Loss property of photonic bandgap fiber made of high-index cylinders in low-index host material

A particular type of antiresonant reflecting optical waveguide (ARROW, or antiguide), whose cladding is formed by high-index cylinders in low-index background material, is studied. Photonic bandgap (PBG) theory is presented to explain the guidance principle in such waveguides. We found that large PBGs, which are opened up among several of the lowest bands in the cladding composite, are responsible for light guidance in the central core (or defect) region. A simple guideline is proposed to locate dominant resonant wavelengths, at which the cladding composite cannot confine light at all.