Numerical analysis of pump propagation and absorption in specially tailored double-clad rare-earth doped fiber

Double-clad fibers for high-power fiber lasers

“…Since the most common circular shape of optical fibers provides poor effective absorption of the pump, various cross-sectional shapes of DC fibers have been investigated both experimentally and theoretically in order to enhance the absorption of the multimode-pump, see examples in Fig. 1(a) [3][4][5]. The beneficial effect of mode mixing of the pump radiation by unconventional coiling was also observed, see example of the twisting effect of the two-fiber bundle in Fig.…”

Novel geometries and layouts of double-clad fibers for fiber lasers

“…1 and 2. However, theoretical studies were mostly limited to the assumption of a straight fiber until recently, when the rigorous model accounting for double-clad fiber bending and twisting was described [1,2,5]. Here we review the results of numerical modeling of pump absorption in various types of double-clad fibers, e. g., with cross-section shape of hexagon, stadium, and circle; two-fiber bundle (so-called GT Wave fiber structure, see Fig.…”