Extended Surface Bands Enabled Lasing Emission and Wavelength Switch from Sulfur Quantum Dots.

Area of Science:

• Materials Science
• Photonics
• Quantum Dots

Background:

• Lasing wavelength switching from single inorganic gain materials is challenging due to fixed bandgap limitations.
• Current methods rely on band-edge states, restricting tunable emission.
• Achieving surface-gain lasing is hindered by limited gain volume and low efficiency.

Purpose of the Study:

• To realize a lasing wavelength switch from a single inorganic gain material.
• To overcome limitations of surface-gain-enabled lasing.
• To introduce an alternative lasing emission strategy.

Main Methods:

• Introducing extended surface bands onto sulfur quantum dots.
• Utilizing surface gain as an alternative to band-edge emission.
• Integrating with whispering gallery mode microcavities.

Main Results:

• Achieved high photoluminescence quantum yield and narrow emission bandwidth from extended surface bands.
• Demonstrated surface gain-enabled lasing with an ultralow threshold of 8.3 µJ cm⁻².
• Enabled reconfigurable perturbation to surface gain via molecular affinity.

Conclusions:

• Successfully developed a single inorganic gain material-based lasing wavelength switch.
• Extended surface bands in sulfur quantum dots provide sufficient gain volume for stimulated emission.
• The proposed strategy allows for tunable laser emission from a single material.