  A photonic analogue of Klein tunneling (KT), i.e. of the exotic property of
relativistic electrons to pass a large repulsive and sharp potential step, is
proposed for pulse propagation in a nonuniform fiber Bragg grating with an
embedded chirped region. KT can be simply observed as the opening of a
transmission window inside the grating stop band, provided that the impressed
chirp is realized over a length of the order of the analogue of the Compton
wavelength.
