Direct emission of broadband terahertz cylindrical vector Bessel beam
Xi Feng, Qingwei Wang, Yongchang Lu, Quan Xu, Xueqian Zhang, Li Niu, Xieyu Chen, Quan Li, Jiaguang Han, Weili Zhang
Abstract
As one kind of special beams, a terahertz (THz) cylindrical vector Bessel beam processes centrosymmetric polarization distribution and nondiffractive propagation properties. Such a vector Bessel beam is potential in various practical applications ranging from THz communication and electron acceleration to sensing and imaging. Here, we propose and experimentally demonstrate a method to directly emit a broadband THz cylindrical vector Bessel (CVB) beam using nonlinear effects. By photo-exciting an indium tin oxide film coated axicon with a circularly polarized femtosecond laser pulse, a high-quality CVB beam is obtained in a broadband THz frequency range. The proposed method is universal and low-cost, opening a simple avenue for the emission of broadband THz specialty beams.