Author Affiliations
Abstract
1 State Key Laboratory of High Field Laser Physics
,
Shanghai Institute of Optics and Fine Mechanics
,
Chinese Academy of Sciences
,
Shanghai 201800
,
China
2 University of Chinese Academy of Sciences
,
Beijing 100049
,
China
3 Collaborative Innovation Center of IFSA
,
Shanghai Jiao Tong University
,
Shanghai 200240
,
China
4 School of Physical Science and Technology
,
ShanghaiTech University, Shanghai 200031
,
China
In this study, we investigate a new simple scheme using a planar undulator (PU) together with a properly dispersed electron beam (
beam) with a large energy spread (
) to enhance the free-electron laser (FEL) gain. For a dispersed
beam in a PU, the resonant condition is satisfied for the center electrons, while the frequency detuning increases for the off-center electrons, inhibiting the growth of the radiation. The PU can act as a filter for selecting the electrons near the beam center to achieve the radiation. Although only the center electrons contribute, the radiation can be enhanced significantly owing to the high-peak current of the beam. Theoretical analysis and simulation results indicate that this method can be used for the improvement of the radiation performance, which has great significance for short-wavelength FEL applications.
free-electron lasers X-rays soft X-rays extreme ultraviolet High Power Laser Science and Engineering
2018, 6(4): 04000e64
通过研究波导两侧缺陷处的折射率对二维光子晶体波导透射光谱的影响,提出一种提高折射率传感器灵敏度的方案。计算结果表明光子透射带上边沿的偏移量与传感区折射率的大小存在一定关系,在相同的折射率变化量下通过改变波导两侧缺陷处圆孔的相关几何参数可极大提高光子透射带上边沿的偏移量,即提高折射率传感器的灵敏度。通过优化设计,传感器的灵敏度由折射率变化区间0.0~1.0 的55 nm/RIU(RIU 表示折射率单元)与1.1~2.0 的36 nm/RIU 分别提高到对应的405 nm/RIU 以及222 nm/RIU。
光学器件 折射率传感器 灵敏度优化 光子晶体波导 光子带隙 时域有限差分法 激光与光电子学进展
2014, 51(5): 052304