Yb3+-doped fiber laser with integrated optical cooler

The quantum defect caused by the difference between the pump and laser photon energies results in heat generation, which deteriorates the performance of lasers. This effect is very significant in high power lasers, since it can cause the stress-induced refractive index change and temperature-induced gain change. The radiation-balanced technique, in which all photons generated in the laser cycle are annihilated with the cooling cycle, has been proposed to solve the problem in the case of solid-state lasers. Unfortunately, in the radiation-balanced laser the radiated energy increases only linearly with the length of the laser medium. We propose a radically new approach to solve the problem of heat generation in lasers by using a co-doped fiber laser with two pump sources. In this laser Yb3+ ions are responsible for the lasing process, and Tm3+ ions serve as a cooler incorporated in the body of the laser. This new technique provides an exponential growth of radiation along the laser medium leading to almost athermal operation.

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