Theoretical and experimental comparison of different configurations of tapered fiber lasers

The aim of this paper is a comparative theoretical and experimental study of two different schemes of fiber lasers with T-DCF as an active medium. In the first scheme, a high reflective (HR) mirror is located at the narrow end of T-DCF, and the wide fiber end serves as an output coupler of the laser. In the second scheme, the HR mirror is placed at the wide end of T-DCF, with the narrow end acting as the output of the laser. Due to the asymmetric active medium, the two schemes have significantly distinct properties, and the choice of configuration is important in terms of potential applications. Using the developed theoretical model, we obtained the distribution of power and power density inside the fiber for both considered schemes with different longitudinal shapes of T-DCF. Furthermore, the problems arising from the mode conversion effect, existing in the T-DCF, have been studied theoretically.