Bandpass and band-rejection filters using dispersive fibers

It is shown that bent optical fibers can have bandpass or band-rejection filter characteristics by selecting the core and cladding materials of appropriate index dispersions. The filter properties are caused by wavelength dependence on the index difference between the core and cladding. The spectral bending loss of dispersive fibres is calculated and their characteristics as in-line fibers are discussed. The magnitude of the loss depends strongly on the fiber curvature. The bending loss of curved optical fibers is evaluated to estimate the filter characteristics