61 to 42.03 and then decreased to 12.11. The corresponding up-conversion luminescence gamut was adjusted from monochrome green to red to red-yellow. This work provides a new thread for realizing upconversion multicolor luminescence by regulating the clusters of rare earth ions.During the real-aperture-scanning imaging process, terahertz (THz) images are often plagued with the problem of low spatial resolution. Therefore, an accommodative super-resolution framework for THz images is proposed. Specifically, the 3D degradation model for the imaging system is firstly proposed by incorporating the focused THz beam distribution, which determines the relationship between the imaging range and the corresponding image restoration level. Secondly, an adjustable CNN is introduced to cope with this range dependent super-resolution problem. By simply tuning an interpolation parameter, the network can be adjusted to produce arbitrary restoration levels between the trained fixed levels without extra training. Finally, by selecting the appropriate interpolation coefficient according to the measured imaging range, each THz image can be coped with its matched network and reach the outstanding super-resolution effect. Both the simulated and real tested data, acquired by a 160 ∼ 220 GHz imager, have been used to demonstrate the superiority of our method.A novel spectroscopy technique to enable the rapid characterization of discrete mid-infrared integrated photonic waveguides is demonstrated. The technique utilizes lithography patterned polymer blocks that absorb light strongly within the molecular fingerprint region. These act as integrated waveguide detectors when combined with an atomic force microscope that measures the photothermal expansion when infrared light is guided to the block. As a proof of concept, the technique is used to experimentally characterize propagation loss and grating coupler response of Ge-on-Si waveguides at wavelengths from 6 to 10 µm. In addition, when the microscope is operated in scanning mode at fixed wavelength, the guided mode exiting the output facet is imaged with a lateral resolution better than 500 nm i.e. below the diffraction limit. The characterization technique can be applied to any mid-infrared waveguide platform and can provide non-destructive in-situ testing of discrete waveguide components.Raman dissipative solitons (RDS) have been investigated numerically. It was found that the area of stable generation is bounded in terms of pump spectral bandwidth and pulse energy. Existing optimum is strongly affected by the net cavity dispersion. The spectral bandwidth of the generated RDS linearly depends on its energy and reaches more than 50 nm in the 5-meters long cavity. Developed numerical model reproduces all the effects observed experimentally. selleck compound It predicts ability to generate high-quality pulses with energy up to 6 nJ compressible down to ∼100 fs duration. The work shows that RDS generation technique can produce high-energy ultrashort pulses at wavelengths not covered by typical active mediums.Manipulation of electromagnetic waves from radio to visible wavelengths could lead to technology to investigate unexplored wavebands. However, flexible control of terahertz waves is difficult, because few naturally occurring, appropriate materials and sophisticated optical components exist. We propose a 2.28-µm (0.02λ) ultra-thin terahertz metasurface collimator with a high directivity of 4.6 times (6.6 dB) consisting of 339 pairs of meta-atoms compared with a single terahertz continuous-wave source. The metasurface exhibits an extremely high refractive index of 15.0 and a low reflectance of 15.5% at 3.0 THz, and with Fresnel reflections for naturally occurring dielectric materials with high refractive indices avoided. This metasurface collimator should facilitate ground-breaking applications such as arbitrary phase converters, solid immersion lenses, and cloaking.In this paper, we propose a coupled-double-photonic-crystal-slab (CDPCS) sensor for simultaneously detecting refractive index (RI) and temperature (T) with high accuracy and strong anti-interference ability, using transverse magnetic-like (TM-like) mode and transverse electric-like (TE-like) mode. Based on the temporal coupled-mode theory, the theoretical model of the structure is established and the transmission formula is derived. The agreement between the theoretical and the simulated transmission spectra is proved. In order to achieve both high quality (Q)-factor and high modulation depth, the structure is optimized by adjusting the geometric parameters. The Q-factors of both TM-like mode and TE-like mode reach a magnitude order of 105. For the dual-parameter sensing, high RI sensitivities of 960 nm/RIU and 210 nm/RIU, and T sensitivities of -66.5 pm/K and 50.75 pm/K, are obtained for TM-like mode and TE-like mode, respectively. The relative deviations of RI and T sensing are as low as 0.6% and 1.0%, respectively, indicating high detection accuracy. Even considering the influence of external interference, the sensor can effectively resist external interference. The proposed CDPCS sensor has remarkable performance improvements in sensitivity, Q-factor, detection accuracy, and anti-interference ability. This study shows great potential in on-chip sensing and multi-parameter detection.We introduce the concept of a liquid compound refractive X-ray zoom lens. The lens is generated by pumping a suitable liquid lens material like water, alcohol or heated lithium through a line of nozzles each forming a jet with the cross section of lens elements. The system is housed, so there is a liquid-circulation. This lens can be used in white beam at high brilliance synchrotron sources, as radiation damages are cured by the continuous reformation of the lens. The focal length can be varied by closing nozzles, thus reducing the number of lens elements in the beam.Two-dimensional van der Waals heterostructures (vdWHs) are drawing growing interest in the investigation of their valley polarization properties of localized excitons. However, most of the reported vdWHs were made by micro-mechanical peeling, limiting their large-scale production and practical applications. Furthermore, the circular polarization characters of localized excitons in WSe2/WS2 heterostructures remain elusive. Here, a bidirectional-flow physical vapor deposition technique was employed for the synthesis of the WSe2/WS2 type-II vertical heterostructures. The interfaces of such heterojunctions are sharp and clean, making the neutral excitons of the constituent layers quenched, which significantly highlights the luminescence of the local excitons. The circular polarization of localized excitons in this WSe2/WS2 heterostructure was demonstrated by circularly-polarized PL spectroscopy. The degree of the circular polarization of the localized excitons was determined as 7.17% for σ- detection and 4.78% for σ+ detection.