The study investigates the unique electronic properties of topological insulators (TIs) by observing Floquet-Bloch states on their surfaces. Using time- and angle-resolved photoemission spectroscopy, the researchers demonstrate that intense mid-infrared (MIR) pulses with energies below the bulk band gap hybridize with the surface Dirac fermions of a TI, forming Floquet-Bloch bands. These bands exhibit polarization-dependent band gaps at avoided crossings, with circularly polarized photons inducing an additional gap at the Dirac point, indicating broken time-reversal symmetry. The observations establish the Floquet-Bloch bands in solids and pave the way for optical manipulation of topological quantum states. The results are consistent with Floquet theory and suggest the existence of a photoinduced anomalous quantum Hall phase without Landau levels, potentially enabling the realization of Floquet Majorana modes in these materials.The study investigates the unique electronic properties of topological insulators (TIs) by observing Floquet-Bloch states on their surfaces. Using time- and angle-resolved photoemission spectroscopy, the researchers demonstrate that intense mid-infrared (MIR) pulses with energies below the bulk band gap hybridize with the surface Dirac fermions of a TI, forming Floquet-Bloch bands. These bands exhibit polarization-dependent band gaps at avoided crossings, with circularly polarized photons inducing an additional gap at the Dirac point, indicating broken time-reversal symmetry. The observations establish the Floquet-Bloch bands in solids and pave the way for optical manipulation of topological quantum states. The results are consistent with Floquet theory and suggest the existence of a photoinduced anomalous quantum Hall phase without Landau levels, potentially enabling the realization of Floquet Majorana modes in these materials.