Optical and thermal modeling of Ti-doped optothermal fiber converter for laser surgery

The structure of a titanium-doped optothermal fiber converter used in contact laser surgery for resection and coagulation of soft tissues was studied. Structural, optical, and thermophysical models of this converter are proposed. Optical and thermal calculations performed within the framework of the proposed models made it possible to estimate the fraction of laser energy absorbed by the converter and the dynamics of its laser heating. The results obtained were compared with the experimental data on the heating of a titanium-doped optothermal fiber converter by the radiation of a 980 nm diode laser in air. The influence of temperature dependences of physical density, specific heat capacity, thermal conductivity coefficient, converter blackness degree, and converter-air and fiber-air heat transfer coefficient on the dynamics of laser heating of the converter are discussed. It is shown that the greatest contribution to the simulation results is made by the temperature dependences of specific heat and converter blackness degree. The results obtained in the work should be taken into account in the future when creating a general model that adequately describes the interaction between the converter and biological tissue in the process of surgical intervention.