Ultralow‐Threshold and High‐Quality Whispering‐Gallery‐Mode Lasing from Colloidal Core/Hybrid‐Shell Quantum Wells

Abstract

The realization of efficient on‐chip microlasers with scalable fabrication, ultralow threshold, and stable single‐frequency operation is always desired for a wide range of miniaturized photonic systems. Herein, an effective way to fabricate nanostructures‐ whispering‐gallery‐mode (WGM) lasers by drop‐casting CdSe/CdS@Cd1−xZnxS core/buffer‐shell@graded‐shell nanoplatelets (NPLs) dispersion onto silica microspheres is presented. Benefiting from the excellent gain properties from the interface engineered core/hybrid shell NPLs and high‐quality factor WGM resonator from excellent optical field confinement, the proposed room‐temperature NPLs‐WGM microlasers show a record‐low lasing threshold of 3.26 µJ cm−2 under nanosecond laser pumping among all colloidal NPLs‐based lasing demonstrations. The presence of sharp discrete transverse electric‐ and magnetic‐mode spikes, the inversely proportional dependence of the free spectra range on microsphere sizes and the polarization anisotropy of laser output represent the first direct experimental evidence for NPLs‐WGM lasing nature, which is verified theoretically by the computed electric‐field distribution inside the microcavity. Remarkably, a stable single‐mode lasing output with an ultralow lasing threshold of 3.84 µJ cm−2 is achieved by the Vernier effect through evanescent field coupling. The results highlight the significance of interface engineering on the optimization of gain properties of heterostructured nanomaterials and shed light on developing future miniaturized tunable coherent light sources.

Deterministic Assembly of Colloidal Quantum Dots for Multifunctional Integrated Photonics

“…We anticipate that this challenge can be addressed by introducing coupled cavities with Vernier effect to create single-mode microlasers with a high quality factor. [34,35] Splitting and coalescence of multiple signals are important for integrated photonic logical circuits. We further demonstrate beam splitting and coupling based on branched microwires and microcavities.…”

Magnetic-Field-Driven Reconfigurable Microsphere Arrays for Laser Display Pixels

“…39 The microspheres used for the construction of RMAs could be doped with laser dye molecules to obtain whisperinggallery-mode (WGM) organic microlasers at low threshold. 40 For instance, coumarin-153 (C153, Figure S11) is used as the gain material in the optical cavity of microspheres due to its high optical gain coefficient. The prepared C153-doped microspheres have uniform dye distribution in a whole microsphere and low crystallinity due to the strong π−π interactions between the phenyl groups of the PS matrix and the π-conjugated molecules (Figure S12 and Figure S13).…”

Motor-like microlasers functioning in biological fluids

“…For instance, optical coupling between two lasing motors may result in single-mode lasing via Vernier effect. [38][39][40][41] 4) As an emerging platform, the possibility of moving these swimming micromotors in the air can be explored, at the same time, some difficulties need to be solved. For example, the formation of CLC sphere-shaped droplets is limited to the solution-based environment to maintain its spherical shape.…”

“…For instance, optical coupling between two lasing motors may result in single-mode lasing via the Vernier effect. [38][39][40][41] Fig. 4…”