<title>Highly selective holographic elements for spectroscopic applications</title>

Abstract

ABSTRACT The goal of our research is to create the holographic optical element with high value ofspectral selectivity, about 0. 1 nm. The operating wavelength of the filter is determined by the particular task which it is made for, therefore this wavelength is usually different than the recordingwavelength. The theoretical analysis was carried out to determine the requirement for such hologramrecording in order to reach the maximal diffraction efficiency. The dependence the required refractive index modulation of the material on the reconstruction wavelength was calculated for both transmission and reflective recording schemes. Standard holographic materials can not be applied forthe recording of the spectral filter with high Selectivity, because the material thickness must be aboutmillimeter. PDA photomaterial (polymer with diffusive amplification) was applied for recording ofthese holograms. Experimentally achieved bandWidth ofthe spectral selectivity contour is 0.5 mu. The dependence of the reconstructed wavelength on the angle of reconstruction for the experimentallyobtained specimen was measured and it occurred higher than for the ordinazy diffraction grating.This makes thick holographic gratings recorded in PDA very promising from the point of view oftheir spectroscopic application as a wavelength demultiplexers in the commuthcation networks and asan optical part of monochromator. The comparison of the characteristics of spectral ifiter and doublemonochromator was carried out. Another possible applications ofthe filter including its usage in solarinvestigations, stabilising oflaser sources, Rainan spectroscopy are also discusseLKEYWORDS: volume holograms, spectral selectivity, holographic materials, spectroscopy