分类: 光学 >> 量子光学 提交时间: 2023-02-19
摘要: Transfer matrix theory (TMT) is used to study the effective-medium theory (EMT) of one dimensional metamaterials (1D MMs). 1D MMs with equal diagonal elements of periodic transfer matrix are defined as 1D perfect MMs (1D PMMs), which can be suitable for EMT with no approximation.
分类: 光学 >> 量子光学 提交时间: 2023-02-19
摘要: Conventional approaches for 3D imaging in or through scattering media are usually limited to 2D reconstruction of objects at some discontinuous locations, although the time-consuming iteration, guide-star, or complex system are implemented. How to quickly visualize dynamic 3D objects behind scattering media is still an open issue. Here, by using structured light illumination, we propose a single-shot technique that can quickly acquire continuous 3D surfaces of objects hidden behind the diffuser. The proposed method can realize the 3D imaging of single, multiple, and dynamic targets from the speckled structured light patterns under broad or narrow band light illumination, in which only once calibration of the imaging setup is needed before conducting the imaging. Our approach paves the way to quickly visualize dynamic objects behind scattering media in 3D and multispectral.
分类: 光学 >> 量子光学 提交时间: 2023-02-19
摘要: Parallel worlds are imaginative ideas in quantum mechanics and cosmology. The superpositions of parallel worlds are novel states of quantum gravity and have no classical correspondences generally. In this letter, we investigate the superposition or the Schr\"odinger's cat state of optical parallel worlds, which could be realized in laboratory and may shed some light on the detection of parallel universes in a real world. We propose two realizable experimental schemes, which enable to explore the mysterious `parallel universes' by a Mach-Zehnder interferometer. The first one is based on an atomic ensemble in a superposition state, which is a fat Schr\"odinger's cat state. The second one is to prepare a photon in a superposition of different paths, where each path lies in an optical parallel universe.
分类: 光学 >> 量子光学 提交时间: 2023-02-19
摘要: Inspired by the capability of structured illumination microscopy in subwavelength imaging, many researchers devoted themselves to investigating this methodology. However, due to the free propagating feature of the traditional structured illumination fields, the resolution can be only improved up to double times compared with the diffractied limited microscopy. Besides, most of the previous studies, relying on incoherent illumination sources, are restricted to fluorescent samples. In this work, a subwavelength nonfluorescent imaging method is proposed based on the terahertz traveling wave and plasmonics illumination. Excited along with a metal grating, the spoof surface plasmons are employed as the plasmonics illumination. When the scattering waves with the SSPs illumination are captured, the high order spatial frequency components of the sample are already encoded into the obtainable low order ones. Then, an algorithm is summarized to shift the modulated SF components to their actual positions in the Fourier domain. In this manner, high order SF components carrying the fine information are introduced to reconstruct the desired imaging, leading to an improvement of the resolution up to 0.12 lambda. Encouragingly, the resolution can be further enhanced by tuning the working frequency of the SSPs. This method holds promise for some important applications in terahertz nonfluorescent microscopy and sample detection with weak scattering.
分类: 光学 >> 量子光学 提交时间: 2023-02-19
摘要: Photonic hooks (PHs) are non-evanescent light beams with a highly concentrated curved optical fields. Since their discovery, PHs always have one single inflection point and thus have a hook-like structure. In this work, a new type of PHs with two inflection points and S-shaped structures (S-PHs) were reported for the first time. We theoretically studied the effects of various physical parameters on the generation of S-PHs. Furthermore, we showed that decorating particles with multiple patches can significantly enhance the curvature and length of the S-PHs. The S-PHs may have potential applications in super-resolution imaging, sub-wavelength micromachining, particle and cell manipulation, etc.
分类: 物理学 >> 核物理学 提交时间: 2024-02-09
摘要: An ultrafast framing camera with a pulse-dilation device and a microchannel plate (MCP) imager as well as an electronic imaging system is reported. The camera achieves a temporal resolution of 10 ps by using a pulse-dilation device and a gated MCP imager, and a spatial resolution of 100 m by using an electronic imaging system composed of combined magnetic lenses. The spatial resolution characteristics of the camera are theoretically and experimentally studied. The results show that the camera with combined magnetic lenses could reduce field curvature and acquire a larger working area. A working area 53 mm in diameter has been achieved by applying four magnetic lenses to the camera. Furthermore, the camera is used to detect X-rays produced from a laser targeting device. The diagnostic results show that the width of the X-ray pulse is about 18 ps.
分类: 天文学 >> 天文学 提交时间: 2023-02-19
摘要: We analyze 4\,050 wide binary star systems involving a white dwarf (WD) and usually a main sequence (MS) star, drawn from the large sample assembled by \citet[][hereafter, T20]{Tian_2020}. Using the modeling code BASE-9, we determine the system's ages, the WD progenitors' ZAMS masses, the extinction values ($A_V$), and the distance moduli. Discarding the cases with poor age convergences, we obtain ages for 3\,551 WDs, with a median age precision of $\sigma_{\tau}/\tau = 20$\%, and system ages typically in the range of 1-6 Gyr. We validated these ages against the very few known clusters and through cross-validation of 236 WD-WD binaries. Under the assumption that the components are co-eval in a binary system, this provides precise age constraints on the usually low-mass MS companions, mostly inaccessible by any other means.
分类: 核科学技术 >> 核科学与技术 提交时间: 2024-01-06
摘要: POLAR-2 is a gamma-ray burst (GRB) polarimeter that is designed to study the polarization in GRB radiation emissions, aiming to improve our knowledge of related mechanisms. POLAR-2 is expected to utilize an on#2;board polarimeter that is sensitive to soft X-rays (210 keV), called low-energy polarization detector (LPD). We have developed a new soft X-ray polarization detector prototype based on gas microchannel plates (GMCPs) and pixel chips (Topmetal). The GMCPs have bulk resistance, which prevents charging-up effects and ensures gain stability during operation. The detector is composed of low-outgassing materials and is gas-sealed using a laser welding technique, ensuring long-term stability. A modulation factor of 41.28% 0.64% is obtained for a 4.5 keV polarized X-ray beam. A residual modulation of 1.96% 0.58% at 5.9 keV is observed for the entire sensitive area.