Effect of Fe³⁺on third-order optical nonlinearity of KDP single crystals

Abstract

A series of trace Fe 3+ -doped KH 2 PO 4 single crystals were grown using the conventional temperature cooling method. The Fe 3+ ion content in the as-grown crystals and the corresponding transmission spectrum were measured, respectively. With an increase of Fe 3+ ion concentration, the transmittance of the crystal gradually decreases within the wavelength range of 200 nm to 370 nm. Under picosecond pulse laser irradiation, third-order nonlinear optical characteristics were systematically measured at λ = 532 nm. The existence of nonlinear absorption and nonlinear refraction was demonstrated. The results show that the nonlinear refractive index n 2 is positive, indicating the presence of a self-focusing effect for the asgrown crystals. Specially, nonlinear absorption and refraction have a heavy dependence on the Fe 3+ ion content and crystal directions (II and z). With increasing Fe 3+ ion concentration, a significant variation has been observed with respect to the nonlinear absorption coefficient β, nonlinear refractive index n 2 and third-order nonlinear susceptibility χ (3) . A similar pattern for II < z has been presented for nonlinear absorption and refraction. The investigations suggest that nonlinear absorption and refraction caused by distortion of the electron cloud might be associated with the H 2 PO 4 − and (FeO 4 ) 2− groups.

Optimizing Structural, Microhardness, Surface Growth Mechanism, Luminescence and Thermal Traits of KH2PO4 Crystal Exploiting Multidirectional H‐Bonding Quality of Dopant Tartaric Acid

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Optical Properties of the Fresnoite Ba2TiSi2O8 Single Crystal

“…The Ba2TiSi2O8 crystals are in the solid state rather than the liquid state, so there likely is no molecular orientation effect. In this experiment, the magnitude of (esu) was about 10 −13 , so we hypothesized that the nonlinear absorption of BTS is most likely related to electron cloud distortion [26,34].…”

Rapid growth of a long-seed KDP crystal

“…The high-power lasers used in the inertial confinement fusion (ICF) system worldwide need large KDP-type crystals as nonlinear crystals on account of their exceptional properties [1][2][3][4][5][6] . The major limitation to growing such large KDP-type crystals by the traditional method is the slow growth rate, leading to a growth cycle of 1-2 years [7][8][9][10][11] . Fortunately, the 'point-seed' rapid growth method was developed in the 1980s [12,13] .…”