Tuning the Nonlinear Response of Coupled Split-Ring Resonators
  We introduce the concept of controlling the nonlinear response of the metamaterial by altering its internal structure. We experimentally demonstrate tuning of the nonlinear response of two coupled split-ring resonators by changing their mutual position. This effect is achieved through modification of the structure of the coupled resonant modes, and their interaction with the incident field. By offsetting the resonators we control the maximum currents through the nonlinear driving elements, which affects the nonlinear response of the system. 
Kirsty E. Hannam, David A. Powell, Ilya V. Shadrivov and Yuri S.   Kivshar
physics.optics