ON THE CRITERION OF ADIABATICITY IN THE COUPLED MODE THEORY

In the present paper, it is pointed out that there are two catagories of adiabatic approximation. within the propagation distance the range-dependent variation of the waveguide may be accummulative (1) or nonaccummula-tive (2). The well-known criterion given by Milder is applicable for the first catagory. The criterion for the second catagory has been derived by the present authors. Two example are discussed, (1) a shallow water waveguide with slight surface roughness and (2) a shallow water waveguide with range-dependent sediment properties.