Design and realization of flexible very large mode area pixelated Bragg fibers

A new Pixelated Bragg Fiber design showing improved optical performances in terms of single-mode behavior and effective area is presented. The cladding is made of 3 rings of cylindrical high refractive index rods (pixels) in which some pixels are removed to act as a modal sieve for an improved rejection of Higher Order Modes (HOMs). Two half-wave-stack conditions are used to increase the confinement losses of the 3 first HOMs: LP11 and LP02-LP21 guided core modes. The realized fiber exhibits a core diameter of 48.5 μm with an effective single-mode behavior observed from 1000 nm to beyond 1700 nm even for a 1-m-long straight fiber. Losses prove to be low with a minimum value of 25  dB/km between 1200 and 1500 nm. Bending radius of 22.5 cm is reported for this structure without any significant extra-losses above a wavelength of 1350 nm.