The paper presents an all-optical system for the detection of bacterial contamination in flowing water that combines the readings from a multi-functional fiber Surface Plasmon Resonance (SPR) sensor with fluorescence measurements. The preliminary application to cases of water contaminated with Escherichia coli is discussed.
The paper discusses all-fiber applicators for the percutaneous laser ablation of tumors, which integrate very dense fiber Bragg grating arrays to add quasi-distributed sensing capabilities. First an assessment of the temperature map distribution reconstruction from the measurements is presented and the impact of some non-idealities is studied; then the developed probes are used to analyze different laser operating conditions, comparing the measurements in ex-vivo porcine livers with modeling expectations.
The paper presents the development and investigation of distributed and a quasi-distributed fiber optic sensors for the real-time monitoring of radiations during cancer treatments. Both sensors rely on ad-hoc developed nanoparticle-doped optical fibers with enhanced sensitivity to radiation. The distributed sensor is interrogated with an OFDR-based instrument and allows the reconstruction of the spatial dose distribution along the fiber. The quasi-distributed sensor is implemented through fiber Bragg gratings inscribed with a femtosecond laser in the few-mode section of a single mode-multi mode-single mode interferometer.
The paper presents the design and preliminary experimental validation of a fiber laser with direct emission in the yellow. The active material is a Dy-doped custom-made phosphate fiber, which is pumped by high-power blue diode lasers emitting at 450 nm. A suitable model has been developed to optimize the laser behavior and validated with a low-power version of the laser cavity with femtosecond written Bragg grating mirrors.
Enhanced Rayleigh backscattering optical fibers, interrogated by an optical frequency domain reflectometer, are used to perform remote real-time measurements of X-ray irradiation profiles, with possible application as dosimeters in radiotherapy treatments. The enhanced Rayleigh backscattering is obtained by proper engineering of the composition of fiber core, either by introduction of Aluminum or Magnesium silicate nanoparticles as radiation-sensitive dopants. A detectable radiation-induced refractive index change can be spatially resolved through the measurement of the frequency shift of the Rayleigh backscattering along the fiber. It is experimentally demonstrated that two mechanisms of radiation-induced refractive index change take place. At doses nearly compatible with those delivered in radiotherapy, a negative refractive index is induced, whereas at high doses the change is positive. This behavior is also confirmed by the shift of Bragg wavelength of a fiber Bragg grating inscribed in the nanoparticles-doped fiber and used as a reference.
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