Large mode area modified clad leakage channel fibers with low bending and higher differential losses

Abstract

In this work, a simple design for all-solid large mode area leakage channel fibers with asymmetric cladding has been proposed to achieve effectively single mode operation through low index doped rods of two different diameters for high power fiber lasers and amplifier applications. Through numerical simulations, carried out by a full-vectorial finite-element method based solver, the modal properties of the proposed design have been investigated and the results have confirmed that the proposed fiber exhibits low fundamental mode bending loss and a very high differential ratio between the fundamental and higher order modes at practically allowable bending radii of 5–15 cm. The effective mode area of the fundamental mode at 1064 nm is 1974.2 μm2 for the straight fiber and shrinks when the fiber is bent at different radii. We have also numerically investigated the mode area enhancement under bent conditions by introducing a microsized center doped capillary in the fiber core.