In this work, we analyze the thermal effects occurring in optical fibres, such as the coating heating due to high power propagation in bent fibres and the fibre fuse effect. Thus, the conjugation of high power propagation and tight bending, resulting from the actual FTTH infrastructures, is responsible for fibre lifetime reduction, mainly caused by the local increase of the coating temperature. It discusses the historical context and recent advancements in understanding these thermal phenomena, alongside. This paper investigates the thermal effects in fused-tapered passive optical fibers under near-infrared absorption. Using the finite element method, the volume changes during fiber.