A novel quasi-ellipsoidal microlenses employing a quadrangular-pyramid-shaped fiber endface

We propose a novel quasi-ellipsoidal microlens employing a quadrangular-pyramid-shaped fiber endface (QPSFE) for the coupling between high-power 980 nm laser diodes and single mode fibers. The QPSFE was fabricated by using a grinding and polishing technique and then heating in a fusing splicer to form a quasi-ellipsoidal microlens endface. A coupling efficiency of 60% has been demonstrated. Based on the Gaussian beam approximation, a simple theoretical calculation of the effect ellipsoidal-axis and working distance on coupling efficiency is presented.