Moiré systems have recently become an important way to explore two-dimensional exotic strongly correlated physics, in which flat bands, generated from twist leading large periodic supercell structures, play a crucial role. Here we propose a valid and feasible scheme for implementing topological flat bands with ultracold atoms trapped in an optical lattice. Instead of introducing a twist, via a spatially dependent Raman coupling between staggered bilayer lattices, we realize a Kekulé supercell with tunable intercell hopping and staggered flux. We demonstrate that the band can be engineered into a quasiflat band with nearly ideal quantum geometry through these tunable parameters. Over a broad parameter range, our system hosts almost ideal flat bands, making it a promising platform for fractional Chern insulator (FCI) states. Performing exact diagonalization on the engineered flat band, we confirm the existence of the FCI state at fractional fillings $\nu =\frac{p}{2p\pm 1}$. Our work provides a practical scheme for engineering flat Chern bands, implementing FCI phase and opening up new possibilities for exploring strongly correlated flat band physics analogous to that in moiré systems using ultracold atoms.

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• Cold gases in optical lattices
• Composite fermions
• Electronic structure
• Flat bands
• Fractional quantum Hall effect
• Quantum simulation
• Topological phase transition
• 2-dimensional systems
• Honeycomb lattice
• Exact diagonalization