We report the observation of topological flat-band states in photonic lattices fabricated using femtosecond laser writing. Topological photonic lattices are optical structures that remain insulating in the bulk while supporting robust, unidirectional edge states immune to backscattering. By embedding a flat-band within the topological bandgap, we introduce compact localized modes that can trap light, enhance light-matter interactions, enable diffraction-free transport and crucially interact with topological edge states. Using helical modulation of waveguides in a Lieb lattice, we realize a photonic Floquet topological insulator where both effects coexist. These results reveal a new interplay between topology and flat-band physics, with promising applications in quantum information processing, imaging, lasing, and optical computing.

Bhargava is currently a PhD student in Dr. Miguel Bandres’ Emergent Photonic Phenomena group. Bhargava received her Bachelor’s degree in Communication and Computer Engineering at the LNM Institute of Technology, a Master’s Degree in Photonic Networks Engineering from Aston University, and a Master’s Degree in Optics from the University of Rochester. Her research focuses on the design, simulation, fabrication, and characterization of photonic lattices, encompassing a range of structures from photonic lanterns to topological arrays.