Recent experimental and numerical results clearly show that blazed-binary d
iffractive elements outperform their standard blazed-echelette counterparts
in the resonance domain. A theoretical study of one-dimensional blazed-bin
ary gratings shows that the reason for this high efficiency is a waveguidin
g effect. The electromagnetic study supports the idea that, through wavegui
ding, a reduction of the shadowing zone is achieved, and thus the efficienc
y is increased. This is intrinsic to high-frequency binary structures and c
annot be achieved with standard echelette diffractive elements. (C) 1999 Op
tical Society of America [S0740-3232(99)00410-X].