  We introduce a glide symmetric optical waveguide exhibiting a stationary
inflection point (SIP) in the Bloch wavenumber dispersion relation. An SIP is a
third order exceptional point of degeneracy (EPD) where three Bloch eigenmodes
coalesce to form a so-called frozen mode with vanishing group velocity and
diverging amplitude. We show that the incorporation of chirped distributed
Bragg reflectors and distributed coupling between waveguides in the periodic
structure facilitates the SIP formation and greatly enhances the
characteristics of the frozen mode regime. We confirm the existence of an SIP
in two ways: by observing the flatness of the dispersion diagram and also by
using a coalescence parameter describing the separation of the three
eigenvectors collapsing on each other. We find that in the absence of losses,
both the quality factor and the group delay at the SIP grow with the cubic
power of the cavity length. The frozen mode regime can be very attractive for
light amplification and lasing, in optical delay lines, sensors, and
modulators.
