Silicon Nanosheets: An Emerging 2D Photonic Material with a Large Transient Nonlinear Optical Response beyond Graphene

The present work reports on the transient nonlinear optical (NLO) responses of two different types of 2D silicon nanosheets (SiNSs), namely hydride-terminated silicon nanosheets (SiNS–H) and 1-dodecene-functionalized silicon nanosheets (SiNS–dodecene). The main motivation of this study was to extend the knowledge regarding the NLO properties of these Si–based materials, for which very few published studies exist so far. For that purpose, the NLO responses of SiNS–H and SiNS–dodecene were investigated experimentally in the nanosecond regime at 532 and 1064 nm using the Z-scan technique, while the obtained results were compared to those of certain recently studied graphene nanosheets. SiNS–dodecene was found to exhibit the largest third-order susceptibility χ(3) values at both excitation wavelengths, most probably ascribed to the presence of point defects, indicating the importance of chemical functionalization for the efficient enhancement and tailoring of the NLO properties of these emerging 2D Si-based materials. Most importantly, the results demonstrated that the present silicon nanosheets revealed comparable and even larger NLO responses than graphene nanosheets. Undoubtedly, SiNSs could be strong competitors of graphene for applications in 2D-material-based photonics and optoelectronics.

A Fluorescence Study on the Extracts of Red Dragon Fruit Peel in Various Solvents

Special attention has been given to red dragon fruit (Hylocereus polyrhizus) because of its unique natural compounds exhibiting wide biological activities. However, the potential use of the red dragon fruit peel has been less addressed. In the present work, simple extraction of red dragon fruit peel was carried out to study the fluorescence properties of the corresponding extracts in various solvents. The red dragon fruit peel was first separated, dried, and macerated for 24 hours using distilled water, ethanol, and acetone, separately. The results demonstrated that the peel extracts exhibited different photoluminescence properties depending on the solvent type. It was revealed that the ethanolic extract gave the highest fluorescence intensity among the other extracts. The ethanolic extract showed two excitation peaks at 290 and 359 nm, yielding different emission properties. Excitation at 290 nm gave one emission peak at 339 nm, while the excitation at 359 nm gave an emission peak at 436 nm. Such strong photoluminescence properties observed in the wide range of UV and visible regions demonstrated the potential use of the red dragon fruit peel as a photonic material. Spectroscopy study also proposed that the ethanolic extract would have polyphenol and chlorogenic acid as the main compounds.

Low-temperature synthesis of carbon nanocages saturable absorber for pulsed erbium-doped fiber laser generation

Exploring a new photonic material with low preparation cost, good optical stability and nonlinearity at the near-infrared waveband is important for ultrafast optical science and device. Here, with a relatively...