Broadband selective excitation of topological bound states in the continuum within two-dimensional supersymmetric photonic lattices

Bound states in the continuum (BICs), which are localized waves within a continuous spectrum of radiating waves, have garnered considerable attention due to their counterintuitive physical properties. However, selectively exciting these bound states from the continuum remains challenging because of their degenerate eigenenergy. In this work, we propose a method to accurately excite high-order topological BICs (TBICs) using supersymmetric (SUSY) structures. By adiabatically transforming the SUSY partner to the original lattice, TBICs can be perfectly excited with simple single-site excitation. We experimentally verify our strategy in photonic waveguides at telecommunication wavelengths, demonstrating efficient excitation and the existence of TBICs across a broadband. Our work highlights the superior capability of SUSY in regulating optical BIC modes, suggesting possibilities for exploring BICs in higher-dimensional lattices.