Spatio-spectrally tailored multimode metasurface lasers in the visible range

Abstract: Spectrally engineered multifrequency nanolasers are highly desirable for on-chip photonics, multiplexed biosensing, and display technologies; yet, achieving them within a single compact platform remains challenging. Here, we demonstrate multimode lasing from symmetry-broken TiO2 metasurfaces integrated with an SU8 slab waveguide containing Rhodamine 6G. By co-engineering guided-mode resonances, surface lattice resonances near Rayleigh anomalies, and quasi-bound states in the continuum, we realize complementary high-Q feedback pathways that overlap with the gain spectrum. The direction of the lasing emission is tailored through outcoupling via second-order Bragg diffraction and Rayleigh anomaly conditions, supporting both normal and oblique emission. Experiments reveal discrete lasing outputs across ~100 nm bandwidth (548-648 nm), spanning nearly the full Rhodamine 6G emission band, with thresholds as low as ~7 nJ per pulse (35.7 uJ/cm^2) and up to four concurrent lasing peaks from a single device. These results establish a metasurface-dye platform for multifrequency and angle-selective lasing, opening new opportunities for compact, multifunctional nanophotonic sources.