High NA pump core double clad Nd:glass fibre laser

The properties of a double clad fiber using Teflon as the outer coating are discussed. This a priori permits the use of laser diodes of lower beam quality or diode arrays of larger output aperture. Indeed, using a pump geometry with an aperture of 0.7, about 80% of the available light intensity could still be coupled to the fiber compared to only 50% using a conventional double clad fiber. However, the high aperture pumping is not without consequences for the conversion of pump light to laser. Nonetheless, evidence suggests that this small loss in conversion efficiency is more than compensated by the additional pump power which can be launched.