Data and figures from: Topological nano-rainbow laser

Multi-wavelength (or multi-frequency) coherent light sources are essential
for diverse applications. Nevertheless, regulating the multiple emission
wavelengths in an ultra-compact scale is challenging. In this work, we
demonstrate a novel topological nano-rainbow laser by exploiting
topological synthetic dimensions in parameter space as a freedom to
manipulate the optical resonances in a photonic crystal gain system. The
system has spectrally isolated and spatially dispersed topological
synthetic modes with near-diffraction-limited mode volumes and
appropriately-designed high quality factors. We achieve high-performance
nano-rainbow lasing with low threshold, broadband spectrum, large
spontaneous emission factor (β), and milliwatt output power,
simultaneously. These emission features are predetermined by the
ultra-small mode volumes and appropriately-designed high quality factors
of the spectrally and spatially isolated topological synthetic modes. This
work enables high-performance, spatially multiplexed multi-wavelength
emission for on-chip photonics, facilitating advances in broadband signal
processing, optical computing, and beyond.