  We demonstrate that exceptional points of degeneracy (EPDs) are obtained in
two coupled waveguides without resorting to gain and loss. We show the general
concept that modes resulting from a proper coupling of forward and backward
waves exhibit EPDs of order two and that there the group velocity vanishes. We
verify our insight by using coupled mode theory and also by fullwave numerical
simulations of light in a dielectric slab coupled to a grating, when one
supports a forward wave whereas the other (the grating) supports a backward
wave. We also demonstrate how to realize photonic indirect bandgaps in guiding
systems supporting a backward and a forward wave, show its relations to the
occurrence of EPDs, and offer a design procedure.
