THE PHYSICAL BASIS FOR THE USE OF REFLECTIVE VOLUME HOLOGRAMS IN RADIO PHOTONICS DEVICES

Предлагается технология создания устройств радиофотоники на основе использования в них объемных отражательных голограмм. Построена математическая модель взаимосвязи параметров радиосигнала и пространственно-спектрального распределения интенсивности оптического поля в плоскости интерферограммы, формируемой световыми потоками, дифрагировавшими на объемной отражательной голограмме. Проведен анализ чувствительности параметров интерферограммы, формируемой в голографическом радиофотонном устройстве. The technology of creating radio-photonics devices based on the use of volume reflective holograms is proposed. A mathematical model of the relationship between the parameters of the radio signal and the spatial-spectral distribution of the optical field intensity in the plane of the interferogram formed by light fluxes diffracted on the volume hologram is constructed. The sensitivity of the parameters of the interferogram generated in a holographic radio photonic device is analyzed.

Analysis of the selectivity properties of volumetric holograms in radio-photonic devices

The importance of the use of radio-photonics in telecommunication equipment is shown. The place and tasks of volumetric holograms in radio-photonic devices are described. The urgency of the problem of studying the properties of selectivity of a volume hologram, which determine the influence of this hologram on the parameters of the light flux in a radio photonics device, has been substantiated. The analysis of the exposure conditions of the volume hologram for the formation of the structure of the striations, providing its spectral and spatial selectivity to the light flux. A reasonable choice of the type of photographic material of a volumetric hologram for its use in the construction of a radio-photonic device is shown. A variant of the optical scheme for recording a volume hologram with two counter propagating light beams with spherical wave fronts and the equation of this hologram are presented. The parameters that determine the structure of the striations of the volume hologram are listed. The analysis of the conditions for the reconstruction of the optical field exposed on the volume hologram is carried out. Conditions for optimal reconstruction of an optical field by a hologram and its destruction are considered. Diagrams of the angles of reconstruction of optical fields by a volumetric reflective hologram are presented. It is shown that when a reconstructing light beam with a spherical wave front is incident on a volume hologram, in order to provide the highest value of the energy of the reconstructed optical field, the reconstructing light beam must be narrowly directed, and its optical axis must coincide with one of the directions of optimal reconstruction. In this case, the reconstructing light beam should be located between the two directions of complete destruction of the optical field. It is concluded that a volume hologram possesses the properties of both spectral (to the wavelength of light) and spatial selectivity, which must be taken into account when using it in a radio-photonic device.

Design and Fabrication of a Holographic Radial Polarization Converter

Radial polarization converters can convert an incident light into a radially polarized light, which is beneficial in a variety of applications. In this paper, a new design of holographic radial polarization converter is proposed which consists of eight space-variant polarization-selective volume hologram gratings. According to the coupled wave theory, a feasible design of the polarization-selective volume hologram gratings was described. The prism-hologram-prism sandwiched recording method was adopted for the recording. The s- and p-polarization diffraction efficiencies of the fabricated polarization-selective volume hologram gratings at 443.29 nm are 90.83% and 22.09%, respectively. The operation bandwidth is about 4.42 nm. A prototype of holographic radial polarization converter was successfully assembled and tested. Due to the introduction of volume hologram gratings, this design should have the advantages of high diffraction efficiency, narrow band, compactness, and planar configuration, meaning it is especially suitable for low-cost mass production and has high application potential in related fields.

Partially Overlapping Printing with Digital Filter to Improve Quality of Volume Hologram Printer – Numerical Simulation –

The volume hologram printer is useful for 3D display, because it is selective to the wavelength and be able to reconstruct with the natural illumination. There are many studies of a volume hologram printer been studied to output a volume hologram from a computer-generated hologram. The final volume hologram consists of tiled small holograms and the tiling manner often causes spilt lines which will have impact on image quality. With an intent to get rid of the split lines and improve the quality, fully overlapping printing was proposed recently. Each elemental hologram is overlapped both in vertical and horizontal directions by 50%. Then, the hologram is printed four times in each area and it makes the printing speed four times slower. For this case, partially overlapping printing is proposed in this paper to improve image quality with small effect in printing speed. For partial overlapping, a digital spatial filter is projected and added to every elemental hologram. Using the digital spatial filter, different partially overlapped holograms are calculated and reconstructed to compare to the non-overlapped ones. The simulation result shows that the overlapped one (10% in both vertical and horizontal) has much weaker gaps and black lines.