Sapphire fiber Bragg gratings （SFBG） can realize in-situ， multipoint， and high-accuracy temperature measurement above 1 800 ℃， making them important sensors for extreme-environment monitoring in aerospace engines， nuclear energy systems， and industrial furnaces. However， the strong multimode characteristics of sapphire fibers lead to broadband reflection spectra， overlapping multiple peaks， and high sensitivity to coupling and packaging conditions， making their demodulation mechanisms significantly different from those of conventional silica fiber Bragg grating （FBG）. Focusing on the wavelength demodulation requirements of SFBG， this paper systematically reviews and compares technical routes including direct spectral measurement by optical spectrum analyzers （OSA） or array spectrometers， as well as optical frequency domain reflectometry （OFDR） demodulation. Representative progress is summarized in terms of key performance indicators such as demodulation speed， resolution/accuracy， measurement range， multiplexing capability， and robustness. Engineering and algorithmic approaches for improving signal-to-noise ratio and stability are further summarized， including mode filtering， mode reduction， single-mode operation and mode stabilization， end-face and coupling optimization， high-temperature packaging， cross-correlation algorithms， and machine-learning-assisted algorithms. Finally， future development trends of SFBG demodulation systems are discussed from three perspectives： miniaturized demodulation based on arrayed waveguide gratings （AWG）， high-speed demodulation based on swept-laser schemes， and high-precision demodulation based on interferometric methods. This review provides a reference for the engineering development of real-time demodulation in high-temperature and strain sensing using optical fibers.

Ferroelectric crystal fibers combine the excellent optical nonlinearity， electro-optic effect， and piezoelectric property of ferroelectric materials with the structural advantages of fiber waveguides， which is a cutting-edge research direction in the field of integrated photonics. In this paper， the preparation techniques， material systems， performance characteristics， and application progress of ferroelectric single-crystal fibers and ferroelectric microcrystalline fibers are systematically reviewed. In terms of preparation techniques， laser-heated pedestal growth （LHPG） and micro-pulling-down （μ-PD） methods can realize the growth of high-quality single-crystal fibers， while in-situ crystallization and low-temperature composition methods provide a general method for large-scale production of microcrystalline composite fibers. Regarding material systems， lithium niobate， lithium tantalate， and relaxor ferroelectric single-crystals represent the mainstream directions for ferroelectric single-crystal fibers. Ferroelectric microcrystalline fibers， on the other hand， embed ferroelectric microcrystals into a glass matrix via in-situ crystallization or low-temperature composition， thereby endowing the fibers with second-order nonlinear optical functionality. In nonlinear optical applications， periodically poled ferroelectric single-crystal fibers can achieve high-efficiency quasi-phase-matching second-harmonic generation. Randomly distributed ferroelectric microcrystalline fibers， benefiting from random quasi-phase-matching mechanisms， exhibit broadband and polarization-robust frequency conversion characteristics. Additionally， ferroelectric crystal fibers also show broad application prospects in nonlinear frequency conversion， electro-optic modulation， energy harvesting， and other fields. Finally， this paper discusses the key scientific issues and challenges in this field and provides an outlook on future development directions.

Crystal fibers combine the excellent optical properties of crystalline materials with the compactness advantage of fiber structure， making them a research hotspot in high-power and ultrafast laser fields. In this work， Nd∶LuScO₃ crystal fibers with different doping concentrations were successfully grown by the laser-heated pedestal growth method. The crystal structure was characterized by X-ray diffraction （XRD）， and the spectroscopic properties， including absorption/emission cross sections， fluorescence lifetimes， and Judd-Ofelt （J-O） analysis were systematically investigated. The effect of doping concentration on fluorescence lifetime was also examined. XRD confirms that the as-grown Nd∶LuScO₃ crystal fibers possess a cubic crystal system without any impurity phases. From the absorption spectrum， the absorption cross section at 807 nm is calculated to be 1.16×10^-20 cm2， with a full width at half-maximum of 10.63 nm. The J-O intensity parameters are Ω₂=0.67×10^-20 cm2， Ω₄=2.59×10^-20 cm2， and Ω₆=0.85×10^-20 cm2. The emission cross sections for the ⁴F_3/2→⁴I_9/2， ⁴I_11/2， ⁴I_13/2 transitions are 0.99×10^-20， 2.06×10^-20， and 0.41×10^-20 cm2， respectively. These results indicate that Nd∶LuScO₃ crystal fiber is a promising gain medium for achieving ultrafast laser output in the near-infrared wavelength range.

To address the trade-off between long sensing distance and high spatial resolution in conventional Raman distributed temperature sensing （RDTS）， this paper presents a sensing scheme based on differential pulse Golay codes （DPG-codes）. The approach integrates the coding gain of differential pulse Golay codes with a differential processing mechanism. By exploiting the excellent autocorrelation characteristics of Golay complementary sequences， the launched optical energy and the far-end signal-to-noise ratio are substantially increased， all while avoiding nonlinear effects within the fiber. In the proposed scheme， Golay-coded sequences independently modulated by long and short pulse widths are sequentially injected into the sensing fiber. A differential operation is then performed on the decoded backscattered Raman signals， yielding a Raman scattering response that corresponds to an equivalent pulse width of just 4 ns and thereby delivers high spatial resolution. Numerical simulation results show that， relative to conventional techniques， the DPG-codes scheme raises the signal-to-noise ratio at the fiber end by 8.89 dB and improves the temperature resolution from 33.06 ℃ to 3.54 ℃. Ultimately， a spatial resolution of 0.40 m is achieved across a sensing distance of 150.0 km.

Aero-engine guide vanes operate under high-temperature gas flow and rapid thermal shock environments. Real-time monitoring of their internal temperature and strain states is important for thermal-structural safety assessment and lifetime evaluation. To address the difficulty of embedded multi-parameter measurement using conventional electrical sensors under high-temperature， strong vibration， and strong electromagnetic interference， this study proposed a temperature-strain synchronous monitoring method based on sapphire fiber Bragg gratings （SFBGs） for guide vanes made of ceramic matrix composites （CMCs）. Low-loss coupling and fusion splicing between sapphire fiber and multimode silica fiber were achieved through end-face polishing， axial-offset fusion splicing， and discharge-current optimization. Cascaded dual SFBGs with center wavelengths of 1 530 and 1 540 nm were fabricated using the femtosecond laser phase-mask method. The -3 dB bandwidths of the two SFBGs are 0.56 and 0.68 nm， and the signal-to-noise ratios are 11.21 and 9.34 dB， respectively. High-temperature performance test show that the SFBG exhibits a stable quadratic function temperature response from room temperature to 1 200 ℃， with determination coefficients of 0.999 47 and 0.999 68 during heating and cooling， respectively. An SFBG was embedded into a specimen made of CMCs for high-temperature strain calibration text. The results show that after temperature compensation， the test results of SFBG in 0 με to 3 000 με are consistent with the test results of high-temperature extensometer， and the relative error is less than 5%. In this study， the cascaded dual SFBGs were further embedded inside a guide vane， and 23 thermal shock cycles were conducted under a 1 200 ℃ high-speed， high-temperature gas flow environment. The temperature-strain synchronous measurement inside the guide vane is realized， and the feasibility of embedding SFBG into the CMCs guide vane to realize thermal shock monitoring is preliminarily verified.

The ultra-wide band gap semiconductor material β-phase gallium oxide （β-Ga₂O₃）， with its ultra-wide band gap （4.8~4.9 eV）， high breakdown field strength （8 MV/cm） and excellent Baliga figure of merit （>3 000）， has shown great application potential in high-voltage and high-power fields such as smart grids， new energy vehicles and rail transit. In recent years， the research on β-Ga₂O₃ has made breakthroughs in many technical fields， and its industrialization process is at a critical stage of transition from laboratory research and development to large-scale production. From the perspective of industrialization， this article systematically sorts out and summarizes the development trend of the whole industrial chain of β-Ga₂O₃， and provides an important reference for industry practitioners to accurately grasp the pace of industrialization of β-Ga₂O₃. Firstly， the mainstream technology path in the whole industrial chain of β-Ga₂O₃ is briefly introduced. Subsequently， the current industrial development status of β-Ga₂O₃ is elaborated in detail around the three core links of “single crystal-epitaxy-device”， and the challenges faced by β-Ga₂O₃ in p-type doping， thermal management， reliability verification and cost control are comprehensively analyzed， as well as the efforts of researchers to solve these problems. Finally， the potential applications of β-Ga₂O₃ power devices in the fields of new energy vehicles， photovoltaic inverters， data center power supplies and high voltage direct current transmission are deeply analyzed， and the future market development prospects are forecasted， in order to provide reference for the industrialization and coordinated development of β-Ga₂O₃ related fields.

The surface quality of optical components directly determines their optical performance and service life. Among these factors， the subsurface damage （SSD） layer is a key factor affecting the functionality and reliability of optical components and has become a focal point in their application. This paper takes CaF₂ crystals as the research subject and focuses on the characterization of the subsurface damage layer and its correlation with photothermal weak absorption in the 355 nm wavelength band. By systematically characterizing the thickness of the subsurface damage layer in crystal samples and measuring their photothermal weak absorption rates at 355 nm， the relationship between subsurface damage layer thickness and photothermal weak absorption rate was systematically analyzed. The results indicate that the photothermal weak absorption rate in the 355 nm band is positively correlated with SSD thickness. As the damage layer thickness increase from 51.57 nm to 154.09 nm， the maximum photothermal weak absorption rise from 2.58×10^-6 to 45.16×10^-6， and the average weak absorption increase from 0.43×10^-6 to 7.85×10^-6. This study has elucidated the mechanism by which subsurface damage layers affect the photothermal weak absorption of CaF₂ crystals， providing both experimental evidence and theoretical support for optimizing crystal processing techniques， mitigating losses due to weak absorption， and enhancing the crystals’ laser damage thresholds.

Large-size polycrystalline silicon carbide （SiC） holds significant application prospects in the fields of semiconductor components， but its growth with high quality and large diameter remains challenges. This study employed the physical vapor transport （PVT） method to fabricate polycrystalline silicon carbide with a diameter of about 360 mm （approximately 14 inches， 1 inch=25.4 mm）. A series of characterization techniques were utilized to evaluate grain structure， crystal type， thermal conductivity， electrical resistivity， carrier concentration， and elastic modulus of polycrystalline silicon carbide. The results show that the as-fabricated polycrystalline silicon carbide exhibits a macroscopically crack-free surface and relatively uniform grain size distribution. The material crystal type is identified as 4H-SiC. The average thermal conductivity is approximately 323.8 W/（m·K）， the carrier concentration is on the order of 10¹⁷ cm^-3， and the elastic modulus ranges from 287 GPa to 311 GPa. This study demonstrates that large-size polycrystalline silicon carbide possesses uniform thermal conductivity and structural integrity， which is expected to meet the demand for cost-effective materials required for semiconductor components and other applications.

Gallium oxide （Ga₂O₃） has attracted widespread attention due to its excellent properties such as wide bandgap and high breakdown field strength. However， the application of Ga₂O₃ in power devices is limited by its low intrinsic thermal conductivity and the lack of effective p-type doping. It is heterogeneously integrated with p-type semiconductor materials with high thermal conductivity， which is considered to be one of the effective solutions to solve the problem of Ga₂O₃. Diamond materials have extremely high thermal conductivity and can achieve controlled p-type doping， and it can be used to construct heterojunction devices with n-type Ga₂O₃， by which the shortcomings of Ga₂O₃ are compensated. In order to improve the breakdown characteristics of Ga₂O₃/diamond heterojunction diodes， a groove terminal structure is proposed to introduce a trench terminal structure into Ga₂O₃/diamond heterojunction， in order to increase the breakdown voltage of the device by improving the electric field. Systematic simulations were conducted using Sentaurus TCAD to evaluate the effects of trench width， depth， and filling dielectric on breakdown voltage. The results show that increasing the trench width significantly raises the breakdown voltage from 347.8 V to 1 197.85 V， an increase of 244.4%. A further increase in trench depth enhances the voltage to 1 334.51 V. In terms of filling media， compared with air， silica （SiO₂）， alumina （Al₂O₃） and hafnium dioxide （HfO₂）， SiO₂ has become the optimal medium choice due to its stable electrical characteristics and significant improvement effect on breakdown voltage. This study offers theoretical guidance for the design and optimization of Ga₂O₃/diamond devices.

Doping is an important means to control the NV color center of diamond. In this paper， NiS₂ （S source） and C₃H₆N₆ （N source） with different addition amounts were added to NiMnCo alloy catalyst by temperature gradient method under high temperature and high pressure （temperature 1 281 ℃， pressure 5.6 GPa） to synthesize N-S co-doped diamond single crystal. The optical microscopic analysis of the synthesized samples shows that when the addition amount of NiS₂ （S source） is constant， with the increase of C₃H₆N₆ addition， the color of diamond gradually changes from yellow to yellow-green， and the crystal defects become more. Infrared spectroscopy analysis shows that the increase of C₃H₆N₆ addition will lead to the increase of C-center nitrogen content in diamond samples， and the larger amount of sulfur will promote more nitrogen into diamond. X-ray photoelectron spectroscopy （XPS） shows that both nitrogen and sulfur atoms have successfully entered the diamond lattice. Nitrogen exists in the form of C—N， N＝O and N—N bonds， and sulfur exists in the form of C-S-O， C-SO₂-S-O and C-S sulfides. Raman spectroscopy shows that the increase of C₃H₆N₆ addition will lead to the increase of Raman peak shift of diamond crystal， the increase of internal distortion and the increase of internal stress. Photoluminescence （PL） spectra show that an appropriate amount of nitrogen and sulfur is beneficial for the C-center nitrogen in the diamond lattice to capture the moving holes to form negatively charged NV^-. This study provides a reference for the study of doping regulation of diamond NV color center.

All-inorganic perovskites exhibit superior stability compared with hybrid organic-inorganic perovskites. Nevertheless， the non-radiative electron-hole recombination is prominent in all-inorganic perovskites， which causes substantial energy loss and acts as a critical factor restricting the improvement of their photoelectric conversion efficiency. In this work， first-principles calculations combined with nonadiabatic molecular dynamics were adopted to systematically investigate the effects of Rb doping at the A-site of CsPbBr₃ and Zn doping at the B-site of CsSnBr₃ on non-radiative electron-hole recombination in all-inorganic perovskites.The results reveal that elemental doping induces lattice distortion in adjacent regions， modulates the band gap of the material， and alters the nonadiabatic coupling strength and decoherence time. Specifically， A-site Rb doping in CsPbBr₃ prolongs the carrier recombination time from 71.45 ps to 124.82 ps， while B-site Zn doping in CsSnBr₃ dramatically extends the carrier recombination time from 20.72 ps to 224.39 ps， thereby effectively suppressing non-radiative electron-hole recombination. This study provides theoretical guidance and fundamental basis for breaking through the bottleneck of photoelectric conversion efficiency of all-inorganic perovskite solar cells.

Thermal transport properties of two antiperovskite compounds Sr₃XO （X=Sb， Bi） were systematically investigated using semiclassical Boltzmann transport theory combined with first-principles calculations. The elastic constants and phonon spectra indicate that both Sr₃XO （X=Sb， Bi） compounds exhibit mechanical and dynamical stability， with melting temperatures of 1 062.4 K and 1 030.5 K， respectively， broadening their potential applications under extreme conditions. Sr₃SbO and Sr₃BiO maintain low lattice thermal conductivity （κ_L） at both room and elevated temperatures. At 300 K， the κ_L values of Sr₃SbO and Sr₃BiO are 1.472 and 3.122 W·m^-1·K^-1， respectively， with Sr₃SbO exhibiting a lower κ_L than the classic thermoelectric material PbTe （2.3 W·m^-1·K^-1）. At 700 K， the κ_L values decrease to 0.671 and 1.343 W·m^-1·K^-1 for Sr₃SbO and Sr₃BiO， respectively. Compared with Sr₃BiO， Sr₃SbO exhibits stronger anharmonicity. Additionally， a comparative analysis of heat capacity， phonon group velocity， and phonon lifetime was conducted for both compounds. This study elucidates the microscopic mechanisms underlying the low lattice thermal conductivity in these compounds and provides theoretical insights for the future design of novel functional materials with low thermal conductivity.

In order to reveal the microscopic interface mechanism of Be₂C/WSi₂N₄ heterostructure and its response to external strain， and further to provide theoretical support for the design of novel tunable optoelectronic devices， this paper systematically investigated the electronic structure， optical properties and biaxial strain modulation effects of Be₂C/WSi₂N₄ heterostructure by employing first-principles calculations based on density functional theory. The results indicate that compared with monolayer materials， the Be₂C/WSi₂N₄ heterostructure exhibits a typical type-Ⅱ band alignment， and a built-in electric field pointing from Be₂C to WSi₂N₄ is formed at the interface， which effectively promotes the spatial separation of photogenerated carriers. The calculated results of optical properties demonstrate that the heterostructure possesses a remarkably enhanced light absorption capacity in contrast with monolayer materials， and its maximum absorption coefficient reaches 22.0×10⁵ cm^-1. Within the biaxial strain range from -4% to +4%， the tensile strain reduces the band gap and induces a red shift of the absorption spectrum， while the compressive strain increases the band gap and leads to a blue shift of the absorption spectrum. In addition， the strain exerts a prominent effect on the transition of band gap types. This research offers a theoretical basis for the application of two-dimensional heterostructures represented by Be₂C/WSi₂N₄ in tunable optoelectronic devices.

A cadmium coordination polymer， ｛［Cd（SCND）（2，2'-bpy）（H₂O）］·1.25H₂O｝ _n （CP1）， was synthesized via solvothermal method using 4-sulfo-N-（4-carboxyphenyl）naphthalene-1，8-dicarboximide （H₂SCND） and 2，2'-bipyridine （2，2'-bpy） as ligands. Elemental analysis （EA）， single-crystal X-ray diffraction （SXRD）， infrared spectroscopy （IR）， thermogravimetric analysis （TGA） and powder X-ray diffraction （PXRD） were employed to characterize CP1. Single-crystal X-ray diffraction analysis reveals that CP1 crystallizes in the monoclinic space group P2₁/n with the following unit cell parameters： a=1.066 58（10） nm， b=1.098 37（10） nm， c=2.361 91（3） nm， and β=100.527（10）°. The central cadmium ion is hexacoordinated， forming a distorted octahedral configuration. Among six atoms involved in the coordination， there comprises three oxygen donors （O2， O1#2， O7#1） derived from three separate SCND ligands， two nitrogen atoms （N2， N3） from the 2，2'-bpy ligand， and one oxygen atom （O1W） from a coordinated water molecule. Through the bridging effect of SCND ligands， the Cd（II） ions are connected into 1D cyclic chains. These adjacent chains are further intertwined into a 3D supramolecular architecture through the cooperative action of C—H…O， O—H…O hydrogen bonding and π…π stacking interactions. Hirshfeld surface analysis was performed to evaluate the distribution of interatomic contact contributions on the molecular surface， among which the H…H interaction contributed 30.5% to the molecular surface， ranking first. Additionally， solid-state fluorescent behavior of CP1 was explored. When excited at 378 nm， CP1 shows an intense emission peak centered at 440 nm， highlighting its potential application as a blue-light material.

Cryo-electron tomography （Cryo-ET） enables in situ structural elucidation of flexible biomacromolecules with structural heterogeneity under near-native conditions. However， conventional tomography suffers from issues such as large-scale image shifts and tilting errors， which often lead to reconstruction artifacts. The individual-particle electron tomography （IPET） method achieves significantly improved reconstruction accuracy and reliability by performing iterative alignment on local regions of individual particles. To address the limitation of conventional electron microscopy in accurately resolving the three-dimensional configurations of flexible and structurally heterogeneous nanomaterials， Cryo-ET combined with IPET was employed for structural characterization of nanomaterials in this study. This approach enables in situ three-dimensional characterization under near-native conditions and facilitates comprehensive acquisition of key structural information， including morphology， internal channels， and interfacial interactions. For example， the microstructure of gold nanocages clearly reveals their shell architecture and characterizes the distribution pattern of channel pathways within the shell. The three-dimensional structure of graphene-phospholipid vesicle complexes offers structural insight into the interaction between graphene and the membrane， revealing their binding sites. Structural analysis of nanofibers resolves their multilevel helical architecture and provides structural insight into their self-assembly behavior. The results demonstrate that the combination of Cryo-ET and IPET offers unique advantages for the three-dimensional structural characterization of flexible nanomaterials， and provides a new characterization approach for investigating structure-property relationships and guiding related functional design of nanomaterials. With the advantages of in situ characterization， high resolution， and adaptability to structurally heterogeneous systems， this approach shows broad potential in structural biology and nanomaterials science and may provide important technical support for elucidating disease mechanisms， new drug development， and nanomaterial design.