Multi-trench fiber with four gaps for improved bend performance.

A modified multi-trench fiber (MTF) design with gaps to create leakage channels is proposed and investigated numerically using the scalar finite-difference beam-propagation method algorithm. Great potential in single-mode operation, mode area enlargement, and resistance to bending is demonstrated. A high loss ratio (>50) between high-order modes and the fundamental mode is possible over a wide range of high-index ring thickness, gap width, and bending orientation. This reduces the required fabrication accuracy. We obtain an effective area of 920  μm2 at a wavelength of 1050 nm and a 20 cm bend radius with a high loss ratio (>100). Our modified gap MTF can possibly be fabricated by drilling holes in an ordinary MTF and inserting rods into the holes.