Phase locking of a four-wave signal in the presence of a wave mismatch

A method for increasing the reflection coefficient of a signal in the case of four-wave mixing by interaction with hypersound is proposed and implemented for the wave mismatch values Δk ≠0. The method relies on the use of a multilayer mixer with the layer thickness π/Δk and the period 2π/Δk, and with identical refractive indices of the active and inactive layers.