DIFFRACTION EFFICIENCY OF BINARY METAL GRATINGS WORKING IN TOTAL INTERNAL-REFLECTION

Experimental and theoretical investigations on the diffraction efficiency of binary metal gratings working in total internal reflection are carried out. Using the method of amplitude transmission an expression that describes the efficiency of high diffraction orders is derived. Equations for the gratings' diffraction efficiency in the form of infinite series are obtained by the convolution method. It is demonstrated that both approaches yield one and the same result. The theoretical results are compared with the experimental data on the diffraction efficiency dependence on the angle of incidence and duty factor. Qualitatively, the theory describes satisfactorily the behaviour of the experimental relationships. A deviation is observed in the even orders and in the vicinity of the critical angle.