  We analyze the formation of localized structures in cavity-enhanced
second-harmonic generation. We focus on the phase-matched limit, and consider
that fundamental and generated waves have opposite sign of group velocity
dispersion. We show that these states form due to the locking of domain walls
connecting two stable homogeneous states of the system, and undergo collapsed
snaking. We study the impact of temporal walk-off on the stability and dynamics
of these localized states.
