Low‐Divergence Wave‐Chaotic Microlasers From Fiber‐Hybridized Colloidal Quantum Dots

Abstract Colloidal quantum dot (QD) lasers have attracted intense interest by virtue of their cost‐effective solution‐processibility and broadband spectral tunability. However, the present QD lasers generally exhibit poor directionality and divergence, which hinders their implementations in fiber optics and photonic circuits. Here, a novel kind of QD laser utilizing a fused silica fiber platform is designed and fabricated, which features directional and low‐divergence output in combination with the high Q‐factors. Based on the comprehensive numerical simulation and spectroscopic characterizations, the merits of the laser are attributed to the presence of a new kind of resonance mode termed waveguide‐multiple islands in the QD‐fiber hybrid resonator. The low divergence is well explained by the converging effect of the high‐refractive curved boundary on the outgoing light. Furthermore, the output angle and the far‐field distribution can be modulated on‐demand by breaking the resonance symmetry through adjusting the diameter of constituted fibers. The laser design is general for QD gain media, such that the low‐divergence red, green, and blue coherent emission is obtained. These findings represent significant progress toward the integration application of QD lasers.