EFFECTIVE NONLINEAR OPTICAL COEFFICIENT OPTIMIZATION METHOD FOR LANGASITE GROUP SOLID SOLUTION CRYSTALS

Abstract

An effective nonlinear optical coefficient optimization method for langasite group solid solution crystals is disclosed. The langasite group crystal A.sub.3BC.sub.3D.sub.2O.sub.14 mainly includes langanite (LGN) crystal, langatate (LGT) crystal and langasite (LGS) crystal. The solid solution crystals are formed by adjusting a component proportion of langasite group crystals with the same structure, so that different ions mix and occupy sites in a polyhedral group, and a polyhedral lattice structure, distortion degree, refractive index and refractive dispersion of the solid solution crystal are changed. The reduction of the phase matching angle and the improvement of the nonlinear optical coefficient are realized, and the effective nonlinear optical coefficient is finally optimized.

Claims

1. An effective nonlinear optical coefficient optimization method for langasite group solid solution crystals, wherein the langasite group crystal A.sub.3BC.sub.3D.sub.2O.sub.14 mainly comprises langanite (LGN) crystal, langatate (LGT) crystal and langasite (LGS) crystal; the solid solution crystals are formed by adjusting a component proportion of langasite group crystals with the same structure, so that different ions mix and occupy sites in a polyhedral group, and a polyhedral lattice structure, distortion degree, refractive index and refractive dispersion of the solid solution crystal are changed.

2. The effective nonlinear optical coefficient optimization method for langasite group solid solution crystals of claim 1, wherein the langanite crystals, langatate crystals or langasite crystals with the same crystal structure and similar composition are mutually dissolved in different proportions to form solid solution crystals, so that the B-site and/or D-site structure of langasite group crystals is changed.

3. The effective nonlinear optical coefficient optimization method for langasite group solid solution crystals of claim 1, wherein the B-site group is mixed with and occupied by Ga.sup.3+, Nb.sup.5+, Ta.sup.5+, Ti.sup.4+, Zr.sup.4+, Hf.sup.4+, Sn.sup.4+, and Sb.sup.5+ ions.

4. The effective nonlinear optical coefficient optimization method for langasite group solid solution crystals of claim 1, wherein the D-site group is mixed with and occupied by Ga.sup.3+, Ge.sup.4+, Si.sup.4+ ions.

5. The effective nonlinear optical coefficient optimization method for langasite group solid solution crystals of claim 1, wherein different ions mix and occupy sites in two types of polyhedral groups of B-site and D-site at same time; Ga.sup.3+ and Zr.sup.4+ ions mix and occupy sites at the B-site, and Ga.sup.3+ and Si.sup.4+ ions mix and occupy sites at the D-site to form lanthanum gallium zirconate solid solution crystals.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to explain the embodiments of the present disclosure or the technical solutions in the prior art more clearly, the following drawings that need to be used in the description of the embodiments or the prior art will be briefly introduced. Obviously, the drawings in the following description are only embodiments of the present disclosure. For those of ordinary skill in the art, other drawings can be obtained based on the drawings disclosed without creative work.

[0014] FIG. 1 is a diagram showing the refractive index comparison of the solid solution crystals of LGNT with Nb.sup.5+/Ta.sup.5+ ratios of 0.9:0.1 and 0.7:0.3, and the crystals of LGN and LGT provided in embodiment 2 of the present disclosure.

[0015] FIG. 2 shows the comparison of the nonlinear optical coefficient of the solid solution crystals of LGNT with Nb.sup.5+/Ta.sup.5+ ratios of 0.9-0.1 and 0.7.0.3 provided in embodiment 2 of the present disclosure.

[0016] FIG. 3 is a diagram showing the comparison of type I phase matching tuning curves of LGNT solid solution crystals with Nb.sup.5+/Ta.sup.5+ ratios of 0.9:0.1 and 0.7:0.3, and LGN crystals and LGT crystals provided in embodiment 2 of the present disclosure.

[0017] FIG. 4 is a diagram showing the comparison of type II phase matching tuning curves of LGNT solid solution crystals with Nb.sup.5+/Ta.sup.5+ ratios of 0.9:0.1 and 0.7:0.3, and LGN crystals and LGT crystals provided in embodiment 2 of the present disclosure.

[0018] FIG. 5 is a structural diagram of the langasite group crystal A.sub.3BC.sub.3D.sub.2O.sub.14 provided by the present disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] Technical solutions of the embodiments of the present disclosure will be clearly and completely described below with reference to the attached drawings. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of them. Based on the embodiments of the disclosure, all other embodiments made by those skilled in the art without sparing any creative effort should fall within the protection scope of the disclosure.

[0020] The embodiments of the present disclosure provide an effective nonlinear optical coefficient optimization method for langasite group solid solution crystals. The gallium silicate lanthanide crystal A.sub.3BC.sub.3D.sub.2O.sub.14 mainly includes langanite (LGN) crystal, langatate (LGT) crystal and langasite (LGS) crystal. The solid solution crystals are formed by adjusting a component proportion of langasite group crystals with the same structure, so that different ions mix and occupy sites in a polyhedral group, and a polyhedral lattice structure, distortion degree, refractive index and refractive dispersion of the solid solution crystal are changed.

[0021] In order to further optimize the above technical scheme, the langanite crystals, langatate crystals or langasite crystals with the same crystal structure and similar composition are mutually dissolved in different proportions to form solid solution crystals, so that the B-site and/or D-site structure of langasite group crystals is changed.

[0022] In order to further optimize the above technical scheme, the B-site group is mixed with and occupied by Ga.sup.3+, Nb.sup.5+, Ta.sup.5+, Ti.sup.4+, Zr.sup.4+, Hf.sup.4+, Sn.sup.4+, and Sb.sup.5+ ions.

[0023] In order to further optimize the above technical scheme, the D-site group is mixed with and occupied by Ga.sup.3+, Ge.sup.4+, Si.sup.4+ ions.

[0024] In order to further optimize the above technical scheme, different ions mix and occupy sites in two types of polyhedral groups of B-site and D-site. Ga.sup.3+ and Zr.sup.4+ ions mix and occupy sites at the B-site, and Ga.sup.3+ and Si.sup.4+ ions mix and occupy sites at the D-site to form lanthanum gallium zirconate solid solution crystals.

[0025] The provided nonlinear optical are the lanthanum gallium niobate tantalate solid solution crystals of langasite group, with the chemical formula of La.sub.3Ga.sub.5.5(Nb.sub.1-xTa.sub.x).sub.0.5O.sub.14, belonging to the trigonal crystal system, 32 point group. There are type I (the polarization mode of the two incident beams is the same, and both are e light) and type I (the polarization directions of the two incident beams are different, one is o light and the other is e light) of phase matching. The corresponding effective second-order nonlinear coefficient is d.sub.eff=d.sub.11 cos.sup.2θ sin 3φ (type I phase matching) and d.sup.eff=d.sub.11 cos θ φ(type II phase matching). θ is the phase matching angle, and φ is the azimuth angle. The B-site group accommodates many ions such as Ga.sup.3+, Nb.sup.5+, Ta.sup.5+, Ti.sup.4+, Zr.sup.4+, Hf.sup.4+, Sn.sup.4+, Sb.sup.5+, etc. The distortion degree of the B-site group can be increased and the nonlinear optical coefficient can be increased by different ion mixing and occupying modes. At the same time, the electron cloud structures of different ions have some differences, and the refractive index and refractive index dispersion of the crystals can be adjusted, the phase matching angle can be reduced, and then the effective nonlinear optical coefficient can be increased. In addition, many ions such as Ga.sup.3+, Nb.sup.5+, Ta.sup.5+, Ti.sup.4+, Zr.sup.4+, Hf.sup.4+, Sn.sup.4+ and Sb.sup.5+ have similar ion radii, and have good lattice matching degree, which can form infinite solid solution crystals and easily obtain large-size single crystals with high optical quality. At the same time, the D-site group can also accommodate a variety of ions, such as Ga.sup.3+, Ge.sup.4+, Si.sup.4+.

[0026] Embodiment 1: Taking the LGNT solid solution crystals formed by LGN crystals and LGT crystals as an example, the LGNT solid solution crystals with Nb.sup.5+/Ta.sup.5+ ratio of 0.5:0.5 are designed. The specific molar ratio of the four raw materials, La.sub.2O.sub.3, Ga.sub.2O.sub.3, Nb.sub.2O.sub.5 and Ta.sub.2O.sub.5, is 0.3:0.55:0.025:0.025. The crystals belong to the trigonal crystal system, 32 point group. With the change of Nb.sup.5+/Ta.sup.5+ component ratio, the distortion of B-site group increases, which is conducive to increase the nonlinear optical coefficient. At the same time, the refractive index and refractive index dispersion of the crystals change, which can reduce the phase matching angle and is beneficial to increase the effective nonlinear optical coefficient of the crystals.

[0027] Embodiment 2: The following LGNT solid solution crystals with different Nb.sup.5+/Ta.sup.5+ ratios are designed. For example, the specific molar ratio of the four raw materials, La.sub.2O.sub.3, Ga.sub.2O.sub.3, Nb.sub.2O.sub.5 and Ta.sub.2O.sub.5, of the LGNT solid solution crystals with different Nb.sup.5+/Ta.sup.5+ ratios of 0.9:0.1, 0.7:0.3, 0.3:0.7, 0.1:0.9, etc. can be 0.3:0.55:0.045:0.005, 0.3:0.55:0.035:0.015, 0.3:0.55:0.015:0.035, 0.3:0.55:0.005:0.045. This series of solid solution crystals also maintain the crystal structures of LGN and LGT, and the refractive index of this group of crystals can be continuously adjusted, so that the phase matching angle can be changed and the effective nonlinear optical coefficient can be increased.

[0028] Embodiment 3: Taking the LZGS solid solution crystals formed by LGZr and LGS as an example, the La.sub.3Zr.sub.0.5Ga.sub.5Si.sub.0.5O.sub.14 solid solution crystals with Zr.sup.4+/Si.sup.4+ ratio of 0.5:0.5 are designed. The specific molar ratio of the four raw materials, La.sub.2O.sub.3, Ga.sub.2O.sub.3, ZfO.sub.2 and SiO.sub.2, is 0.3:0.5:0.1:0.1. The crystals belong to the trigonal crystal system, 32 point group. The B-site and the D-site are respectively occupied by Ga.sup.3+/Zr.sup.4+ and Ga.sup.3+/Si.sup.4+ ions, so that the degree of distortion of the B-site group and the D-site group is increased, which is beneficial to increasing the nonlinear optical coefficient. At the same time, the refractive index and the refractive index dispersion of the crystals change accordingly, which can reduce the phase matching angle, and is beneficial to increase the effective nonlinear optical coefficient of the crystals.

[0029] Embodiment 4: Taking the LZGS solid solution crystals formed by LGZr and LGS as an example, the LZGS solid solution crystals with different Zr.sup.4+/Si.sup.4+ ratios are designed. For example, the specific molar ratio of the four raw materials, La.sub.2O.sub.3, Ga.sub.2O.sub.3, ZrO.sub.2 and SiO.sub.2, of the solid solution crystals with different Zr.sup.4+/Si.sup.4+ ratios of 0.9:0.1, 0.7:0.3, 0.3-0.7, 0.1:0.9, etc. can be 0.3:0.5:0.18:0.02, 0.3:0.5:0.14:0.06, 0.3:0.5:0.06:0.14, 0.3:0.5:0.02:0.18. The crystals belong to the trigonal crystal system, 32 point group. The B-site and the D-site are respectively jointly occupied by Ga.sup.3+/Zr.sup.4+ and Ga.sup.3+/Si.sup.4+ ions, so that the degree of distortion of the B-site group and the D-site group is increased, which is beneficial to increasing the nonlinear optical coefficient. At the same time, adjusting the refractive index and refractive index dispersion of the crystals can reduce the phase matching angle and increase the effective nonlinear optical coefficient of the crystals.

[0030] Various embodiments in the present specification are described in a progressive manner, and the emphasizing description of each embodiment is different from the other embodiments. The same and similar parts of various embodiments can be referred to for each other. For the apparatus disclosed in the embodiments, since the apparatus corresponds to the method disclosed in the embodiments, the description is simplified, and reference may be made to the method part for description.

[0031] The above description of the disclosed embodiments enables those skilled in the art to realize or use the present disclosure. Many modifications to these embodiments will be apparent to those skilled in the art. The general principle defined herein can be realized in other embodiments without departing from the spirit or scope of the present disclosure. Therefore, the present disclosure will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principle and novel features disclosed herein.