Ultra-secure optical encryption based on tightly focused perfect optical vortex beams
Yang Qingshuai,
Xie Zijian,
Zhang Mengrui,
Ouyang Xu,
Xu Yi,
Cao Yaoyu,
Wang Sicong,
Zhu Linwei,
Li Xiangping
Affiliations
Yang Qingshuai
Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou, 510632, China
Xie Zijian
Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou, 510632, China
Zhang Mengrui
Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou, 510632, China
Ouyang Xu
Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou, 510632, China
Xu Yi
Department of Electronic Engineering, College of Information Science and Technology, Jinan University, Guangzhou, 510632, China
Cao Yaoyu
Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou, 510632, China
Wang Sicong
Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou, 510632, China
Zhu Linwei
School of Physics and Optoelectronic Engineering, Ludong University, Yantai, 264025, China
Li Xiangping
Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou, 510632, China
Light’s orbital angular momentum (OAM) with inherent mode orthogonality has been suggested as a new way to the optical encryption. However, the dependence of annular intensity profiles on the topological charge complicates nanoscale light–matter interactions and hampers the ultra-secure encryption application. In this paper, we demonstrate ultra-secure image encryption by tightly focusing perfect optical vortex (POV) beams with controllable annular intensity profiles and OAM states. A simple scheme composed of single spatial light modulator to implement Fourier transform of an ideal Bessel mode with both amplitude and phase modulations is proposed to generate radius-controllable POV in tightly focused beams. Such focused POV beams with identical intensity profiles but varied local OAM density are applied to disorder-coupled gold nanorod aggregates to selectively excite electromagnetic hot spots for encoding information through photothermal deformation. As such, ultra-secure image encryption in OAM states of POV beams in combination with different polarizations can be achieved. Our results lay the ground for diverse nanophotonic applications harnessing the OAM division of POV beams.
