Two-dimensional photorefractive spatial solitons in centrosymmetric paraelectric potassium–lithium–tantalate–niobate

DelRe, Eugenio; Tamburrini, M.; Segev, Mordechai; Refaeli, Eli; Agranat, Aharon J.

doi:10.1063/1.121708

Cited by 67 publications

(32 citation statements)

References 15 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…For these, no electro-optic modulation effects are possible: for whatever value of external constant electric field E ext , the original soliton supporting guiding pattern remains unchanged. In centrosymmetrics, such as photorefractive potassium-lithium-tantalate-niobate (KLTN), solitons are supported by the quadratic electro-optic effect [12] [13] [14] [15]. In this case, the "nonlinear" combination of the internal photorefractive field with an external electric field can give rise to new and useful soliton-based electro-optic phenomena, which we here study for the first time.…”

mentioning

confidence: 99%

“…(1a) Fig. (1b), where a 11µm soliton is formed for u Experiments are carried out with an apparatus that is well documented in literature [13] [14]. An enlarged TEM 00 Gaussian beam from a CW Argon-ion laser operating at λ =514nm, is focused be means of an f=150mm cylindrical lens onto the input facet of an 3.7 (x) × 4.6 (y) × 2.4 (z) mm sample of zero-cut paraelectric KLTN, at T=20…”

mentioning

confidence: 99%

See 1 more Smart Citation

Soliton electro-optic effects in paraelectrics

DelRe

Tamburrini²,

Agranat³

2000

Opt. Lett.

Self Cite

View full text Add to dashboard Cite

The combination of charge separation induced by the formation of a single photorefractive screening soliton and an applied external bias field in a paraelectric is shown to lead to a family of useful electro-optic guiding patterns and properties.Apart from their inherent interest as peculiar products of nonlinearity, spatial solitons hold the promise of allowing viable optical steering in bulk environments [1] [2]. Photorefractive screening solitons differ from other known manifestations of spatial self-trapping for their peculiar ease of observation and versatility [3], and recent experiments in photorefractive strontium-bariumniobate (SBN) and potassium-niobate (KNbO 3 ) have demonstrated two conceptual applications of their guiding properties. In the first case, a tunable directional coupler was realized making use of two independent slabsolitons [4]; in the second, self-induced phase-matching was observed to enhance second-harmonic-generation [5]. Although results suggest a means of obtaining all-optical functionality, actual implementation is hampered by the generally slow nonlinear response [6], that can be "accelerated" only at the expense of stringent intensity requirements [7]. In contrast, non-dynamic guiding structures have been observed by fixing a screening soliton [8], or in relation to the observation of spontaneous selftrapping during a structural crystal phase-transition [9]. One possible method of obtaining acceptable dynamics is to make directly use of the electro-optic properties of the ferroelectrics involved, in combination with the internal photorefractive space charge field deposited by the soliton. Since photorefractive charge-activation is wavelength dependent, one can induce charge separation in soliton-like structures at one active wavelength (typically visible), and then read the electrooptic index modulation at a different, nonphotorefractive, wavelength (typically infrared) [10] [11]. For noncentrosymmetric samples (such as the above mentioned crystals) that typically host screening soliton formation, the electro-optic index of refraction modulation is proportional to the static crystal polarization P, and thus to the electric field (linear electro-optic effect). For these, no electro-optic modulation effects are possible: for whatever value of external constant electric field E ext , the original soliton supporting guiding pattern remains unchanged. In centrosymmetrics, such as photorefractive potassium-lithium-tantalate-niobate (KLTN), solitons are supported by the quadratic electro-optic effect [12] [13] [14] [15]. In this case, the "nonlinear" combination of the internal photorefractive field with an external electric field can give rise to new and useful soliton-based electro-optic phenomena, which we here study for the first time.The basic mechanism leading to screening soliton formation is the following: a highly diffracting optical beam ionizes impurities hosted in the lattice of an electro-optic crystal. An externally applied electric field makes these mobile charges drift...

show abstract

mentioning

confidence: 99%

mentioning

confidence: 99%

Soliton electro-optic effects in paraelectrics

DelRe

Tamburrini²,

Agranat³

2000

Opt. Lett.

Self Cite

View full text Add to dashboard Cite

show abstract

“…5 It it imprinted in the soliton-supporting screening charge distribution. If a positive soliton is formed by biasing of the sample with V 1V sol and is supported by the resulting E sc , its negative optical twin, formed with V 2V sol , is supported by 2E sc .…”

mentioning

confidence: 99%

“…Photorefractive solitons, 1,2 which have opened the way to an array of novel nonlinear effects, are considered one of the promising avenues for achieving a new generation of beam-steering and -manipulation devices. 3 The observation of twodimensional solitons, 4,5 i.e., beams that propagate in a bulk environment without suffering diffraction or distortion in both transverse directions (needle solitons), permits the integration of a bulk material with the confined propagation of an optical circuit. Circumventing the refined and costly development of a waveguide growth technology, needle self-trapping opens the door to guided coupling from one spatial mode to another in three dimensions.…”

mentioning

confidence: 99%

See 1 more Smart Citation

Electro-optic beam manipulation through photorefractive needles

et al. 2002

Self Cite

View full text Add to dashboard Cite

show abstract

Observation of Two-Dimensional Spatial Solitons in Iron-Doped Barium-Calcium Titanate Crystals

Shandarov

Wesner

et al. 2002

phys. stat. sol. (a)

View full text Add to dashboard Cite

Subject classification: 42.65. Dp; 78.20.Jq Since the discovery of photorefractive spatial solitons [1,2], these non-diffracting waves have been the subject of an intense research effort, because they are particularly interesting for building alloptical diodes, transistors, switches, and all-optical computers. Until now steady-state bright spatial solitons have been observed in BTO [3], SBN [4], InP:Fe [5], KNbO 3 [6], KLTN [7], and BaTiO 3 [8] crystals. Barium-calcium titanate (BCT) [9, 10] is a promising photorefractive material and an alternative to BaTiO 3 , which is much easier to grow and does not have any phase transition within the temperature range from À120 C to 100 C. This crystal also possesses slightly larger electrooptic coefficients r 13 (20 pm/V) and r 33 (130 pm/V) compared to BaTiO 3 . However, no studies of photorefractive spatial soliton formation have been reported so far in BCT crystals. In this contribution, we investigate photorefractive spatial soliton formation in iron-doped BCT crystals and observe, for the first time to our knowledge, the formation of steady-state two-dimensional (2D) screening solitons in this material.Samples of the congruently melting composition Ba 0:23 Ca 0:77 TiO 3 are grown in the crystalgrowth laboratory of the Department of Physics at the University of Osnabr€uck [9, 10]. The dimension of our sample that is doped with 290 ppm Fe is 5 Â 5 Â 5 mm 3 . All surfaces are polished to optical quality. On both faces normal to the c-axis of the crystal, electrodes are prepared with silver paste. The light propagates along the a-axis in our experiment. Our experiments are conducted in a standard setup for soliton formation, in which an external electric field E 0 is applied along the ferroelectric c-axis. A frequency-doubled Nd:YAG laser (l ¼ 532 nm) is used as the light source. Because of the low dark conductivity of our sample s d % 6 Â 10 À14 W À1 cm À1 [9], a background illumination is necessary to tune the degree of saturation of the nonlinearity. This ordinarily polarized background light of the same wavelength 532 nm is made spatially incoherent by passing it through a rotating diffuser. The ratio r between the soliton light intensity (extraordinary polarization) and the background irradiance is r % 5. The soliton intensity is always kept below 50 mW/cm 2 to minimize photovoltaic self-defocusing. Figure 1 shows a characteristic result of 2D soliton formation. In this experiment, the beam intensity is I % 30 mW/cm 2 . The beam diameter at the crystal's input face is d in % 14 mm. Without an external electric field E 0 applied, the beam width d increases during propagation due to both, phys. stat. sol. (a) 189, No. 1, R4-R5 (2002) # WILEY-VCH Verlag Berlin GmbH, 13086 Berlin, 2002 0031-8965/02/18901-00R4 $ 17.50þ.50/0 Fig. 1. Formation of 2D solitons in BCT crystals. a) Images of the input beam (left hand), the diffracted output beam (center) and the selftrapped soliton beam (right hand). b) Horizontal (parallel to c-axis, k) and vertical (perpendicular to c-axis...

show abstract

Two-dimensional photorefractive spatial solitons in centrosymmetric paraelectric potassium–lithium–tantalate–niobate

Abstract: We report the observation of steady-state two-dimensional photorefractive self-trapping and screening spatial soliton formation in a sample of potassium–lithium–tantalate–niobate in the centrosymmetric paraelectric phase.

Cited by 67 publications

References 15 publications

Soliton electro-optic effects in paraelectrics

Soliton electro-optic effects in paraelectrics

Electro-optic beam manipulation through photorefractive needles

Observation of Two-Dimensional Spatial Solitons in Iron-Doped Barium-Calcium Titanate Crystals

Contact Info

Product

Resources

About