Impact of the heat load on the laser performance of chirally-coupled-core fibers.

As the heat load within the central core of chirally-coupled-core (CCC) fibers will change the pre-designed refractive index profile through the thermo-optic effect, its impact on the laser performance of CCC fibers is investigated. Analysis and simulation results on two typical CCC fibers show that the effects of the heat load include the modal loss reduction and the transmission spectrum drift. The former comes from the thermal lensing effect in the central core, and the latter is caused by the change in the refractive index difference between the central core and the side core. Considering the non-uniform axial heat distribution in the actual laser operation, the overall laser performance of CCC fibers with different pump power is simulated. It is found that, because of the high pre-designed high-order mode loss, the single-mode operation of CCC fibers will be maintained but the slope efficiency may reduce dramatically if the fundamental mode loss is strongly dependent on the heat load.