感应耦合等离子休技术用于熔融石英表面凹凸光栅的刻蚀

感应耦合等离子体(ICP)刻蚀技术是一种新的干法刻蚀技术，具有刻蚀速率高和各向异性刻蚀等优点，并且能够独立控制等离子体密度和自偏置电压。然而，在利用这种技术进行刻蚀的过程中，经常会发生聚合物的沉积，从而阻碍了刻蚀过程的继续。我们报道了在熔融石英表面刻蚀光栅时不产生聚合物沉积的技术，给出了优化参数。所制作的熔融石英普通光栅和600线／mm的高密度光栅的表面很干净，没有聚合物沉积。光栅衍射效率的实际测量值和预期的理论值吻合得很好。最后还研究了ICP技术的刻蚀速度．刻蚀均匀性和过程可重复性等参数。     

圆环形达曼光栅

提出了一种新型的衍射位相器件：圆环形达曼光栅，该种器件可以实现等强度分布的吲环衍射场。介绍了该器件的设计方法，给出了数值设计模拟结果，同时也给出了一个5环4阶的圆环形达曼光栅的验证实验。因为光学系统大多是圆形的，圆环形达曼光栅可以很好地和光学系统的圆形孔径匹配，具有广泛的用途。     

双层全息图研制成功

自从德国科学家罗曼于60年代提出计算机全息图以来，计算全息图已成为信息光学最重要的一个学科分支，得到了广泛的应用，极大地促进了信息光学技术的发展。与此相关．最早提山全息概念的盖伯获得了1971年的诺贝尔奖。     

电子散斑归一化互相关法测位移

把粗糙物体表面受到相干光照明时产生的散斑场看作是一个稳态随机信号,在此基础上,本文提出了一种能做到大量程,高精度位移测量的新方法——电子散斑归一化互相关法测位移或称电子散斑照相法测位移.该法实质上是借助数字图像处理技术,通过物体位移前后二个散斑场之间的相关性来进行位移测量方法的发展.文中给出了理论分析和实验系统.实验结果表明,该法有诸如准实时,大量程(毫米级),高精度和线性可靠等优点.     

光计算的发展趋势:模拟或数字？

受益于光子独特的优势,光计算技术在构建高速、高算力和高能效比的专用计算加速器方面被寄予厚望,目前已经涌现出了许多极具吸引力的方案。特别是对于涉及运算量巨大的二维矩阵-矩阵乘加操作的专用场景,光计算有望在算力和能效比等方面实现超越当前最先进电子计算机几个数量级的性能提升。不同于电子计算通过构建逻辑门实现通用数字计算,主要受深度学习驱动而复兴的光计算更倾向于模拟计算。本文从模拟和数字光计算的角度出发对主流的光计算架构进行分析和讨论,指出了目前光计算技术发展面临的瓶颈,并对光计算未来的发展趋势进行了展望。     

光折变晶体中全息相位栅的包迹

联立稳态带传输方各程和波方程,基于Kukhtarev模型和Moharam的场函数,以光强调制度为主要变量,求得了适用于任意干涉光强调制度及光激发效率为任意常数时的光折变晶体中全息相位栅包迹的解析解。在此基础上,分析了非破坏性读出情况罡的衍射效率。     

Laser writing system for fabrication of diffractive optics elements

We report a laser writing system for fabrication of diffractive optical elements with He-Cd laser. The wavelength of the light source is 441.6 nm. The output beam is collimated into parallel light with uniform intensity distribution after passing through the spatial filter with a pinhole of 25μm and the collimating device. A microscopy objective lens with numerical aperture (NA) of 0.65 is used to focus the beam into a small diffraction spot. Any pattern can be written with this system. Experimental results are presented.The written gratings and the phase patterns were verified with a conventional optical microscopy and the Taylor Hobson equipment.     

Narrow-wavelength-spread spectral combining laser with a reflector for a double pass with a single grating

We proposed a novel wavelength-spread compression technique for spectral beam combining of a diode laser array. A reflector, which is parallel to the grating, is introduced to achieve a double pass with a single grating.This facilitated the reduction of the wavelength spread by half and doubled the number of combined elements in the gain range of the diode laser. We achieved a power of 26.1 W under continuous wave operation using a19 element single bar with a wavelength spread of 6.3 nm, which is nearly half of the original wavelength spread of 14.2 nm, demonstrating the double-compressed spectrum capability of this structure. The spectral beam combining efficiency was 63.7%. The grating efficiency and reflector reflectance were both over 95%; hence, the efficiency loss of the double-pass grating with a reflector is acceptable. In contrast to double-grating methods,the proposed method introduces a reflector that efficiently uses the single grating and shows significant potential for a more efficient spectral beam combining of diode laser arrays.     

Optically fixed photorefractive correlator

An optically fixed photorefractive correlator is presented,where two-centre non-volatile holographic recording is employed to write and fix the matched filter in doubly doped LiNbO3 crystals.This correlator shows good correlation characteristics and insensitivity to the writing beam during readout.It can be used in cased requiring stability and not requiring modification for a long period,and it is refreshed optically when new information needs to be registered.     

不等间距达曼型滤波器的飞秒脉冲时空变换整形与识别技术

研究了以不等间距达曼(Dammann)型滤波器为模板的飞秒激光时空变换与识别技术。优化设计出不等间距多脉冲达曼型滤波器,并在高斯光谱分布的模拟中讨论产生的超快时域多脉冲平均度和光谱平面上调制周期重复数的相关性。给出了频率分辨光开关法(FROG)技术识别超快时域两脉冲的实验结果。