A dedicated data acquisition system has been developed and commissioned for the tender-energy spectroscopy beamline BL16U1 at the Shanghai Synchrotron Radiation Facility. The system implements a distributed architecture integrating EPICS-based hardware control with the Bluesky experiment orchestration environment, supporting multiple X-ray absorption spectroscopy modes including transmission, total electron yield, total fluorescence yield, and partial fluorescence yield detection. A key technical feature is the hardware-level synchronization between a multi-channel silicon drift detector and a multichannel scaler, enabling precise timing for fluorescence-XAS measurements. A unified graphical interface based on Control System Studio provides streamlined experiment control and real-time data visualization. System validation using standard reference samples demonstrates successful acquisition of high-quality Cl K-edge XANES spectra in fluorescence mode, high signal-to-noise Co K-edge EXAFS data in transmission mode with extended k-space coverage up to 16 & Aring;-1, and high-sensitivity Ti K-edge fluorescence XAFS on dilute (1-3%) TiO2 polymorphs. These results confirm the system's capability for reliable, high-precision spectroscopy across the tender-energy range (2-16 keV), supporting both trace-element analysis and detailed local-structure determination. The fully integrated system is now operational at the beamline, providing a robust platform for advanced X-ray absorption studies in environmental, catalytic, and materials science.

This study addresses the challenging problem of accurately measuring the energy resolution of beamlines in the 2.1-4 key tender X-ray region by proposing a high-precision measurement method based on Brewster-angle polarization modulation. This method effectively utilizes the compression of the diffraction bandwidth of ppolarized light when the light is incident near the Brewster angle onto the analytical crystal, successfully overcoming the limitations induced by the broad Darwin widths of the analytical crystal in traditional measurement. Experimental verification on the Shanghai Synchrotron Radiation Facility BL16U1 Beamline demonstrates that, using this method the analytical crystal systematic error in energy resolution measurement has been largely reduced. After further eliminating the influence of the Darwin width of the analytical crystal from the high-quality experimental data obtained, the measured energy resolution of a Si (111) double-crystal monochromater reached 1.04 & times; 10-4 at 2.5 key (the theoretical value is 0.95 & times; 10-4), significantly outperforming the result, 1.20 & times; 10-4 , obtained via conventional methods using s-polarized light. By selecting appropriately matched crystals, this method can be applied to the entire tender X-ray range (2.1-4 key). This finding further confirms the superiority of p-polarized light in improving measurement accuracy, with the resulting precision approaching the theoretical energy resolution of the double-crystal monochromator. This work successfully applies the polarization modulation method to high-precision measurements in tender-energy X-ray range. By controlling polarization to compress the inherent bandwidth of optical systems and thereby enhance measurement accuracy, it has expanded the application boundaries of polarization optical measurement technology.

With the development of the semiconductor industry below the 7 nm scale, critical dimension small-angle X-ray scattering (CD-SAXS) has emerged as a powerful tool for quantitatively measuring nanoscale deviations. In this study, the effects of X-ray beam size and photon energy on the accuracy of critical dimension measurements were investigated. Critical dimensions measured using beams with different spot sizes showed different deviations from the expected values. Beam sizes that were either too large or too small did not improve confidence intervals. As the incident energy increased, the X-ray transmission rate increased, while the scattering cross section decreased, resulting in a gradual decrease in the signal-to-noise ratio of the diffraction peaks, which reduced the accuracy of the CD-SAXS measurements. An optimal accuracy was obtained at 12 keV with a smaller beam size. Using an effective trapezoid model, the results yielded an average pitch of 100.4 ± 0.2 nm, width of 49.8 ± 0.2 nm, height of 130.0 ± 0.2 nm, and a sidewall angle below 1.1^∘± 0.1^∘ . These results provide crucial guidance for the future development of CD-SAXS laboratories and the construction of X-ray machines as well as robust support for research in related fields.

With the continuous scaling of advanced semiconductor manufacturing processes, device critical dimensions (CD) are shrinking rapidly and transistor structures are evolving from planar to complex 3D architectures. These trends make critical dimension small-angle X-ray scattering (CD‑SAXS) an indispensable metrology technique for nanostructures. However, conventional CD‑SAXS workflows suffer from two major efficiency bottlenecks: time‑consuming multi‑angle data acquisition and low‑efficiency inverse modeling based on nonlinear fitting. This study aims to overcome these limitations and realize high‑efficiency CD‑SAXS measurement. A dual‑path acceleration strategy is proposed, which integrates a ResNet34‑based deep regression network with Test‑Time Training (TTT). The neural network is pre‑trained on physically simulated scattering data and then fine‑tuned with unlabeled experimental data to reduce the simulation‑to‑reality domain shift and improve generalization. Raw scattering data is converted into a ω‑qxz coordinate format suitable for convolutional neural networks, thereby avoiding the reconstruction of qx‑qz reciprocal space patterns. The TTT mechanism ensures high prediction accuracy under sparse angular sampling. Experimental results demonstrate that the proposed method achieves measurement accuracy comparable to traditional nonlinear fitting methods, while reducing the total time of measurement and data processing by more than 30‑fold. The dual‑path acceleration strategy effectively breaks through the efficiency bottlenecks of conventional CD‑SAXS. It enables accurate nanostructure measurement with greatly reduced data acquisition and processing time, showing strong potential for CD‑SAXS in real‑time, in‑line metrology of complex nanostructures in semiconductor manufacturing.

Synchrotron radiation X-ray fluorescence spectroscopy (SR-XRF) has revolutionized elemental analysis by achieving detection sensitivity enhancements of up to three orders of magnitude compared with conventional laboratory X-ray tube-based XRF systems. This enables trace element analysis from parts per million (ppm) to parts per billion (ppb) levels in environmental, materials and biomedical applications. The Tender-Energy Spectroscopy Beamline (BL16U1 beamline) at the Shanghai Synchrotron Radiation Facility (SSRF), equipped with a high-brightness undulator, operating within the 2.1-16 keV energy range. The beamline has been optimized in the tender-energy range (2-5 keV), and supports high-sensitivity analysis of medium-Z elements (e.g., sulfur, phosphorus) at its experimental station. At the station an exceptional detection limit of 4.1 ppb for copper has been achieved, which supports highly sensitive fluorescence XANES/EXAFS detection, and there integrates multiple advanced features: Kirkpatrick-Baez mirror system enabling micrometer/sub-micrometer spatial resolution, and wavelength-dispersive spectroscopy technology supporting simultaneous multi-element detection. These capabilities support diverse cutting-edge applications, ranging from energy and environmental analysis to cellular trace element imaging, cultural heritage examination, and battery materials research. BL16U1 beamline and experimental station represents a significant platform for advancing XRF methodologies, with ongoing developments expected to further expand its impact on trace element research across multiple scientific disciplines.

This paper describes the design and performance of the tender energy spectroscopy beamline (BL16U1), a phase II beamline, at the Shanghai Synchrotron Radiation Facility. The beamline, based on an in-vacuum undulator source with 26 mm period, provides an operable energy range between 2.1 keV and 16 keV, covering the K-edges of P to Rb and L_3 -edges of Zr to Bi. The principal optical elements of the beamline are a toroidal mirror, a liquid nitrogen-cooled double-crystal monochromator, a high-harmonic-rejection mirror, and two pairs of Kirkpatrick–Baez (KB) mirrors. Three end-stations, including non-focusing, microprobe, and sub-microprobe types, are installed on the beamline. X-ray fluorescence (XRF) and X-ray absorption spectroscopy (XAS), including X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS), are performed under vacuum or He atmosphere at the non-focusing end-station (with a beam spot size of ∼670 m×710 m ). Using two KB mirrors systems, micro-XRF ( XRF) mapping and micro-XANES ( XANES) studies can be performed with a spot size of approximately ∼3.3 m×1.3 m at the microprobe end-station and with a smaller spot size of ∼0.5 m×0.25 m at the sub-microprobe end-station. The non-focusing end-station was officially opened to users in January 2024. The microprobe and sub-microprobe end-stations will be opened to users in the near future. This paper presents the characteristics, short-term technical developments, and early experimental results of this new beamline.

Electron beam lithography (EBL) and extreme ultraviolet lithography (EUVL) have been continuously improved and applied in semiconductor and biomedical device manufacturing. With the development of biomedical nanodevices, the demand for biodegradable, and environmentally friendly materials is growing. Some biocompatible photoresists have been reported, and their sensitivity, resolution, and line edge roughness need to be further improved. In this work, porphyrin derivatives (H 2 TP‐4Epoxy and CuTP‐4Epoxy) are introduced for EBL and EUVL. Owing to their smaller sizes and higher EUV absorptivity compared to traditional polymer photoresists, CuTP‐4Epoxy shows good resolution and etch resistance. As a result of EBL studies, 18 nm line/space patterns have been achieved at a dose of 1014 µC cm −2 . Meanwhile, 20 nm dense patterns are also achieved using EUVL at a dose of 88.8 mJ cm −2 , revealing the great potential of this approach for high resolution patterning. Etching experiments show an etch selectivity for silicon of 11.7, significantly higher than some of commercial photoresists. Biocompatibility experiments show that metalloporphyrin photoresist have potential applications in the fabrication of chips that are biocompatible with living organisms. This work demonstrates the structural advantages of porphyrin derivatives as high‐resolution biocompatible photoresist materials, inspiring future exploration of metalloporphyrin materials for advanced lithography and biocompatible nanodevices.

The limited pattern area of periodic nanostructures limits the development of practical devices. This study introduces an X-ray interference lithography (XIL) stitching technique to fabricate a large-area (1.5 cm × 1.5 cm) two-dimensional photonic crystal (PhC) on the YAG: Ce scintillator, which functions as an encoder in a high numerical aperture optical encoding imaging system to effectively capture high-frequency information. An X-ray imaging experiment revealed a substantial 7.64 dB improvement in the signal-to-noise ratio (SNR) across a large field of view (2.6 mm × 2.6 mm) and achieved comparable or superior image quality with half the exposure dose. These findings have significant implications for advancing practical applications of X-ray imaging.

Structured beams carrying orbital angular momentum (OAM) provide powerful capabilities for applications in optical tweezers, super-resolution imaging, quantum optics, and ad-vanced microparticle manipulation. However, it is challenging for generate and control the OAM beams at the extreme ultraviolet (EUV) region due to the lack of suitable wave front shaping optics arise from being limited to the strong absorption of most materials. Here, we use a modified Fermat-spiral photon-sieve splitter to simultaneously generate two focused doughnut beams with opposite helical phase. Our technique enables us to produce splitting focused vortex beams with different rotation directions at EUV wavelengths. Additionally, we provide experimental evidence showcasing the capabilities of our method and further detect the helical phase by self-reference interferometry. This work not only opens a route for OAM-driven applications in EUV radiation, but also paves the way to studies of holographic technique by EUV splitter.

Traditional small angle X-ray scattering (SAXS) techniques utilize a focused microbeam for spatial scanning to achieve spatially resolved imaging of the nanostructures of nonuniform materials. However, this method is notably inefficient regarding information acquisition, and its spatial resolution is constrained by the beam's focusing capabilities. We propose a proof-of-concept experiment using structured illumination to demonstrate a SAXS method capable of achieving high spatial resolution. This method leverages the experimental setup of real-space ghost imaging in intensity correlation measurements. It maps reciprocal space signals—specifically, small angle scattering signals—to real space, enabling small angle scattering imaging with enhanced spatial resolution without needing beam-focusing elements. Due to its inherent compatibility with compressed sensing, this method can significantly reduce the number of measurements. Successfully validated using synchrotron radiation X-rays, this approach theoretically applies to scattering imaging of photons and high-energy particles across various wavelength bands. It holds broad application prospects in the fields of nanomaterials and biomedicine.

Objective Compared to traditional electronic devices, silicon-based optoelectronic devices have larger information capacities, lower exchange latencies, and larger transmission bandwidths. Thus, they are expected to solve the problems caused by the rapid growth in global network capacity caused by the emergence of new generation information technologies such as the Internet of Things, cloud computing, and big data since the beginning of the 21st century. Polarization beam splitters are important devices for implementing polarization insensitive photonic integrated circuits, while traditional silicon- based polarization beam splitters typically have larger dimensions but cannot be integrated compactly on a chip. The introduction of subwavelength structures makes it possible to miniaturize silicon optoelectronic devices. The design of subwavelength devices is usually based on physical intuition in forward design and computer optimization in reverse design. The reverse design of subwavelength devices allows for the free optimization of the shape of metasurfaces, with greater degrees of freedom and the ability to obtain very fine structures. However, most existing research on designing subwavelength structures using inverse design methods requires high computational power and low diversity. Our previous proposal of using a two-dimensional code metasurface silicon polarization beam splitter based on a gradient index to theoretically analyze the gradient refractive index physical model effectively prevents the solutions from being trapped in local optimums and eliminates the uncertainty resulting from the sensitivity to the stochastic initial values. This design method has the characteristics of low dependence on the computational power, high design freedom, and great optimization potential. Although the error tolerance is considered in the design process, there are various forms of errors in actual processing. Thus, there are high requirements for fabricating. It is necessary to optimize processing methods such as electron beam lithography ( EBL) and inductively coupled plasma etching (ICP) to improve fabrication. Strict control of the EBL exposure accuracy, etching depth, sidewall roughness, and steepness is required during the fabrication process. This article shows how a device is manufactured and tested using a silicon optical testing platform. The theory of the physical constraint inverse design of metasurface silicon optical devices and the corresponding integrated polarization beam splitter design are experimentally verified on a silicon-on- insulator (SOI) platform. Methods We optimized methods such as EBL and ICP to meet the fabrication requirements for metasurface polarization beam splitters. We optimized the scanning field, exposure beam current, and other parameters of EBL. We obtained good exposure results using an photoresist consisting of HSQ and MIBK with volume fraction ratio of 1:2. The exposure linewidth error did not exceed 5 nm, and the metasurface exposure morphology was good, meeting the design requirements. The etching formula was also optimized, and after optimization, the edge roughness and steepness of the etching were both good (Fig. 3). After optimizing the process, a silicon metasurface polarization beam splitter was manufactured. First, the metasurface structure was exposed using a 180 nm thick photoresist and developed using a 25 degrees o TMAH solution at 50 degrees C for 1 min. Then, the optimized etching formula was used for etching to a depth of 120 nm. Finally, the photoresist was removed with a 2 degrees o HF solution. Two overlay marks needed to be exposed simultaneously with the metasurface structure for the overlay exposure. For the second exposure, a 500 nm thick HSQ photoresist was spun on the SOI. Then, the waveguide layer structure was exposed. After development, the top silicon of the SOI was etched to the bottom, and the photoresist was removed with the HF solution. After the fabrication of the metasurface polarization beam splitter structure, a grating coupler for testing was fabricated using the PMMA photoresist, with an etching depth of 70 nm. Results and Discussions An SEM image (Fig. 5) shows that the final fabricated metasurface structure has a linewidth error of less than 5 nm and an etching error of less than 10 nm. Although the morphology after etching is slightly worse than that before etching, it still meets the design requirements. The fabricated metasurface polarization beam splitter is tested using the constructed silicon optical testing platform (Fig. 6), and the test results are normalized (Fig. 7). In the range of 1510-1590 nm, the extinction ratios of the TE and TM modes exceed 20 dB. The insertion losses of the TE and TM modes are less than 3.8 dB and 3.9 dB, respectively. At the center wavelength, the extinction ratios of the TE and TM modes are approximately 20 dB and 25 dB, respectively. The testing and simulation errors may be caused by machining errors as regards the metasurface etching uniformity, etching steepness, and metasurface morphology. Conclusions A metasurface silicon polarizing beam splitter designed based on a gradient index physical model is prepared using micro- and nano- processing methods such as EBL and ICP on an SOI platform. The fabrication process is optimized to meet the manufacturing requirements of the metasurface device. The size error of the metasurface structural features of the prepared device is less than 5 nm, and the etching depth error is less than 10 nm. Finally, actual testing conducted using the constructed silicon optical probe platform shows that within the wavelength range of 1510-1590 nm covering the C- band, the TE and TM mode insertion losses are less than 3.9 dB and 3.8 dB, respectively, and the extinction ratios are greater than 20 dB. The fabricated metasurface polarization beam splitter has good extinction ratios and acceptable insertion losses in the wavelength range of 1510-1590 nm. The experimental results verify the theory of the physical constraint inverse design of metasurface silicon optical devices and the corresponding design conclusions regarding integrated polarization beam splitters. The difference between the experimental and simulation results may be due to processing errors. In subsequent work, the micro- and nano- processing technologies for metasurface silicon optical devices can be Objective Compared to traditional electronic devices, silicon- based optoelectronic devices have larger information capacities, lower exchange latencies, and larger transmission bandwidths. Thus, they are expected to solve the problems caused by the rapid growth in global network capacity caused by the emergence of new generation information technologies such as the Internet of Things, cloud computing, and big data since the beginning of the 21st century. Polarization beam splitters are important devices for implementing polarization insensitive photonic integrated circuits, while traditional silicon- based polarization beam splitters typically have larger dimensions but cannot be integrated compactly on a chip. The introduction of subwavelength structures makes it possible to miniaturize silicon optoelectronic devices. The design of subwavelength devices is usually based on physical intuition in forward design and computer optimization in reverse design. The reverse design of subwavelength devices allows for the free optimization of the shape of metasurfaces, with greater degrees of freedom and the ability to obtain very fine structures. However, most existing research on designing subwavelength structures using inverse design methods requires high computational power and low diversity. Our previous proposal of using a two-dimensional code metasurface silicon polarization beam splitter based on a gradient index to theoretically analyze the gradient refractive index physical model effectively prevents the solutions from being trapped in local optimums and eliminates the uncertainty resulting from the sensitivity to the stochastic initial values. This design method has the characteristics of low dependence on the computational power, high design freedom, and great optimization potential. Although the error tolerance is considered in the design process, there are various forms of errors in actual processing. Thus, there are high requirements for fabricating. It is necessary to optimize processing methods such as electron beam lithography (EBL) and inductively coupled plasma etching (ICP) to improve fabrication. Strict control of the EBL exposure accuracy, etching depth, sidewall roughness, and steepness is required during the fabrication process. This article shows how a device is manufactured and tested using a silicon optical testing platform. The theory of the physical constraint inverse design of metasurface silicon optical devices and the corresponding integrated polarization beam splitter design are experimentally verified on a silicon- on- insulator (SOI) platform. Methods We optimized methods such as EBL and ICP to meet the fabrication requirements for metasurface polarization

Scintillation-based X-ray imaging can provide convenient visual observation of absorption contrast by standard digital cameras, which is critical in a variety of science and engineering disciplines. More efficient scintillators and electronic postprocessing derived from neural networks are usually used to improve the quality of obtained images from the perspective of optical imaging and machine vision, respectively. Here, we propose to overcome the intrinsic separation of optical transmission process and electronic calculation process, integrating the imaging and postprocessing into one fused optical-electronic convolutional autoencoder network by affixing a designable optical convolutional metasurface to the scintillator. In this way, the convolutional autoencoder was directly connected to down-conversion process, and the optical information loss and training cost can be decreased simultaneously. We demonstrate that feature-specific enhancement of incoherent images is realized, which can apply to multi-class samples without additional data precollection. Hard X-ray experimental validations reveal the enhancement of textural features and regional features achieved by adjusting the optical metasurface, indicating a signal-to-noise ratio improvement of up to 11.2 dB. We anticipate that our framework will advance the fundamental understanding of X-ray imaging and prove to be useful for number recognition and bioimaging applications.

Evaluating the comprehensive characteristics of extreme ultraviolet (EUV) photoresists is crucial for their application in EUV lithography, a key process in modern technology. This paper highlights the capabilities of the Shanghai Synchrotron Radiation Facility (SSRF) 08U1B beamline in advancing this field. Specifically, it demonstrates how this beamline can create fringe patterns with a 15-nm half-pitch on a resist using synchrotron-based EUV lithography. This achievement is vital for evaluating EUV photoresists at the advanced 5-nm node. We provide a detailed introduction to the methods and experimental setup used at the SSRF 08U1B beamline to assess an EUV photoresist. A significant part of this research involved the fabrication of high-resolution hydrogen silsesquioxane mask gratings. These gratings, with an aspect ratio of approximately 3, were created using electron beam lithography on an innovative mask framework. This framework was crucial in eliminating the impact of zeroth-order light on interference patterns. The proposed framework propose offers a new approach to mask fabrication, particularly beneficial for achromatic Talbot lithography and multicoherent-beam interference applications.

Spectropolarimetry detection provides multi-dimensional accurate information with broad applications from biomedicine to remote sensing. Existing methods for simultaneously obtaining spectra and polarizations are either large and complex systems or miniaturized devices with too low spectral resolution or poor polarization selectivity, which inherently generate cross-talk of substantial information. Here, we propose a compact and single-chip integrated high-performance mid-infrared spectropolarimetry filter (SPF), whose narrowband spectral and polarization characteristics can be independently modulated by different polarization modes. A SPF is designed with a polarization extinction ratio (ER) over 106, spectral resolution (SR, λ/Δλ) up to 822 and a transmission efficiency of 90% in the mid-infrared band. The experimental ER and SR are over 3 × 104 and up to 387 respectively with a transmission efficiency of 60%. These results agree well with the theoretical results and can accurately obtain spectral and polarization information simultaneously. This device has been used in tumor diagnostics to well distinguish striated muscle and rhabdomyosarcoma tissue for demonstration. It can be easily extended to different wavelength ranges and provides a new and powerful approach for multi-dimensional optical information acquisition, target detection and accurate identification.

In this study, a series of molecular resists based on a bis(4-butoxyphenyl) sulfone core attached to a varying number of radiation-sensitive triphenylsulfonium units (BPSSn, where n = 2, 3, and 4) were designed and synthesized. We evaluated the physical properties of these resists, including solubility, film-forming ability, and thermal stability, to assess their viability as photoresist materials. The materials allowed for negative patterning through organic development in both e-beam and extreme ultraviolet (EUV) lithography. Through manipulating the average number of triphenylsulfonium units in the molecule and optimizing the developing agents, BPSS4 resists demonstrated high resolution (16/13 nm) and low line edge roughness (2.5/2.5 nm) in e-beam and EUV dense line patterning, respectively. We further explored the EUV and e-beam exposure mechanisms of BPSS4 resist using X-ray photoelectron spectroscopy. We also investigated the outgassing behavior of the film during EUV irradiation via in situ mass spectroscopy. Remarkably, this nonchemically amplified resist exhibited high etch resistance and accurate pattern transfer capabilities. The etch durability of BPSS4 (under SF6/O-2 plasma chemistry) with respect to the Si wafer was 21:1, highlighting its significant potential for practical applications in high-resolution lithography.

A series of t-butyloxycarbonyl (t-Boc) protected tetraphenylsilane derivatives (TPSi-Boc x , x = 60, 70, 85, 100%) were synthesized and used as resist materials to investigate the effect of t-Boc protecting ratio on advanced lithography. The physical properties such as solubility, film-forming ability, and thermal stability of TPSi-Boc x were examined to assess the suitability for application as candidates for positive-tone molecular glass resist materials. The effects of t-Boc protecting ratio had been studied in detail by electron beam lithography. The results suggest that the TPSi-Boc x resist with different t-Boc protecting ratios exhibit a significant change in contrast, pattern blur, and the density of bridge defect. The TPSi-Boc70% resist achieves the most excellent patterning capability. The extreme ultraviolet (EUV) lithography performance on TPSi-Boc70% was evaluated by using the soft X-ray interference lithography. The results demonstrate that the TPSi-Boc70% resist can achieve excellent patterning capability down to 20 nm isolated lines at 8.7 mJ/cm2 and 25 nm dense lines at 14.5 mJ/cm2. This study will help us to understand the relationship between the t-Boc protecting ratio and the patterning ability and supply useful guidelines for designing molecular resists.

Ultrafast x-ray diffraction imaging provides an opportunity to realize x-ray nanoimaging of biomolecules before radiation damage, while the image resolution is still restricted by the photon flux. Fourier-transform ghost imaging based on the temporal intensity correlation can achieve diffraction-limited imaging. However, a large number of temporal samplings are inevitable, which makes it almost impossible to be implemented in the ultrafast x-ray imaging. Here, we propose an x-ray single-exposure Fourier-transform ghost imaging (SFGI) approach. The Fourier information of an unknown sample can be obtained by measuring the spatial intensity correlation between two speckle fields, and the sample needs to be exposed only once. In our demonstration experiment of SFGI, the Fourier-transform diffraction pattern of a two-dimensional sample is achieved, and its face-centered-cubic feature in the spatial domain is retrieved successfully. The simulation results of the DNA origami and rice dwarf virus indicate that a spatial resolution of 10 nm may be reached, and x-ray ghost imaging with 0.1 photon/pixel speckle detection can be expected. Our research paves the way for the future application of ultrafast x-ray ghost imaging.

Ultrafast x-ray diffraction imaging provides an opportunity to realize x-ray nanoimaging of biomolecules before radiation damage, while the image resolution is still restricted by the photon flux. Fourier-transform ghost imaging based on the temporal intensity correlation can achieve diffraction-limited imaging. However, a large number of temporal samplings are inevitable, which makes it almost impossible to be implemented in the ultrafast x-ray imaging. Here, we propose an x-ray single-exposure Fourier-transform ghost imaging (SFGI) approach. The Fourier information of an unknown sample can be obtained by measuring the spatial intensity correlation between two speckle fields, and the sample needs to be exposed only once. In our demonstration experiment of SFGI, the Fourier-transform diffraction pattern of a two-dimensional sample is achieved, and its face-centered-cubic feature in the spatial domain is retrieved successfully. The simulation results of the DNA origami and rice dwarf virus indicate that a spatial resolution of 10 nm may be reached, and x-ray ghost imaging with 0.1 photon/pixel speckle detection can be expected. Our research paves the way for the future application of ultrafast x-ray ghost imaging.

Metasurface attracts much attention but lacks the modulation ability along the beam propagation direction, which confines its ability to control the wavelength and polarization of light. We propose a new concept of metainterface by embedding a two-dimensional metamaterial in a layered structure with vertical control ability. It can hugely improve the light control power and generate excellent characteristics while keeping simple fabrication processes. A high-performance spectro-polarimetric filter, which is based on the interface composed of one-dimensional photonic crystals and 10 nm thick Al grating, is fabricated for demonstration. Experimental results show that it can simultaneously have a polarization extinction ratio (PER) of 800 and a spectral resolution power (SRP, .1/Delta.1) of 113, which are, respectively, 74 and 9 times better than the recently obtained best results of the metasurface. Moreover, it can break the limitation of diffraction and achieve much higher PER with limited size gratings. Because of these characteristics, it has great potential in miniature and integrated spectropolarimeters.

Gd2O2S:Tb (P43) powder was widely used in soft X-ray detection due to its high light yield. Compared with P43, GAGG:Ce scintillator has high light transmittance, fast decay time and strong radiation resistance. Photonic crystals (PhCs) can be used to enhance the light output of scintillator. In this paper, two-dimensional (2D) photonic crystals that consist of square arrays of air holes etched into TiO2 layer were fabricated on the exit surface of GAGG:Ce scintillator to enhance its light output. The luminescence spectra and the light output of GAGG:Ce scintillator with/without PhCs were measured at the BL08U1A beamline of Shanghai Synchrotron Radiation Facility. The results showed that the light output of GAGG:Ce scintillator with PhCs can be enhanced by a factor of 1.43 times compared with the reference GAGG:Ce scintillator, 2.35 times compared with YAG:Ce scintillator, 1.24 times compared with Gd2O2S:Tb scintillation ceramic and 0.76 times compared with P43 powder layer with the mass thickness of about 1.3mg/cm 2 with optical grease coupling. No significant change was observed in luminescence decay time between GAGG:Ce scintillator with and without PhCs. It makes GAGG:Ce scintillator with PhCs a promising material instead of P43 powder and YAG:Ce scintillator in soft X-ray detector.