Ultra‐Compact Topological Photonic Crystal Rainbow Nanolasers Operating in the 1550 nm Telecom Band with Wavelength‐Scale Mode Volumes

Abstract

Abstract Topological rainbow trapping, spatially separating and confining multiple topologically protected light frequencies, offers a prospective scheme for achieving robust multi‐wavelength single‐mode coherent emission within a single nanodevice. Here, ultra‐compact topological photonic crystal rainbow nanolasers operating in the 1550 nm telecom band are experimentally demonstrated. Specifically, rainbow‐like single‐mode emission with a controllable free spectral range and a wavelength‐scale mode volume is presented in a one‐dimensional topological rainbow nanolaser, exhibiting robust rainbow spectral emission across a wide temperature range and a spectral tuning capability of approximately 70 nm. Additionally, an ultra‐compact two‐dimensional topological rainbow nanolaser is demonstrated in an exceptionally small footprint, featuring a broad rainbow spectrum with 64 continuously tuned single‐mode lasing peaks. This work provides a promising approach for realizing robust and nanoscale multi‐wavelength single‐mode coherent emission within a single device, paving the way for numerous potential applications in ultra‐compact high‐throughput data processing systems, including on‐chip wavelength‐division‐multiplexing and optical interconnects.