Spectral properties of a cascade of holographic reflection gratings separated by a uniform layer

This paper presents the results of experimental studies of the spectral properties of stratified structures consisting of two volume holographic reflection gratings separated by an optically uniform layer. When such structures are illuminated by polychromatic light, the interference of the waves generated by these gratings leads to the formation of a set of narrow spectral passbands. The period of arrangement of the passbands is determined by the optical thickness of the intermediate layer, and their envelope coincides with the spectral selectivity contour of one grating. The existence of this type of spectra with local passbands spaced 2–8 Å apart (in different experiments) was confirmed experimentally. A high-resolution Ramanor U1000 spectrometer and an optical Fabry–Perot interferometer were used. It is found that the nonuniformity of the internal structure of the holographic gratings due to the imperfection of the recording medium substantially distorts the spectral characteristics of the studied structures in comparison with their simple theoretical models: the spectrum is asymmetric and the transmission of the local bands is significantly lower than the estimated value. Similarity between the experimental data and simulation results was achieved by selecting the parameters of said nonuniformity.