Recently, researchers from Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, have made progress in electromagnetic (EM) soliton carrying angular momentum (AM). The research team has proposed a method to produce EM solitons with AM induced by the interaction of circularly polarized laser and underdense plasma and revealed that the physical essence is the conversion from spin angular momentum (SAM) to orbital angular momentum (OAM). The corresponding work has been published in Optics Letters on Jan. 15, 2021.

In this work, researchers found that when a circularly polarized (CP) laser is incident into underdense plasma, the conversion of SAM to OAM can be realized inside the plasma, forming EM solitons that carry AM. When the circularly polarized laser enters the plasma, the longitudinal plasma oscillations, which is characterized by the current, plays an irreplaceable role. The EM soliton with AM driven by a circularly polarized laser reveals characteristics such as spatial and broken polarization symmetry and provide a deep insight into laser plasma interactions and AM conversion.

It shows that the conversion of spin to orbital AM can be realized inside the plasma driven by a CP laser. This work provides another insight into laser plasma interaction and AM conversion.

This work was supported by the Key Research Program of Frontier Sciences of CAS, Youth Innovation Promotion Association of the Chinese Academy of Sciences, Strategic Priority Research Program, Shanghai Sailing Program, Shanghai Rising Star Program and National Natural Science Foundation of China.

Fig. 1. (a) Cross sections of electron density distributions at different times and (b) 3D contour surfaces of distribution of electron density. (Image by SIOM) 

Fig. 2. (a)-(d) Distribution of longitudinal electric field at different times and (e) the Fourier transform of the longitudinal electric field. (Image by SIOM)

Article website:
https://www.osapublishing.org/ol/abstract.cfm?uri=ol-46-2-336

Contact:
WU Xiufeng
General Administrative Office
Shanghai Institute of Optics and Fine Mechanics, CAS
Email: xfwu@siom.ac.cn
Web: http://english.siom.cas.cn/