用于超快激光器碳纳米饱和吸收体的研究进展

碳纳米管及石墨烯饱和吸收体与目前广泛使用的锁模器相比,具有强饱和吸收、超快恢复时间、宽带宽、高光损伤阈值、易制作以及与光纤和纳米器件兼容等优点.对用于超短脉冲激光器的碳纳米管及石墨烯饱和吸收体的制作方法进行综述,针对目前存在的问题,指出了其发展方向.     

Role of graphene in improving catalytic behaviors of AuNPs/MoS2/Gr/Ni-F structure in hydrogen evolution reaction

The efficient production of hydrogen through electrocatalytic decomposition of water has broad prospects in modern energy equipment. However, the catalytic efficiency and durability of hydrogen evolution catalyst are still very deficient, which need to be further explored. Here in this work, we prove that introducing a graphene layer (Gr) between the molybdenum disulfide and nickel foam (Ni-F) substrate can greatly improve the catalytic performance of the hybrid. Owing to the excitation of local surface plasmon resonance (LSPR) of gold nanoparticles (NPs), the electrocatalytic hydrogen releasing activity of the MoS₂/Gr/Ni-F heterostructure is greatly improved. This results in a significant increase in the current density of AuNPs/MoS₂/Gr/Ni-F composite material under light irradiation and in the dark at 0.2 V (versus reversible hydrogen electrode (RHE)), which is much better than in MoS₂/Gr/Ni-F composite materials. The enhancement of hydrogen release can be attributed to the injection of hot electrons into MoS₂/Gr/Ni-F by AuNPs, which will improve the electron density of MoS₂/Gr/Ni-F, promote the reduction of H₂O, and further reduce the activation energy of the electrocatalyst hydrogen evolution reaction (HER). We also prove that the introduction of graphene can improve its stability in acidic catalytic environments. This work provides a new way of designing efficient water splitting system.     

溅射时间对脉冲激光沉积制备β-FeSi2薄膜的影响

本文基于脉冲激光沉积 (PLD)方法及热退火处理方式,利用输出波长为1064 nm的Nd:YAG脉冲激光器在P型Si (100) 衬底上生长了均匀的单相 β-FeSi₂薄膜。采用X 射线衍射(XRD)、扫描电镜(SEM)、原子力显微镜(AFM)分析技术,研究了β-FeSi₂薄膜的结构、组分、结晶质量和表面形貌。结果发现,在其他相同沉积条件下,随着溅射时间的增加,薄膜晶化程度、颗粒大小和形状、表面粗糙度都发生规律性变化,通过分析比较得出,在本实验条件下溅射时间为40 min制备的 β-FeSi₂薄膜结晶质量较好。     

Experimental generation of Kagome lattices using metasurface of integrated convex lens

In this Letter,we fabricate integrated metasurface of encoded dynamic phases and experimentally generate nonconventional Kagome-type lattices of no-second-order phase vortices.The thin metasurface acts analogous to an integration of three conventional optical elements,i.e.,six pinholes located at the vertices of two concentric regular triangles of size ratio 1:2,six transparent discs of different thicknesses to introduce a total phase shift difference of 6π,and a Fourier lens with a focal length in the micro-scale.A Kagome lattice with the required vortex distribution is realized at the"focal"plane of the metasurface under illumination of the plane wave.