Broadband spectral shaping in a Ti:sapphire regenerative amplifier

A birefringent crystal quartz plate of known thickness has been used as a spectral filter for spectral shaping in a Ti:sapphire regenerative amplifier. The spectral profile of the amplified pulse ejected from the regenerative amplifier was observed while adjusting the birefringent crystal plate in the cavity. By altering the gain spectrum, the bandwidth of the regeneratively amplified pulse was increased from 18 to 35 nm by using a 0.34-mm thick birefringent plate. The output pulse spectrum from the regenerative amplifier neared the bandwidth of the seed pulse. As a comparison, we used a coated filter outside the regenerative amplifier cavity, and the bandwidth of the regeneratively amplified pulse was stretched to 28 nm. When the bandwidth was stretched to 35 nm, the pulse was compressed to 35 fs.     

From borophosphate to fluoroborophosphate: a rational design of fluorine-induced birefringence enhancement

The introduction of oxofluoride anion into anionic group assists to tune optical properties owing to the change of coordination,electronegativity,and according anionic framework.Here,we proposed a rational design of new compounds by fluorine-driven structure and optical property evolution.A new borophosphate Ba_2BP_3O_(11)with the monoclinic space group P2_1/c has been synthesized in the sealed system.Ba_2BP_3O_(11)exhibits a rare P–O–P bridge formation,which is the first example in alkaline-earth metal borophosphates.By further substituting[BO_4]~(3-)with[BO_3F]~(4-),the first alkaline-earth metal/lead fluoroborophosphates M_2BP_2O_8F (M=Ba and Pb) with the same space group were designed.Since the scissors effect of fluorine,in M_2BP_2O_8F (M=Ba and Pb),a BO_3F tetrahedron corner-sharing with three PO_4tetrahedra forms 1D chains along the b-axial direction,which are filled by MO_n(M=Ba/Pb,n=5,6,8) distorted polyhedra.The first principles calculation shows that the borophosphate Ba_2BP_3O_(11)has a birefringence about 0.013@1,064 nm,while the fluoroborophosphates M_2BP_2O_8F (M=Ba and Pb) have the values of 0.035 and 0.043@1,064 nm,respectively.Such an apparent enhancement in birefringence is derived from synergies of the oxyfluoride and cation.The introduction of fluorine-containing heteroanionic groups provides a feasible strategy to design novel promising optical materials.     

Synthesis,Structure, and Properties of Nonlinear Optical Crystal Na2SiF6

Nonlinear optical crystals of fluosilicate Na₂SiF₆ are synthesized via hydrothermal method and its structure is determined by single‐crystal X‐ray diffraction (XRD). The space group of Na₂SiF₆ is P321 with cell parameters a = 8.8715(3) Å, c = 5.0484(5) Å, Z = 3, V = 344.09(4) ų. The properties of the crystal are measured by powder XRD, infrared (IR) spectroscopy, ultraviolet/visible (UV/Vis) near‐infrared (NIR) diffuse reflectance spectroscopy, thermogravimetric (TG), and differential scanning calorimetry (DSC) analysis. The bandgap calculated using CASTEP is 7.41 eV, indicating that the cut‐off edge of the Na₂SiF₆ crystal can be down to deep‐UV energy region. The first‐principles studies were performed to elucidate the structure/property relationship of Na₂SiF₆.     

含磷/氮/硫环交联磷腈微纳米管的合成及对环氧树脂的阻燃作用

采用原位模板法,以六氯环三磷腈(HCCP)和二羟基二苯砜(BPS)为原料合成了一种环状交联型不溶不熔的磷腈大分子——聚环三磷腈-二羟基二苯砜(PZS)微纳米管,研究了PZS对环氧树脂(EP)的阻燃作用及阻燃机理.利用红外光谱(FTIR)、扫描电子显微镜(SEM)及透射电子显微镜(TEM)对PZS微纳米管进行了表征;采用热重分析(TG)考察了EP/PZS阻燃材料的热稳定性,并通过极限氧指数(LOI)和微型量热分析(MCC)测试了EP/PZS的阻燃性能.热降解实验结果表明,PZS微纳米管的加入使环氧树脂热降解温度降低,但残炭率显著提高.PZS微纳米管可以显著提高环氧树脂的阻燃性能,当阻燃剂添加量为5%时,环氧树脂的残炭率提高了46%,热释放速率峰值降低了约40%;LOI值从纯环氧树脂的26.0%提高到了30.6%.PZS微纳米管的加入还增强了环氧树脂的力学强度.阻燃性能的显著提高和力学性能的改善归因于PZS微纳米管在环氧树脂基体中的良好分散,以及燃烧炭化过程中生成的石墨化程度较高的类石墨烯结构的残炭,具有较高的抗氧化能力.研究结果表明,PZS微纳米管是一种优良、高效的具有潜在应用价值的阻燃剂.     

Beam quality improvement and focused peak intensity measurement of an intense femtosecond Ti:sapphire laser system

Micro-lens arrays were adopted to homogenize the beam profile of 532-nm pumping laser for the main amplifier of an intense femtosecond, chirped pulse amplification (CPA) Ti:sapphire laser. Experimental measurements showed a great improvement of the near-field pattern of the CPA beam after the main amplifier and the size of the focal spot was improved from 2.7 times diffraction limitation (DL) to 1.6 DL.The spot size focused by an f/4 off-axis parabola (OAP) in the target chamber was measured to be 5.8μm (full-width at half-maximum (FWHM)), and a peak intensity of 2.6 × 1020 W/cm2 was obtained at the output power of 120 TW. Peak intensity exceeding 1021 W/cm2 or even 1022 W/cm2 can be expected with smaller f-number focusing configuration and wavefront correction.     

多方位做好实验辅助提升教学质量

以实验技术人员的视角,从不同实验环节出发,全面总结实验辅助工作,并提炼为实验辅助大三部曲和小三部曲。该方面的工作体系源于实验室开设的"化学生物学综合实验",反哺了实验室多门实验课程,取得了良好的效果,促进了实验教学质量的提升,同时也为环境育人创造了有利的条件。     

BSA‐IrO2: Catalase‐like Nanoparticles with High Photothermal Conversion Efficiency and a High X‐ray Absorption Coefficient for Anti‐inflammation and Antitumor Theranostics

Intrinsically integrating precise diagnosis, effective therapy, and self‐anti‐inflammatory action into a single nanoparticle is attractive for tumor treatment and future clinical application, but still remains a great challenge. In this study, bovine serum albumin–iridium oxide nanoparticles (BSA‐IrO₂ NPs) with extraordinary photothermal conversion efficiency, good photocatalytic activity, and a high X‐ray absorption coefficient were prepared through one‐step biomineralization. The nanoparticles allow tumor phototherapy and simultaneous photoacoustic/thermal imaging and computed tomography. More importantly, BSA‐IrO₂ NPs can also act as a catalase to protect normal cells against H₂O₂‐induced reactive oxygen pressure and inflammation while significantly enhancing photoacoustic imaging through microbubble‐based inertial cavitation. These remarkable features may open up the exploration iridium‐based nanomaterials in theranostics.     

超短脉冲激光再生与多程放大器的理论分析与实验建立Ⅰ.理论部分

从半经典理论的麦克斯韦－布洛赫方程出发,对种子激光脉冲在再生和多程放大器中的放大过程进行了分析,结合实际的物理条件得出了放大器的峰值输出的解析表达式。     

Anisotropic partial differential equation noise-reduction algorithm based on fringe feature for ESPI

Noise reduction is one of the most exciting problems in electronic speckle pattern interferometry. We present a new anisotropic partial differential equation noise-reduction algorithm based on fringe orientation for interferometric fringe patterns. The proposed equation performs diffusion along the two directions of fringe gradient and isophote line, which are extracted accurately according to fringe feature. By restriction of diffusion in the gradient direction of fringe patterns, this method can provide optimal results in denoising but does not destroy fringe edges. The experimental results show that this technique is more capable of significantly improving the quality of the fringe patterns than the classical anisotropic diffusion equation proposed by Perona and Malik. Based on our filtered fringe patterns, the phase map obtained by phase-shifting technique can be extracted more accurately. It is an effective pre-processing method for electronic speckle pattern interferometry.     

彩色负片印片颗粒指数的准确测定

分析了彩色负片印片颗粒指数σper实际测试中不同性能负片的测试特点和影响因素。印片颗粒指数的测试点应根据彩色负片的感光特性确定,为正常扩印时对应正片0．74中灰密度的负片密度点。影响印片颗粒指数值的两个主要因素是彩色相纸的反差修正系数α和彩色负片的覆盖力系数ECP;建立了α和ECP的实验求取方法,并通过对几种负片参量的实际测定,分析和说明了参量变化对印片颗粒指数数值的影响程度和应进行的修正。