Giant nonlinearity in a superconducting sub-terahertz metamaterial

We report a superconducting sub-THz metamaterial operating in a CW-regime, which exhibits a record-breaking resonant third-order nonlinearity with effective n(2) similar to 10 cm(2)/W. The nonlinear response is caused by the radiation-induced resistive heating, suppressing the superconductivity in the nano-scale constrictions of the structure's meta-molecules. The nonlinearity has a relaxation time of 25 mu s and leads to a substantial change of the amplitude and phase of the transmitted radiation at intensities of only 500 mu W/cm(2). (C) 2016 AIP Publishing LLC.