Efficient coupling of multiple diode laser arrays to an optical fiber

Abstract

Diode lasers are efficient sources of laser radiation, but their coupling to an optical fiber has been limited to applications that require low power. Here we demonstrate that three high-power diode lasers can be coupled with high efficiency into a single multimode optical fiber by geometric multiplexing. In principle, many more diodes could be used and tens of watts of power could be obtained from a single fiber with incoherent multiplediode input. We have coupled three highpower diode arrays to a 200 µm core, 0.2 N.A. optical fiber with 59% efficiency and have obtained 700 mW at the output of the fiber for 1.19 W at the input. Based on the properties of the beams from these high-power diode laser sources, it should be possible to efficiently couple over 100 of these lasers to this optical fiber and obtain tens of watts of deliverable power. Calculations show that the number of identical sources that can be efficiently coupled to an optical fiber is proportional to the square of the product of the core diameter and numerical aperture.