▎ 摘　　要

We present a nonperturbative quasiclassical theory of graphene photoconductivity. We consider the influence of low-frequency (microwave, terahertz, midinfrared) radiation on the static conductivity of a uniform graphene layer and calculate its photoconductivity as a function of the frequency, polarization, and strength of the external ac electric field, as well as on the material properties (electron density, scattering time) and temperature. The theory is valid at frequencies (h) over bar omega less than or similar to 2E(F) and at arbitrarily strong ac electric fields. We compare our results with those of the third-order perturbation theory and determine the applicability range of the perturbative solutions.