Bicircular Light-induced Space Symmetry Breaking in Topological Insulating States

Periodic modulation of materials by optical drives has led to the discovery of non-equilibrium topological states of matter, such as the Floquet topological insulator. Conventionally, monochromatic and polarized light sources that break time-reversal symmetry while preserving inversion symmetry in matter have achieved materials’ topological phase tuning. A superposition of left and right circularly polarized sources of light with an integer frequency difference is known as bicircular (BC) light. In addition to breaking time-reversal symmetry, BC light facilitates the manipulation of materials’ space symmetries. In this work, we consider a three-dimensional topological insulator subjected to BC light, and we find the Floquet Hamiltonian of the system for a general light incidence direction. We determine the irradiated system’s effective Hamiltonian at high frequencies and characterize the light-induced terms’ space symmetries. Additionally, we analyze the dependence of light-induced effects on the BC light incidence direction, frequency ratio, and amplitude. Finally, our analysis characterizes the set of BC light parameters that facilitate the tuning of the topological insulator into a higher-order topological phase.