We report on the employment of a biodegradable phosphate-based optical fiber as a pH sensing probe in physiological environment. The phosphate-based optical fiber preform was fabricated by the rod-in-tube technique. The fiber biodegradability was first tested in-vitro and then its biodegradability and toxicity were tested in-vivo. Optical probes for pH sensing were prepared by the immobilization of a fluorescent dye on the fiber tip by a sol-gel method. The fluorescence response of the pH-sensor was measured as a ratio of the emission intensities at the excitation wavelengths of 405 and 450 nm.
This paper reports on the design of the surface enhanced Raman spectroscopy (SERS) structures that were optimized
through computation and simulation to obtain the best enhancement of the surface plasmon-polariton (SPP) response on
these structures. The structure of the silver nano-grating was designed, fabricated, optimized and measured. The
enhancement factor and the increase in the absorption capabilities associated with SPP were evaluated. The rigorous
coupled wave analysis (RCWA) and finite-difference time-domain (FDTD) computational/simulation methods were
utilized. The comparison between the computation simulation outputs and the measured outputs of the fabricated
samples was performed.
We report about properties of epoxy novolak resin polymer doped with dysprosium ions. The polymer layers were
fabricated by spin-coating onto silicon substrates, or pouring epoxy novolak resin solution into bottomless molds placed
on a quartz substrate and leaving them to dry. Rather strong bands around 3366 cm<sup>-1</sup> in the infrared spectra indicated
presence of the O-H groups. Absorption measurements were done in the spectral range from 300 nm to 3000 nm and
showed six strong bands at 758 nm (<sup>6</sup>F<sub>3/2</sub>), 807 nm (<sup>6</sup>F<sub>5/2</sub>), 906 nm (<sup>6</sup>F<sub>7/2</sub>), 1100 nm (<sup>6</sup>F<sub>9/2</sub>), 1280 nm (<sup>6</sup>F<sub>11/2</sub>) and 1685 nm
(<sup>6</sup>H<sub>11/2</sub>) corresponding to Dy<sup>3+</sup> ions. Optical band gap E<sub>g</sub> was determined from the absorption coefficient values using
Tauc's procedure, i.e., from the relationship αhv = A(hv - E<sub>g</sub>)<sup>2</sup> and the obtained values varied from 3.489 eV to 3.539 eV
depending on the amount of dysprosium ions involved in the samples. Photoluminescence spectra around 1300 nm were
investigated by using excitation of He-Ne laser (632.8 nm) and two semiconductor lasers (980 nm and 827 nm).