Raman dissipative soliton source of ultrashort pulses in NIR-III spectral window.

We present a novel fiber source of ultrashort pulses at the wavelength of 1660 nm based on the technique of external cavity Raman dissipative soliton generation. The output energy of the generated 30 ps chirped pulses is in the range of 0.5-3.6 nJ with a slope efficiency of 57%. Numerical simulations are in excellent agreement with the experimental results and the shape of the compressed pulses. The compressed pulses consist of a central part with a duration of 300 fs and a weak pedestal. Our results clearly demonstrate the potential to extend the spectral range of the Raman-assisted technique for generating ultra-short pulses to new frequency regions, including biomedical windows. This paves the way for the development of new dissipative soliton sources in these bands.

The role of gold nanoparticles' aspect ratio in plasmon-enhanced luminescence and the singlet oxygen generation rate of Mo6 clusters.

Here we present a study on the effect of the aspect ratio (AR) of gold nanoparticles on the emission intensity and singlet oxygen production rate of hexamolybdenum cluster-doped silica particles. It was shown that these parameters can be enhanced gradually up to 6.7- and 13-fold with the AR.

Synergetic Effect of Mo6 Clusters and Gold Nanoparticles on the Photophysical Properties of Both Components.

Photodynamic and photothermal therapies (PDT, and PTT, respectively) are promising candidates for multimodal anticancer therapies (i.e., combinations of therapies), since their action is based on mechanisms that generally cannot be resisted by cancer cells, that is, generation of highly oxidizing oxygen species and high temperature, respectively. Herein, hybrid materials that combine octahedral molybdenum clusters as potential PDT agents and plasmonic spherical gold nanoparticles (AuNPs) as PTT agents are reported. Partial overlap of the photoemission spectrum of the cluster and the surface plasmon resonance band of the AuNPs facilitates energy transfer between the photoactive components, which resulted in synergetic enhancement of their photophysical properties. Specifically, by careful selection of the spacing between the cluster and the gold nanoparticle, a significant increase in luminescence and photosensitizing properties of the cluster was achieved in comparison with similar, but gold-free, particles. On the other hand, the cluster complex facilitated energy conversion to heat by gold particles and hence increased the heating rate under laser irradiation.

THz Sensing With Anomalous Extraordinary Optical Transmission Hole Arrays.

Subwavelength hole array (HA) metasurfaces support the so-called extraordinary optical transmission (EOT) resonance that has already been exploited for sensing. In this work, we demonstrate the superior performance of a different resonant regime of HA metasurfaces called anomalous EOT, by doing a thorough numerical and experimental study of its ability in thin-film label-free sensing applications in the terahertz (THz) band. A comprehensive analysis using both the regular and anomalous EOT resonances is done by depositing thin layers of dielectric analyte slabs of different thicknesses on the structures in different scenarios. We carry out a detailed comparison and demonstrate that the best sensing performance is achieved when the structure operates in the anomalous EOT resonance and the analyte is deposited on the non-patterned side of the metasurface, improving by a factor between 2 and 3 the results of the EOT resonance in any of the considered scenarios. This can be explained by the comparatively narrower linewidth of the anomalous EOT resonance. The results presented expand the reach of subwavelength HAs for sensing applications by considering the anomalous EOT regime that is usually overlooked in the literature.