High power fiber lasers are gaining increasing shares in the laser material processing market due to their many advantages over gas and solid-state lasers. The design approaches for the typical architectures used in continuous emission fiber lasers are revised and the impact of the different choices on the specifications of the cavity components are analyzed. Then, some results on the fabrication of key components for an all-fiber setup, such as pump (PCs) and signal combiners (SCs), are reported. Finally, an example of a high power module, suitable for the development of an over 4 kW system is presented.

The development and preliminary characterisation of a novel fibre probe for laser thermotherapy of solid tumours are presented. The probe introduces two innovative features: the tailoring of the laser irradiation pattern to adapt it also for larger tumour applications, and the all-optical real time evaluation of the induced temperature increase. These features are simultaneously obtained by integrating in a single capillary tube a laser delivery fibre with properly micro-structured tip surface together with some fibre Bragg gratings. Preliminary validation examples in human liver phantoms have demonstrated the viability of the proposed approach for the development of a whole set of new probes for laser ablation in medical applications.

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The paper presents our recent results towards the development of a miniaturized all-fiber probe for laser induced thermal ablation of tumor cells, which combines the optimal delivery of a near-infrared high power ablating beam, a low power visible aiming beam and fast Bragg grating (FBG) temperature sensors. Specific combiner and probe end-cap based on dual cladding fibers have been developed to allow the simultaneous handling of the laser beams and of the signal that feeds the temperature sensor. Moreover, a very fast FBG interrogation system has been implemented to track abrupt temperature variations during medical treatment.

The paper reports on the development and characterization of an innovative all-optical laser delivery fibre probe for cancer cell ablation with simultaneous temperature sensing capabilities. The probe integrates a grating-based temperature sensor and a laser delivery fibre whose tip surface is micro-structured for adapting the beam diffusion to the tumour geometry. Different temperature sensor configurations are analysed; then the most promising is characterized in a simulated laser ablation process using a specific phantom to emulate real liver tissue.