In this paper, we report on recent experimental results obtained with fiber-Bragg-grating (FBG) hydrophones for underwater acoustic detection. The optical hydrophones under investigation consist of FBGs coated with ring-shaped polymers of different size and mechanical properties. The coating materials were selected and designed in order to provide mechanical amplification, via judicious choice of their acousto-mechanical properties and by exploiting selected resonances occurring in different frequency ranges. Our underwater acoustic measurements, carried out within the range 4–35 kHz, reveal the resonant behavior of these optical hydrophones, as well as its dependence on the coating size and type of material. These experimental data are also in good agreement with our previously published numerical results. By comparison with bare (i.e., uncoated) FBGs, responsivity enhancements of up to three orders of magnitude were found, demonstrating the effectiveness of polymeric coatings in tailoring the acoustic response of FBG-based hydrophones.

Radiochromic film dosimetry has been widely employed in most of the applications of radiation physics for over twenty years. This is due to a number of appealing features of radiochromic films, such as reliability, accuracy, ease of use and cost. However, current radiochromic film reading techniques, based on the use of commercial densitometers and scanners, provide values of dose only after the exposure of the films to radiation. In this work, an innovative methodology for the real-time reading of radiochromic films is proposed for some specific applications. The new methodology is based on opto-electronic instrumentation that makes use of an optical fiber probe for the determination of optical changes of the films induced by radiation and allows measurements of dose with high degree of precision and accuracy. Furthermore, it has been demonstrated that the dynamic range of some kinds of films, such as the EBT3 Gafchromic films (intensively used in medical physics), can be extended by more than one order of magnitude. Owing to the numerous advantages with respect to the commonly used reading techniques, a National Patent was filed in January 2018.

The “lab-on-fiber” concept envisions novel and highly functionalized technological platforms completely integrated in a single optical fiber that would allow the development of advanced devices, components and sub-systems to be incorporated in modern optical systems for communication and sensing applications. The realization of integrated optical fiber devices requires that several structures and materials at nano- and micro-scale are constructed, embedded and connected all together to provide the necessary physical connections and light-matter interactions. This paper reviews the strategies, the main achievements and related devices in the lab-on-fiber roadmap discussing perspectives and challenges that lie ahead.