Toward the development of a distributed all-fiber temperature sensor for biomedical applications

A Chirped Fiber Bragg Grating is investigated as distributed temperature sensor for medical applications such as laser ablation. The motivation for this research and a brief comparison of this sensor with more established temperature monitoring techniques are analyzed. A numerical model based on equivalent electrical transmission lines is developed to predict the sensor behavior to thermal stimuli. The simulation are then experimentally verified by comparison with measurements performed on a commercial 4.5 cm long Chirped Fiber Bragg Grating mounted on a thermal cooler and interrogated in reflection. The experimental results, resembling the simulations, show that the reflection spectrum changes according to the thermal profile applied along the grating with a coefficient of 8 pm/°C. These preliminary results are promising since they prove that the Chirped Fiber Bragg Grating can be employed as distributed temperature sensor in a range of few centimeters, as it is required by thermo-related therapies.