ABSTRACT
We report two different types of all-fibre pseudo-slit reformatters made either by tapering bundles of single-mode fibres or by postprocessing a photonic crystal fibre. These devices convert the modes of a multimode core to the modes of a linear pseudo-slit output structure, achieving a diffraction limited pattern in one direction.
ABSTRACT
Simple all-fiber three-mode multiplexers were made by adiabatically merging three dissimilar single-mode cores into one multimode core. This was achieved by collapsing air holes in a photonic crystal fiber and (in a separate device) by fusing and tapering separate telecom fibers in a fluorine-doped silica capillary. In each case the LP01 mode and both LP11 modes were individually excited from three separate input cores, with losses below 0.3 and 0.7 dB respectively and mode purities exceeding 10 dB. Scaling to more modes is challenging, but would be assisted by using single-mode fibers with a smaller ratio of cladding to core diameter.
