(5 + 1) × 1 pump and signal power combiner with 9/80 μm feed-through signal fiber.

In this paper we demonstrate our concept and fabrication details of a (5 + 1) × 1 pump power combiner with signal feed-through. The (5 + 1) × 1 configuration is based on a feed-through signal fiber with reduced clad diameter in comparison to multimode fibers (MMFs) used in the combiner. Our idea is to use a 9/80 μm signal fiber and five conventional 105/125 μm MMFs. Using this number of MMFs with 125 μm clad diameter and signal fiber with 80 μm clad diameter allows for easy placement of all fibers in proper position in a capillary tube – the signal fiber is always in the central position, surrounded by the MMFs. It also enables reducing the taper ratio parameter, and thus increase the signal transmission efficiency. Using this approach, signal transmission at the level of 94.3% was achieved, which is better than typical values offered by commercially available singlemode devices. [ABSTRACT FROM AUTHOR]