共查询到20条相似文献,搜索用时 46 毫秒
1.
A. Thompson N. Nazhestkina A. Siahmakoun G. Duree N. Roesler 《Applied physics. B, Lasers and optics》2003,76(5):547-554
We present experimental investigations of electrical fixing techniques in Ce:SBN:60. The effect of crystal fatigue on the
diffraction efficiency of electrically fixed photorefractive gratings is studied. We observed that applying an ac field to
the crystal eliminated crystal fatigue and improved diffraction efficiency. A controllable diffraction efficiency of a photorefractive
grating is presented. A reproducible diffraction efficiency of up to 75% is obtained using a write-reveal grating technique
with high-voltage pulses of opposite polarity. We also show that the diffraction efficiency can be controlled by varying the
intensity of the writing beams incident to the crystal during the recording process. A method of determining the hysteresis
loop using the domain-fixing technique is proposed. The dependence of the diffraction efficiency on the direction of the applied
electric field while writing the hologram is studied. Our experiments show that, during writing, when the electric field is
applied opposite to the c axis the grating can be successfully revealed with both positive and negative dc voltages. However,
when the grating is written with a field parallel to the c axis, the grating can be revealed only with a field applied in
the opposite direction.
Received: 28 October 2002 / Revised version: 28 February 2003 / Published online: 14 May 2003
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ID="*"Corresponding author. Fax: +1-812/872-6167, E-mail: azad.siahmakoun@rose-hulman.edu 相似文献
2.
M. Weber F. Rickermann F. Abbing G. von Bally 《Applied physics. B, Lasers and optics》1999,68(5):1069-1072
A holographic double-exposure interferometer for quasi real-time analysis is realized, utilizing a photorefractive BTO:Cd
crystal for hologram recording. Heating of the crystal reduces the time required to reach the steady-state working situation.
Light-induced absorption losses are reduced by heating as well. Additionally, the diffraction efficiency is increased by this
method. A sixfold increase in the light intensity of the reconstructed interferogram is achieved.
Received: 2 December 1998 / Revised version: 28 January 1999 / Published online: 7 April 1999 相似文献
3.
We present a compact holographic interferometer that uses a photorefractive crystal of the sillenite family as a holographic
recording medium. Its development is based on a previous prototype that showed lack of flexibility and portability. We briefly
discuss the main improvements leading to a compact device. Applications of this instrument in various metrological problems
are shown, among which are two that were not already considered using holography, namely measurement of a thermal expansion
coefficient and detection of fingerprints.
Received: 20 December 2000 / Revised version: 8 February 2001 / Published online: 20 April 2001 相似文献
4.
Jorge A. Gómez Edgar RuedaÁngel Salazar Myriam TebaldiNestor Bolognini Alberto Lencina 《Optics and Lasers in Engineering》2012,50(3):359-365
In this work, we show that it is possible to change the properties of an optical vortex formed in a speckle pattern by the control of an external electric field applied to a sillenite-type photorefractive material in a non-holographic configuration. To show it, a scheme that allows the recovering of both, the polarization state and the phase distribution of an optical field was implemented. Changes in the polarization state of the light in the neighborhood of the vortex were observed with the application of an external electric field. Likewise, changes in the phase structure around the vortex and displacements of the vortices themselves were measured. These displacements have a fairly linear dependence on the applied field to the photorefractive crystal. Experimental results are qualitatively explained with the theoretical treatment of non-holographic recording in photorefractive crystals. 相似文献
5.
We present the development of a holographic interferometer that uses a photorefractive crystal of the sillenite family as
holographic recording medium. The aim of this work is to achieve a transportable and breadboard instrument, with a flexible
design and which is user friendly for the quantified measurements of displacements on large scattering objects. The state
of the art of the use of photorefractive crystals in holographic interferometry is presented. Based on the latter, a method
that is the best suited to our mentioned objectives is chosen: the real-time interferometric technique associated with the
crystal configuration exhibiting diffraction anisotropy. On this basis, we have studied and compared two imaging systems,
we have experimentally determined the holographic figures of merit of three sillenite crystals samples, and, finally, we have
shown the use of two measurement quantification methods. The result of these investigations is a certified and transportable
holographic camera prototype containing all the necessary equipment for its operation, which can be easily adapted to various
applications. Among these, we show its use in the detection of defects in composite structures, in the measurement of time-evolving
deformations, and in the measurement of vibration modes.
Received: 4 December 1998 / Revised version: 6 March 1999 / Published online: 12 April 1999 相似文献
6.
Efficient frequency-doubling is experimentally demonstrated in presence of beam self-trapping in congruent lithium niobate crystal. The self-trapping is induced by the generated second harmonic beam via photorefractive effect under an external applied field. The local space charge field distribution, formed by the second harmonic beam, is shown to efficiently trap both wavelengths. The dynamics of self-focusing is studied along with the power evolution of the second harmonic beam. Fast tuning of phase matching conditions in the written waveguide is realized by an externally applied voltage also used for the photorefractive confinement. 相似文献
7.
Roman V. Romashko Yuri N. Kulchin Alexei A. Kamshilin 《Journal of Russian Laser Research》2010,31(1):55-60
A multichannel adaptive interferometer based on dynamic reflecting holograms multiplexing in a photorefractive crystal of
cubic symmetry is proposed. The efficiency of hologram multiplexing is studied theoretically and experimentally. For the recording
geometry used, a crosstalk between channels is shown to be less than the single-channel inherent noise for a wide angular
range of beams entering the crystal, and the sensitivity depletion in one channel is insignificant for a large number of channels. 相似文献
8.
A.A. Kamshilin K. Paivasaari N.I. Nazhestkina V.V. Prokofiev S. Ashihara Y. Iida T. Shimura K. Kuroda 《Applied physics. B, Lasers and optics》1999,68(5):1031-1038
The experimental study of the in-plain vibration of the speckle pattern in photorefractive GaP and BTO crystals using the
polarization self-modulation effect are presented. The simple model based on the propagation of the Gaussian beam through
the crystal with recorded space-charge field is proposed to explain main features of the experiment. It is shown that these
results allow designing a linear sensor of the speckle-pattern displacement in an effective way. The optical system is very
simple and does not include any reference or readout beam. The sensitivity of this system is the same as that of an interferometer.
Received: 27 November 1998 / Revised version: 26 January 1999 / Published online: 12 April 1999 相似文献
9.
强外加电场与大调制度下光折变动力学光栅形成研究 总被引:1,自引:0,他引:1
强外加电场与大调制度在光折变效应的研究中已经得到了广泛应用。采用PDECOL算法,严格求解光折变带输运方程,得到外加电场时不同调制度下光折变晶体中随时间变化的空间电荷场、载流子浓度,并讨论了外加电场对它们的影响。通过将物质方程与耦合波方程联立数值求解,可得到光折变光栅形成过程中两波耦合增益系数以及光束条纹相位的变化。模拟结果表明,在强外加电场作用下,两束记录光之间的光强与相位耦合都得到了增强,而原有的解析式忽视了强外加电场与大调制度对空间电荷场相位耦合的影响,此时不再适用。同时发现折射率光栅与记录光束条纹均发生弯曲,并不再保持平行。 相似文献
10.
M.P. Petrov A.P. Paugurt V.V. Bryksin S. Wevering B. Andreas E. Krätzig 《Applied physics. B, Lasers and optics》1999,69(4):341-344
During holographic recording in photorefractive crystals (BSO, BGO, and BTO) by an oscillating interference pattern we observe
a strong dynamic deflection of the laser beams reflected from the crystal’s surface. The theoretical treatment shows that
this new effect is associated with a nonlinear interaction of space charge gratings resulting in a quasi-homogeneous oscillating
space charge field which provides deformations of the crystal via the piezoelectric effect.
Received: 3 August 1999 / Accepted 5 August 1999 / Published online: 8 September 1999 相似文献
11.
O. T. Kamenev Yu. S. Petrov R. V. Hizhnyak I. N. Zavestovskaya Yu. N. Kulchin R. V. Romashko 《Bulletin of the Lebedev Physics Institute》2017,44(7):202-204
A prototype of a mobile laser seismometer based on a multiturn fiber-optic sensitive element and an adaptive holographic interferometer is developed. The possibility of recording weak seismic waves propagating in the “land-sea” interface region by the laser seismometer is shown. The original multiturn design of the sensitive element of the seismometer provides a threshold sensitivity of 1.6 · 10?7 m/s2 to seismic acceleration. The long-term operation stability of the laser seismometer is provided due to adaptive properties of the interferometer constructed using a dynamic hologram formed in the photorefractive bismuth titanate crystal. 相似文献
12.
The dynamics of the photorefractive response in the Bi12TiO20 crystal with double-ionized donor centers and shallow traps is analyzed. Consideration is given to the time dependences of the recording of a photorefractive grating in the absence of an external electric field, its storage in the dark, and its development upon the application of an external field and turning on of a reading light beam. 相似文献
13.
It is shown that under uniform illumination and application of an external electric field, a phase volume hologram in a photorefractive crystal exists in the form of relaxing running wave. Effective recording of such a running hologram is possible only by an interference pattern moving synchronously with the recorded grating. The physical nature of this phenomenon, the possible enhancement of the hologram diffraction efficiency upon recording of a running pattern and the main factors limiting its value are discussed for the case of photorefractive Bi12SiO20 crystals. 相似文献
14.
A novel setup for imaging and interferometry through reflection holography with Bi12TiO20(BTO) sillenite photorefractive crystals is proposed. A variation of the lensless Denisiuk arrangement was developed resulting in a compact, robust and simple interferometer. A red He-Ne laser was used as light source and the holographic recording occurred by diffusion with the grating vector parallel to the crystal [0 0 1]-axis. In order to enhance the holographic image quality and reduce noise a polarizing beam splitter (PBS) was positioned at the BTO input and the crystal was tilted around the [0 0 1]-axis. This enabled the orthogonally polarized transmission and diffracted beams to be separated by the PBS, providing the holographic image only. The possibility of performing deformation and strain analysis as well as vibration measurement of small objects was demonstrated. 相似文献
15.
The signal-to-noise ratio of the output of an adaptive holographic interferometer (AHI) based on a Bi(12)TiO(20) crystal is investigated. We show experimentally that the sensitivity of an AHI using the non-Bragg orders of diffraction in a thin photorefractive material is more than an order of magnitude greater than that of an AHI employing two-wave mixing in photorefractive volume holograms. 相似文献
16.
A novel method of obtaining shearing interferogram by slightly moving the crystal in a photorefractive interferometer is proposed. This method can measure the phase of an object itself instead of its diffraction field, and it is easy to realize continuously changeable shearing distance in any lateral direction and introduce carrier fringes at the same time. Both the theoretical analysis and experimental verification are given. 相似文献
17.
A method of detecting the magnetic field variation is proposed and implemented experimentally. The method employs the rotation
of the speckle pattern of light transmitted through an optical fiber that is placed into a longitudinal magnetic field and
the recording of a holographic grating in a photorefractive crystal using the speckle field. The possibility of detecting
the shape of a 0.15-s magnetic field pulse is demonstrated experimentally. 相似文献
18.
Salvatore Di Girolamo Roman V. Romashko Alexei A. Kamshilin 《Optics Communications》2010,283(1):128-317
We present a novel configuration of an interferometer which is implemented by using vectorial wave mixing in the orthogonal geometry of wave interaction in a cubic photorefractive crystal, for the detection of small phase transients. The orthogonal geometry of wave interaction allows the linear regime of the phase-to-intensity transformation even when phase transients are encrypted in a depolarized wave without using any polarizing element. The use of a depolarized beam without a polarizing element strongly diminishes the noise level, thus increasing the sensitivity to phase transients. 相似文献
19.
The performance of an adaptive interferometer based on mixing of light waves with different polarization states in a photorefractive GaP crystal at lambda=0.633mum is described. Both high sensitivity and fast response time are achieved with a low-power He-Ne laser. The parameters of the interferometer are appropriate for remote ultrasound detection in an industrial environment. 相似文献
20.
We find a way to record and retrieve images in a photorefractive LiNbO3 crystal using a single white light source instead of a coherent light source. According to the experimental results, we think this recording is not due to the recording of fanning gratings, but a variation of refractive index responding to the non-uniform illumination. We have also simulated the recording using the band transport model taking into account the photovoltaic effect. The simulation result agrees with the experimental results. 相似文献