Dynamic Holographic Recording Research Articles

Synthesis and structure of novel Ag2Ga2SiSe6 crystals: promising materials for dynamic holographic image recording

Phase diagrams of the AgGaSe2–SiSe2 system were explored by differential thermal analysis (DTA) and X-ray diffraction (XRD) analysis methods for the first time.

Real-Time Optical Information Processing Through the Use of Low-Saturable Absorption in Bacteriorhodopsin Films

We have shown that the mechanism for a reversible anisotropic photoselection of bacteriorhodopsin (BR) molecules and a very small saturation intensity of a BR film allow for the blocking of any intensity feature from an image by just varying the intensity of a He-Ne laser beam without conventional frequency filters or rotation of an analyzer. It is found that the E204Q variant of BR offers additional valuable features. The photochemical cycle with a red-light absorbing O intermediate, B→M→O→B, and a distortion of the grating profile due to the low-saturation absorption are responsible for a large initial peak sharpness of the dynamic holographic recording kinetics.

An updatable holographic three-dimensional display

Holographic three-dimensional (3D) displays provide realistic images without the need for special eyewear, making them valuable tools for applications that require situational awareness, such as medical, industrial and military imaging. Currently commercially available holographic 3D displays use photopolymers that lack image-updating capability, resulting in restricted use and high cost. Photorefractive polymers are dynamic holographic recording materials that allow updating of images and have a wide range of applications, including optical correlation, imaging through scattering media and optical communication. To be suitable for 3D displays, photorefractive polymers need to have nearly 100% diffraction efficiency, fast writing time, hours of image persistence, rapid erasure, and large area-a combination of properties that has not been shown before. Here, we report an updatable holographic 3D display based on photorefractive polymers with such properties, capable of recording and displaying new images every few minutes. This is the largest photorefractive 3D display to date (4 x 4 inches in size); it can be recorded within a few minutes, viewed for several hours without the need for refreshing, and can be completely erased and updated with new images when desired.

Deoxyribonucleic acid-based photochromic material for fast dynamic holography

The authors report on a biopolymeric material made of deoxyribonucleic acid (DNA) complexed with the cationic surfactant cetyltrimethyl-ammonium (CTMA) and doped with the photochromic disperse red 1 dye (DR1) for dynamic holographic recording. The molar ratio of the DNA-CTMA to the dye is about 5:1. They have found that the photochromic properties of DR1 in the DNA-CTMA matrix are favorably modified in speed of response with respect to conventional polymeric matrices. Dynamic holographic gratings which were inscribed in DR1:DNA-CTMA films are characterized by switching times within a 1–10ms range. An excellent reversibility of the recording process is reported.

Fast dynamic holographic recording based on conductive ionic metal-alkanoate liquid crystals and smectic glasses

Recordings of dynamic holograms with microsecond relaxation times under the action of nanosecond laser pulses are obtained in composites on the base of a novel class of liquid crystals (LCs) in ionic metal-alkanoates. Holographic parameters and relaxation characteristics are measured for doped lyotropic ionic LC, for sandwichlike cells (consisting of a dye layer and a layer of the lyotropic ionic LC), and for colored ionic smectic glasses. The structure of the materials is investigated by use of the small-angle x-ray technique. The mechanism of resonance nonlinearity in photosensitive centers and mechanisms of the grating erasure connected with a charge transport in the ionic conductive LC matrix are discussed.

A dynamic narrow-band tunable optical filter

A tunable filter based on dynamic holographic recording in BaTiO3 is described. A selectivity of the filter of 0.1 nm and a tuning range of not less than 100 nm have been obtained. The transformation of the stop band filter transfer function into the pass band transfer function has been demonstrated in real time. A theoretical description of the transfer function of the filter with the grating phase jump is given.

Analytic steady-state solutions to dynamic grating envelope

Abstract The photorefractive holographic recording is a dynamic grating formulation process, where the grating is induced by the interference modulation of two beams, and the energies of the beams are exchanged with each other owing to their interaction in the induced grating. The grating modulation envelope is a comprehensive analysis for holographic dynamic recording and non-destructive readout, but analytic solutions can only be obtained by simultaneously solving the materials equations and the coupled wave equations. In this paper, based on Kukhtarev's model and Moharam's field function exact steady-state analytic expressions for dynamic grating envelopes are deduced for any constant values of light modulation depth and light excitation efficiency. Thus their approximations for straight formulation instead of parametric formulation are then obtained. These steady-state analytic solutions to envelopes describe the dynamic holographic recording and readout more clearly and exactly.

Analytic steady-state solutions to dynamic grating envelope

The photorefractive holographic recording is a dynamic grating formulation process, where the grating is induced by the interference modulation of two beams, and the energies of the beams are exchanged with each other owing to their interaction in the induced grating. The grating modulation envelope is a comprehensive analysis for holographic dynamic recording and non-destructive readout, but analytic solutions can only be obtained by simultaneously solving the materials equations and the coupled wave equations. In this paper, based on Kukhtarev's model and Moharam's field function exact steady-state analytic expressions for dynamic grating envelopes are deduced for any constant values of light modulation depth and light excitation efficiency. Thus their approximations for straight formulation instead of parametric formulation are then obtained. These steady-state analytic solutions to envelopes describe the dynamic holographic recording and readout more clearly and exactly.

Indium oxide thin-film holographic recorders grown by excimer laser reactive sputtering

O3) thin films on glass substrates is performed by pulsed laser ablation of a metallic indium target in an oxygen atmosphere. X-ray diffraction analysis verifies that a transition, from amorphous to polycrystalline film growth, occurs at a temperature of 150 °C. Films grown under optimized conditions exhibit optical transmission higher than 80% in the visible light. Ultraviolet radiation (λ= 325 nm) induced dynamic holographic recording in films deposited at specific temperature and oxygen pressure settings is also demonstrated.

Polarisation-independent linear homodyne detection of optical phase modulation with adaptive photodetectors

A simple configuration for the linear homodyne detection of fast phase modulation in the presence of relatively slow polarisation/phase drift in the signal beam is proposed and experimentally demonstrated. It uses adaptive photodetectors which are based on principles of dynamic photorefractive holographic recording (two-wave mixing or photo-EMF effect).

Noise filtering in the interference pattern by dynamic holographic recording in photorefractive Bi_12TiO_20 crystals

The possibilities of stabilization of the interference pattern by filtration of a random-phase noise caused by vibrations, turbulence, and other local changes in the wave front in interferometric measurements are investigated. Dynamic holographic recording in photorefractive Bi(12)TiO(20) crystals is used. The parameters of the holographic recording are presented for determination of the dynamic range for filtering. Noise filtering takes place in real time and contributes to the enhancement of the contrast and the signal-to-noise ratio of the interference pattern. This results in a considerable increase in the sensitivity and the accuracy of the interferometric measurements.

Nonlinear techniques in optical synthetic aperture radar image generation and target recognition

One of the most successful optical signal-processing applications to date has been the use of optical processors to convert synthetic aperture radar (SAR) data into images of the radar reflectivity of the ground. We have demonstrated real-time input to a high-space-bandwidth optical SAR imagegeneration system by using a dynamic organic holographic recording medium and SAR phase-history data. Real-time speckle reduction in optically processed SAR imagery has been accomplished by the use of multilook averaging to achieve nonlinear modulus-squared accumulation of subaperture images. We designed and assembled an all-optical system that accomplished real-time target recognition in SAR imagery. This system employed a simple square-law nonlinearity in the form of an optically addressed spatial light modulator at the SAR image plane to remove the effects of speckle phase profiles returned from complex SAR targets. The detection stage enabled the creation of an optical SAR automatic target recognition system as a nonlinear cascade of an optical SAR image generator and an optical correlator.

Optical implementation of a wavelet transform by the use of dynamic holographic recording in a photorefractive material

An optical system that employs holographic recording in a photorefractive material is proposed and experimentally demonstrated for the implementation of a wavelet transform of two-dimensional mages. A scaling operation, to derive the family of wavelet filters from a mother wavelet filter, is performed by the use of an optical feedback loop. The selection of a desired wavelet filter from the family and the correlation for a wavelet transformation are made by the use of a holographic recording in a photorefractive material. The principle of operation of the system relies on the frequency detuning introduced inside the loop and the subsequent variation in the holographic grating diffraction. Experimental results on wavelet-filter selection and wavelet transformation are presented. This nonlinear optical wavelet-transform system is advantageous for pattern recognition applications.

New azo-dye-doped polymer systems as dynamic holographic recording media

Polymer materials show their impact on optical storage technology for developing high information density and fast access-type memories with a high read-out efficiency. New azo-dye-doped polymer materials have been developed and used for recording dynamic holograms. Dynamic holograms with reasonably high diffraction efficiency have been recorded at 468 nm, and the efficiency of the Write, Read and Erase (WRE) cycle in these azo-dye-doped polymer materials was determined. Significant observations in these materials are: (i) there is no need to change the polarization of the writing beam to erase the recorded holograms, (ii) the whole WRE cycle is very fast (3–6 s) and (iii) recording of more than 250 WRE cycles without any fatigue of the recording materials is possible.

New azo-dye-doped polymer systems as dynamic holographic recording media

New azo-dye-doped polymer systems as dynamic holographic recording media

Real-time joint transform correlation with photoanisotropic dye–polymer films

The results of joint transform correlation with photoanisotropic organic materials are presented. The materials' dynamic holographic recording capability and high resolution permit the operation of such a correlator in real time. Both theoretical and experimental results show that the photoanisotropic properties cause a dependence of the correlation output on the state of the polarization of the readout beam and can be used to produce an output polarization orthogonal to the input, which permits polarization filtering to be used, greatly increasing the signal-to-noise ratio. The effect of the saturation of the nonlinearity on correlation performance is investigated and is shown to be able to improve correlator recognition and discrimination. The correlation results of binary images and of a highresolution synthetic-aperture radar image are presented, demonstrating excellent optical quality, nonlinear edge enhancement, and real-time operation.

Holographic interferometry using anisotropic self-diffraction in Bi_12SiO_20

Anisotropic self-diffraction in photorefractive Bi(12)SiO(20) crystals is applied to the investigation of dynamic holographic recording through the diffusion process. Specific attention is paid to optimization of experimental parameters for real-time holographic interferometry. The resultant interferometer is applied to obtain both timeaverage and double-exposure interferograms of vibrating and displaced structures.

Photochromism and dynamic holographic recording in a rigid solution of fluorescein

An investigation was made of the spectra, the kinetics of induction and thermal decay and the dichroism of the photoinduced triplet absorption band in a rigid solution of fluorescein in orthoboric acid. Dynamic holographic recording was possible on this material. An experimental study was conducted into the polarizing properties of the volume transmission holograms. The experiments on four-wave mixing with continous laser light revealed a very high resolution for this rigid solution when used as a medium for optical recording. As a result of the investigations, some possible applications of the rigid solution of fluorescein are pointed out.

Dynamic holograms in semiconducting (ZnSe)x–(GaP)1–xcrystals

Dynamic holographic recording and erasure was investigated for the first time in a new class of mixed ZnSe)x–(GaP)1–x semiconductor crystals. At high excitation rates the Auger recombination process became important and it limited seriously the diffraction efficiency of nonequilibrium-carrier holograms. This process and the absorption of light by free carriers results in additional heating of crystals and formation of thermal holograms.

Application of phase conjugation in Bi 12Si O 20 crystals to mode pattern visualisation of diffuse vibrating structures

We analyse in this paper the dynamic holographic recording and phase conjugation of 3-D diffuse objects in photorefractive B.S.O. crystals. Application of these concepts to mode pattern visualisation of a vibrating loudspeaker membrane is demonstrated.