Coherent random fiber laser emission from CdSe/ZnS quantum dots

Area of Science:

• Materials Science
• Optics and Photonics
• Nanotechnology

Background:

• Random lasers offer unique emission properties but often suffer from high thresholds and poor coherence.
• Colloidal quantum dots (QDs) provide tunable optical gain, making them promising for laser applications.
• Hollow optical fibers offer a versatile platform for integrating gain media and controlling light propagation.

Purpose of the Study:

• To demonstrate coherent random laser emission using CdSe/ZnS colloidal QDs within a hollow optical fiber.
• To investigate the role of silver nanoparticles (Ag NPs) and QD density in achieving random lasing.
• To explore the tunability of the random laser emission characteristics.

Main Methods:

• Combining CdSe/ZnS colloidal QDs with hollow optical fibers.
• Utilizing localized surface plasmon resonance (LSPR) induced by Ag NPs for enhanced lasing.
• Employing high packing-density QD solutions to achieve lasing without Ag NPs.
• Conducting angle-resolved emission measurements to study directional properties.

Main Results:

• Observed well-distinguished discrete spikes indicative of coherent random laser emission from Ag-modified fibers.
• Achieved low-threshold coherent random laser action in hollow optical fibers filled with high-density CdSe/ZnS QDs, even without Ag NPs.
• Identified self-assembled QD clusters acting as both gain media and scattering centers.
• Demonstrated adjustable directional emission by varying pumping methods.

Conclusions:

• Coherent random laser emission is successfully demonstrated using CdSe/ZnS QDs in hollow optical fibers.
• Both Ag NP-enhanced LSPR and high QD density contribute to low-threshold random lasing.
• The developed random laser is facile, inexpensive, and tunable, with broad applications in photonic devices and display imaging.