Mode theory of three-dimensional superimposed holograms: III. Hologram crosstalk

Crosstalks of three-dimensional superimposed holograms, caused by multiple wave diffraction at crossmodulation and intermodulation hologram gratings, were studied. It was shown that the intensity of these interferences depends on the method of data coding in physical parameters of hologram object waves during holographic recording. A coding method efficiently lowering the interference intensity was considered.     

Localized one-dimensional theory for volume holograms

Coupled partial differential equations are derived, consistent with localized use of one-dimensional theory in a thin volume hologram, from modifications to both one-dimensional and two-dimensional theory. The approximations inherent in the model and the range of validity of the solution are discussed.     

Diffraction efficiency of volume holograms

In this paper we give an exact solution of the coupled differential equation system as developed by Kogelnik [1] for the case of symmetrical recording without neglecting the second differentials. This generalized solution is applicable to dielectric, absorption and so-called mixed volume holograms. It is shown that under special assumptions and approximations we get the same equations for the diffraction efficiency as derived by Kogelnik. In this first part of the paper transmission holograms are only investigated and in the second part we will give the solution for reflection holograms.     

Microscopic theory of the long-wavelength modes of two component plasmas and ionic liquids: I. The transverse modes

The long wavelength modes of a system of two kinds of particles are studied starting from first principles while accounting for the presence of Coulomb interactions. It is shown that in order to cope with the Coulomb singularity the use of two-fluid hydrodynamical variables is indicated. Microscopic expressions for the various hydrodynamical modes as well as a number of interspecies relaxation modes are obtained for arbitrary density and coupling. In this paper only the transverse modes are considered. The results for the longitudinal modes as well as their contribution to a number of correlation functions will be considered in two compagnon papers.     

Simulation of diffraction from volume holograms

Coupled wave equations that consider two-dimensional distribution and phases of gratings are derived by using weak grating and slow varying approximation. The result of angular selectivity on rand binary data page shows that each minimum is nonzero and each maximum that is not the middle maximum is a little bit smaller than that on plane wave volume hologram. Angular multiplexing is also modeled using the same method, and the middle page is read out in two different angular spacings. The relationship about PSNR versus angular spacing at different multiplexing pages is analyzed to reflect crosstalk between pages. All simulative results show this method is effective for volume holograms simulation.     

Mode theory of three-dimensional superposed holograms: II. The wave field arising from the reconstruction of a superposed hologram

The wave field arising in the volume of superposed holograms is obtained with allowance for multiple wave diffraction on holographic cross-modulation gratings. It is shown that cross-talk interference waves are generated as a result of multiple diffraction, and their intensity depends on the degree of mutual orthogonality of hologram object waves.     

Coupled wave theory for volume holograms recorded by two strong andN weak plane waves

A set ofN + 2 coupled differential equations is derived for the amplitudes of the waves, and an analytic solution is presented for a simple case. The effect of the weak beams on the maximum conversion efficiency between the strong waves is discussed.     

Spatial-frequency version theory of three-dimensional holograms

A spatial-frequency version of high efficiency three-dimensional holograms of complex wave fields has been achieved. It has been shown that a three-dimensional hologram recorded by a plane reference wave may be described by means of a complex transfer function, which is found here analytically. Analysis of amplitudephase wave field distortions, under different recording and reconstruction conditions, has been carried out.     

Grassmann phase space methods for fermions. I. Mode theory

In both quantum optics and cold atom physics, the behaviour of bosonic photons and atoms is often treated using phase space methods, where mode annihilation and creation operators are represented by c-number phase space variables, with the density operator equivalent to a distribution function of these variables. The anti-commutation rules for fermion annihilation, creation operators suggest the possibility of using anti-commuting Grassmann variables to represent these operators. However, in spite of the seminal work by Cahill and Glauber and a few applications, the use of Grassmann phase space methods in quantum–atom optics to treat fermionic systems is rather rare, though fermion coherent states using Grassmann variables are widely used in particle physics.     

Formation kinetics of volume holograms in reversible photochromic media

The specific features of recording a volume hologram in a photochromic reversible medium, which is characterized by simultaneous occurrence of hologram recording and relaxation, have been considered by the example of two ion crystals, i.e., cadmium fluoride with bistable gallium centers and calcium fluoride with color centers.     

Selective properties of volume phase holograms in photorefractive crystals

The paper deals with the selective properties (both angular and spectral) of volume phase holograms in birefringent and cubic optically active photorefractive crystals. It is shown that in birefringent crystals of LiNbO₃ type, the spectral selectivity of the grating depends remarkably on the type of diffraction (isotropic or anisotropic) and the polarization of the reconstructing plane light wave. In cubic optically active crystals the peculiarities of diffraction reveal themselves in a fine structure of differently polarized peaks in the Bragg maximum that can be easily observed, in particular in Bi₁₂SiO₂₀ samples with a thickness d ≈ 8 mm.     

Polarization volume holograms in layers of polymethylmethacrylate with phenanthrenequinone

Polarization volume holograms are recorded in the polymethylmethacrylate layers that contain phenanthrenequinone at a molar content of 2.5–3%. The effect of the polarization of recording beams on the kinetics of diffraction efficiency and properties of holograms is analyzed. Polarization hologram recording in the polymethylmethacrylate layers with phenanthrenequinone and a relatively high optical stability of the holograms are demonstrated.     

High longitudinal selectivity of shifting multiplexing in volume holograms

High longitudinal selectivity of the shifting multiplexing with spherical reference wave is proposed and demonstrated. A simplified method based on wave optics is used for calculating the selectivity, and the result fits well the experimental measurement. Under the paraxial condition, a simple formula for the longitudinal selectivity is introduced. With use of an object lens with effective NA=0.817, we obtain that an FWHM of selectivity is as small as 1 μm.     

Rotation selectivity of random phase encoding in volume holograms

We present the study of angular selectivity for holographic multiplexing based on random phase encoding by a ground glass. The rotational selectivity of the volume hologram is calculated theoretically and coincides with the experimental measurement. By controlling the parameters including rotational center, effective numerical aperture of both volume hologram and the ground glass, we can obtain different rotational selectivity applied to random phase encoding in volume holographic storage.     

Profiles in volume phase holograms in Cp2TiCl2:PMMA

A method for measuring depth profiles in volume phase gratings recorded in doped poly-(methyl methacrylate) (PMMA) is demonstrated. The profiles are the product of photosensitivity and light distribution. Photosensitivity is governed by the distribution of residual monomer. Insensitive PMMA samples may be sensitized by in-diffusion of monomer. The photoinitiator bis(cyclopentadienyl)-titanium-dichloride (Cp₂TiCl₂) is found to be moisture sensitive.     

A complement to the theory of Lohmann-type computer holograms

The introduction by Lohmann and co-workers of the detour phase method in realizing synthetic holograms has been an important step in the history of computer generated holography. In 1969, Brown and Lohmann proposed an improvement to their method: they used true phase and amplitude coding at the center of the diffracting aperture instead of periodically sampled phases and amplitudes. We present a mathematical analysis of this procedure and examine the approximation related to its practical realization.     

Diffraction efficiency of sequentially stored gratings in reflection volume holograms

On the basis of the theory of coupled waves the amplitudes of the first-order diffracted waves and the diffraction efficiency is calculated for sequentially superposed phase gratings stored in dielectric reflection holograms. The investigations are restricted to the case of a fixed reference wave during recording and Bragg-angle incidence.By analogy to the transmission volume grating the coupling effects which appear between incident beams and diffracted waves give the possibility of building up beam-couplers and -splitters with certain coupling parameters determined by the recording process. Moreover, reflection gratings allow a favourable combination between coupling and reflecting properties and avoid the diffraction efficiency oscillations that are characteristic of transmission gratings. The performance of the reconstruction process with several waves simultaneously allows the tuning of the intensities of diffracted waves with dependence on amplitude or phase differences between incident beams.     

Microscopic theory of the long-wavelength modes of two-component plasmas and ionic liquids: II. The longitudinal modes

The modification of the damping rate of the sound modes by Coulomb phenomena is demonstrated from first principles. The heat modes of one- and two-component systems of charged particles are shown to differ by a factor c_p/c_v. Microscopic expressions for the interspecies energy and longitudinal momentum relaxation frequencies are provided. The charge relaxation modes are shown to reduce in the limit of weak-coupling to a pair of plasma oscillations occurring slightly below the plasma frequency while being slightly damped even at infinite wavelength. In the opposite limit of strong-coupling the same pair of charge relaxation modes is shown to split into an interspecies momentum relaxation mode and an approximate hydrodynamic diffusion mode. An Einstein relation between the diffusion constant and the electric conductivity is also demonstrated. All expressions are obtained for arbitrary density and coupling.