Plasmonic vortex lens (PVL) is one of the most representative branches of surface plasmon polaritons (SPPs). The PVL has lots of potential applications in recent years because of the tight focusing and nanoscale confinement of SPPs. Especially, the PVL can convert the right or left circularly polarized light into a sharp focal spot without phase singularity. These features make the PVL can be applied in nanofocusing and circular polarization analyzer. In addition, the PVL can couple the orbital angular momentum (OAM) into the form of various Bessel functions and it was employed to measure the OAM of light. OAM beams have been widely used in a variety of interesting applications, such as quantum information and optical communication. Apparently, the capability of retrieving different OAM modes is essential in OAM-based optical system. In fact, the OAM modes can be mapped to different Bessel functions through reasonably designing the PVL structure and this feature shows potential for retrieving the OAM distribution of light from the intensity patterns of SPPs.

Several researchers in Wuhan National Lab for Optoelectronics, including Prof. Xinliang Zhang, Prof. Jianji Dong, and Dr. Hailong Zhou, etc. have put forward a scheme to retrieve the OAM distribution of light with a PVL. The OAM modes are coupled to the SPPs in the form of various Bessel functions respectively. By decomposing the interference pattern of SPPs into these Bessel functions, we can retrieve the relative amplitude and the relative phase of input OAM modes simultaneously. Our scheme shows advantage in integration and can measure hybrid OAM states by one measurement.

This work has been on-line published in Scientific Reports on 3 June 2016 [1]. Relative work was partially supported by the National Basic Research Program of China (Grant No. 2011CB301704), the Program for New Century Excellent Talents in Ministry of Education of China (Grant No. NCET-11-0168), a Foundation for the Author of National Excellent Doctoral Dissertation of China (Grant No. 201139), the National Natural Science Foundation of China (Grant No. 11174096 and 61475052), Foundation for Innovative Research Groups of the Natural Science Foundation of Hubei Province (Grant No. 2014CFA004). Full text can be viewed by http://dx.doi.org/10.1038/srep27265

1 Zhou, H., Dong, J., Zhang, J. & Zhang, X. Retrieving orbital angular momentum distribution of light with plasmonic vortex lens. Sci. Rep. 6, 27265, doi:10.1038/srep27265 (2016).

Fig. 1. (a) The structure of PVL and the measurement system. (b) Top view of the PVL