Feedback-controlled two-wave coupling in reflection geometry: application to lithium niobate crystals subjected to extremely high external electric fields

Gorkunov, M. V.; Sturman, B.; Luennemann, M.; Buse, K.

doi:10.1007/s00340-003-1258-8

Cited by 12 publications

(9 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…(17) and (18) we express by the intensity ratio for the recording waves ␤ = ͉R͉ 2 / ͉S͉ 2 (taken at z = 0 and d) and the phase difference = arg͑R d S d R 0 * S 0 * ͒,…”

Section: ͑20͒mentioning

confidence: 99%

Description of readout processes during strong beam coupling

Sturman

Giel²

2004

Phys. Rev. E

Self Cite

View full text Add to dashboard Cite

We show, using the symmetry properties of the coupled-wave equations for the transmission and reflection geometries, that any readout characteristic of dynamic spatially nonuniform index gratings in photorefractive crystals can be explicitly expressed through the characteristics of the recording light beams. This approach is applied to describe the impact of beam coupling on the diffraction efficiency of dynamic gratings and on the output intensities of the light beams at instantaneous input phase changes (light grating translation). Further implications of this general approach are discussed.

show abstract

“…(17) and (18) we express by the intensity ratio for the recording waves ␤ = ͉R͉ 2 / ͉S͉ 2 (taken at z = 0 and d) and the phase difference = arg͑R d S d R 0 * S 0 * ͒,…”

Section: ͑20͒mentioning

confidence: 99%

Description of readout processes during strong beam coupling

Sturman

Giel²

2004

Phys. Rev. E

Self Cite

View full text Add to dashboard Cite

show abstract

“…18 By using these techniques, phase-locked photorefractive waves moving at constant velocities have been generated in different applications. [28][29][30] In a recent paper, Bryushinin and Sokolov 31 presented an optoelectronic feedback loop suitable for generating photorefractive wave oscillations. The developed method is based on the effect of the non-steady-state photoelectromotive force ͑photo-emf͒ and positive feedback.…”

Section: Introductionmentioning

confidence: 99%

Oscillating holograms recorded in photorefractive crystals by a frequency detuned feedback loop

Freschi

Telles

Frejlich

et al. 2009

Journal of Applied Physics

View full text Add to dashboard Cite

We report an optoelectronic feedback loop suitable for generating noise-free interference patterns oscillating at arbitrary waveforms. The technique allows controlling the frequency detuning between the interfering beams through a phase modulator in a closed-loop interferometer. We use the dither signal method and propose a quasisynchronous demodulation scheme to create a phase modulated error signal for driving the loop. The dynamics of the interference fringes is easily controlled by a voltage waveform from a function generator, which is used in association with a time delay circuit for shifting the frequency of the reference signal used for lock-in demodulation. The technique is specially suited for applications involving low-frequency phase oscillations, such as those frequently encountered in the generation of space-charge waves in highly resistive photorefractive materials. The processing scheme allows real time monitoring of the hologram strength, and absolute values for the diffraction efficiency and the holographic phase shift can be obtained. Photorefractive wave oscillations ranging from approximately 100 mHz to 10 Hz were produced in a nominally undoped Bi 12 TiO 20 sample. The technique can be readily applied to other fields of optical interferometry, such as for testing optical surfaces, optimizing adaptive holographic devices, measuring physical quantities, among other applications.

show abstract

“…A congruently melted LiNbO 3 : Fe crystal with an iron concentration N Fe ' 18 Â 10 18 cm À3 and a thickness d ¼ 0:22 mm was used in the feedback experiments [36,37]. The polar axis was perpendicular to the input faces.…”

Section: Resultsmentioning

confidence: 99%

“…Both analytical and numerical calculations give a positive answer to this question [36,37]. Thus the feedback is expected to lead to the resonant excitation of weakly damped space-charge waves.…”

Section: Application To Linbo 3 : Fe Crystalsmentioning

confidence: 93%

“…Experimental and theoretical studies of the feedback-controlled beam coupling and grating recording in LiNbO 3 crystals have led to the following main results for the reflection case [36,37]: The AEp=2 feedback ensures maximization of the diffraction efficiency of the dynamic index grating. The feedback brings the system to a steady state (not to a periodic state); this state is characterized by a frequency shift between the light beams (moving grating).…”

Section: Introductionmentioning

confidence: 97%

See 1 more Smart Citation

Feedback-Controlled Photorefractive Beam Coupling

Sturman

Podivilov

Gorkunov

et al.

Springer Series in Optical Sciences

View full text Add to dashboard Cite

Implementation of certain electronic feedbacks between the optical output and input is able not only to stabilize the photorefractive setups against phase fluctuations, but also to shape the characteristics of grating recording and beam coupling. In particular, the feedback can make the index gratings fully diffractive and transparent. We summarize the results of experimental and theoretical studies of the feedback-controlled beam coupling. This includes the feedback loop specification, an analysis of the operation modes of the whole nonlinear system, a description of the observable characteristics, and comparison with experiment. We consider both the transmission and reflection coupling geometries and touch upon the major applications.It is important that the feedback-controlled beam coupling represents a fundamentally new nonlinear system, which has no close analogs among the known optical phenomena. This is concerned with several aspects: Formulation of the feedback conditions for the light amplitudes requires a refined notion of the diffractive properties of dynamic index gratings-it cannot be accomplished in the terms of spatially-uniform gratings. Inertia of the feedback loop ensures the permanent operation of the whole system. The conventional set of dynamic equations for the light and grating amplitudes, being supplemented by the feedback conditions, ceases often to admit both the traditional means for analytical analysis and the familiar steady-state solutions. Instead of a steady state, the system arrives at a periodic state that is characterized by a strong phase modulation.

show abstract

Feedback-controlled two-wave coupling in reflection geometry: application to lithium niobate crystals subjected to extremely high external electric fields

Cited by 12 publications

References 13 publications

Description of readout processes during strong beam coupling

Description of readout processes during strong beam coupling

Oscillating holograms recorded in photorefractive crystals by a frequency detuned feedback loop

Feedback-Controlled Photorefractive Beam Coupling

Contact Info

Product

Resources

About