Angle-multiplexed storage of 5000 holograms in lithium niobate

Mok, Fai

doi:10.1364/ol.18.000915

Cited by 534 publications

(173 citation statements)

References 5 publications

Supporting

Mentioning

171

Contrasting

Order By: Relevance

“…[1][2][3] However, erasure of the holograms during readout has been one of the major problems in the practical realization of holographic read/write memories. We recently proposed a method to solve this problem by using doubly doped LiNbO 3 .…”

mentioning

confidence: 99%

Effect of annealing in two-center holographic recording

Adibi

Buse

1999

Applied Physics Letters

View full text Add to dashboard Cite

Persistent holograms are recorded with red light in lithium niobate crystals doped with manganese and iron. We find that the oxidation/reduction state of the crystal has a profound impact on the recording and readout performance. The underlying physical processes are investigated and the recording and readout responses are explained and optimized. © 1999 American Institute of Physics. ͓S0003-6951͑99͒05325-5͔Photorefractive materials are the best reversible storage materials known so far and several holographic storage demonstrators using iron-doped photorefractive lithium niobate (LiNbO 3 :Fe) were presented in the last few years. 1-3 However, erasure of the holograms during readout has been one of the major problems in the practical realization of holographic read/write memories. We recently proposed a method to solve this problem by using doubly doped LiNbO 3 . 4 In this letter, we explain the effects of annealing the crystal on the performance of the recently proposed twocenter recording method.In the recent work, 4 LiNbO 3 doped with manganese ͑Mn͒ and iron ͑Fe͒ was used. The energy band diagram of such a crystal is shown in Fig. 1. Fe and Mn ions occur in the valence states Mn 2ϩ/3ϩ and Fe 2ϩ/3ϩ , 5 and thermal depletion plays no role in room temperature. Electrons can be excited by ultraviolet light either from Mn 2ϩ or from Fe 2ϩ into the conduction band while red light excites electrons only from the shallower Fe 2ϩ . The conduction-band electrons can recombine with both centers, and thus, ultraviolet illumination populates the Fe 2ϩ/3ϩ level partially while red light illumination empties the Fe sites. The filled Fe levels cause a broad-band absorption in the visible with a maximum at a 477 nm wavelength. 6 Thus, ultraviolet light sensitizes the material while red light bleaches it. The basic idea of twocenter holographic recording is to bring with the ultraviolet light electrons from Mn to Fe via the conduction band, use these electrons to record the hologram with red light, and eventually transfer the electrons from iron back to the manganese centers by red light. This results in a hologram stored in Mn centers that persists against further red illumination.One of the key material parameters in two-center holographic recording is the initial electron concentration in Mn and Fe traps. These concentrations can be varied by an annealing treatment. 7 Since Mn traps are deeper in the band gap than Fe traps, electrons would fill the Mn traps before Fe traps when the crystal is reduced. For persistent holographic recording, it is necessary that the final hologram be stored in Mn centers. Therefore, it is essential that at the end of the annealing process all Fe traps be empty, and only a portion of the Mn traps be filled. To investigate the effect of the oxidation/reduction state of the crystal we performed experiments with four x-cut congruent LiNbO 3 crystals doped with 0.075 wt % Fe 2 O 3 and with 0.01 wt % MnO. The crystals were all from the same boule. The samples were strongly oxidized ͑LN1͒, oxidized ͑...

show abstract

mentioning

confidence: 99%

Effect of annealing in two-center holographic recording

Adibi

Buse

1999

Applied Physics Letters

View full text Add to dashboard Cite

show abstract

“…The basic approach to be employed for this makes use of a holographic video disk, which is discussed in detail in reference 22. Since the query clips have to be periodically refreshed, based on the event of interest, one can make use of a rewritable memory, namely a lithium niobate crystal 34,35 . During the operation of the AER system, the data read from the crystal will be made co-linear with the data read from the holographic video disc using a 50/50 beam splitter, as illustrated in figure 14.…”

Section: Implementing Aer Employing a Vapor Cell A Holographic Videomentioning

confidence: 99%

All optical three dimensional spatio-temporal correlator for automatic event recognition using a multiphoton atomic system

Monjur

Fouda

Shahriar

2016

Optics Communications

View full text Add to dashboard Cite

We describe an automatic event recognition (AER) system based on a three-dimensional spatio-temporal correlator (STC) that combines the techniques of holographic correlation and photon echo based temporal pattern recognition. The STC is shift invariant in space and time. It can be used to recognize rapidly an event (e.g., a short video clip) that may be present in a large video file, and determine the temporal location of the event. Using polar Mellin transform, it is possible to realize an STC that is also scale and rotation invariant spatially. Numerical simulation results of such a system are presented using quantum mechanical equations of evolution. For this simulation we have used the model of an idealized, decay-free two level system of atoms with an inhomogeneous broadening that is larger than the inverse of the temporal resolution of the data stream. We show how such a system can be realized by using a lambda-type three level system in atomic vapor, via adiabatic elimination of the intermediate state. We have also developed analytically a three dimensional transfer function of the system, and shown that it agrees closely with the results obtained via explicit simulation of the atomic response. The analytical transfer function can be used to determine the response of an STC very rapidly. In addition to the correlation signal, other nonlinear terms appear in the explicit numerical model. These terms are also verified by the analytical model. We describe how the AER can be operated in a manner such that the correlation signal remains unaffected by the additional nonlinear terms. We also show how such a practical STC can be realized using a combination of a porous-glass based Rb vapor cell, a holographic video disc, and a lithium niobate crystal.

show abstract

“…On the other hand, due to the high-density storage capacity of a volume hologram and its parallel processing property, holographic data storage has become the most promising candidate to meet the challenge. To increase the data storage capacity, many techniques based on the Bragg diffraction condition have been proposed, including angular multiplexing [11], phase multiplexing [12,13], wavelength multiplexing [14], and shift multiplexing [15,16].…”

Section: Introductionmentioning

confidence: 99%

Implementation of single-beam multiplexing encoding with a dually modulated spatial light modulator

et al. 2010

View full text Add to dashboard Cite

We propose a novel method for signal storage and encryption, called single-beam multiplexing encoding. The single beam is composed of an inside signal beam and an outside reference beam. The signal beam is amplitude modulated, and the reference beam is phase modulated. The dual modulation is implemented by a spatial light modulator (SLM). Multiplexing holography with different reference beams from different directions, called directional multiplexing, is analyzed in detail. With an SLM based on a twisted nematic liquid crystal display, we demonstrate a single-beam directional multiplexing method using a holographic encoding technique, and the retrieved signals are presented. This encoding system is more stable, miniaturized, and flexible. It should be of great interest for applications in signal encryption as well as for high-capacity data storage.

show abstract

Angle-multiplexed storage of 5000 holograms in lithium niobate

Cited by 534 publications

References 5 publications

Effect of annealing in two-center holographic recording

Effect of annealing in two-center holographic recording

All optical three dimensional spatio-temporal correlator for automatic event recognition using a multiphoton atomic system

Implementation of single-beam multiplexing encoding with a dually modulated spatial light modulator

Contact Info

Product

Resources

About