Coherent optical vortex generation with multiple topological charges based on a seeded free electron laser

Hao Sun; Xiaofan Wang; Chao Feng; Lingjun Tu; Weijie Fan; Bo Liu

doi:10.1017/hpl.2021.52

Journals >High Power Laser Science and Engineering >Volume 9 >Issue 4 >Page 04000e65 > Article

High Power Laser Science and Engineering
Vol. 9, Issue 4, 04000e65 (2021)

Coherent optical vortex generation with multiple topological charges based on a seeded free electron laser

Hao Sun^1、2, Xiaofan Wang^3、4、*, Chao Feng^5、*, Lingjun Tu^1、2, Weijie Fan^1、2, and Bo Liu^5、*

Author Affiliations

¹Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai201800, China

²University of Chinese Academy of Sciences, Beijing100049, China

³Institute of Advanced Science Facilities, Shenzhen518000, China

⁴Southern University of Science and Technology, College of Science, Shenzhen518055, China

⁵Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai201210, China

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DOI: 10.1017/hpl.2021.52 Cite this Article Set citation alerts

Hao Sun, Xiaofan Wang, Chao Feng, Lingjun Tu, Weijie Fan, Bo Liu. Coherent optical vortex generation with multiple topological charges based on a seeded free electron laser[J]. High Power Laser Science and Engineering, 2021, 9(4): 04000e65 Copy Citation Text

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Abstract

To generate optical vortex with multiple topological charges, a simple scheme based on the phase mask shaping technique is proposed and applied in a seeded free electron laser. With a tailored phase mask, an extreme-ultraviolet (EUV) vortex with multiple topological charges can be produced. To prove the feasibility of this method, an eight-step phase mask is designed to shape the seed laser. The simulation results demonstrate that 100-MW, fully coherent EUV vortex pulses with topological charge 2 can be generated based on the proposed technique. We have also demonstrated the possibility of generating higher topological charges by using a phase mask with more steps.

Keywords

free electron laser high-gain harmonic generation optical vortex phase mask

$$\begin{align} \textrm{Phase}_{\mathrm{mask}}=\left[\kern-4pt\begin{array}{cccc}\frac{3\pi }{2}& \pi & \frac{\pi }{2}& 0\\ {}0& \frac{\pi }{2}& \pi & \frac{3\pi }{2}\end{array}\kern-4pt\right]. \end{align}$$

((1))

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$$\begin{align} \textrm{Phase}_{\mathrm{rad}}=n\cdot \textrm{Phase}_{\mathrm{ebeam}}=n\cdot \left[\kern-4pt\begin{array}{cccc}\frac{3\pi }{2}& \pi & \frac{\pi }{2}& 0\\ {}0& \frac{\pi }{2}& \pi & \frac{3\pi }{2}\end{array}\kern-4pt\right]\operatorname{mod}2\pi,\end{align} $$

((2))

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$$\textrm{Phase}_{\mathrm{rad}}=\begin{bmatrix}0 & 0 & 0 & 0\\0& 0& 0& 0\end{bmatrix}\left(n=4m\right),$$

((3))

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$$\textrm{Phase}_{\mathrm{rad}}=\begin{bmatrix}\pi & 0& \pi & 0\\ {}\pi & 0& \pi & 0\end{bmatrix}\left(n=4m+2\right).$$

((4))

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$$\begin{align}\textrm{Phase}_{\mathrm{rad}}=\left[\kern-4pt\begin{array}{cccc}\frac{3\pi }{2}& \pi & \frac{\pi }{2}& 0\\ {}0& \frac{\pi }{2}& \pi & \frac{3\pi }{2}\end{array}\kern-4pt\right]\left(m:\mathrm{even}\right),\end{align}$$

((5))

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$$\begin{align}\textrm{Phase}_{\mathrm{rad}}=\left[\kern-4pt\begin{array}{cccc}\frac{\pi }{2}& \pi & \frac{3\pi }{2}& 0\\ {}0& \frac{3\pi }{2}& \pi & \frac{\pi }{2}\end{array}\kern-4pt\right]\left(m:\mathrm{odd}\right).\end{align}$$

((6))

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$$\begin{align}{\tilde{E}}^{\prime}\left({x}_1,{y}_1\right)=\tilde{E}\left({x}_1,{y}_1\right)\exp \left[-\frac{ik}{2f}\left({x}_1^2+{y}_1^2\right)\right].\end{align}$$

((7))

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$$\begin{align}E\left(x,y\right)&=\frac{\exp \left({i} kf\right)}{{i}\lambda f}\exp \left[\frac{ik}{2f}\left({x}^2+{y}^2\right)\right] \nonumber\\ & \quad \times \mathrm{\mathcal{F}}\left\{{\tilde{E}}^{\prime}\left({x}_1,{y}_1\right)\exp \left[\frac{ik}{2f}\left({x}_1^2+{y}_1^2\right)\right]\right\}.\end{align}$$

((8))