Cadmium chalcogenide nanoplatelets (NPLs) and their heterostructures have been reported to have low gain thresholds and large gain coefficients, showing great potential for lasing applications. However, the further improvement of the optical gain properties of NPLs is hindered by a lack of models that can account for their optical gain characteristics and predict their dependence on the properties (such as lateral size, concentration, and/or optical density). Herein, we report a systematic study of optical gain (OG) in 4-monolayer thick CdSe NPLs by both transient absorption spectroscopy study of colloidal solutions and amplified spontaneous emission (ASE) measurement of thin films. We showed that comparing samples with the same optical density at the excitation, the OG threshold is not dependent of the NPL lateral area, while the saturation gain amplitude is dependent on the NPL lateral area when comparing samples with the same optical density at the excitation wavelength. Both the OG and ASE thresholds increase with the optical density at the excitation wavelength for samples of the same NPL thickness and lateral area. We proposed an OG model for NPLs that can successfully account for the observed lateral area and optical density dependences. The model reveals that OG originates from stimulatedmore »
Stimulated Emission with Evanescent Gain in the Total Internal Reflection Geometry
We demonstrated amplified spontaneous emission (ASE) enabled by evanescent gain at an interface between two adjacent dielectrics. The ASE wave is outcoupled to the high-index medium at the critical angle, enabling observation of spectacular emission rings.
- Award ID(s):
- Publication Date:
- NSF-PAR ID:
- Journal Name:
- CLEO Conference (virtual), May 9 – May 14, 2021, paper JW1A.128
- Sponsoring Org:
- National Science Foundation
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