We have studied surface modes in a dielectric array of parallel cylind
ers having a square cross-section and forming a square lattice. The su
rface plane is parallel to one cylinder side, itself parallel to one s
ide of the (square) unit cell. We have found that surface electromagne
tic modes can propagate along the surface in the direction perpendicul
ar to the cylinders. The properties of these modes are strongly depend
ent on the position of the surface, that is on the cut-plane through t
he cylinders. They can propagate for both complete and incomplete (tru
ncated) layers of cylinders and can exist within incomplete band-gaps.
The modes reported here are characterized by a maximum value of the p
ropagation constant, determined by a bulk band or by the crossing of t
wo such bands. Copyright (C) 1996 Elsevier Science Ltd