  We predict that interfaces of modulated photonic lattices can support a novel
type of generic surface states. Such linear surface states appear in truncated
but otherwise perfect (defect-free) lattices as a direct consequence of the
periodic modulation of the lattice potential, without any embedded or
nonlinearity-induced defects. This is in a sharp contrast to all previous
studies, where surface states in linear or nonlinear lattices, such as Tamm or
Shockley type surface states, are always associated with the presence of a
certain type of structural or induced surface defect.
