High thermal stability crosslinked electro-optic polymers, their preparation methods and applications

Abstract

This invention relates to the field of optical materials technology, and more particularly to a high thermal stability crosslinked electro-optic polymer, its preparation method, and its application. The preparation method of the crosslinked electro-optic polymer containing diazo compounds provided by this invention is simple and easy to implement. Highly efficient crosslinking can be achieved using only a small proportion of crosslinking agent. This is because the activation temperature of the crosslinking agent is slightly higher than the glass transition temperature of the polymer material's polarization. After electric field polarization, electro-optic properties are obtained while crosslinking and curing can be performed, resulting in an organic electro-optic thin film material with both high thermal stability and a high electro-optic coefficient.

Description

Technical Field

[0001] This invention relates to the field of optical materials technology, and in particular to highly thermally stable cross-linked electro-optic polymers, their preparation methods, and applications. Background Technology

[0002] Electro-optic polymers, as key materials for developing high-speed electro-optic modulators, have attracted much attention due to their promising applications in high-speed optical communication, optical computing, phased array radar, and sensing. Developing electro-optic polymers that simultaneously possess high electro-optic performance and high thermal stability is crucial for developing high-performance, high-reliability devices. However, under high-temperature conditions, the ordered arrangement of chromophore molecules in traditional electro-optic polymers undergoes a certain degree of relaxation, leading to a degradation in electro-optic performance. This problem severely restricts the practical application of these materials in devices. Among organic electro-optic material systems, host-guest doped electro-optic materials are the most widely studied. These systems are simple to fabricate, low in cost, and have good reproducibility. Commonly used polymers include polymethyl methacrylate (PMMA) and amorphous polycarbonate (APC). PMMA polymers, in particular, offer better optical transparency, are inexpensive, and have better adhesion, which is beneficial for subsequent device fabrication. However, they also suffer from a relatively low glass transition temperature (Tg), meaning that even after doping with chromophores, they still exhibit rapid electro-optic coefficient relaxation. Summary of the Invention

[0003] To address the aforementioned problems in the prior art, this invention provides a highly thermally stable crosslinked electro-optic polymer, its preparation method, and its application.

[0004] This invention discovers that crosslinking reactions can form stable three-dimensional network structures in electro-optic polymers. Specifically, this network structure can increase the glass transition temperature of the polymer film and restrict the orientation of chromophores, effectively reducing the nonlinear relaxation of the material and thus improving the long-term stability of the electro-optic coefficient. Furthermore, crosslinking reactions can improve the mechanical strength of the polymer, making it less prone to deformation or damage under external forces, thereby enhancing the overall stability of the material. The crosslinked polymer is relatively stable to various chemical substances such as water, acids, alkalis, and organic solvents. This stability allows the electro-optic polymer to maintain its structural integrity and performance in various environments.

[0005] The carbene crosslinking mechanism of this invention, which involves activation and insertion of active carbene C-H bonds, is applicable to all polymers and chromophore structures containing C-H bonds, making the crosslinking process more efficient. Diazo compounds, as carbene precursors, offer more convenient preparation and milder activation conditions (slightly above the glass transition temperature of organic materials, eliminating the need for high-temperature thermal initiation). This allows the crosslinking reaction to occur simultaneously with the polarization process of organic materials, enabling the polymer material to withstand higher voltages during polarization. Furthermore, the crosslinking reaction can be carried out in an air atmosphere without the need for an inert atmosphere, reducing environmental control requirements and facilitating practical applications. These advantages greatly broaden the application research of carbene crosslinking reactions in the field of electro-optic devices for high thermal stability organic electro-optic polymers.

[0006] Based on this, the present invention has the following technical solution:

[0007] In a first aspect, the present invention provides a cross-linked electro-optic polymer, wherein the cross-linked electro-optic polymer comprises a host polymer, the aforementioned organic chromophore, and a solid cross-linking agent, wherein the solid cross-linking agent is a diazo compound.

[0008] Preferably, the diazo compounds include any one or two of the following:

[0009] .

[0010] Preferably, the organic chromophore includes any one or more of BHG2, JRD1, HJD, F, HLD, and CLD:

[0011]

[0012]

[0013] In this invention, the organic chromophore molecule has a D-π-A structure. This invention has found that the electro-optic polymer containing the above-mentioned organic chromophore molecule uses diazo compounds as crosslinking agents to generate active carbene through heating effect. The active carbene then undergoes an insertion reaction with the CH bonds of the surrounding chromophore molecules and the main polymer chain segments to form a three-dimensional crosslinked network structure, thereby improving the long-term stability of the electro-optic coefficient of the polymer material.

[0014] Preferably, the mass ratio of the organic chromophore to the solid crosslinking agent is (2~10):1.

[0015] Preferably, the main polymer includes one or more of the following: polymethacrylate polymers, polymethacrylate copolymer polymers, polystyrene polymers, polycarbonate polymers, polyaryl ether polymers, and polyimide polymers.

[0016] Preferably, the cross-linked electro-optic polymer comprises the following components in parts by weight:

[0017] 50-80 parts of the main polymer,

[0018] Organic chromophores, 20-50 parts

[0019] 5-20 parts of solid crosslinking agent.

[0020] This invention provides a crosslinked electro-optic polymer containing diazo compounds. The prepared electro-optic polymer uses diazo compounds as crosslinking agents and as carbene precursors, which provides more convenient preparation and milder activation conditions (slightly higher than the glass transition temperature of organic materials, without the need for high-temperature thermal initiation). This allows the crosslinking reaction to occur simultaneously during the polarization process of organic electro-optic materials. The network structure formed by crosslinking can increase the glass transition temperature of the polymer film, restrict the orientation of chromophores, effectively suppress the relaxation phenomenon of the electro-optic coefficient of the material, and improve the long-term stability of the electro-optic coefficient of the polymer material.

[0021] Secondly, the present invention provides a method for preparing the cross-linked electro-optic polymer, comprising: dissolving the host polymer, the organic chromophore and the solid cross-linking agent in 1,1,2-trichloroethane, filtering, spin-coating the filtrate onto a glass substrate, and drying it under vacuum at room temperature.

[0022] In a preferred embodiment of the present invention, the method for preparing the cross-linked electro-optic polymer includes:

[0023] The main polymer is dissolved in 1,1,2-trichloroethane, and then the organic chromophore is added. After thorough and uniform dissolution, the mixture is filtered, and then a crosslinking agent is added. After dissolution, a mixed solution is obtained. The mixed solution is spin-coated onto an ITO glass substrate and vacuum dried at room temperature for 12 to 24 hours to obtain the electro-optic polymer. Preferably, the film thickness is 1 to 2 μm.

[0024] After the electro-optic polymer is made into a thin film, it is sputtered with a gold electrode and then polarized by an electric field to obtain electro-optic properties. At the same time, it is cross-linked and cured at the electric field polarization temperature to obtain an electro-optic thin film with a high glass transition temperature and a high electro-optic coefficient. The prepared cross-linked electro-optic polymer thin film is used as an optical material in the development of devices such as electro-optic modulators.

[0025] Preferably, the cross-linked electro-optic polymer film obtained by the preparation method of the cross-linked electro-optic polymer has a thickness of 1~2 μm.

[0026] Thirdly, the present invention provides an optical material containing the aforementioned cross-linked electro-optic polymer.

[0027] Fourthly, the present invention provides an electro-optic modulator containing the aforementioned optical material.

[0028] The present invention provides a simple and easy method for preparing a cross-linked electro-optic polymer containing diazo compounds. Highly efficient cross-linking can be obtained by using a small amount of cross-linking agent. This is because the activation temperature of the cross-linking agent is slightly higher than the glass transition temperature of the polymer material polarization. While obtaining electro-optic properties through electric field polarization, cross-linking and curing can be carried out simultaneously to obtain an electro-optic thin film with high glass transition temperature, high stability and high electro-optic coefficient. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0030] Figure 1 This is the 1H NMR spectrum of the tribranched diazo compound in Example 1 of the present invention.

[0031] Figure 2 The image shows the DSC diagram of the polymer films obtained from JRD1 and PMMA in Comparative Example 1.

[0032] Figure 3 The image shows the DSC diagram of the polymer film obtained from JRD1, PMMA, and crosslinking agent in Example 1.

[0033] Figure 4 The image shows the DSC diagram of the polymer film obtained from JRD1, PMMA, and crosslinking agent in Example 2.

[0034] Figure 5 The image shows the DSC diagram of the polymer film obtained from JRD1, PMMA, and crosslinking agent in Example 3.

[0035] Figure 6 The image shows the DSC diagram of the polymer film obtained from BHG2, PMMA, and crosslinking agent in Example 4.

[0036] Figure 7 The curves show the change in the electro-optic coefficient of the polarized electro-optic polymer films of Comparative Example 1 and Examples 1-4 after long-term heating at 85°C for 500 hours. Detailed Implementation

[0037] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0038] Unless otherwise specified, all raw materials used in the examples and comparative examples are commercially available conventional raw materials, and the technical means used are conventional means well known to those skilled in the art.

[0039] Example 1

[0040] This embodiment provides a crosslinked electro-optic polymer, the preparation method of which includes:

[0041] 16 mg of polymethyl methacrylate (PMMA) was added to 0.244 mL of 1,1,2-trichloroethane and stirred for 2 hours until the PMMA was completely dissolved. Then, 6.8 mg of JRD1 chromophore was added and stirred for 1 hour until the chromophore was fully dissolved. Finally, 1.6 mg of a diazo crosslinking agent was added to obtain a mixed solution of chromophore molecules, PMMA, and crosslinking agent (mass ratio 3:7:0.7). The resulting mixed solution was filtered through a 0.22 μm needle filter and then spin-coated onto ITO glass (rotation speed controlled at 1000~1200 rpm). The film was then dried in a vacuum drying oven at 50 °C for 24 hours. The thickness of the resulting polymer film was 1.6 μm.

[0042] In this embodiment, the diazo compound crosslinking agent is... The 1H NMR spectrum of the diazo crosslinking agent is shown below. Figure 1 The chromophore is JRD1, and the chemical structural formula of JRD1 is as follows: .

[0043] Example 2

[0044] This embodiment provides a crosslinked electro-optic polymer, the preparation method of which includes:

[0045] 16 mg of polymethyl methacrylate (PMMA) was added to 0.282 mL of 1,1,2-trichloroethane and stirred for 2 hours until the PMMA was completely dissolved. Then, 10.6 mg of JRD1 chromophore was added and stirred for 1 hour until the chromophore was fully dissolved. Finally, 1.6 mg of a diazo crosslinking agent was added to obtain a (4:6:0.6) mixed solution of an organic second-order nonlinear optical chromophore compound, PMMA, and crosslinking agent. The resulting mixed solution was filtered through a 0.22 μm needle filter and then spin-coated onto ITO glass (rotation speed controlled at 1000~1200 rpm). The film was then dried in a vacuum drying oven at 50 °C for 24 hours. The thickness of the resulting polymer film was 1.8 μm.

[0046] In this embodiment, the diazo compound crosslinking agent is... The chromophore is JRD1.

[0047] Example 3

[0048] This embodiment provides a cross-linked electro-optic polymer, the preparation method of which differs from that of Example 1 only in that the diazo compound cross-linking agent is replaced with an equal amount of .

[0049] Example 4

[0050] This embodiment provides a cross-linked electro-optic polymer, the preparation method of which differs from that of Example 1 only in that the chromophore JRD1 is replaced with BHG2, and the structural formula of BHG2 is as follows: .

[0051] The synthetic route for BHG2 is as follows:

[0052]

[0053] 1) The synthesis of compound 1 shown in Formula 1 can be found in the reference (WW Jin, PV Johnston, DLElder, KT Manner, KE Garrett, W. Kaminsky, RM Xu, BH Robinson, LR Dalton, J. Mater. Chem. C 2016, 4, 3119-3124.).

[0054] 2) Synthesis of compound 2 as shown in formula 2

[0055] 3.85 g (10 mmol) of compound 1, 5.30 g (30 mmol) of p-toluenesulfonyl chloride, and 30 mL of redistilled tetrahydrofuran (THF) were added to a 50 mL three-necked glass flask. After dissolution, the reaction system was cooled to 0 °C in an ice bath under nitrogen (N2) atmosphere, and triethylamine was added dropwise. After the reaction proceeded for 1 hour, the ice bath was removed, and the system was allowed to continue reacting overnight at room temperature. After the reaction was completed, the mixture was poured into 50 mL of deionized water to terminate the reaction. The mixture was extracted three times with ethyl acetate, and the organic phase was collected. The unreacted p-toluenesulfonyl chloride was washed away with 10% NaOH solution. The product was dried over anhydrous magnesium sulfate and then rotary evaporated to give a red solid crude product, which was compound 2, with a yield of 80%.

[0056] 3) Synthesis of compound 3 as shown in formula 3

[0057] 1.386 g (2 mmol) of compound 2 obtained in step 2), 3.50 g (10 mmol) of fluorene-9-bisphenol, 1.40 g (26 mmol) of anhydrous potassium carbonate, and 50 mL of redistilled N,N-dimethylformamide (DMF) were added to a 100 mL round-bottom flask. The mixture was heated to 100 °C and reacted for 24 hours under nitrogen protection. After the reaction was completed, the mixture was poured into 200 mL of deionized water to obtain an orange solution. The solution was extracted three times with ethyl acetate, and the organic phases were combined and washed with saturated sodium chloride solution. The organic phase was dried with anhydrous magnesium sulfate and the organic solvent was removed by rotary evaporation. The residue was separated by column chromatography (using 200-300 mesh silica gel as the stationary phase and a mixture of n-hexane and ethyl acetate as the mobile phase, wherein the volume ratio of n-hexane to ethyl acetate was 1:20). After drying, a red solid was obtained as compound 3, with a yield of 52%.

[0058] MS(MALDI-TOF), m / z:1049.47 (M+); 1 H NMR (400 MHz, CDCl3) δ 10.05 (d, J= 8.3 Hz, 1H), 7.96 (s, 1H), 7.71 (d, J = 7.4 Hz, 4H), 7.36–7.28 (m, 10H),7.25–7.20 (m, 5H), 7.04 (dd, J = 20.2, 7.9 Hz, 8H), 6.67 (d, J = 8.4 Hz,11H), 6.31 (d, J = 8.2 Hz, 1H), 4.07 (s, 4H), 3.79 (s, 4H), 3.61 (s, 3H), 2.71 (s, 2H), 2.37 (s, 2H), 1.04 (s, 6H).

[0059] 4) Synthesis of compound 4 as shown in formula 4

[0060] 10.50 g (10 mmol) of compound 3 and 1.66 g (24 mmol) of imidazole were dissolved in 20 mL of DMF. Under N2 protection, 3.68 g (24 mmol) of tert-butyldimethylchlorosilane was slowly added to the mixture. After stirring at room temperature for 3 hours, the reaction system was poured into 100 mL of water. The organic phase was extracted with n-hexane, washed with brine, dried with anhydrous magnesium sulfate, and the solvent was removed by rotary evaporation. The crude product was separated by column chromatography (using 200-300 mesh silica gel as the stationary phase and a gradient elution of a mixture of ethyl acetate and n-hexane as the mobile phase, wherein the volume ratio of ethyl acetate to n-hexane was gradually increased from 1:15 to 1:10). After drying, a red oily liquid was obtained as compound 4, with a yield of 93.1%.

[0061] MS(MALDI-TOF), m / z:1278.6458 (M+); 1 H NMR (400 MHz, CDCl3) δ 10.08 (d, J = 8.3 Hz, 1H), 7.71 (d, J = 7.5 Hz, 4H), 7.33 (dt, J = 14.8, 5.4 Hz, 10H), 7.21(t, J = 7.3 Hz, 5H), 7.05 (dd, J = 13.2, 8.7 Hz, 8H), 6.67 (dd, J = 8.5, 4.9 Hz, 11H), 6.33 (d, J = 8.3 Hz, 1H), 4.05 (t, J = 5.6 Hz, 4H), 3.78 (t, J = 5.5 Hz, 4H), 3.64 (s, 3H), 2.72 (s, 2H), 2.37 (s, 2H), 1.05 (s, 6H), 0.95 (s, 18H), 0.15 (s, 12H).

[0062] 5) Synthesis of BHG2

[0063] 1.2 mmol of compound 4 obtained in step 4 and 0.45 g (1.4 mmol) of trifluoro-substituted tricyanodihydrofuran (CF3-TCF) were dissolved in 20 mL of ultradry ethanol, and then refluxed at 80 °C for 0.5 h. After the reaction was completed, the solvent was removed by rotary evaporation, and the crude product was separated by column chromatography (the stationary phase was 200-300 mesh silica gel, and the mobile phase was a mixture of ethyl acetate and n-hexane, with the volume ratio of ethyl acetate to n-hexane increasing from 1:10 to 1:5). The solid obtained after drying was an organic second-order nonlinear optical chromophore BHG2 with a D-π-A structure, with a yield of 38.2%.

[0064] MS(MALDI-TOF), m / z:1575.6972 (M+); 1 H NMR (400 MHz, CDCl3) δ 8.00 (t, J =13.3 Hz, 1H), 7.73 (d, J = 7.5 Hz, 4H), 7.54 – 7.48 (m, 5H), 7.40 – 7.29 (m,10H), 7.23 (dd, J = 13.3, 5.7 Hz, 6H), 7.04 (dd, J = 18.4, 8.5 Hz, 8H), 6.81 (d, J = 16.1 Hz, 1H), 6.72 – 6.63 (m, 10H), 6.44 (d, J = 14.7 Hz, 1H), 4.09 (t, J = 5.4Hz, 4H), 3.84 (d, J = 5.1 Hz, 4H), 3.65 (s, 3H), 2.42 (s, 2H), 2.30 (s, 2H), 1.01 (s, 3H), 0.94 (s, 21H), 0.14 (s, 12H).

[0065] Comparative Example 1

[0066] This comparative example provides a cross-linked electro-optic polymer, the preparation method of which includes:

[0067] 16 mg of polymethyl methacrylate (PMMA) was added to 0.228 mL of 1,1,2-trichloroethane and stirred for 2 hours until the PMMA was completely dissolved. Then, 6.8 mg of JRD1 chromophore was added to obtain a mixed solution of chromophore molecules and PMMA (30 wt.% chromophore). The resulting mixed solution was filtered through a 0.22 μm needle filter and then coated onto an ITO glass substrate by spin coating (controlling the rotation speed at 1000~1200 rpm). The film was then dried in a vacuum drying oven at 50 °C for 24 hours. The thickness of the resulting polymer film was 1.6 μm.

[0068] Experimental Example 1

[0069] 1) Contact polarization was performed on the polymer film obtained by reacting the organic chromophore molecule (JRD1) of Comparative Example 1 with PMMA. The electrode material was gold (Au), the electrode thickness was 50 nm, the polarization temperature was between 95℃ and 105℃, the polarization time was 20 to 30 minutes, and the polarization voltage was controlled at approximately 150 to 250 V; the electro-optic coefficient (r) 33 The maximum electro-optic coefficient was measured to be 180 pm / V@1310 nm using the Teng-man simple reflectance method.

[0070] 2) A polymer film with a thickness of 1.6 μm, obtained from the organic chromophore molecule (JRD1), PMMA, and crosslinking agent in Example 1, was subjected to a contact polarization process. The electrode material was gold (Au), the electrode thickness was 50 nm, the polarization temperature was between 95°C and 105°C, the polarization time was 20 to 30 minutes, and the polarization voltage was controlled at around 150 to 250 V. The electro-optic coefficient (r33) was measured by the Teng-Man simple reflectance method, and the maximum electro-optic coefficient measured was 150 pm / V@1310 nm.

[0071] 2) The polymer film obtained from the organic chromophore molecule (JRD1), PMMA, and crosslinking agent of Example 2 was subjected to contact polarization. The electrode material was gold (Au), the electrode thickness was 50 nm, the polarization temperature was between 95°C and 105°C, the polarization time was 20 to 30 minutes, and the polarization voltage was controlled at approximately 150 to 250 V; the electro-optic coefficient (r) 33 The maximum electro-optic coefficient was measured to be 230 pm / V@1310 nm using the Teng-Man simple reflectance method.

[0072] 3) The polymer film obtained from the organic chromophore molecule (JRD1), PMMA, and crosslinking agent of Example 3 was subjected to contact polarization. The electrode material was gold (Au), the electrode thickness was 50 nm, the polarization temperature was between 95°C and 105°C, the polarization time was 20 to 30 minutes, and the polarization voltage was controlled at approximately 150 to 250 V; the electro-optic coefficient (r) 33 The maximum electro-optic coefficient was measured to be 165 pm / V@1310 nm using the Teng-Man simple reflectance method.

[0073] 4) The polymer film obtained from the organic chromophore molecule (BHG2), PMMA, and crosslinking agent of Example 4 was subjected to contact polarization. The electrode material was gold (Au), the electrode thickness was 50 nm, the polarization temperature was between 110°C and 125°C, the polarization time was 20 to 30 minutes, and the polarization voltage was controlled at approximately 150 to 250 V; the electro-optic coefficient (r) 33 The maximum electro-optic coefficient was measured to be 263 pm / V@1310 nm using the Teng-Man simple reflection method.

[0074] Experimental Example 2

[0075] 1) The glass transition temperature (Tg) of the polymer film obtained from the organic chromophore molecule (JRD1) of Comparative Example 1 and PMMA was determined by differential scanning calorimetry (DSC). g The test was conducted in a nitrogen atmosphere with a heating rate of 10°C / min, and the curves were obtained as shown below. Figure 2 As shown;

[0076] 2) The glass transition temperature (Tg) of the polymer film obtained from the organic chromophore molecule (JRD1) of Example 1 and PMMA was determined by differential scanning calorimetry (DSC). g The test was conducted in a nitrogen atmosphere with a heating rate of 10°C / min, and the curves were obtained as shown below. Figure 3 As shown;

[0077] 3) The glass transition temperature (Tg) of the polymer film obtained from the organic chromophore molecule (JRD1) of Example 2 and PMMA was determined by differential scanning calorimetry (DSC). g The test was conducted in a nitrogen atmosphere with a heating rate of 10°C / min, and the curves were obtained as shown below. Figure 4 As shown;

[0078] 4) The glass transition temperature (Tg) of the polymer film obtained from the organic chromophore molecule (JRD1) of Example 3 and PMMA was determined by differential scanning calorimetry (DSC). gThe test was conducted in a nitrogen atmosphere with a heating rate of 10°C / min, and the curves were obtained as shown below. Figure 5 As shown;

[0079] 5) The glass transition temperature (Tg) of the polymer film obtained from the organic chromophore molecule (BHG2) of Example 4 and PMMA was determined by differential scanning calorimetry (DSC). g The test was conducted in a nitrogen atmosphere with a heating rate of 10°C / min, and the curves were obtained as shown below. Figure 6 As shown.

[0080] Experimental Example 3

[0081] The polarized electro-optic polymer films of Comparative Example 1 and Examples 1-4 were heated to 85°C, and the electro-optic coefficients were tested every 12-72 hours for a total of 500 hours. The stability curves of their electro-optic properties are shown below. Figure 7 As shown, the polarized cross-linked electro-optic polymer film exhibits good stability in its electro-optic properties. After heating to 85°C, the electro-optic properties decay within the first 10 hours or so, but the electro-optic coefficient remains essentially unchanged thereafter. After being placed at 85°C for 500 hours, the electro-optic properties of the material still maintain above 85% (89% and 87%) of the initial values. However, the uncross-linked electro-optic polymer film shows very poor stability in its electro-optic coefficient; after heating at 85°C for 24 hours, the electro-optic coefficient drops to 9% of its original value. Therefore, the prepared polarized electro-optic polymer film can be used as an optical material.

[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A cross-linked electro-optic polymer, characterized in that, The cross-linked electro-optic polymer comprises a host polymer, an organic chromophore, and a solid cross-linking agent, wherein the solid cross-linking agent is a diazo compound; The diazo compounds include any one or two of the following: ； ； The organic chromophore is BHG2: 。 2. The cross-linked electro-optic polymer according to claim 1, characterized in that, The mass ratio of the organic chromophore to the solid crosslinking agent is (2~10):

1.

3. The cross-linked electro-optic polymer according to claim 1, characterized in that, The main polymer includes one or more of the following: polymethacrylate polymers, polymethacrylate copolymer polymers, polystyrene polymers, polycarbonate polymers, polyaryl ether polymers, and polyimide polymers.

4. The cross-linked electro-optic polymer according to any one of claims 1 to 3, characterized in that, The components include the following parts by weight: 50-80 parts of the main polymer, Organic chromophores, 20-50 parts 5-20 parts of solid crosslinking agent.

5. The method for preparing the cross-linked electro-optic polymer according to any one of claims 1 to 4, characterized in that, include: The main polymer, the organic chromophore, and the solid crosslinking agent were dissolved in 1,1,2-trichloroethane, filtered, and the filtrate was spin-coated onto a glass substrate and dried under vacuum at room temperature.

6. The method for preparing the cross-linked electro-optic polymer according to claim 5, characterized in that, The cross-linked electro-optic polymer film obtained by the aforementioned method has a thickness of 1~2 μm.

7. An optical material, characterized in that, It contains the cross-linked electro-optic polymer as described in any one of claims 1 to 4 or the cross-linked electro-optic polymer prepared by the preparation method described in claim 5 or 6.

8. An electro-optic modulator, characterized in that, It contains the optical material as described in claim 7.

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