  We propose a novel chirped structure consisting of a low index polymer core
bounded by modulated multilayer claddings, to realize an optical field
concentrator with virtually zero propagation losses in a wide spectral range,
independent of wave polarization. In spite of the absence of the total internal
reflection mechanism, properly designed multilayer claddings ensure the
achievement of unitary transmittance in a wide spectral range, including the
widely used wavelengths for optical communications. Several cladding geometries
obtained by varying the thicknesses of the cladding layers are reported and
discussed.
