Efficient heat transfer in high-power fiber lasers

Abstract

The maximum output power of fiber lasers limited by the thermal degradation of double-clad fiber coatings is theoretically simulated. We investigated the thermal effects on high-power continuous wave (CW) fiber lasers with a focus on heating at the splice joints as well as on the doped fiber caused by quantum defects. Whether thermal interface materials are used or not, the thermal contact resistances between the fiber and its heat sink are measured separately while using different cooling equipments. Though the thermal management of splices is more difficult than that of active fibers, a temperature increase of 0.019 K/W is obtained for a splice joint into which the pump light launches. The splice joint sustains 3 kW of total passing power.

Fiber core mode leakage induced by refractive index variation in high-power fiber laser

“…When the fiber laser is influenced by external thermal disturbance, the propagation of the LP 01 mode is relatively stable while the propagation of the LP 11 mode suffers from large fluctuation caused by strong coupling effect. Using the coupled mode theory, we have described the interaction between the fiber core modes and the cladding modes, established a power attenuation model under thermally-induced refractive index variation conditions, and then obtained the fiber core loss under conventional cooling conditions [13] at multi-kW power levels.…”

Opto-Electronics Review

“…Heat transfer equation was analytically solved for the case of a high-power fibre laser with a double cladding [10]. Relation for the temperature distribution in a three-layer cylindrical structure of a double-clad fibre was given [11] and an efficient heat transfer technique was discussed [12]. Considering [3] and [11], temperature dependent effects in Tm-doped fibres lasers were analysed [13].…”