Optical transmission spectra and electrical properties of langasite and langatate crystals as dependent on growth conditions

Бузанов, О. А.; Козлова, Н. С.; Забелина, Е. В.; Козлова, А. П.; Siminel, Nikita

doi:10.1134/s1063739711080063

Cited by 14 publications

(10 citation statements)

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“…An absorption band at λ ~490 nm is observed in LGS and LGT Fo and M19 spectra was previously attributed to F centers (VO •• , 2é) and to orange coloration [16]. The defect responsible for the absorption band at 450 nm can be at the origin of the green color of LGT Fo.…”

Section: Uv-visible Spectroscopymentioning

confidence: 91%

“…LGT crystal color depends on the growth atmosphere and the post growth treatment, and it is H. Kimura et al [15] and O.A Busanov et al [16] observed that the color of LGS and LGT crystals depends on the oxygen partial pressure in growth atmosphere. The color of LGT crystals decreases progressively in intensity when the Oxygen concentration in an Argon-Oxygen growth atmosphere is reduced [16].…”

Section: Electron Color Centersmentioning

confidence: 99%

“…The color of LGT crystals decreases progressively in intensity when the Oxygen concentration in an Argon-Oxygen growth atmosphere is reduced [16]. Different researchers [4] [5] [9] [11] [13] studied the relationship between the color and the composition of LGT crystals using Xray (XRD) and neutron diffraction (ND).…”

Section: Electron Color Centersmentioning

confidence: 99%

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Color Origins in Langatate Crystals

Allani¹,

Batis²,

Nehari³

et al. 2017

Int. Ann. Sci.

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A B S T R A C TLangatate La3Ga5.5Ta0.5O14 is piezoelectric crystal from langasite family, commonly grown by Czochralski method from Ir crucible. Langatate crystals of different colors (colorless, orange, green) have been studied by optical spectroscopy in UV-Visible (200 -800 nm) and IR (7000 -1000 cm -1 ) ranges. Furthermore, the effects of irradiation by ultraviolet laser source (λ=266 nm) and post-growth annealing in N2+O2 atmosphere have been investigated. The yellow-orange is mainly due to an absorption centered in the ultraviolet that extends into the blue of the visible spectrum (250-500 nm). The IR optical absorption spectra of Langatate crystals exhibit an absorption band at 5370 cm -1 . It seems linked to a point defect responsible for color. The intensity of the absorption band at 3430 cm -1 increases after annealing in oxygen containing atmosphere. We have discussed phenomenon that can occur simultaneously in langatate crystals and produce very similar colors which are related to structural defects. First, metal ions impurities (as Iron, Titanium…), whose presence is previously confirmed by femtosecond laser ablation coupled with ICP-MS spectroscopy, can contribute to langatate color. Second, ultraviolet absorption leads us to think about charge transfer phenomenon such as O 2-→ Fe 3+ and/or Fe 3+ -Fe 3+ pair transitions. Third, the irradiation by ultraviolet (λ=266 nm) laser source locally color the langatate sample by the creation of color centers. Origins of color centers, particularly those related to oxygen vacancies, (V O .. , 2e′) x , are discussed. And, finally, point defects changes the band gap of langatate, leading to extend the absorption to visible light regions.

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Section: Uv-visible Spectroscopymentioning

confidence: 91%

Section: Electron Color Centersmentioning

confidence: 99%

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Color Origins in Langatate Crystals

Allani¹,

Batis²,

Nehari³

et al. 2017

Int. Ann. Sci.

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“…One can see that they are well described by a squared dependences. The fit of obtained data by Y=A·X 2 law allowed us to reveal the value of the second order nonlinear susceptibility χ (2) . One can see that in LGS crystal χ (2) is 7 times higher than that in quartz and 2.8 times lower than that in LiIO 3 .…”

mentioning

confidence: 99%

“…Originally LGS crystal was proposed as a laser host materials [1]. It has high transmission in visible and near IR spectral regions [2]. Developing of multifunctional laser materials that combine high laser and nonlinear properties is a challenge of modern laser physics.…”

mentioning

confidence: 99%

Second harmonic generation in langasite crystal

Zverev¹,

Shilova²

2014

2014 International Conference Laser Optics

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The second order nonlinear susceptibility was measured in langasite crystal. It was found to be 7 times larger than that in quartz.Langasite crystal (LGS, chemical formula La 3 Ga 5 SiO 14 ) is well known piezoelectric material. It exhibits a unique combination of optical and physical properties, including high piezo-, acousto-and electro-optical coefficients. These features allows LGS to be used not only in acoustoelectronics, but also in laser physics. Originally LGS crystal was proposed as a laser host materials [1]. It has high transmission in visible and near IR spectral regions [2]. Developing of multifunctional laser materials that combine high laser and nonlinear properties is a challenge of modern laser physics. That's why the aim of this work was to investigate SHG and measure the second order nonlinear susceptibility of LGS.Due to small birefringence there is no direction in LGS crystal that can satisfy phase-matching condition for second harmonic generation (SHG) of 1.064 m radiation. Table 1 presents the literature the calculated results for coherence length of SHG (type I) of 1.064 µm radiation in the direction perpendicular to the optical axis in LGS, LiIO 3 and quartz crystals. To proceed comparative measurements of SHG in the above crystals we used powders of these crystals with the grain size of the order of the coherence length [3].LGS single crystal was grown by Czochralski technique in "FomosMaterials" company. TABLE I. LITERATURE DATA OF REFRACTIVE INDEX AND THE CALCULATED COHERENCE LENGTH FOR LGS, LIIO3 AND QUARTZ CRYSTALS. Crystal nо(ω) nе(2ω) lcoh, µm LiIO3 [4] 1,8571 1,7480 2,43 Quartz [4] 1,535 1,556 12,66 La3Ga5SiO14 [5] 1,877 1,923 5,761The experimental setup used a single-frequency YAG:Nd laser operating at a wavelength of 1.064 m. The pump radiation was focused to the crystal powder at a small angle. The back-scattering radiation including SHG radiation was collected by a lens and delivered by the fiber to the input slit of the Ocean Optics spectrometer.The dependence of the SHG intensity vs pump power is presented in Fig.1. One can see that they are well described by a squared dependences. The fit of obtained data by Y=A·X 2 law allowed us to reveal the value of the second order nonlinear susceptibility χ (2) . One can see that in LGS crystal χ (2) is 7 times higher than that in quartz and 2.8 times lower than that in LiIO 3 . From the known χ (2) value for LiIO 3 we calculated χ (2) values for LGS and quartz and estimated maximal values of nonlinear susceptibility tensor d (Table 2). One can see that d value in quartz is very close to literature data. While d value in LGS is higher than that obtained in [5]. We attributed this to better optical quality of the samples used in our experiments. TABLE II. THE VALUES OF SECOND ORDER NONLINEAR SUSCEPTIBILITY AND AVERAGED CALCULATED. Crystal , m/V d, m/V (exp) d, m/V [4]LGS 5,

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