Abstract
Localized hyperthermia therapy involves heating a small volume of tissue in order to kill cancerous cells selectively and with limited damage to healthy cells and surrounding tissue. However, these features are only achievable through real-time control of the tissue temperature and heated volume, both of which are difficult to obtain with current heating systems and techniques. This work introduces an optical fiber-based active heater that acts both as a miniature heat source and as a thermometer. The heat-induced damage in the tissue is caused by the conductive heat transfer from the surface of the device, while the heat is generated in an absorptive coating on the fiber by near-infrared light redirected from the fiber core to the surface by a tilted fiber Bragg grating inscribed in the fiber core. Simultaneous monitoring of the reflection spectrum of the grating provides a measure of the local temperature. Localized temperature increases between 0 degrees C and 100 degrees C in 10 mm-long/5 mm-diameter cylindrical volumes are obtained with continuous-wave pump power levels up to 1.8W. Computational and experimental results further indicate that the temperature rise and dimensions of the heated volume can be maintained at a nearly stable level determined by the input optical power. (C) 2021 Optical Society of America