a reference blackbody is not needed. An experimental facility was built up and three samples with emissivities around 0.100, 0.500, and 0.900 were measured in (8~14) μm. The relative expanded uncertainties were 9.6%, 4.0%, and 1.5% at 60 °C, respectively, and 8.8%, 5.8%, and 1.2% at 85 °C (k = 2), respectively. The experimental results showed consistency with the results obtained using other methods, indicating the effectiveness of the developed method. The developed method might be suitable for samples whose emissivities are temperature insensitive.

Si-based double-layer underpass open microchannels have been designed and fabricated for microfluidic applications in the field of microelectromechanical systems. The top channel has been carefully designed into S-shaped, spiral, and F-shaped configurations along the < 100 > crystal direction to facilitate fluid steering, velocity modulation, splitting, and fusion. Meanwhile, the bottom channel has been prepared along the < 110 > direction, enabling it to be semi-buried into the top channel at a 45-deg angle. A 25% tetramethylammonium hydroxide solution has been utilized to create a distinctive overlapping microchannel structure by removing material from the overlapping part of the two layers of channels. This resulted in intersecting microchannels that are not connected, exhibiting significant structural advantages over traditional single-layer microchannels. With this innovative design, two distinct liquids can be delivered independently and efficiently in the same area.

The noise equivalent temperature difference (NETD) indicates the minimum temperature difference resolvable by using an infrared detector. The lower the NETD, the better the sensor can register small temperature differences. In this work, we proposed a strategy to achieve a high temperature resolution using a superconducting nanowire single-photon detector (SNSPD) with ultra-high sensitivity. We deduced the model for calculating the NETD of a photon-counting-type detector and applied it to our SNSPD-based set-up. Experimentally, we obtained an NETD as low as 0.65 mK, which is limited by the background radiation of the environment, and the required infrared radiation power is calculated to be <1 pW. Furthermore, the intrinsic NETD of this SNSPD is estimated to be <0.1 mK. This work demonstrated a sub-mK temperature resolution when using the SNSPD, paving the way for future remote infrared thermal imaging with high temperature resolution.

We design a transmission type flexible metasurface which operates at 0.1 THz. The metasurface consists of a polyimide substrate and a metallic copper film. Using the geometric phase principle, four vortex beams with different channels and different topological charges are generated under the linearly polarized beam incident. Through three-dimensional electromagnetic field simulation and experimental tests, it is proved that the designed metasurface can generate multi-channel vortex beams, where the topological charges of the vortex beam are +/- 1 and +/- 2. The metasurface has high transmittance in the frequency band of 0.092THz to 0.106THz, 0.202THz to 0.283THz, 0.318THz to 0.345THz, and so on, which can generate multi-channel vortex beams at multiple frequency bands. Metasurfaces designed based on this method can be applied in optical communication.

The aim of this paper is to investigate the focusing properties of linearly polarized Lorenz–Gaussian vortex beams modulated with power order space-variant (POSV) phase, which is based on vector diffraction theory. The results show that the shape of focal spot can be adjusted by changing the POSV parameter n . In addition, the adjustable phase parameter C can flexibly control the position of the focus on the X -axis. Immediately after that, it is revealed that with the increase of topological charge number m , the focused pattern can be separated along y = x direction. Even more interesting is the fact that the waist width ω is inversely proportional to the length of the bar focusing peak. Specifically, when the value of waist width ω is increased, the length of the strip-shaped focusing peak is continuously shortened. And the value of NA is inversely proportional to the size of the circular spot. A range of focal properties were acquired through the introduction of a space-variant phase with a power order. These new properties hold potential applications within various fields, including particle manipulation, optical modulation, and particle confinement.

In order to broaden the wavelength range of the standards,the glass doped with praseodymium and neodymium rare earth elements with stable physical and chemical properties was used as the raw material of the visible wavelength reference material.At the same time,the polystyrene sheet(thickness of 1 mm)with stable physical and chemical properties was used as the raw material of the near-infrared wavelength reference material.The visible and near-infrared wavelength reference material was developed by using the characteristics that the two did not affect each other,and the superposition of the two would expand the band range.The uniformity of the sample was tested by F test method,and the stability of the sample was investigated by linear fitting method.The traceability was solved by tracing to the national standard.The band range of standard material was determined to be 430 nm～2 550 nm,and the uncertainty was 0.1 nm～1.0 nm,which made up for the defect that the wave range coverage in the current reference material is too narrow.

The escalating environmental concerns have stimulated the demand for NH3 gas sensors, which are indispensable for real‐time data collection in pollution monitoring. To address this need, optimized NH3 sensor based on femtosecond‐laser textured silicon decorated with Au nanoparticles (Au‐NP) is designed. The morphologies and microstructures of the fabricated samples are characterized by scanning electron microscopy (SEM) and X‐ray diffraction (XRD) technologies. The gas‐sensing results demonstrated that the modification of Au‐NPs significantly enhances the NH3 gas‐sensing performances. Specifically, the sensor based on the textured silicon decorated with Au NPs exhibits a remarkable response of 16.02% toward 20 ppm NH3, which is 4.7 times higher than that of the pristine textured silicon gas sensor at room temperature. In addition, it also demonstrates shortened response and recovery time (26 s/98 s), showing good selectivity and long‐term availability. The enhanced NH3‐sensing mechanism of the sensor is elucidated, mainly due to the synergistic effect of textured silicon and Au NPs. These contribute to the development of portable, wearable, and intelligent sensor equipment.

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Information security is particularly important in the information age. Traditional optical encryption devices rely on phase, amplitude, and even polarization modulation, with the phase typically produced by the phase accumulation effect of diffractive elements in space, which requires a gradual change in the medium’s refractive index and thickness to achieve. This also causes the shortcomings of traditional optical encryption devices such as large volume, high design complexity and poor resolution, which is not conducive to miniaturization. Metasurface, as a two-dimensional form of metamaterials, has artificial sub-wavelength structure, which can flexibly manipulate the phase, amplitude, wavelength and orbital angular momentum of electromagnetic waves by changing the shape, size, spin and arrangement of meta-atoms. Due to the design flexibility of the metasurface and its arbitrary wavefront operation, more and more research is linking it to efficient and reliable encryption devices in the future. This paper introduces the control of metasurface on single dimension, double dimension and three-dimensional degree of freedom of electromagnetic wave to realize information encryption, and other dimensions such as spatial frequency control and some common computational imaging encryption algorithms, and analyzes the advantages and disadvantages of these encryption methods. Compared with traditional optical encryption devices, metasurface encryption has the advantages of compact, high resolution and high security factor, and has a good development prospect.