Amplified Spontaneous Emission and Lasing in Colloidal Nanoplatelets

Abstract

Colloidal nanoplatelets (NPLs) have recently emerged as favorable light-emitting materials, which also show great potential as optical gain media due to their remarkable optical properties. In this work, we systematically investigate the optical gain performance of CdSe core and CdSe/CdS core/crown NPLs having different CdS crown size with one- and two-photon absorption pumping. The core/crown NPLs exhibit enhanced gain performance as compared to the core-only NPLs due to increased absorption cross section and the efficient interexciton funneling, which is from the CdS crown to the CdSe core. One- and two-photon absorption pumped amplified spontaneous emission thresholds are found as low as 41 μJ/cm(2) and 4.48 mJ/cm(2), respectively. These thresholds surpass the best reported optical gain performance of the state-of-the-art colloidal nanocrystals (i.e., quantum dots, nanorods, etc.) emitting in the same spectral range as the NPLs. Moreover, gain coefficient of the NPLs is measured as high as 650 cm(-1), which is 4-fold larger than the best reported gain coefficient of the colloidal quantum dots. Finally, we demonstrate a two-photon absorption pumped vertical cavity surface emitting laser of the NPLs with a lasing threshold as low as 2.49 mJ/cm(2). These excellent results are attributed to the superior properties of the NPLs as optical gain media.

Colloidal synthesis and optical properties of type-II CdSe–CdTe and inverted CdTe–CdSe core–wing heteronanoplatelets

“…Both core-shell and core-wing CdSe-CdS heterostructured NPLs were shown to outperform bare CdSe NPLs as lasing and optical gain media and exhibit much superior properties as compared to semiconductor NPs of other dimensionalities. 35,39,40 In this paper we further extend our approach reported earlier 38 on the preparation of type-II CdSe-CdTe core-wing heteronanoplatelets. During the submission of this manuscript we became aware of related work reporting the realization of straight type-II CdSe-CdTe heteronanoplatelets obtained by different protocols.…”

Alloyed Heterostructures of CdSexS1–x Nanoplatelets with Highly Tunable Optical Gain Performance

“…It is also important to note that, although we used highly uniform and rectangularshaped CdSe x S 1−x alloyed core NPLs as seeds, the formation of the CdS crown region was nonuniform in the lateral direction, which is typically observed for the CdSe/CdS core/crown NPLs in literature. 11,15,16 Compared to the CdSe x S 1−x core NPLs, CdSe x S 1−x /CdS core/crown NPLs exhibit substantially improved optical properties along with enhanced stability ( Figure S2). The absorption spectra of CdSe x S 1−x /CdS core/crown NPLs were presented in Figure 2b together with that of CdSe x S 1−x core NPLs for a better comparison.…”

Active photonic devices based on colloidal semiconductor nanocrystals and organometallic halide perovskites

“…Authors also analyzed the influence of a CdS shell grown on the bottom and on the top of the CdSe NP concluding that the shell can reduce ASE threshold down to 6 μJ/cm 2 . In the same way, the grown of a crown (or winds) of CdS shell on the sides of the CdSe core allowed obtaining a reduction of the ASE threshold from 200 to 40 μJ/cm 2 [45].…”

“…Integrate PL grows sublinearly for low excitations fluencies, followed by a superlinear transition before the linear regime of the laser. The emission efficiency of CdSe/CdS NPs coupled to the modes of a VCSEL cavity was also exploited in [45] to demonstrate lasing under two photon pumping with a threshold of 2.49 mJ/cm 2 . The VCSEL was constructed with a periodic stack of SiO 2 and TiO 2 layers.…”