1 中国科学院上海光学精密机械研究所信息光学与光电技术实验室, 上海 201800
2 中国科学院大学材料与光电研究中心, 北京 100049
基于严格耦合波分析方法和模拟退火优化算法,设计了一种在正入射条件下具有宽入射波长和角度范围的偏振无关高效率多层倾斜光栅。为了提高衍射效率和带宽范围,提出了一种折射率渐变的四层三明治光栅结构。基于这种结构,设计了一种可见光波长范围内偏振无关异常反射光栅器件。数值结果表明,正入射下,该光栅具有130 nm(550~680 nm)的波长带宽,在此范围内-1级衍射效率均高于93%,同时偏振相关损耗均小于0.2 dB。此外,这种光栅结构还具有47°(-2°~45°)的入射角度带宽,以及较大的制造容差范围。因此,本文提出的这种多层斜光栅在虚拟现实和增强现实显示系统、基于超表面的器件,特别是可见光波段的超透镜等方面具有潜在的应用价值。
光栅 倾斜光栅 异常反射 偏振无关 正入射 宽带 光学学报
2020, 40(14): 1405001
Author Affiliations
Abstract
1 Laboratory of Information Optics and Optoelectronic Technology, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
2 Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
An encapsulated metal-dielectric reflective grating is presented for broadband polarization-independent two-port beam splitting under normal incidence at the central wavelength of 800 nm. Different from traditional two-port grating splitters in the resonant region, this grating splitter is capable of separating light energy into ±1st orders with high efficiency in a broad waveband for both TE and TM polarizations. A unified method is proposed here for designing this grating splitter, which enables one to choose a grating structure quickly to realize an ultrabroad working waveband. The simulation results indicate that a bandwidth of 46.4 nm could be achieved for diffraction efficiency (defined as the ratio of the light energy diffracted only at the first order to the incident light energy) over 46% at the central wavelength of 800 nm. Moreover, the parameters of the grating structure can be flexibly adjusted with wavelengths using the unified method for various other applications, such as augmented reality, optical interconnections for computing, coherent beam combination, and complex vector beam shaping.
diffractive optics resonant grating polarization independence unified design method Chinese Optics Letters
2020, 18(7): 070501
1 中国科学院上海光学精密机械研究所信息光学与光电技术实验室, 上海 201800
2 中国科学院大学材料与光电研究中心, 北京 100049
3 暨南大学光子技术研究院, 广东 广州 511443
二维光栅是光刻机光栅尺系统的核心元件。搭建了超精密激光直写系统,基于二维超精密工件台,通过旋转基片90°进行两次曝光,制作出栅线密度为1200 line/mm的二维光栅掩模。原子力显微镜和扫描电镜结果表明,所制作的掩模轮廓清晰,空间分布均匀。实验结果证明了超精密激光直写系统能够制作出二维光栅掩模,在制作大尺寸、高精度二维计量光栅方面有着广阔的应用前景。
光栅 超精密系统 激光直写 栅距测量
1 上海大学机电工程与自动化学院, 上海 200072
2 中国科学院上海光学精密机械研究所信息光学与光电技术实验室, 上海 201800
3 中国科学院大学, 北京 100049
衍射光栅在各行各业有着广泛的应用, 这就要求光栅必须具有良好的质量。在制作大尺寸光栅的各种方法中, 激光直写技术具有明显优势, 采用并行激光直写技术制作出了尺寸为100 mm×100 mm、线数为1780 line/mm的正弦形光栅。首先对光栅进行理论分析, 找出正弦形光栅在效率最高时的槽深;然后用激光直写技术制作光栅, 最后在光栅表面镀上一层金膜。测量了光栅的衍射效率, 并预估光栅的均匀性。结果表明：光栅的衍射效率约为90%, 与理论值接近, 而且分布很均匀, 证明了并行激光直写技术制作高质量、大尺寸光栅的可行性。
光栅 镀金光栅 测量 激光直写 衍射效率
Author Affiliations
Abstract
1 Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, China
2 University of Chinese Academy of Sciences, Beijing 100049, China
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 a 19 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.
140.2010 Diode laser arrays 140.3290 Laser arrays 140.3298 Laser beam combining Chinese Optics Letters
2018, 16(7): 071402
