Linearly Polarized Broadband Emission and Multiwavelength Lasing in Solution‐Processed Quantum Dots

Abstract A miniature laser with linear polarization is a long sought‐after component of photonic integrated circuits. In particular, for multiwavelength polarization lasers, it supports simultaneous access to multiple, widely varying laser wavelengths in a small spatial region, which is of great significance for advancing applications such as optical computing, optical storage, and optical sensing. However, there is a trade‐off between the size of small‐scale lasers and laser performance, and multiwavelength co‐gain of laser media and multicavity micromachining in the process of laser miniaturization remain as significant challenges. Herein, room‐temperature linearly polarized multiwavelength lasers in the visible and near‐infrared wavelength ranges are demonstrated, by fabricating random cavities scattered with silica in an Er‐doped Cs 2 Ag 0.4 Na 0.6 In 0.98 Bi 0.02 Cl 6 double‐perovskite quantum dots gain membrane. By regulating the local symmetry and enabling effective energy transfer in nanocrystals, multiwavelength lasers with ultralow thresholds are achieved at room temperature. The maximum degree of polarization reaches 0.89. With their advantages in terms of miniaturization, ultralow power consumption, and adaptability for integration, these lasers offer a prospective light source for future photonic integrated circuits aimed at high‐capacity optical applications.