Confined wave packets in the domain of Rayleigh-Wood anomalies

It is known that near grating anomalies of the resonance type a beam may un dergo a lateral shift of the order of the beam width, and a pulse may be de layed by a time of the order of the pulse duration. These numerical investi gations are extended to Rayleigh anomalies that occur when, upon variation of the wavelength or the angle of incidence, an additional propagating diff raction order emerges. It is shown that delays and displacements are 1 orde r of magnitude smaller than in the resonance case. However, with increasing beam width (or pulse duration), the lateral displacement (or the temporal delay) can become large. (C) 2000 Optical Society of America [S0740-3232(00 )01601-X].