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

Area of Science:

• Materials Science
• Optics
• Nanotechnology

Background:

• Miniaturized photonic systems require efficient on-chip microlasers with scalable fabrication and stable single-frequency operation.
• Whispering-gallery-mode (WGM) lasers offer high-quality optical confinement, but achieving ultralow thresholds remains a challenge.

Purpose of the Study:

• To develop efficient room-temperature colloidal nanoplatelet (NPL)-based WGM microlasers.
• To demonstrate stable single-frequency operation using the Vernier effect in NPL-WGM microlasers.

Main Methods:

• Fabrication of CdSe/CdS@Cd1-xZnxS core/buffer-shell@graded-shell nanoplatelets (NPLs).
• Drop-casting NPL dispersion onto silica microspheres to create NPLs-WGM microlasers.
• Utilizing evanescent field coupling and the Vernier effect for enhanced lasing performance.

Main Results:

• Achieved a record-low lasing threshold of 3.26 µJ cm⁻² for colloidal NPLs-WGM microlasers.
• Demonstrated stable single-mode lasing with an ultralow threshold of 3.84 µJ cm⁻² via the Vernier effect.
• Provided experimental and theoretical evidence of NPLs-WGM lasing nature, including mode characteristics and polarization anisotropy.

Conclusions:

• Interface engineering of heterostructured nanomaterials significantly optimizes gain properties for microlaser applications.
• The developed NPL-WGM microlasers represent a promising platform for future miniaturized tunable coherent light sources.