Herein,
hybrid nanoparticles composed of a red-emitting conjugated
oligomer (COL) and gold nanoparticles (Au-NPs) were prepared through
a one-pot synthetic method in which the oligomer acts as a reducing
agent as well as a matrix to wrap the newly formed Au nanoparticles.
These hybrid nanoparticles (COL-Au-NPs) exhibited photodynamic and
photothermal activity against both Gram-positive and Gram-negative
bacterial strains. They were also proven to possess high photostability
and thermal reversibility. Dark cytotoxicity of COL-Au-NPs toward
pathogens and mammalian breast cancer cells (MCF-7) reduced significantly
upon complexation with cucurbit[7]uril while preserving their light-induced
cytotoxic activity when irradiated with a 915 nm laser for photothermal
therapy and white light for photodynamic therapy, respectively. Furthermore,
these nanoparticles have cellular imaging capability because of their
intrinsic fluorescence characteristics and can be used in image-guided
therapy.
We demonstrate a 1018 nm ytterbium-doped all-fiber laser pumped by tunable pump sources operating in the broad absorption spectrum around 915 nm. In the experiment, two different pump diodes were tested to pump over a wide spectrum ranging from 904 to 924 nm by altering the cooling temperature of the pump diodes. Across this so-called pump wavelength regime having a 20 nm wavelength span, the amplified stimulated emission (ASE) suppression of the resulting laser was generally around 35 dB, showing good suppression ratio. Comparisons to the conventional 976 nm-pumped 1018 nm ytterbium-doped fiber laser were also addressed in this study. Finally, we have tested this system for high power experimentation and obtained 67% maximum optical-to-optical efficiency at an approximately 110 W output power level. To the best of our knowledge, this is the first 1018 nm ytterbium-doped all-fiber laser pumped by tunable pump sources around 915 nm reported in detail.
Ytterbium (Yb)-doped optical fibers are mainly used in the fiber laser resonator and amplifier systems. These systems have been widely utilized for applications in air and space, the defense industry, and the medical field. Particularly for the applications yielding operation in harsh environments consisting of radiation, it is essential to determine the radiation hardness of the Yb-doped optical fibers and their long-term performance in such environments. This study analyzed the optical properties of four different Yb-doped aluminophosphosilicate fibers before and after gamma irradiation. For each fiber, the effect of different total dose values including 0.5, 1, 10, and 50 kGy were determined at different operation wavelengths, such as 495 nm, 590 nm, 685 nm, and 730 nm, using radiation-induced attenuation (RIA) analysing curves. The total dose values of 10 kGy and 50 kGy were studied to demonstrate the results under extreme environmental conditions such as large hadron colliders (LHCs). Our findings reveal that the formation of radiation-induced color centers (e.g. AlOHC, POHC, and NBOHC) are highly dependent on the Yb-concentration, the amount of excess alumina (Al 2 O 3 ) compared to the phosphorous pentoxide (P 2 O 5 ), total irradiation dose and wavelength at which the respective RIA is recorded.
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