基于45°倾斜光纤光栅的线偏振输出掺镱光纤激光器

对工作于1 064nm波段的45°倾斜光纤光栅的偏振依赖损耗特性与工作机理进行了分析.利用紫外曝光法,将周期为1 070nm的常规相位模板旋转33°后,在光敏光纤上写制了45°倾斜光纤光栅,写制的光栅栅区长度为12mm,在1 040~1 085nm范围内偏振依赖损耗值为7dB左右.影响其偏振依赖损耗值的主要原因为相位模板的周期不是最佳值和栅区长度不够.利用写制的45°倾斜光纤光栅作为起偏器件,实现了线偏振输出的掺镱光纤激光器,其激光消光比高于30dB,输出波长为1 065.4nm,3dB线宽为0.08nm,最高输出功率8.7mW,可长时间保持高偏振度稳定工作.     

A New Algorithm for Die-to-Wafer-like Image Mask Inspection in Real Time

The effect of variations in defect printability must be considered in order to correctly evaluate mask defect inspection procedures. Because of nonlinear transfer effects and strong dependence of printability on defect types, it is difficult to define the boundary between real defect and false defect. To overcome this problem we developed a new algorithm for die-to-wafer-like image (D-to-WI) inspection in real time. This inspection method compares the die (wafer image calculated from CAD data) with the wafer-like image (WI) calculated from the mask image detected by the mask inspection system. To precisely calculate WI in real time, we developed a new simulation-based software. Since the phase of a mask inspection image cannot be measured, we introduce some assumptions regarding its phase. Moreover, we introduce some corrections for WI such as adding a DC component and multiplying by a proper value. To calculate the die which realizes the desired image with sufficient accuracy in real time, we also introduce a perturbation approach. We demonstrate numerically the possibility of a new algorithm for D-to-WI inspection. We confirm that this technique of generating WI from a measured mask pattern is well suited for attenuated phase shift masks (PSMs) and Cr binary masks.     

光存储技术中超分辨近场结构研究进展

超分辨近场结构(Super-RENS)是近场光学存储中最具有潜力和应用前景的方案之一。介绍了Super-RENS从基本类型到第三代Super-RENS的发展历程,简述了掩膜材料的研究进展以及Super-RENS在不同记录系统中的应用。展望了它的发展前景。     

Etching mask optimization of InAs/GaSb superlattice mid-wavelength infared 640×512 focal plane array

In this paper we focused on the mask technology of inductively coupled plasma(ICP) etching for the mesa fabrication of infrared focal plane arrays(FPA).By using the SiO_2 mask,the mesa has higher graphics transfer accuracy and creates less micro-ripples in sidewalls.Comparing the IV characterization of detectors by using two different masks,the detector using the SiO_2 hard mask has the R_0A of 9.7×10~6 Ω·cm~2,while the detector using the photoresist mask has the R_0A of3.2 × 10~2 Ω·cm~2 in 77 K.After that we focused on the method of removing the remaining SiO_2 after mesa etching.The dry ICP etching and chemical buffer oxide etcher(BOE) based on HF and NH4 F are used in this part.Detectors using BOE only have closer R_0A to that using the combining method,but it leads to gaps on mesas because of the corrosion on AlSb layer by BOE.We finally choose the combining method and fabricated the 640×512 FPA.The FPA with cutoff wavelength of 4.8 μm has the average R_0A of 6.13 × 10~9 Ω·cm~2 and the average detectivity of 4.51 × 10~9 cm·Hz~(1/2).W~(-1)at 77 K.The FPA has good uniformity with the bad dots rate of 1.21%and the noise equivalent temperature difference(NEDT) of 22.9 mK operating at 77 K.     

Orthogonal wavelets on direct products of cyclic groups

We describe a method for constructing compactly supported orthogonal wavelets on a locally compact Abelian group G which is the weak direct product of a countable set of cyclic groups of pth order. For all integers p, n ≥ 2, we establish necessary and sufficient conditions under which the solutions of the corresponding scaling equations with p ⁿ numerical coefficients generate multiresolution analyses in L ²(G). It is noted that the coefficients of these scaling equations can be calculated from the given values of p ⁿ parameters using the discrete Vilenkin-Chrestenson transform. Besides, we obtain conditions under which a compactly supported solution of the scaling equation in L ²(G) is stable and has a linearly independent system of “integer” shifts. We present several examples illustrating these results.     

Vector refinement equations with infinitely supported masks

In this paper we investigate the L₂-solutions of vector refinement equations with exponentially decaying masks and a general dilation matrix. A vector refinement equation with a general dilation matrix and exponentially decaying masks is of the form

where the vector of functions φ=(φ₁,…,φ_r)^T is in is an exponentially decaying sequence of r×r matrices called refinement mask and M is an s×s integer matrix such that lim_n→∞M^-n=0. Associated with the mask a and dilation matrix M is a linear operator Q_a on given by

The iterative scheme is called vector subdivision scheme or vector cascade algorithm. The purpose of this paper is to provide a necessary and sufficient condition to guarantee the sequence to converge in L₂-norm. As an application, we also characterize biorthogonal multiple refinable functions, which extends some main results in [B. Han, R.Q. Jia, Characterization of Riesz bases of wavelets generated from multiresolution analysis, Appl. Comput. Harmon. Anal., to appear] and [R.Q. Jia, Convergence of vector subdivision schemes and construction of biorthogonal multiple wavelets, Advances in Wavelet (Hong Kong, 1997), Springer, Singapore, 1998, pp. 199–227] to the general setting.     

高精度等晕角测量关键技术研究

等晕角是重要大气光学参数之一,对天文光学站址选择、大气湍流效应自适应光学校正效果评价等有着重要的意义。分析了国内外等晕角测量技术,介绍了等晕角测量的基本原理,设计了三环变迹镜并开展了数值验证,分析并提出了高精度等晕角测量仪的主要技术指标,研制了一套高精度等晕角测量仪,结果表明,该仪器能够满足全天时的等晕角测量。     

基于电感耦合等离子体的InP基半导体材料干法刻蚀的研究

研究了基于电感耦合等离子体(ICP)刻蚀系统的InP基半导体材料的干法刻蚀.采用Cl2/Ar/H:混合刻蚀气体,分别研究了氯气体积分数和ICP功率与刻蚀速率之间的关系,及镍、二氧化硅和二者结合型掩膜版的适用范围.获得有效的刻蚀速率为450～1 200 nm/min,InP对金属镍的选择性刻蚀比值为175～190.掩膜版...     

波前编码双共轭梯度平方稳定解码算法及其 TMS320DM642平台的实现

波前编码是一种新型的光学-数字混合二步成像系统,采用三次光学编码相位板可以得到系统的非对称点扩散函数和相当景深内模糊程度一致的中间图像.本文利用空间域光学成像模型,结合反镜像边界束缚条件以及矩阵的直积分解,提出一种基于双共轭梯度平方稳定算法(Bi-CGSTAB)的图像复原算法实现波前编码系统的数字解码.该算法具有计算量小、计算速度快,几乎没有边界效应等优点.在此基础上结合TMS320DM642平台并行计算的特点,将新的算法重新优化并移植到TMS320DM642平台上.整个平台由图像采集模块、图象显示模块以及外部存储器等模块组成.通过专门设计的光学系统,分别对物距为1m、5m和10m处的物体以及人像进行成像.对中间模糊像的恢复实验结果表明,新的算法在TMS320DM642平台上图像复原速度快,效果好,为波前编码系统的真正便携和实用提供了可能.     

Visualization of the inverse layer-plus-island growth in Fe islands on W(110) substrate

Many experiments have been conducted so far to control the growth mode in heterostructures, but success has only been restricted to strain-controlled growth systems. In this study, using the shadow mask deposition technique, we have changed the growth mode in the Fe/W heterostructures from the layer-plus-island growth mode to island-plus-layer growth mode. From this, we have ignited the competing growth between forming the islands and wetting the first layer, and have directly visualized the island-plus-layer growth by controlling the annealing temperature of the system. This unconventional growth mode may play an important role in studying the hidden boundaries of hetero-interfaces.