REFLECTION AND REFRACTION OF THE EVANESCENT PLANEWAVE ON PLANE INTERFACES

Both the reflection and the refraction of a harmonic evanescent plane wave on an isotropic immersed layer are dealt with. Theoretical results are compared with experimental data. A bulk inhomogeneous (or evanescent) plane wave is generated in water by transmission through a prism made in an absorbing material. By using this method, the generated plane wave exhibits planes of constant amplitude orthogonal to the planes of constant phase. The incident wave propagates in the phase direction and is attenuated in its orthogonal direction. This wave is then reflected and transmitted by an isotropic and nonabsorbing layer. The most important result is the observation of reflection and transmission coefficients greater than unity. This effect agrees with the evanescent plane wave theory.