A bismuth-based infrared nonlinear optical crystal, a preparation method and use thereof

Abstract

The application belongs to the technical field of inorganic nonlinear optical materials, and particularly discloses a bismuth-based infrared nonlinear optical crystal, a preparation method and application thereof. The molecular formula of the optical crystal is RbBiP2S6, and the crystal structure belongs to a monoclinic system and a space group P21. The optical crystal has excellent second-order nonlinear optical properties, can realize phase matching in an infrared waveband, has a wide light transmission range, and has strong infrared frequency doubling response. The powder frequency doubling intensity of the optical crystal can reach 10-15 times of that of a commercial material AgGaS2, and the laser damage threshold of the optical crystal is 9-13 times of that of an AgGaS2 crystal. The optical crystal has important application value in high-tech fields such as laser frequency conversion, near-infrared probe and photorefractive information processing, and is particularly used for infrared detectors and infrared lasers.

Description

Technical Field

[0001] This invention belongs to the field of inorganic nonlinear optical materials technology, specifically relating to a bismuth-based infrared nonlinear optical crystal, its preparation method and applications. Background Technology

[0002] Nonlinear optical crystals are a very important class of optoelectronic functional materials, with wide applications in laser communication, optical information processing, integrated circuits, and military technology. Generally speaking, an ideal nonlinear optical crystal must meet the following conditions: (1) a large second-order frequency doubling coefficient; (2) a high laser damage threshold; (3) an appropriate birefringence; (4) a wide optical transmission range; and (5) good physicochemical and mechanical properties. Nonlinear optical materials can be classified into inorganic materials, organic materials, polymer materials, and organometallic complex materials according to their physicochemical properties. Currently, most commercially available nonlinear optical crystals are inorganic materials, which can be divided into three main categories according to their application bands: ultraviolet, visible, and infrared. Among them, nonlinear optical crystal materials in the ultraviolet and visible bands can already meet the requirements of practical applications.

[0003] Nonlinear optical crystal materials in the infrared band are mainly ABC2-type chalcopyrite-structured semiconductor materials, such as AgGaS2, AgGaSe2, and ZnGeP2. These compounds possess large nonlinear optical coefficients and high mid-to-far infrared transmittance, but they also suffer from serious drawbacks such as low laser damage threshold and two-photon absorption, thus limiting their applications. Therefore, exploring novel infrared nonlinear optical crystal materials with promising applications is a current challenge and hot topic in the field of nonlinear optical materials research. Summary of the Invention

[0004] This invention aims to provide a bismuth-based infrared nonlinear optical crystal, its preparation method and applications. This optical crystal material has excellent second-order nonlinear optical properties, can achieve phase matching in the infrared band, and its powder frequency doubling intensity can reach 10 to 15 times that of commercial material AgGaS2. Moreover, its laser damage threshold is 9 to 13 times that of AgGaS2 crystal, thus achieving a good balance between a large second-order frequency doubling coefficient and a high laser damage threshold.

[0005] This invention provides the following technical solution:

[0006] The present invention provides an optical crystal with the molecular formula RbBiP2S6.

[0007] According to an embodiment of the present invention, the optical crystal has a monoclinic crystal system, a space group of P21, and a unit cell parameter of... α=90°, β=90~95°, γ=90°.

[0008] For example, the unit cell parameters of the optical crystal are: α=90°, β=93.09±0.1°, γ=90°.

[0009] According to an embodiment of the present invention, the optical crystal has a non-central two-dimensional layered structure, formed by highly polarized [BiS7] polyhedra and ethane-like [P2S6] polyhedra interconnected through shared vertices S; the alkali metal ion Rb + It is dispersed and filled between the layers of the two-dimensional layered structure to serve as a charge balance.

[0010] Preferably, the optical crystal has the following structure: Figure 1 As shown.

[0011] According to an embodiment of the present invention, the optical crystal has substantially the following characteristics: Figure 2 The X-ray crystal diffraction pattern shown in 'a' is an example of this pattern.

[0012] According to an embodiment of the present invention, the optical crystal is an infrared nonlinear optical crystal.

[0013] According to an embodiment of the present invention, the powder frequency doubling intensity of the optical crystal is 10 to 15 times that of commercial material AgGaS2 crystal, for example, 11.9 times.

[0014] According to an embodiment of the present invention, the laser damage threshold of the optical crystal is 9 to 13 times that of commercial material AgGaS2 crystal, for example, 11.3 times.

[0015] The present invention also provides a method for preparing the above-mentioned optical crystal, comprising the following steps: mixing raw materials uniformly, and preparing the optical crystal by a high-temperature solid-state method;

[0016] The raw materials include: bismuth oxide (Bi2O3), elemental B, elemental P, elemental S, and alkali metal halide RbX.

[0017] According to an embodiment of the present invention, in the alkali metal halide RbX, X is selected from Cl, Br or I, preferably I.

[0018] According to an embodiment of the present invention, the molar ratio of Bi2O3, B, P, S and RbX can be 1:(1.5-2.5):4:12:(1-5).

[0019] Preferably, the molar ratio of Bi2O3, B, P, S and RbI is 1:2:4:12:(1-3). For example, the molar ratio of Bi2O3, B, P, S and RbI is 1:2:4:12:2.

[0020] According to an embodiment of the present invention, the high-temperature solid-state method specifically includes: placing the raw material into a sealed container and placing it in a heating device, heating to a high temperature, maintaining the temperature at a high temperature, and cooling to room temperature to obtain the optical crystal. In this invention, room temperature refers to a temperature not exceeding 100°C, preferably not exceeding 50°C.

[0021] Preferably, the high-temperature solid-state method is carried out under vacuum conditions. More preferably, the sealed container has a vacuum environment, for example, a vacuum pressure of 10... -4 ~10 -3 Pa.

[0022] Preferably, the sealed container is a sealed quartz reaction tube.

[0023] Preferably, the heating refers to heating to a holding temperature, which is selected from 500 to 1000°C, preferably 600 to 800°C. For example, the temperature can be 700°C.

[0024] Preferably, the high-temperature insulation time is not less than 50 hours, and more preferably 100 to 150 hours. For example, the high-temperature insulation refers to insulation at 700°C for 120 hours.

[0025] Preferably, the cooling refers to cooling the product prepared by the high-temperature solid-state method, preferably cooling it to 150-300°C at a rate not exceeding 3°C / hour and then cooling it to room temperature; for example, cooling it to 200°C at a rate not exceeding 2°C / hour and then cooling it to room temperature.

[0026] Preferably, the preparation method further includes washing and drying the product obtained by natural cooling to room temperature to obtain the optical crystal, for example, washing with water (e.g., deionized water) and drying with ethanol.

[0027] The present invention also provides an optical crystal prepared by the above method, wherein the optical crystal has the meaning as described above.

[0028] The present invention also provides applications for the above-mentioned optical crystal, such as for use in infrared detectors, infrared lasers, photorefractive information processing, etc.

[0029] The present invention also provides uses for the above-described optical crystal, such as for laser frequency conversion.

[0030] The present invention also provides uses for the above-described optical crystal, such as for near-infrared probes.

[0031] The present invention also provides an infrared detector containing the aforementioned optical crystal.

[0032] The present invention also provides an infrared laser comprising the aforementioned optical crystal.

[0033] The beneficial effects of this invention are:

[0034] This invention provides a bismuth-based infrared nonlinear optical crystal material with excellent second-order nonlinear optical properties, namely, phase matching in the infrared band, moderate birefringence, wide transmission range, and strong frequency doubling response. Its frequency doubling intensity can reach 10 to 15 times that of commercial material AgGaS2, and its laser damage threshold is 9 to 13 times that of AgGaS2 crystal, thus achieving a good balance between a large second-order frequency doubling coefficient and a high laser damage threshold.

[0035] This infrared nonlinear optical crystal has important application value in high-tech fields such as laser frequency conversion, near-infrared probes, and photorefractive information processing, especially for infrared detectors and infrared lasers. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the RbBiP2S6 crystal structure of the present invention.

[0037] Figure 2 This is the X-ray diffraction pattern of the sample RbBiP2S6 prepared in Example 1. Detailed Implementation

[0038] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention, and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0039] Unless otherwise stated, the raw materials and reagents used in the following examples are commercially available products or can be prepared by known methods.

[0040] Example 1

[0041] Bi₂O₃, B, P, S, and RbI were mixed evenly in a molar ratio of 1:2:4:12:2 to obtain the raw material. The raw material was placed in a carbon-coated quartz crucible, and the crucible containing the raw material was placed in a quartz reaction tube. A vacuum of 10⁻⁶ was then applied. -3 Pa was used to melt and seal the quartz reaction tube with an oxyhydrogen flame. The quartz reaction tube was placed in a tube furnace equipped with a temperature controller and heated to 700°C, which was maintained for 120 hours. Then, the temperature was programmed to decrease to 200°C at a rate not exceeding 2°C / hour, and then heating was stopped. After natural cooling to room temperature, the product was washed with deionized water and dried with ethanol. The resulting red blocky crystal was the infrared nonlinear optical crystal material RbBiP2S6, denoted as Sample 1.

[0042] (1) Structural characterization of the sample

[0043] X-ray single-crystal diffraction of the sample in Example 1 was performed on a Mercury 724 single-crystal diffractometer with a Mo target and K. α The radiation source was λ = 0.07107 nm, and the test temperature was 293 K. The structure was analyzed using a Shelx-2014 crystallography system. The crystallographic data of the sample are shown in Table 1, and the crystal structure diagram is shown below. Figure 1 As shown.

[0044] Table 1 Crystallographic data of sample RbBiP2S6

[0045]

[0046] The resulting crystal structure is mainly composed of highly polarized [BiS7] polyhedra and ethane-like [P2S6] polyhedra, interconnected through shared vertices S to form a two-dimensional layered structure, with alkali metal Rb. + They act as charge-balancing ions, filling the spaces between layers in a two-dimensional layered structure.

[0047] X-ray powder diffraction (XRD) phase analysis was performed on sample 1 using a Rigaku MiniFlex II X-ray diffractometer with a Cu target and K0. α Radiation source (λ = 0.154184 nm). The XRD pattern obtained by fitting the powder XRD pattern of sample 1 with the single crystal diffraction data is shown below. Figure 2 As shown. By Figure 2 As can be seen, the XRD pattern of sample 1 ( Figure 2 The XRD pattern obtained by fitting a) of the single-crystal diffraction data to the XRD pattern ( Figure 2 This is consistent with b) in Example 1, indicating that the sample obtained in Example 1 has a high degree of crystallinity and purity (purity reaches over 95%).

[0048] (2) Characterization of optical properties of the sample

[0049] The powder frequency doubling performance and laser damage threshold of the samples are shown in Table 2.

[0050] Table 2 Optical performance data of the samples

[0051]

[0052] The exemplary embodiments of the present invention have been described above. However, the scope of protection of this application is not limited to the above embodiments. Any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An optical crystal, characterized in that, The molecular formula of the optical crystal is RbBiP2S6. The optical crystal has a monoclinic crystal system and a space group of [missing information]. P 21. The unit cell parameters of the optical crystal are a=6.72±0.05Å, b=7.41±0.05Å, c=10.21±0.05Å, α=90°, β=93.09±0.1°, and γ=90°.

2. The optical crystal according to claim 1, characterized in that, The optical crystal has a non-central two-dimensional layered structure, formed by highly polarized [BiS7] polyhedra and ethane-like [P2S6] polyhedra interconnected through shared vertices S; alkali metal ions Rb + It is dispersed and filled between the layers of the two-dimensional layered structure to serve as a charge balance.

3. The optical crystal according to claim 1, characterized in that, The optical crystal is an infrared nonlinear optical crystal; The frequency doubling intensity of the optical crystal powder is 10 to 15 times that of commercial material AgGaS2 crystal; The laser damage threshold of the optical crystal is 9 to 13 times that of the commercial material AgGaS2 crystal.

4. The method for preparing the optical crystal according to any one of claims 1-3, characterized in that, The preparation method includes the following steps: mixing the raw materials evenly, and preparing the optical crystal by a high-temperature solid-state method; The raw materials include: bismuth oxide, elemental B, elemental P, elemental S and alkali metal halide RbX.

5. The preparation method according to claim 4, characterized in that, In the alkali metal halide RbX, X is selected from Cl, Br or I; The molar ratio of Bi2O3, B, P, S and RbX is 1:1.5~2.5:4:12:1~5.

6. The preparation method according to claim 5, characterized in that, The molar ratio of Bi2O3, B, P, S and RbI is 1 : 2 : 4 : 12 : 1~3.

7. The preparation method according to claim 5, characterized in that, The molar ratio of Bi2O3, B, P, S and RbI is 1 : 2 : 4 : 12 :

2.

8. The preparation method according to claim 4, characterized in that, The high-temperature solid-state method specifically includes: loading the raw material into a sealed container and placing it in a heating device, heating it to a holding temperature for high-temperature holding, and then cooling it to room temperature to obtain the optical crystal; the holding temperature is selected from 500~1000℃, and the high-temperature holding time is not less than 50 hours. The high-temperature solid-state method is carried out under vacuum conditions; the sealed container has a vacuum environment with a vacuum pressure of 10. -4 ~10 - 3 Pa; The sealed container is a sealed quartz reaction tube; The cooling process includes cooling to 150-300°C at a rate not exceeding 3°C / hour, followed by natural cooling to room temperature.

9. The preparation method according to claim 8, characterized in that, The insulation temperature is 600~800℃; The high-temperature insulation time is 100-150 hours. The cooling process involves cooling the temperature to 200°C at a rate not exceeding 2°C / hour, and then cooling it back to room temperature.

10. The preparation method according to claim 4, characterized in that, The preparation method further includes washing and drying the product obtained by natural cooling to room temperature to obtain the optical crystal.

11. Use of the optical crystal according to any one of claims 1-3 for use in infrared detectors, infrared lasers, or photorefractive information processing.

12. Use of the optical crystal according to any one of claims 1-3 for laser frequency conversion.

13. Use of the optical crystal according to any one of claims 1-3 for use in a near-infrared probe.

14. An infrared detector, characterized in that, The infrared detector contains the optical crystal according to any one of claims 1-3.

15. An infrared laser, characterized in that, The infrared laser contains the optical crystal according to any one of claims 1-3.

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