Tunable terahertz radiation from arbitrary profile dielectric grating coated with graphene excited by an electron beam

Zhao Tao^a),^b), Zhong Ren-Bin†^a),^b), Hu Min^a),^b), Chen Xiao-Xing^a),^b), Zhang Ping^a),^b), Gong Sen^a),^b), Liu Sheng-Gang^a),^b)

(a) Dispersion curves for the structure of a monolayer graphene suited on the rectangular (the magenta dashed curves) and symmetrical trapezoidal (the blue solid curves) gratings, where b is equal to 0.3. (b) The radiation spectra of rectangular and symmetrical trapezoidal gratings, the peak frequencies correspond to the points A and C .