Bismuth doped fiber laser performance on effective fiber cooling

In the past, bismuth doped fiber (BiDF) lasers, operating in the 1160-1300 nm wavelength range, have gained much attention as they are promising for many applications; including medical and astronomy. However, the poor lasing efficiency of BiDF laser, compared to the widely used rare-earth doped fiber lasers, requires further investigations. One possible reason that can impair the BiDF laser efficiency is the presence of high unsaturable loss in the fiber, which is temperature dependent. Thus, temperature rise in the BiDF under strong pumping can be a limiting factor for such laser systems. Here, we report the dependence of BiDF laser efficiency on effective cooling of the fiber.