结构光束的制备(特邀)

结构光束是指在空间和时间上“定制”的光场,其振幅、相位和偏振态在空间和时间上有着特殊的分布。近些年,结构光束的研究发展迅速,光学参量的特殊分布从特定的空间横向结构、纵向结构,发展到定制的时空结构。这种具有不同时空结构的光束为众多领域带来了突破,包括光学通信、光学传感、光学微操作、量子信息处理和超分辨率成像。因此,人们提出了许多方法,并制造了相关器件,通过调整光束的各种光学参量在空间域和时空域的分布来生成结构化光束。本文主要介绍不同类型结构光束(包括空间结构光束以及时空结构光束)的制备方法,对已产生的结构光束进行了总结,并进一步讨论和展望了结构光束在未来的发展方向。

光束轨道角动量谱的测量技术研究进展(特邀)

自Allen等证明具有螺旋相位波面的激光束携带有轨道角动量以来,对光束轨道角动量调控技术的研究取得了跨越式的发展,获得了包括相位涡旋光束、矢量涡旋光束、激光束阵列等多种新型结构光场,在超大容量光通信、遥感探测、激光加工、高分辨率成像等领域展现出广阔的应用前景。准确测量光束的轨道角动量是其应用的重要基础,早期人们更多地关注对待测光束所包含的轨道角动量成分分布的测量,后来逐步拓展至对各个轨道角动量成分的强度比重即轨道角动量谱的测量。文中系统地回顾并总结近年来光束轨道角动量谱测量技术的发展,主要介绍了包括基于衍射、模式分束等方法的新型光束轨道角动量谱测量技术。

新型高性能红外二氧化碳传感器

介绍了红外二氧化碳传感机理,提出了一种新型空间双光束测量结构,并基于RBF神经网络建立了传感器数学模型。为了提高传感器动态特性,设计了动态补偿滤波器,研制成功一种新型高性能传感器。实验结果表明,上述技术有效地提高了传感器的精度、实时性及可靠性。

Solution of an Inverse Eigenvalue Problem by Newton＇s Method on a Fibre Bundle with Structure Group SO（n）

We present a differential geometric perspective of the IEP for symmetric matrices in the framework of a fibre bundle with structure group SO（n）. In particular, a Newton type algorithm is developed to construct a non singular symmetric matrix for given target eigenvalues using a singular symmetric matrix as the initial matrix for the iteration. Explicit computations are performed for 2 x 2 non singular symmetric matrix to illustrate the result.

Artificial Chiral Nanostructure at Oblique Incidence

We propose in this paper the design of artificial nanostructure chirality obtained by oblique illumination. This structure is based on anisotropic metamaterial having an optical activity induced by the special geometry of the pattern and the incident beam. Starting from a non-chiral material, the artificial chirality is obtained thanks to the rectangular apertures which form the periodic perfect metal nanostructure （one layer） and the oblique incidence of the light beam. An extraordinary light transmission （93%） through the metal nanostructure is achieved by exciting the cavity modes. The extrinsic chirality obtained can be granted to the desired value by appropriately adjusting the geometric parameters and the angle of incidence.

A Study on the Wing Characteristics of Flies

This paper is concerned with the aerodynamic functions of fly wings. The free and tethered flight analyses were performed by using a digital high-speed video camera system. A liquid droplet impacting with a wing surface of fly was conducted to examine the wing characteristics. Microscopic observation of fly＇s wings were also conducted by using a laser beam microscope. The results of a series of observation and measurement revealed the flight characteristics of flies, such as the wing tip velocity, wing path, wing flexibility, wing structure, resistance to rain drops, and so forth.

Study of metamorphic InGaAs/GaAs quantum well laser materials grown on GaAs substrate by molecular beam epitaxy

The GaAs based InGaAs metamorphic structures and their growth by molecular beam epitaxy (MBE) are investigated. The controlling of the source temperature is improved to realize the linearly graded InGaAs metamorphic structure precisely. The threading dislocations are reduced. We also optimize the growth and annealing parameters of the InGaAs quantum well (QW). The 1.3-μm GaAs based metamorphic InGaAs QW is completed. A 1.3-μm GaAs based metamorphic laser is reported.

Numerical study on explosion-induced fractures of reinforced concrete structure by beam-particle model

In the field of disaster prevention mitigation and protection engineering,it is important to identify the mechanical behaviors of reinforced concrete(RC)under explosive load by simulation.A three dimensional beam-particle model(BPM),which is suitable to simulate the fracture process of RC under explosive load,has been developed in the frame of discrete element method (DEM).In this model,only the elastic deformations of beams between concrete particles were considered.The matrix displacement method(MDM)was employed to describe the relationship between the deformation and forces of the beam.A fracture criterion expressed by stress was suggested to identify the state of the beam.A BPM for steel bar,which can simulate the deformation of steel bar under high loading rate,was also developed based on the Cowper-Symonds theory.A program has been coded using C++language.Experiments of RC slab under explosive load were carried out using the program.Good agreement was achieved between the experimental and simulated results.It is indicated that the proposed theoretical model can well simulate the fracture characteristics of RC slab under explosive load such as blasting pit formation,cracks extension, spallation formation,etc.

Design and analysis of spectral beam combining system for fiber lasers based on a concave grating

A novel fiber laser spectral beam combining scheme based on a concave grating is presented.The principle of the presented system is analyzed,and a concave grating with blazed structure for spectral beam combining is designed.The combining potential of the system is analyzed,and the results show that 39 Yb-doped fiber laser can be spectrally beam combined via the designed system.By using scalar diffraction theory,the combining effect of the system is analyzed.The results show that the diffraction efficiency of the designed concave grating is higher than 72% over the whole gain bandwidth,and the combining efficiency is 73.4%.With output power of 1 kW for individual fiber laser,combined power of 28.6 kW can be achieved.