Using the Floquet Hamiltonian derived based on the time-dependent perturbation theory. we investigated the quasienergy bands of a one-dimensional time-Floquet photonic crystal (PC). The PC contains two alternating layers with different permittivies in the static case which are labeled as A and B. The permittivity of layer A is modulated periodically in time. https://www.perfumetank.com/product-category/kids-apparel/