Parametric analysis of wavelength-dependent laser heating in skin tissue using coupled light transport and DPL-based thermoelastic models

This study numerically investigates laser-induced photo-thermo-mechanical interactions in multilayered human skin. A two-dimensional axisymmetric finite element model was developed, coupling three light transport models comparing Beer-Lambert (BLM), Modified Beer-Lambert (MBLM), and Light Diffusion (LDM)—with a Dual-Phase-Lag (DPL) bioheat framework to evaluate responses to pulsed irradiation from 500 to 1600 nm. Simulation results demonstrate that model selection and wavelength critically influence thermal and mechanical outcomes. At 1500 nm, the absorption-only BLM predicted surface temperatures exceeding 140 °C, whereas the MBLM and LDM, which incorporate scattering, limited this rise to 70–80 °C and 60–70 °C, respectively. Similarly, the BLM produced von Mises stresses up to 799 kPa and surface displacements over 42 μm, values that were reduced by 40–50 % in scattering-inclusive models. Thermal phase lag effects further reduced peak temperatures by 15–20 %, and both scattering and thermal lag notably mitigated necrotic tissue formation. These results highlight the critical importance of selecting appropriate optical models that account for scattering and finite-speed heat conduction for accurate predictive simulations in laser medicine.