Recent experimental and theoretical work on nonlinear waveguide arrays
is presented. Experimental results of the observation of ultrafast sw
itching in both uniformly and nonuniformly three-, four-, and eight-co
re couplers are discussed. The experimental results agree well with nu
merical simulations of the couplers produced with a fast-Fourier-trans
form beam propagation code. (C) 1997 Optical Society of America.