Abstract Nonlinear responses of superconductors to intense terahertz radiation has been an active research frontier. Using pump-terahertz probe spectroscopy, we investigate the c-axis nonlinear optical response a high-temperature superconducting cuprate. After excitation by single-cycle pump pulse, reflectivity pulse oscillates as pump-probe delay is varied. Interestingly, oscillatory central f...

In this paper, frequency-domain analysis based on frequency sweep method is presented for a nonlinear double integrator and a new linear integrator. All the two types of integrators can estimate the onefold and double integrals of a signal synchronously. With respect to the linear double integrator, the nonlinear integrator has better estimation performance and stronger robustness. Importantly,...

In this paper, a new method for evaluating output frequency responses of nonlinear systems under multiple inputs, defined as a sum of sinusoids of different frequencies, is developed. The method circumvents difficulties associated with the existing “frequency-mix vector” based approaches and can easily be applied to investigate nonlinear behaviors of practical systems, including electronic circ...