Amplified spontaneous emission and lasing in colloidal nanoplatelets

Area of Science:

• Materials Science
• Optics
• Nanotechnology

Background:

• Colloidal nanoplatelets (NPLs) are promising light-emitting materials.
• Their potential as optical gain media requires systematic investigation.

Purpose of the Study:

• To investigate the optical gain performance of CdSe core and CdSe/CdS core/crown NPLs.
• To compare gain performance under one- and two-photon absorption pumping.
• To evaluate NPLs as advanced optical gain media.

Main Methods:

• Fabrication of CdSe/CdS core/crown NPLs with varying CdS crown sizes.
• Systematic optical gain measurements using one- and two-photon absorption pumping.
• Demonstration of a two-photon absorption pumped vertical cavity surface emitting laser.

Main Results:

• CdSe/CdS core/crown NPLs exhibit enhanced optical gain over core-only NPLs.
• Achieved amplified spontaneous emission thresholds as low as 41 μJ/cm² (one-photon) and 4.48 mJ/cm² (two-photon).
• Measured a gain coefficient up to 650 cm⁻¹, significantly exceeding colloidal quantum dots.
• Demonstrated a vertical cavity surface emitting laser with a low lasing threshold of 2.49 mJ/cm².

Conclusions:

• CdSe/CdS core/crown NPLs possess superior optical gain properties.
• These NPLs outperform state-of-the-art colloidal nanocrystals in optical gain media applications.
• The enhanced performance is attributed to increased absorption cross-section and efficient interexciton funneling.