The multicore fiber - a novel design for a diode pumped fiber laser

A multicore fiber serving as the gain medium for a fiber laser is introduced. Nearly 40 monomode cores are fitted into a standard multimode silica glass fiber. The cores are arranged on an annulus situated near the border of the fiber. The multimode fiber guides the pump radiation with which the Nd3+-doped cores are excited. The pump waveguide was modelled presupposing that the absorption is nearly homogeneously distributed. The lasing properties of this sophisticated design are quite promising giving about 450 mW at lambda = 1050 nm for a pump power(lambda = 805 nm) of 1800 mW and a fiber length of 40 cm. The slope efficiency amounts to 40%. The far field intensity pattern possessing an angular width defined by a single source resembles that of an ensemble of emitters with random phases. (C) 1998 Published by Elsevier Science B.V. All rights reserved.