Measurement of Refractive Index and Absorption Coefficient of Congruent and Stoichiometric Lithium Niobate in the Terahertz Range

Unferdorben, Márta; Szaller, Zs.; Hajdara, Ivett; Hebling, J.; Pálfalvi, László

doi:10.1007/s10762-015-0165-5

Cited by 64 publications

(29 citation statements)

References 14 publications

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“…The results of refractive index and absorption coefficient lower than 0.9 THz at different temperatures were unrevealed, which are essential in the intense THz generation by the tilted pulse front method. Although Unferdorben et al recently reported the measurements by using a THz time-domain spectrometer (THz-TDS) on a series of lithium niobate crystals with parallel surfaces [25], the results of temperature dependence are still lacking.…”

Section: Introductionmentioning

confidence: 99%

“…The temperature was varied from 300 K to 50 K in the THz-TDS system. We measured the refractive index and absorption coefficient for both ordinary (THz polarization parallel to the X-axis of lithium niobate crystal) and extraordinary polarizations (THz polarization parallel to the Z-axis) [25] at different crystal temperatures. Based on the temperature dependent measurements, we find that cryogenic cooling not only decreases the absorption for THz waves but also decreases the refractive index of the crystal in the THz frequency range, which makes the optimization conditions for low temperature and room temperature not the same.…”

Section: Introductionmentioning

confidence: 99%

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Temperature dependent refractive index and absorption coefficient of congruent lithium niobate crystals in the terahertz range

Zhou

Huang

et al. 2015

Opt. Express

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Optical rectification with tilted pulse fronts in lithium niobate crystals is one of the most promising methods to generate terahertz (THz) radiation. In order to achieve higher optical-to-THz energy efficiency, it is necessary to cryogenically cool the crystal not only to decrease the linear phonon absorption for the generated THz wave but also to lengthen the effective interaction length between infrared pump pulses and THz waves. However, the refractive index of lithium niobate crystal at lower temperature is not the same as that at room temperature, resulting in the necessity to re-optimize or even re-build the tilted pulse front setup. Here, we performed a temperature dependent measurement of refractive index and absorption coefficient on a 6.0 mol% MgO-doped congruent lithium niobate wafer by using a THz time-domain spectrometer (THz-TDS). When the crystal temperature was decreased from 300 K to 50 K, the refractive index of the crystal in the extraordinary polarization decreased from 5.05 to 4.88 at 0.4 THz, resulting in ~1° change for the tilt angle inside the lithium niobate crystal. The angle of incidence on the grating for the tilted pulse front setup at 1030 nm with demagnification factor of −0.5 needs to be changed by 3°. The absorption coefficient decreased by 60% at 0.4 THz. These results are crucial for designing an optimum tilted pulse front setup based on lithium niobate crystals.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Temperature dependent refractive index and absorption coefficient of congruent lithium niobate crystals in the terahertz range

Zhou

Huang

et al. 2015

Opt. Express

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“…In ISRS excitation, the excited volume is the sample thickness of 500 µm. On the other hand, the THz radiation is strongly absorbed leading to an excitation depth (and therefore excited volume) of only ~ 60 µm [23]. The bottom-axis shows the 800 nm fluence for the ISRS traces, and the upper-axis shows the peak-topeak field strength for THz excitation, and the inset is a zoomed-in look at the lower amplitude region.…”

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confidence: 99%

Experimental determination of the interatomic potential in LiNbO3 via ultrafast lattice control

Dastrup

Hall

Johnson

2017

Applied Physics Letters

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We present a direct comparison between resonant terahertz (THz) and nonresonant impulsive stimulated Raman scattering (ISRS) excitation of phonon-polaritons in ferroelectric lithium niobate. THz excitation offers advantages of selectively driving only the forward propagating phonon-polariton mode to exceedingly high amplitudes, without complications due to nonlinear processes at the high 800 nm pump fluences used in Raman excitation. At peak-to-peak THz electric field strengths exceeding 1 MV/cm, the ferroelectric lattice is driven into the anharmonic regime, allowing experimental determination of the shape of the potential energy surface.Ultrafast control over a crystalline lattice is of interest in developing a basic understanding of how light can influence material properties, as well as potential practical applications such as the development of ultrafast switches and a variety of optoelectronic applications [1][2][3][4]. Strong THz radiation, with frequencies resonant to the modes of interest, has been promoted as a preferred means of lattice control [1] over two common routes: displacive excitation [5,6] and nonresonant Raman excitation of vibrations [7][8][9]. In typical displacive-type excitation, energy is deposited into the material's electronic subsystem, transiently distorting the lattice. Such excitation may coherently drive many modes simultaneously, but potentially leaves large amounts of (unwanted) incoherent thermal energy. Nonresonant ultrafast Raman excitation, termed impulsive stimulated Raman scattering (ISRS) [7-9], can coherently excite lattice modes without the excess thermal energy, but it is an inefficient process and thus extremely high-fluence laser pulses are required to a

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“…LiNbO 3 has negative birefringence and smaller extraordinary absorption compared to ordinary both in the optical and in the THz ranges [16,17].…”

Section: Resultsmentioning

confidence: 99%

Index of Refraction and Absorption Coefficient Spectra of Paratellurite in the Terahertz Region

Unferdorben

Buzády

Hebling

et al. 2016

J Infrared Milli Terahz Waves

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Index of refraction and absorption coefficient spectra of pure paratellurite (α-TeO 2 ) crystal as a potential material for terahertz (THz) applications were determined in the 0.25-2 THz frequency range at room temperature by THz time domain spectroscopy (THz-TDS). The investigation was performed with beam polarization both parallel (extraordinary polarization) and perpendicular (ordinary polarization) to the optical axis

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Measurement of Refractive Index and Absorption Coefficient of Congruent and Stoichiometric Lithium Niobate in the Terahertz Range

Cited by 64 publications

References 14 publications

Temperature dependent refractive index and absorption coefficient of congruent lithium niobate crystals in the terahertz range

Temperature dependent refractive index and absorption coefficient of congruent lithium niobate crystals in the terahertz range

Experimental determination of the interatomic potential in LiNbO3 via ultrafast lattice control

Index of Refraction and Absorption Coefficient Spectra of Paratellurite in the Terahertz Region

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