Ultra‐Dark on‐Chip Plasmonic Lattice Lasers for High‐Density Integrations

ABSTRACT Due to out‐of‐plane diffraction channels or scattering channels of defects, on‐chip micro‐lasers always suffer from severe emission of free‐space photons. This severely hampers not only the development of ultra‐high Q and ultra‐dark on‐chip micro‐lasers but also the high‐density integration with other nanophotonic components. Herein, ultra‐dark on‐chip plasmonic lasers are experimentally realized in high‐quality Ag‐SiO 2 nanodisk lattices. The out‐of‐plane diffraction channel is eliminated by using the first‐order‐feedback mechanism. The losses of the scattering channels are greatly decreased by fabricating high‐quality Ag‐SiO 2 nanodisk lattices. As a result, an “ultra‐dark” plasmonic lattice laser with ultra‐high Q is realized at room temperature. Linewidths of as small as Δ λ FWHM‐T ≈ 0.003 nm at visible wavelengths are deconvolution‐inferred, and the corresponding Q factor is as high as Q ≈ 2.1 × 10 5 , which is approximately 75 times the largest Q factor in previous plasmonic lattice lasers. The in‐plane coupling efficiency of the on‐chip plasmonic lasers is approximately 99%, indicating that there is hardly any emission of free‐space laser photons. The ratio of laser emission in free space (∼1%) is approximately 20 times lower than that (≥20%) reported in previous works. Based on the “ultra‐dark” plasmonic lasers, the high‐density integration of multiple components and functions is demonstrated.