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.

Pixelated high-index ring Bragg fibers.

A new type of Anti Resonant Reflecting Optical Waveguide (ARROW) fiber with a low refractive index contrast is reported. This waveguide is similar to a Bragg fiber for which the high index rings are replaced by discontinuous rings made of circular High Index Inclusions (HII). As compared to conventional Bragg fibers, such a new structure enables true Photonic BandGap (PBG) guidance and limits the number of cladding modes located within the high index regions, thus enhancing the guiding properties. A Mode Field Diameter (MFD) of 26 µm is reported at a wavelength of 1400 nm. Single Mode (SM) behavior is also observed beyond 1400 nm for a 1 m-long fiber.

UV-induced Bragg grating inscription into single-polarization all-solid hybrid microstructured optical fiber.

We demonstrate a single-polarization all-solid hybrid microstructured optical fiber with a UV-induced Bragg grating. A strong (∼20 dB) UV-induced Bragg grating was inscribed within the 30 nm-wide single-polarization window of the fiber, producing polarized Bragg reflection. The sharp band-edge cutoff allows a large polarization-extinction ratio of the Bragg reflection. The hybrid structure of the fiber enabled minimal UV exposure to the high-index regions and the location of the single-polarization window was maintained after the grating was inscribed.