Thermally-induced birefringence in solid-core photonic crystal fiber lasers

The authors report photo-thermal effects in solid-core photonic crystal fiber lasers (PCFLs) using a finite element method. Thermal stresses and birefringence due to self-heating of PCFLs in the core and the cladding regions were simulated as a function of induced heat per meter. Simulations were devoted to three kinds of PCFLs with various d/Λ ratios (d is the hole diameter and Λ is the hole-to-hole distance) where large-mode-area solid-core PCFLs with air-holes triangular lattice as cladding and polymer coating were considered. For thermal modeling, all cooling mechanisms such as convection and radiation have been taken into account. We showed that thermally-induced birefringence has rather strong impact on the phase difference between perpendicular polarization components and so on depolarization.