Fig. 1. The unit structure and THz wave generation diagram of L shape metamaterial

Fig. 2. The linear and nonlinear optical responses of monolayer L shape metamaterial

Fig. 3. Linear optical response of L shaped metamaterial covered with the same direction SRRs and the reverse direction SRRs

Fig. 4. THz waves generated by different metamaterials and polarization angle dependence

Fig. 5. The THz amplitudes as a function of the geometric size of metamaterials and the pulse width of the femtosecond pulse light