Visible upconversion luminescence of Tb3+ ions in Y2O3 nanoparticles induced by a near-infrared femtosecond laser

Transparent glass-ceramic composites embedded with Ln-fluoride nanocrystals are prepared in this work to enhance the upconversion luminescence of Tm3+. The crystalline phases, microstructures, and photoluminescence properties of samples are carefully investigated. KYb3F10 nanocrystals are proved to controllably precipitate in the glass-ceramics via the inducing of Yb3+ when the doping concentration varies from 0.5 to 1.5 mol%. Pure near-infrared upconversion emissions are observed and the emission intensities are enhanced in the glass-ceramics as compared to in the precursor glass due to the incorporation of Tm3+ into the KYb3F10 crystal structures via substitutions for Yb3+. Furthermore, KYb2F7 crystals are also nano-crystallized in the glass-ceramics when the Yb3+ concentration exceeds 2.0 mol%. The upconversion emission intensity of Tm3+ is further enhanced by seven times as Tm3+ enters the lattice sites of pure KYb2F7 nanocrystals. The designed glass ceramics provide efficient gain materials for optical applications in the biological transmission window. Moreover, the controllable nano-crystallization strategy induced by Yb3+ opens a new way for engineering a wide range of functional nanomaterials with effective incorporation of Ln3+ ions into fluoride crystal structures.

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Antireflective and Superhydrophilic Structure on Graphite Written by Femtosecond Laser

Micromachines ◽

10.3390/mi12030236 ◽

2021 ◽

Vol 12 (3) ◽

pp. 236

Author(s):

Rui Lou ◽

Guangying Li ◽

Xu Wang ◽

Wenfu Zhang ◽

Yishan Wang ◽

...

Keyword(s):

Femtosecond Laser ◽

Near Infrared ◽

High Efficiency ◽

Electronic Devices ◽

Sample Surface ◽

Graphite Surface ◽

Hazardous Substances ◽

Functional Surface ◽

Nano Structures ◽

Average Reflectance

Antireflection and superhydrophilicity performance are desirable for improving the properties of electronic devices. Here, we experimentally provide a strategy of femtosecond laser preparation to create micro-nanostructures on the graphite surface in an air environment. The modified graphite surface is covered with abundant micro-nano structures, and its average reflectance is measured to be 2.7% in the ultraviolet, visible and near-infrared regions (250 to 2250 nm). The wettability transformation of the surface from hydrophilicity to superhydrophilicity is realized. Besides, graphene oxide (GO) and graphene are proved to be formed on the sample surface. This micro-nanostructuring method, which demonstrates features of high efficiency, high controllability, and hazardous substances zero discharge, exhibits the application for functional surface.

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Regulating disordered plasmonic nanoparticles into polarization sensitive metasurfaces

Nanophotonics ◽

10.1515/nanoph-2020-0651 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Shulei Li ◽

Mingcheng Panmai ◽

Shaolong Tie ◽

Yi Xu ◽

Jin Xiang ◽

...

Keyword(s):

Femtosecond Laser ◽

Spatial Resolution ◽

Metallic Nanoparticles ◽

Near Infrared ◽

Optical Memory ◽

Laser Pulses ◽

Femtosecond Laser Pulses ◽

Optical Diffraction ◽

Plasmonic Nanoparticles ◽

Direct Laser

Abstract Metasurfaces composed of regularly arranged and deliberately oriented metallic nanoparticles can be employed to manipulate the amplitude, phase and polarization of an incident electromagnetic wave. The metasurfaces operating in the visible to near infrared spectral range rely on the modern fabrication technologies which offer a spatial resolution beyond the optical diffraction limit. Although direct laser writing is an alternative to the fabrication of nanostructures, the achievement of regular nanostructures with deep-subwavelength periods by using this method remains a big challenge. Here, we proposed and demonstrated a novel strategy for regulating disordered plasmonic nanoparticles into nanogratings with deep-subwavelength periods and reshaped nanoparticles by using femtosecond laser pulses. The orientations of the nanogratings depend strongly on the polarization of the femtosecond laser light. Such nanogratings exhibit reflection and polarization control over the reflected light, enabling the realization of polarization sensitive optical memory and color display with high spatial resolution and good chromacity.

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Upconversion Luminescence of Silica–Calcia Nanoparticles Co-doped with Tm3+ and Yb3+ Ions

Materials ◽

10.3390/ma14040937 ◽

2021 ◽

Vol 14 (4) ◽

pp. 937

Author(s):

Katarzyna Halubek-Gluchowska ◽

Damian Szymański ◽

Thi Ngoc Lam Tran ◽

Maurizio Ferrari ◽

Anna Lukowiak

Keyword(s):

Energy Transfer ◽

Near Infrared ◽

Upconversion Luminescence ◽

Sol Gel ◽

Emission Spectra ◽

Transmission Electron ◽

Characteristic Emission ◽

Diffraction Patterns ◽

Size Of Particles ◽

Average Size

Looking for upconverting biocompatible nanoparticles, we have prepared by the sol–gel method, silica–calcia glass nanopowders doped with different concentration of Tm3+ and Yb3+ ions (Tm3+ from 0.15 mol% up to 0.5 mol% and Yb3+ from 1 mol% up to 4 mol%) and characterized their structure, morphology, and optical properties. X-ray diffraction patterns indicated an amorphous phase of the silica-based glass with partial crystallization of samples with a higher content of lanthanides ions. Transmission electron microscopy images showed that the average size of particles decreased with increasing lanthanides content. The upconversion (UC) emission spectra and fluorescence lifetimes were registered under near infrared excitation (980 nm) at room temperature to study the energy transfer between Yb3+ and Tm3+ at various active ions concentrations. Characteristic emission bands of Tm3+ ions in the range of 350 nm to 850 nm were observed. To understand the mechanism of Yb3+–Tm3+ UC energy transfer in the SiO2–CaO powders, the kinetics of luminescence decays were studied.

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