论文部分内容阅读
The Pancharatnam–Berry geometric phase has attracted great interest due to the elegant phase control strategy via geometric transformation of optical elements. The commonly used geometric phase is associated with circular polarization states. Here, we show that by exploiting the geometric phase associated with the two elliptical eigen-polarization states in a racemic metallic helix array, exotic features including full range phase modulation for linear polarization states, diverse polarization conversion, and full complex amplitude modulation can be obtained with rotation of the helices. As a proof of concept, several devices for implementing polarization conversion, vortex beam generating, and lateral dual focusing are built with a racemic helix array in the microwave regime. The calculated and experimental results validate our proposals, which can stimulate various advanced metadevices.
其他文献
提出一种可实现大功率输出、重复频率为80 MHz的皮秒锁模振荡器，当抽运功率为22.4 W 时，可实现功率为5.1 W，频谱信噪比大于60 dB，脉冲宽度为23.7 ps 的皮秒脉冲的稳定输出。通过选择合理的半导体可饱和吸收镜(SESAM)参数和合适的腔型，实现SESAM 长期无损伤运转并进行500 h 的实验验证。采用888 nm 激光二极管(LD)端面抽运Nd∶YVO4 晶体的两级功率放大系统将皮秒锁模振荡器的功率提升至44 W。放大系统的光-光转换效率大于25%，输出光具有良好的光斑模式，光束质量因
The hollow core photonic crystal waveguide biosensor is designed and described. The biosensor was tested in experiments for artificial sweetener identification in drinks. The photonic crystal waveguide biosensor has a high sensitivity to the optical prope
用热电二极管探测了热管炉中Ba原子Rydberg态的双光子吸收脉冲信号,对信号的幅度、信号峰值和出现时间与气压、温度、偏压、作用区位置的关系进行了实验观察和理论分析.
研究了CO2激光辐照对PZT-4陶瓷介电性能的影响。在一定的激光辐照功率密度下，PZT-4陶瓷的介电常数下降约5%，介电损耗下降约60%，矫顽场增加。结合拉曼光谱、扫描电子显微镜、X射线衍射以及后退火处理探讨了激光辐照PZT-4陶瓷的改性机理，结果表明，激光辐照后陶瓷介电性能的变化主要与其微结构有关，辐照使得陶瓷产生了较大的张应力，晶格常数变大，B位离子更容易偏离氧八面体中心，氧八面体扭曲，使其电畴活性下降，阻碍了极化翻转，材料性能变“硬”。
In this paper, the Raman spectrum signal de-noising based on stationary wavelet transform is discussed. Haar wavelet is selected to decompose the Raman spectrum signal for several levels based on stationary wavelet transform. The noise mean square {sigma}
对基于变形镜(DM)生成的Airy光束进行了光束特性研究。采用Zernike多项式对立方相位进行分解,建立了由多个Zernike多项式线性组合的相位调谐模型,并对组合中的每一个Zernike多项式引入一个系数。模拟分析了不同Zernike多项式系数对Airy光束结构和光束质量的影响。利用69单元变形镜进行了Airy光束生成实验,测试分析了不同系数组合下的Airy光束强度分布,通过控制Zernike多项式系数实现了Airy光束特性的控制。
针对传统阴影叠栅轮廓术深度测量范围有限的问题,根据阴影叠栅条纹对比度的变化特点,提出了大深度范围内的阴影叠栅轮廓新型测量方法。该方法将光栅置于不同的高度,在物体表面形成叠栅条纹,通过将不同高度范围内的条纹相位测量结果相互融合,实现了大深度范围内的阴影叠栅轮廓测量。分析了光栅处于不同位置时叠栅条纹的相位分布特点,提出了基于重叠区域的相位融合方法和误差补偿方法。通过实验验证了所提出方法的可行性和准确性