The fabrication and spectroscopic characterization of Ho³⁺ and Yb³⁺ co-doped phosphate glasses, also containing silver nanoparticles (SNPs), is reported. The nucleation and formation of nanoparticle structures in the samples are confirmed using transmission electron microscopy analyses. It is found that the Ho³⁺-Yb³⁺-SNP phosphate glasses exhibit an enhancement of both the resonant-absorption and the fluorescence properties when the SNP concentration is increased.

The use of magnetic materials, such as ferrofluids, is of great importance in biomedical applications, and as a result, interest in studying their magneto-optical properties has grown significantly in recent years. Therefore, in this work, magnetic nanoparticles were synthesized with chitosan coating, leaving the product as a ferrofluid in aqueous solution. Structural, morphological, magnetic, and optical characterization was carried out obtaining a cubic structure centered on the faces, a spherical morphology with a size distribution of 10–14 nm according to TEM images and a magnetic saturation of 53 emu/g. In the optical properties, the effect of chitosan shell on the forbidden band was studied, showing a blue-shifting effect, due to reduction on the inner magnetic nanoparticles size.

In this study, we demonstrate a proof of principle of an all-fiber random laser due to the plasmonic effect. This was achieved in a fiber co-doped with Bismuth/Aluminum/Yttria/Silver in which a microsphere (microcavity) at the fiber’s tip was made using a splicing machine. The presence in the fiber of Bismuth- and silver nanoparticles along with Bismuth-Aluminum phototropic centers stands behind the observed phenomenon. The effect can be attributed to in-pair functioning of this unit as an active medium and volumetric plasmonic feedback, with the result being lasing at 807 nm under 532-nm pumping with notably low (~2 mW) threshold.

In this study, we demonstrate a proof of principle of an all-fiber random laser due to the plasmonic effect. This was achieved with a fiber co-doped with bismuth/aluminum/yttria/silver in which a microsphere (microcavity) at the fiber’s tip was made using a splicing machine. The presence of bismuth and silver nanoparticles in the fiber along with bismuth–aluminum phototropic centers stands behind the observed phenomenon. The effect can be attributed to the in-pair functioning of this unit as an active medium and volumetric plasmonic feedback, resulting in lasing at 807 nm under 532 nm pumping with a notably low (~2 mW) threshold.