A broadband polymer-based optical waveguide amplifier and a preparation method thereof

Abstract

The present invention discloses a broadband polymer-based optical waveguide amplifier and a preparation method thereof, belonging to the field of broadband optical communication technology. The method includes preparing multi-layer core-shell rare earth nanoparticles doped with multiple lanthanide luminescent center ions, and preparing a broadband polymer gain medium by physically doping or chemically bonding the multi-layer core-shell rare earth nanoparticles; using the obtained broadband polymer gain medium as the core layer to prepare an optical waveguide amplifier. By co-doping two or more kinds of lanthanide luminescent center ions in the matrix of rare earth nanomaterials, the present invention realizes broadband luminescence of rare earth nanoparticles by constructing a core-shell structure; prepares a polymer-based optical waveguide amplifier capable of realizing optical amplification functions in at least two or more bands, so as to greatly broaden its gain response range. The broadband polymer optical waveguide amplifier prepared by the preparation method of the present invention can amplify optical signal lights of various different wavelengths, and eliminates the limitation of the single gain frequency band of the polymer optical waveguide amplifier.

Description

Technical Field

[0001] The present invention belongs to the technical field of broadband optical communication, and particularly relates to a broadband polymer-based optical waveguide amplifier and a preparation method thereof. Background Art

[0002] An optical amplifier is an important optical device widely used in optical communication networks. It can compensate for the transmission loss of the signal optical power in the optical network, thereby effectively improving the effective distance and transmission quality of optical communication. Whether in fiber amplifiers or optical waveguide amplifiers, doping lanthanide rare-earth ions and utilizing the radiative transitions between their energy levels are the main methods to achieve the optical amplification function of the device. Optical waveguide amplifiers are easy to integrate with a variety of optical waveguide devices and can better adapt to the planar photon integration environment. They are a new type of active optical amplification device with high research value.

[0003] The rare-earth doped optical waveguide amplifier forms a gain medium by doping rare-earth ions in the waveguide. The signal light and the pump light are coupled in the waveguide, and the rare-earth ions are stimulated to radiate under the action of the pump light to achieve signal light amplification. From the perspective of the gain medium material, optical waveguide amplifiers can be divided into two categories: inorganic optical waveguide amplifiers and polymer-based optical waveguide amplifiers. The research on inorganic optical waveguide amplifiers started relatively early, and the preparation process is relatively mature. However, the preparation cost is high, the process is complex, and there are also disadvantages such as poor compatibility with silicon-based substrate materials during the preparation process. Therefore, there are still great difficulties in the field of planar silicon-based integrated applications. In contrast, polymer-based optical waveguide devices can be prepared on a silicon-based substrate by means of spin coating, photolithography, etching, etc., so they are more suitable for the integration of on-chip optical devices.

[0004] Traditional rare-earth doped polymer optical waveguide amplifiers usually utilize the radiative transitions of a kind of lanthanide rare-earth ion to achieve the amplification of optical signals. The radiative transitions of lanthanide rare-earth ions are 4f-4f electron transitions. Affected by the shielding effect of the outer 5d and 6s electrons, their radiative transitions are generally sharp spectral line light emissions, and their characteristic emission peaks generally do not shift with the change of the matrix. Therefore, the gain bandwidth of optical waveguide amplifiers is often limited. For example, erbium-doped optical waveguide amplifiers mainly utilize the 3+ ) of erbium ions (Er 4 I 13 / 2 → 4 I 15 / 2 transition for C-band optical amplification; thulium-doped optical waveguide amplifiers mainly utilize the 3+ ) of thulium ions (Tm 3 H4→ 3F4 transition, for S-band optical amplification. For an optical amplifier prepared by doping a single rare earth ion with gain activity, its gain bandwidth in a certain wavelength band generally does not exceed 100 nm, and the emission peak of the rare earth ion generally does not shift with the matrix. To expand the gain bandwidth of the optical amplifier, cooperative emission of multiple rare earth ions is required. If loss compensation is to be performed on signal light in multiple wavelength bands, multiple optical amplifiers corresponding to each wavelength band need to be used, which increases the complexity of using the optical amplifier and reduces the transmission rate of the optical network at the same time. Summary of the Invention

[0005] The object of the present invention is to provide a broadband polymer-based optical waveguide amplifier and its preparation method. By constructing nanoparticles with a multi-layer core-shell structure, multiple rare earth ions with gain activity in different wavelength bands are doped in different core-shell structures respectively, and an inert shell layer is prepared between the active layers to solve the problem of weakening of the emission intensity due to energy transfer between multiple luminescent active ions; broadband broadening in different wavelength bands is realized in the same nanoparticle, and then a polymer optical waveguide amplifier capable of realizing broadband optical amplification function is obtained to solve the problem of single gain frequency band of the existing polymer optical waveguide amplifier.

[0006] The principle of the preparation method of a broadband polymer-based optical waveguide amplifier of the present invention is as follows:

[0007] By co-doping two or more lanthanide luminescent center ions in a rare earth nanomaterial matrix, broadband luminescence of rare earth nanoparticles is realized by constructing a core-shell structure; a polymer-based optical waveguide amplifier capable of realizing optical amplification function in at least two or more wavelength bands is prepared, and its gain response range is greatly broadened. The broadband polymer optical waveguide amplifier prepared by the preparation method of the present invention can amplify signal light of multiple different wavelengths, and lift the limitation of single gain frequency band of the polymer optical waveguide amplifier.

[0008] The present invention is realized through the following technical solutions:

[0009] A preparation method of a broadband polymer-based optical waveguide amplifier specifically includes the following steps:

[0010] Step 1: Prepare multi-layer core-shell rare earth nanoparticles doped with multiple lanthanide luminescent center ions, dope the luminescent center ions in different shell layers, and add a barrier layer; by adjusting the doping position and doping ratio of the luminescent center ions and adjusting the thickness of the growth barrier layer, relatively flat broadband luminescence of the luminescent center ions in multiple wavelength bands is realized.

[0011] Step 2: Prepare a broadband polymer gain medium from the multi-layer core-shell rare earth nanoparticles doped with multiple lanthanide luminescent center ions prepared in Step 1 by physical doping or chemical bonding.

[0012] Step 3: Use the broadband polymer gain medium obtained in Step 2 as the core layer to fabricate an optical waveguide amplifier, and adjust the refractive index of the core layer by adjusting the carrier matrix, baking temperature, and exposure time.

[0013] Further, Step 1 specifically includes the following:

[0014] A1: Prepare core-multishell rare earth nanoparticles MREF4 using hydrothermal method, high-temperature pyrolysis method or precipitation method, where RE is a rare earth element and M is an alkali metal;

[0015] A2: Dope multiple luminescent center ions at different positions in the core and shell respectively; the luminescent center ions include Er 3+ , Tm 3+ , Pr 3+ , Nd 3+ , Ho 3+ , Eu 3+ or Tb 3+ ;

[0016] A3: Prepare an intermediate barrier layer in the shell doped with different luminescent center ions;

[0017] A4: Regulate the doping positions and doping ratios of different luminescent center ions, and regulate the thickness of the growth barrier layer, so that the emission peak intensities of the luminescent center ions in each shell in their characteristic emission bands match, obtaining a broadband luminescence spectrum covering multiple bands in the same rare earth nanoparticle, and the spectra of each band are relatively flat, laying a foundation for obtaining gain in each band of the broadband optical amplifier.

[0018] Further, in Step A2, the concentration of the luminescent center ion is defined as: the amount of substance of each luminescent center ion / the total amount of substance of the rare earth element in the rare earth nanoparticle, with a range of 0% - 2%; the total concentration of the luminescent center ions is defined as: the sum of the concentrations of all types of luminescent center ions, with a range not exceeding 10%, the concentration of the sensitizer ion is defined as: the amount of substance of the sensitizer ion / the total amount of substance of the rare earth element in the rare earth nanoparticle, specifically 20%; and the sum of the total concentration of the luminescent center ions and the concentration of the sensitizer ion does not exceed 30%;

[0019] The thickness of the barrier layer ≥ 3 nm, and the barrier layer is a fluoride matrix material or an oxide material such as SiO2, TiO2, etc.

[0020] Further, the physical doping method in Step 2 specifically includes the following:

[0021] B1: Disperse the rare earth nanoparticles prepared in Step 1 in an organic solvent under ultrasonic dispersion or high-speed stirring to obtain a solution in which the rare earth nanoparticles are uniformly dispersed;

[0022] B2: Mix the dispersion obtained in step B1 with a polymer photoresist at a mass percentage of 10%-30%; ultrasonically disperse or stir the mixture at high speed to obtain a gain medium with uniformly dispersed rare earth nanoparticles.

[0023] Further, the organic solvents in step B1 include: alcohols, ketones, esters or heterocyclic compounds; the alcohols include methanol, ethanol, ethylene glycol or glycerol; the ketones include acetone, butanone or cyclohexanone; the esters include methyl formate, ethyl acetate, ethyl formate or butyl acetate; the heterocyclic compounds include furan, thiophene, pyrrole, thiazole or imidazole; the polymer photoresist in step B2 includes SU-8 series, BPO or BP212.

[0024] Further, the chemical bonding method in step two specifically includes the following content:

[0025] C1: Disperse the rare earth nanoparticles prepared in step one in a solvent, add a polymer monomer and an initiator, and the mass of the initiator is 0.01%-1% of the mass of the polymer monomer;

[0026] C2: Polymerize the nanoparticles in a polymer matrix by bulk polymerization, solution polymerization, suspension polymerization or emulsion polymerization to obtain a gain medium; the doping concentration of the rare earth nanoparticles in the polymer after polymerization is 0.01%-50%.

[0027] Further, in step C1, the polymer monomer is a monomer that can undergo addition polymerization or condensation polymerization; the monomers that can undergo addition polymerization include ① monomers with unsaturated double bonds and triple bonds: such as unsaturated acid esters [specifically including: acrylate esters and their derivatives (methyl acrylate, methyl methacrylate, deuterated methyl methacrylate, fluorinated methyl methacrylate, ethyl acrylate, methyl ethyl acrylate, ethyl ethyl acrylate, propyl ethyl acrylate, etc.); crotonate esters and their derivatives (methyl crotonate, methyl methyl crotonate, ethyl crotonate, methyl ethyl crotonate, ethyl ethyl crotonate, propyl ethyl crotonate, etc.); pentenoate esters and their derivatives, etc.]; olefin monomers [specifically including: ethylene and vinyl monomers (such as vinyl chloride, vinyl acetate, vinyl naphthalene, vinyl pyrrolidone, vinyl epoxyethane, vinyl cyclohexanol, etc.), propylene and propylene monomers (acrylonitrile, butene, butadiene, etc.]; ② monomers with epoxy groups: glycidyl methacrylate, epoxy resin monomers, 1,2-epoxybutane, 1,2-epoxy-9-decene, 1,2-epoxyheptane, glycidyl methyl ether; the monomers that can undergo condensation polymerization include phenolic resin monomers (epichlorohydrin, bisphenol A), polyesters, lactide monomers, etc.

[0028] Further, in step C2, the polymerization temperature is controlled at 10°C to 120°C, the polymerization time is 0.5 hours to 48 hours, and the degree of polymerization of the composite polymer gain medium is adjusted according to the changes in the manufacturing process of the optical waveguide device, and the degree of polymerization of the composite polymer is controlled at 5% - 95%.

[0029] Further, step three specifically includes the following content:

[0030] Using the broadband polymer gain medium obtained in step two as the core layer, a rectangular waveguide amplifier, an inverted ridge waveguide amplifier, or a loaded strip waveguide amplifier is prepared by means of spin coating, evaporation coating, photolithography, plasma etching, and ultraviolet imprinting.

[0031] Compared with the prior art, the advantages of the present invention are as follows:

[0032] 1. The erbium-thulium co-doped broadband polymer optical waveguide amplifier proposed by the present invention can achieve broadband amplification in the range of 1.45 μm - 1.57 μm, making up for the problem of single amplification wavelength of traditional polymer waveguide amplifiers;

[0033] 2. The erbium-thulium co-doped broadband polymer optical waveguide amplifier proposed by the present invention can achieve multi-band amplification in the visible light region, making up for the problem of single amplification wavelength of visible light polymer waveguide amplifiers;

[0034] 3. By changing the doping ratios of the two luminescent center ions, Er 3+ , Tm 3+ , the intensity of the emission spectral lines can be regulated;

[0035] 4. The waveguide gain medium can control the refractive index difference with the cladding by changing the doping matrix, controlling the heating temperature, adjusting the doping ratio, etc.;

[0036] 5. The method has high repeatability and good long-term stability of the prepared device. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for use in the description of the specific embodiments or the prior art. In all the drawings, similar elements or parts are generally identified by similar reference numerals. In the drawings, the elements or parts are not necessarily drawn to actual scale.

[0038] Figure 1 : Schematic structural diagram of NaYF4:Tm,Yb@NaYF4@NaYF4:Er nanoparticles;

[0039] Figure 2 : Transmission electron microscope photograph of rare earth NaYF4:Tm,Yb@NaYF4@NaYF4:Er nanoparticles prepared by the thermal decomposition method;

[0040] Figure 3 : XRD test results of rare earth NaYF4:Tm,Yb@NaYF4@NaYF4:Er nanoparticles prepared by the thermal decomposition method;

[0041] Figure 4 : By exciting NaYF4:Tm,Yb@NaYF4@NaYF4:Er nanoparticles with a 980 nm infrared laser, a broadband emission spectrum with wavelengths of 1.45 μm - 1.57 μm is obtained;

[0042] Figure 5 : Schematic diagram of the preparation of a rectangular optical waveguide amplifier by the lithography method;

[0043] Figure 6 : Gain test results.

[0044] Figure 7 : Schematic diagram of the structure of NaYF4:Er,Yb@NaYF4@NaYF4:Tm,Yb nanoparticles;

[0045] Figure 8 : Visible light region emission spectrum of NaYF4:Er,Yb@NaYF4@NaYF4:Tm,Yb nanoparticles excited by a 980 nm infrared laser;

[0046] Figure 9 : Schematic diagram of the structure of NaYF4:Ho,Yb@NaYF4@NaYF4:Tm,Yb nanoparticles;

[0047] Figure 10 : Schematic diagram of the microstructure of the composite polymer;

[0048] Figure 11 : Schematic diagram of the preparation of an inverted ridge optical waveguide amplifier by the etching method. Detailed implementation manners

[0049] The present invention will be further described below in conjunction with specific embodiments. These embodiments of the present invention are only used to explain the specific implementation manners of the present invention, rather than limiting the scope of the present invention. After reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0050] In the following embodiments, core-shell NaYF4 nanoparticles doped with rare-earth ions such as Tm, Yb, Er, and Ho are prepared by high-temperature pyrolysis method, and a broadband polymer gain medium is obtained by physical doping method and chemical bonding method. A rectangular waveguide amplifier and an inverted-ridge waveguide amplifier prepared by using the gain medium can use a 980 nm laser as a pump source and exhibit gain characteristics in the visible light band and near-infrared band.

[0051] A preparation method of a broadband polymer-based optical waveguide amplifier specifically includes the following steps:

[0052] Step 1: Prepare multi-layer core-shell rare-earth nanoparticles doped with multiple lanthanide luminescent center ions, dope the luminescent center ions in different shell layers, and add a barrier layer; and by controlling the doping position and doping ratio of the luminescent center ions and controlling the thickness of the growth barrier layer, the luminescent center ions can achieve relatively flat broadband luminescence in multiple bands; specifically as follows:

[0053] A1: Prepare core-multi-shell rare-earth nanoparticles NaREF4 by hydrothermal method, high-temperature pyrolysis method or precipitation method, where RE is a rare-earth element;

[0054] A2: Dope multiple luminescent center ions at different positions in the core and shell respectively; the luminescent center ions include Er 3+ , Tm 3+ , Pr 3+ , Nd 3+ , Ho 3+ , Eu 3+ or Tb 3+ ;

[0055] Among them, the concentration of the luminescent center ion is defined as: the amount of substance of each luminescent center ion / the total amount of substance of the rare-earth element in the rare-earth nanoparticles, and the range is 0% - 2%; the total concentration of the luminescent center ions is defined as: the sum of the concentrations of all types of luminescent center ions, and the range does not exceed 10%, and the concentration of the sensitizer ion is defined as: the amount of substance of the sensitizer ion / the total amount of substance of the rare-earth element in the rare-earth nanoparticles, specifically 20%; and the sum of the total concentration of the luminescent center ions and the concentration of the sensitizer ion does not exceed 30%;

[0056] The thickness of the barrier layer ≥ 3 nm, and the barrier layer is a fluoride matrix material or an oxide material such as SiO2 or TiO2;

[0057] A3: Prepare an intermediate barrier layer in the shell layer doped with different luminescent center ions;

[0058] A4: By regulating the doping positions and doping ratios of different luminescent center ions and the thickness of the growth barrier layer, making the emission peak intensities of the luminescent center ions in each shell layer match in their characteristic emission bands, a broadband luminescence spectrum covering multiple bands is obtained in the same rare earth nanoparticle, and the spectra of each band are relatively flat, laying a foundation for the broadband optical amplifier to obtain gain in each band.

[0059] Step 2: Prepare the multilayer core-shell rare earth nanoparticles doped with multiple lanthanide luminescent center ions prepared in Step 1 into a broadband polymer gain medium by physical doping or chemical bonding methods;

[0060] Among them, the physical doping method specifically includes the following contents:

[0061] B1: Disperse the rare earth nanoparticles prepared in Step 1 in an organic solvent under ultrasonic dispersion or high-speed stirring to obtain a solution in which the rare earth nanoparticles are uniformly dispersed;

[0062] The organic solvents include: alcohols, ketones, esters or heterocyclic compounds; the alcohols include methanol, ethanol, ethylene glycol or glycerol; the ketones include acetone, butanone or cyclohexanone; the esters include methyl formate, ethyl acetate, ethyl formate or butyl acetate; the heterocyclic compounds include furan, thiophene, pyrrole, thiazole or imidazole;

[0063] B2: Mix the dispersion obtained in Step B1 with a polymer photoresist at a mass percentage of 10%-30%; ultrasonically disperse or high-speed stir the mixture to obtain a gain medium in which the rare earth nanoparticles are uniformly dispersed; the polymer photoresist includes SU-8 series, BPO or BP212;

[0064] The chemical bonding method specifically includes the following contents:

[0065] C1: Disperse the rare earth nanoparticles prepared in Step 1 in a solvent, add a polymer monomer and an initiator, and the mass of the initiator is 0.01%-1% of the mass of the polymer monomer;

[0066] Among them, the polymer monomer is a monomer capable of undergoing addition polymerization or condensation polymerization; the monomers capable of undergoing addition polymerization include: ① monomers with unsaturated double bonds and triple bonds: such as unsaturated acid esters [specifically including: acrylate esters and their derivatives (methyl acrylate, methyl methacrylate, deuterated methyl methacrylate, fluorinated methyl methacrylate, ethyl acrylate, ethyl methacrylate, ethyl ethyl acrylate, ethyl propyl acrylate, etc.); crotonate esters and their derivatives (methyl crotonate, methyl methyl crotonate, ethyl crotonate, ethyl methyl crotonate, ethyl ethyl crotonate, ethyl propyl crotonate, etc.); pentenoate esters and their derivatives, etc.]; olefin monomers [specifically including: ethylene and vinyl monomers (such as vinyl chloride, vinyl acetate, vinyl naphthalene, vinyl pyrrolidone, vinyl ethylene oxide, vinyl cyclohexanol, etc.), propylene and propenyl monomers (acrylonitrile, butene, butadiene, etc.)]; ② monomers with epoxy groups: glycidyl methacrylate, epoxy resin monomers, 1,2-epoxybutane, 1,2-epoxy-9-decene, 1,2-epoxyheptane, glycidyl methyl ether; the monomers capable of undergoing condensation polymerization include phenolic resin monomers (epichlorohydrin, bisphenol A), polyesters, lactide monomers, etc.

[0067] C2: Polymerize the nanoparticles in the polymer matrix by bulk polymerization, solution polymerization, suspension polymerization or emulsion polymerization to obtain a gain medium; the doping concentration of rare earth nanoparticles in the polymer after polymerization is 0.01% - 50%.

[0068] Among them, the polymerization temperature is controlled at 10°C to 120°C, the polymerization time is 0.5 hours to 48 hours, and the degree of polymerization of the composite polymer gain medium is adjusted according to the changes in the manufacturing process of the optical waveguide device, and the degree of polymerization of the composite polymer is controlled (5% - 95%).

[0069] Furthermore, the reaction temperature is related to the type of polymerization reaction. For example, in radical polymerization using photoinitiators [specifically 2-hydroxy-2-methyl-1-phenylpropan-1-one (1173), 1-hydroxycyclohexyl phenyl ketone (184), 2-methyl-2-(4-morpholinyl)-1-[4-(methylthio)phenyl]propan-1-one (907), 2,4,6-trimethylbenzoyl-diphenylphosphine oxide (TPO), ethyl 2,4,6-trimethylbenzoyl phenylphosphinate (TPO-L), 2-dimethylamino-2-benzyl-1-[4-(4-morpholinyl)phenyl]butan-1-one (IHT-PI910), 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]propan-1-one (IHT-PI 910), 2-hydroxy-2-methyl-1-[4-(2-hydroxyethoxy)phenyl]propan-1-one (659), methyl benzoylformate (MBF), IHT-PI 4265 50% IHT-PI TPO and 50% IHT-PI 1173, IHT-PI1000 20% IHT-PI 184 and 80% IHT-PI 1173, IHT-PI500 50% IHT-PI 184 and 50% IHT-PI BP, etc.], it can be carried out at room temperature (10 °C to 30 °C); in radical polymerization using thermal initiators (alkyl peroxides, alkyl hydroperoxides (such as cumene hydroperoxide, tert-butyl hydroperoxide), peresters, azobisisobutyronitrile, diacyl peroxides, persulfates, etc.), the polymerization temperature should be controlled at 50 °C to 120 °C.

[0070] Step 3: Use the broadband polymer gain medium obtained in Step 2 as the core layer, and prepare a rectangular waveguide amplifier, an inverted ridge waveguide amplifier, or a loaded strip waveguide amplifier by means of spin coating, evaporation coating, photolithography, plasma etching, and ultraviolet imprinting, and adjust the refractive index of the core layer by adjusting the carrier matrix, baking temperature, and exposure time.

[0071] Example 1

[0072] This example provides a method for preparing a broadband polymer-based optical waveguide amplifier, which specifically includes the following steps:

[0073] (1) Prepare NaYF4:Tm,Yb nanoparticles by high-temperature pyrolysis: The matrix of the rare-earth nanoparticles is fluoride NaYF4, the sensitizer ion is Yb 3+ , and the luminescent center ion is Tm 3+. The specific synthesis steps are as follows: Take 2 mmol of rare earth chloride RECl3·6H2O [including 1% TmCl3·6H2O, 20% YbCl3·6H2O, 79% YCl3·6H2O], and add it together with 12 mL of oleic acid and 30 mL of octadecene into a three-necked flask. During the experiment, maintain high-speed stirring of the liquid and introduce argon as a protective gas. Heat the mixed liquid to 160 °C and keep it for 30 min, then naturally cool it to room temperature. Then, gradually add a 20 mL methanol solution containing 0.296 g of ammonium fluoride and a 10 mL methanol solution containing 0.2 g of sodium hydroxide dropwise into the three-necked flask. After the dropping is completed, raise the temperature of the mixed solution to 58 °C and keep it for 60 min to remove the methanol in the solution. After the methanol is completely removed, raise the temperature of the reaction system to 305 °C and keep it for 60 min, and then let the liquid naturally cool to room temperature. After the reaction system naturally cools to room temperature, precipitate the product with excessive absolute ethanol, and wash the product multiple times with a mixed solution of absolute ethanol and cyclohexane to obtain NaYF4:Tm, Yb nanoparticles.

[0074] (2) Coating an inert barrier layer by high-temperature pyrolysis method: The matrix of the rare earth nanoparticles is fluoride NaYF4 without doping active rare earth ions. The specific synthesis steps are as follows: Take 2 mmol of rare earth chloride YCl3·6H2O, and add it together with 12 mL of oleic acid and 30 mL of octadecene into a three-necked flask. During the experiment, maintain high-speed stirring of the liquid and introduce argon as a protective gas. Heat the mixed liquid to 160 °C and keep it for 30 min, then naturally cool it to room temperature. Then, gradually add a 20 mL methanol solution containing 0.296 g of ammonium fluoride and a 10 mL methanol solution containing 0.2 g of sodium hydroxide dropwise into the three-necked flask. After the dropping is completed, raise the temperature of the mixed solution to 58 °C and keep it for 60 min to remove the methanol in the solution. Add the NaYF4:Tm, Yb nanoparticles prepared in step (1) into the three-necked flask as the nanocore for shell growth. After the methanol is completely removed, raise the temperature of the reaction system to 305 °C and keep it for 60 min, and then let the liquid naturally cool to room temperature. After the reaction system naturally cools to room temperature, precipitate the product with excessive absolute ethanol, and wash the product multiple times with a mixed solution of absolute ethanol and cyclohexane to obtain NaYF4:Tm, Yb@NaYF4 nanoparticles.

[0075] (3) Coating a NaYF4:Er layer by high-temperature pyrolysis method: The matrix of the rare earth nanoparticles is fluoride NaYF4 doped with rare earth ion Er 3+As the luminescent center. The specific synthesis steps are as follows: Take 2 mmol of rare earth chloride RECl3·6H2O [including x% ErCl3·6H2O and (100 - x)% YCl3·6H2O], add it together with 12 mL of oleic acid and 30 mL of octadecene into a three-necked flask. During the experiment, maintain high-speed stirring of the liquid and introduce argon as the protective gas. Heat the mixed liquid to 160 °C and keep it for 30 min, then naturally cool it to room temperature. After that, gradually add a 20 mL methanol solution containing 0.296 g of ammonium fluoride and a 10 mL methanol solution containing 0.2 g of sodium hydroxide dropwise into the three-necked flask. After the dropping is completed, raise the temperature of the mixed solution to 58 °C and keep it for 60 min to remove the methanol in the solution. Add the NaYF4:Tm,Yb@NaYF4 nanoparticles prepared in step (2) into the three-necked flask as the nanocore for shell growth. After the methanol is completely removed, raise the temperature of the reaction system to 305 °C and keep it for 60 min, and then let the liquid naturally cool to room temperature. After the reaction system naturally cools to room temperature, precipitate the product with excess absolute ethanol and wash the product multiple times with a mixed solution of absolute ethanol and cyclohexane to obtain NaYF4:Tm,Yb@NaYF4@NaYF4:Er nanoparticles. The structural schematic diagram is as shown in Figure 1 shown, and the characterization of the properties of the nanoparticles is as shown in Figure 2 , Figure 3 and Figure 4 shown. The particle size of the nanoparticles is about 22 nm, all of which are hexagonal phases, and under the excitation of a 980 nm infrared pump light, an emission spectrum covering 1.45 μm - 1.57 μm that can be adjusted with the doping concentration can be generated, and the emission spectrum can be regulated by changing the doping concentration of the luminescent center ion Tm 3+ .

[0076] (4) Prepare a gain medium by doping the NaYF4:Tm,Yb@NaYF4@NaYF4:Er nanoparticles prepared in step (3) with SU-8 photoresist. Take 0.3 mmol of the washed rare earth nanoparticles, dissolve them in 2 mL of cyclohexane solvent and ultrasonically disperse them evenly. Take 1 mL of the above solution and blend it with SU-8 2002 photoresist according to a mass ratio of 1:4, and ultrasonically irradiate it for 120 min in the dark to obtain a photoresist polymer gain medium with uniformly dispersed rare earth nanoparticles.

[0077] (5) Prepare an optical waveguide amplifier using the gain medium obtained in step (4). The process of preparing a rectangular optical waveguide amplifier using photolithography technology is as shown in Figure 5 . First, as shown in (a) of Figure 5 , spin-coat a gain medium film on a silicon substrate with a silicon dioxide layer grown on its surface at a rotation speed of 3000 r / min for 30 s, as shown in Figure 5as shown in (b) of , and the temperature is raised step by step to 90 °C for pre-baking for 30 min. Then, the photomask with the waveguide structure is placed on the sample surface, as Figure 5 shown in (c) of . Ultraviolet exposure is carried out for 4 s using a photolithography machine, and then the temperature is raised step by step to 95 °C for post-baking for 30 min. After the sample is cooled to room temperature, it is developed using a special SU-8 developer, as Figure 5 shown in (d) of . Each immersion is for 1 s, and after 5 - 10 times, the development is completed to obtain a sample with a rectangular waveguide structure on the surface, and it is baked at 150 °C for 30 min, as Figure 5 shown in (e) of . Finally, polymethyl methacrylate is spin-coated on the sample surface at a speed of 3000 r / min to form the upper cladding of the device, and after baking at 120 °C for 150 min, the preparation of the device is completed, as Figure 5 shown in (f) of . The optical amplifier is pumped by a 980 nm laser to obtain a relative gain of about 3 dB at 1.45 μm - 1.75 μm; the gain test results are as Figure 6 shown in ; the relative gain of the polymer-based optical waveguide amplifier in the 1460 nm - 1575 nm band can reach 6 - 8 dB.

[0078] Example 2

[0079] This example provides a preparation method for a broadband polymer-based optical waveguide amplifier, which specifically includes the following steps:

[0080] (1) Preparation of NaYF4:Er,Yb nanoparticles by high-temperature pyrolysis method: The matrix of the rare-earth nanoparticles is fluoride NaYF4, the sensitizer ion is Yb 3+ , and the luminescent center ion is Er 3+ . The specific synthesis steps are as follows: Take 2 mmol of rare-earth chloride RECl3·6H2O [including 2% ErCl3·6H2O, 20% YbCl3·6H2O, 78% YCl3·6H2O], and add it together with 12 mL of oleic acid and 30 mL of octadecene into a three-necked flask. During the experiment, keep high-speed stirring of the liquid and introduce argon as a protective gas. Heat the mixed liquid to 160 °C and keep it for 30 min, then naturally cool it to room temperature. Then, a 20 mL methanol solution containing 0.296 g of ammonium fluoride and a 10 mL methanol solution containing 0.2 g of sodium hydroxide are added dropwise to the three-necked flask. After the dropping is completed, the mixed solution is heated to 58 °C and kept for 60 min to remove methanol in the solution. After the methanol is completely removed, the temperature of the reaction system is raised to 305 °C and kept for 60 min, and then the liquid is naturally cooled to room temperature. After the reaction system is naturally cooled to room temperature, the product is precipitated with excessive absolute ethanol, and the product is washed multiple times with a mixed solution of absolute ethanol and cyclohexane to obtain NaYF4:Er,Yb nanoparticles.

[0081] (2) Coating an inert barrier layer using the high-temperature pyrolysis method: The matrix of the rare-earth nanoparticles is fluoride NaYF4, and no active rare-earth ions are doped. The specific synthesis steps are as follows: Take 2 mmol of rare-earth chloride YCl3·6H2O, add it together with 12 mL of oleic acid and 30 mL of octadecene into a three-necked flask. During the experiment, maintain high-speed stirring of the liquid and introduce argon as a protective gas. Heat the mixed liquid to 160 °C and keep it for 30 min, then naturally cool it to room temperature. Then, gradually add 20 mL of methanol solution dissolved with 0.296 g of ammonium fluoride and 10 mL of methanol solution dissolved with 0.2 g of sodium hydroxide dropwise into the three-necked flask. After the dropping is completed, raise the temperature of the mixed solution to 58 °C and keep it for 60 min to remove methanol in the solution. Add the NaYF4:Er,Yb nanoparticles prepared in step (1) into the three-necked flask as the nanocore for shell growth. After the methanol is completely removed, raise the temperature of the reaction system to 305 °C and keep it for 60 min, and then let the liquid naturally cool to room temperature. After the reaction system naturally cools to room temperature, precipitate the product with excessive absolute ethanol and wash the product multiple times with a mixed solution of absolute ethanol and cyclohexane to obtain NaYF4:Er,Yb@NaYF4 nanoparticles.

[0082] (3) Coating the NaYF4:Tm,Yb layer using the high-temperature pyrolysis method: The matrix of the rare-earth nanoparticles is fluoride NaYF4, and the rare-earth ion Tm 3+ is used as the luminescence center. The specific synthesis steps are as follows: Take 2 mmol of rare-earth chloride RECl3·6H2O [including 1% TmCl3·6H2O, 20% YbCl3·6H2O, 79% YCl3·6H2O], add it together with 12 mL of oleic acid and 30 mL of octadecene into a three-necked flask. During the experiment, maintain high-speed stirring of the liquid and introduce argon as a protective gas. Heat the mixed liquid to 160 °C and keep it for 30 min, then naturally cool it to room temperature. Then, gradually add 20 mL of methanol solution dissolved with 0.296 g of ammonium fluoride and 10 mL of methanol solution dissolved with 0.2 g of sodium hydroxide dropwise into the three-necked flask. After the dropping is completed, raise the temperature of the mixed solution to 58 °C and keep it for 60 min to remove methanol in the solution. Add the NaYF4:Er,Yb@NaYF4 nanoparticles prepared in step (2) into the three-necked flask as the nanocore for shell growth. After the methanol is completely removed, raise the temperature of the reaction system to 305 °C and keep it for 60 min, and then let the liquid naturally cool to room temperature. After the reaction system naturally cools to room temperature, precipitate the product with excessive absolute ethanol and wash the product multiple times with a mixed solution of absolute ethanol and cyclohexane to obtain NaYF4:Er,Yb@NaYF4@NaYF4:Tm,Yb nanoparticles. The structural schematic diagram is as Figure 7 shown, and the emission spectrum in the visible light band is as Figure 8 shown.

[0083] (4) Prepare a gain medium by doping the NaYF4:Er,Yb@NaYF4@NaYF4:Tm,Yb nanoparticles prepared in step (3) with SU-8 photoresist. Take 0.3 mmol of the washed rare earth nanoparticles, dissolve them in 2 mL of cyclohexane solvent and ultrasonically disperse them evenly. Take 1 mL of the above solution and fuse it with SU-8 2002 photoresist according to a mass ratio of 1:4, and ultrasonically irradiate for 120 min in the dark to obtain a photoresist polymer gain medium with uniformly dispersed rare earth nanoparticles.

[0084] (5) Prepare an optical waveguide amplifier using the gain medium obtained in step (4). The process of preparing a rectangular optical waveguide amplifier using photolithography is as Figure 5 shown. First, spin-coat for 30 s at a speed of 3000 r / min on a silicon substrate with a silica layer grown on its surface to obtain a gain medium thin film, and stepwise heat up to 90 °C for pre-baking for 30 min. Then place a photomask with a waveguide structure on the sample surface, perform ultraviolet exposure for 4 s using a photolithography machine, and then stepwise heat up to 95 °C for post-baking for 30 min. After the sample is cooled to room temperature, develop it using a special SU-8 developer, soak it for 1 s each time, and finish developing after 5 - 10 times to obtain a sample with a rectangular waveguide structure on its surface, and harden the film at 150 °C for 30 min. Finally, spin-coat polymethyl methacrylate on the sample surface at a speed of 3000 r / min to form the upper cladding of the device, and complete the preparation of the device after baking at 120 °C for 150 min. Under the pumping of a 980 nm laser, the optical amplifier obtains a relative gain of approximately 2 dB at 0.45 μm, 0.54 μm, and 0.65 μm in the visible light band.

[0085] Example 3

[0086] (1) Prepare NaYF4:Ho,Yb nanoparticles by high-temperature pyrolysis method: The matrix of the rare earth nanoparticles is fluoride NaYF4, the sensitizer ion is Yb 3+ , and the luminescent center ion is Ho 3+The specific synthesis steps are as follows: Take 2 mmol of rare earth chloride RECl3·6H2O [including 0.5% HoCl3·6H2O, 20% YbCl3·6H2O, 79.5% YCl3·6H2O], and add it together with 12 mL of oleic acid and 30 mL of octadecene into a three-necked flask. During the experiment, maintain high-speed stirring of the liquid and introduce argon as a protective gas. Heat the mixed liquid to 160 °C and keep it for 30 min, then naturally cool it to room temperature. Then, gradually add 20 mL of methanol solution containing 0.296 g of ammonium fluoride and 10 mL of methanol solution containing 0.2 g of sodium hydroxide dropwise into the three-necked flask. After the addition is completed, raise the temperature of the mixed solution to 58 °C and keep it for 60 min to remove methanol in the solution. After the methanol is completely removed, raise the temperature of the reaction system to 305 °C and keep it for 60 min, and then let the liquid naturally cool to room temperature. After the reaction system naturally cools to room temperature, precipitate the product with excessive absolute ethanol and wash the product multiple times with a mixed solution of absolute ethanol and cyclohexane to obtain NaYF4:Ho, Yb nanoparticles.

[0087] (2) Coating an inert barrier layer by high-temperature pyrolysis method: The matrix of the rare earth nanoparticles is fluoride NaYF4 without doping active rare earth ions. The specific synthesis steps are as follows: Take 2 mmol of rare earth chloride YCl3·6H2O, and add it together with 12 mL of oleic acid and 30 mL of octadecene into a three-necked flask. During the experiment, maintain high-speed stirring of the liquid and introduce argon as a protective gas. Heat the mixed liquid to 160 °C and keep it for 30 min, then naturally cool it to room temperature. Then, gradually add 20 mL of methanol solution containing 0.296 g of ammonium fluoride and 10 mL of methanol solution containing 0.2 g of sodium hydroxide dropwise into the three-necked flask. After the addition is completed, raise the temperature of the mixed solution to 58 °C and keep it for 60 min to remove methanol in the solution. Add the NaYF4:Ho, Yb nanoparticles prepared in step (1) into the three-necked flask as the nanocore for shell growth. After the methanol is completely removed, raise the temperature of the reaction system to 305 °C and keep it for 60 min, and then let the liquid naturally cool to room temperature. After the reaction system naturally cools to room temperature, precipitate the product with excessive absolute ethanol and wash the product multiple times with a mixed solution of absolute ethanol and cyclohexane to obtain NaYF4:Ho, Yb@NaYF4 nanoparticles.

[0088] (3) Coating the NaYF4:Tm,Yb layer by high-temperature pyrolysis method: The matrix of the rare earth nanoparticles is fluoride NaYF4 doped with rare earth ion Tm 3+as the luminescent center. The specific synthesis steps are as follows: Take 2 mmol of rare earth chloride RECl3·6H2O [including 1% TmCl3·6H2O, 20% YbCl3·6H2O, 79% YCl3·6H2O], and add it together with 12 mL of oleic acid and 30 mL of octadecene into a three-necked flask. During the experiment, maintain high-speed stirring of the liquid and introduce argon as the protective gas. Heat the mixed liquid to 160 °C and keep it for 30 min, then naturally cool it to room temperature. After that, gradually add a 20 mL methanol solution containing 0.296 g of ammonium fluoride and a 10 mL methanol solution containing 0.2 g of sodium hydroxide dropwise into the three-necked flask. After the dropping is completed, raise the temperature of the mixed solution to 58 °C and keep it for 60 min to remove the methanol in the solution. Add the NaYF4:Ho,Yb@NaYF4 nanoparticles prepared in step (2) into the three-necked flask as the nanocore for shell growth. After the methanol is completely removed, raise the temperature of the reaction system to 305 °C and keep it for 60 min, and then let the liquid naturally cool to room temperature. After the reaction system naturally cools to room temperature, precipitate the product with excessive absolute ethanol and wash the product multiple times with a mixed solution of absolute ethanol and cyclohexane to obtain NaYF4:Ho,Yb@NaYF4@NaYF4:Tm,Yb nanoparticles, and its structural schematic diagram is as Figure 9 shown;

[0089] (4) Copolymerize the NaYF4:Ho,Yb@NaYF4@NaYF4:Tm,Yb nanoparticles prepared in step (3) with methyl methacrylate (MMA) monomer. After uniformly mixing 10 g of MMA, 2 mL of butyl acetate, and 0.02 g of azobisisobutyronitrile (AIBN) by low-speed stirring, pour them into a dry 50 mL straight two-necked round-bottom flask, and use a spherical condenser as the cooling reflux device. Keep uniform stirring throughout the reaction process. Heat the reaction system in a water bath to 65 °C and keep it for 60 min to complete the prepolymerization. Take 0.1 mmol of the nanoparticles obtained in step (1), ultrasonically disperse them in 4 mL of butyl acetate solvent, and gradually add them dropwise into the straight two-necked flask at the end of the prepolymerization. After the dropping is completed, raise the temperature to 80 °C and keep it for 10 min - 25 min to obtain a clear and transparent viscous liquid, and the preparation of the composite polymer gain medium is completed. Its microscopic structural schematic diagram is as Figure 10 shown.

[0090] (5) Use the composite polymer prepared in step (4) to prepare an optical waveguide amplifier, and the process is as Figure 11 shown. First, as shown in (a) of Figure 11 , evaporate an aluminum film on a silicon substrate with a 10 μm - 15 μm thick silica layer grown on it, and spin-coat BP212 photoresist. As shown in (b) of Figure 11 , cover the sample surface with a photomask plate with a waveguide structure. As shown in Figure 11As shown in (c), ultraviolet exposure is carried out for 6 s using a lithography machine to obtain a photoresist layer with local exposure of the waveguide topography, as Figure 11 As shown in (d), a sodium hydroxide aqueous solution with a concentration of 0.1 mol / L is prepared using deionized water and solid sodium hydroxide as the developer, and the sample is soaked in portions 4 - 6 times, with each time being 10 s, as Figure 11 As shown in (e), the photoresist and aluminum film in the unexposed area are removed, so that the part of the silica layer corresponding to the waveguide structure is exposed. Subsequently, a silica groove is obtained through ion etching. Then, the residual photoresist and aluminum film are removed using a sodium hydroxide aqueous solution with a concentration of 0.5 mol / L, and the silica lower cladding of the device is prepared, as Figure 11 As shown in (f). Then, the composite polymer prepared in step (2) is spin-coated on the silica surface at a rotation speed of 3000 r / min for 30 s to form an inverted ridge-shaped waveguide core layer structure, and baked at 100 °C for 120 min. Finally, PMMA is spin-coated on the sample surface at a rotation speed of 3000 r / min for 30 s, and after baking at 120 °C for 150 min, the preparation of the device is completed. The optical amplifier obtains a relative gain of approximately 2 dB at 0.45 μm, 0.65 μm, and 1.48 μm under the pumping of a 980 nm laser.

[0091] The preferred embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0092] In addition, it should be noted that, in the case of no contradiction, the various specific technical features described in the above specific embodiments can be combined in any appropriate manner. To avoid unnecessary repetition, the present invention will not separately describe various possible combination methods.

[0093] Furthermore, any combination can be made between various different embodiments of the present invention as long as it does not violate the idea of the present invention, and it should also be regarded as the content disclosed by the present invention.

Claims

1. A preparation method of a broadband polymer-based optical waveguide amplifier, characterized in that Specifically, it includes the following steps: Step 1: Prepare multi-layer core-shell rare earth nanoparticles doped with multiple lanthanide luminescent center ions. Dope the luminescent center ions in different shell layers respectively, and add a barrier layer. By adjusting the doping position and doping ratio of the luminescent center ions and controlling the thickness of the growth barrier layer, the luminescent center ions can achieve relatively flat broadband luminescence in multiple bands. Step 2: Prepare a broadband polymer gain medium by physically doping or chemically bonding the multi-layer core-shell rare earth nanoparticles doped with multiple lanthanide luminescent center ions prepared in Step 1. Step 3: Use the broadband polymer gain medium obtained in Step 2 as the core layer to prepare an optical waveguide amplifier, and adjust the refractive index of the core layer by adjusting the substrate carried, baking temperature, and exposure time.

2. The preparation method of a broadband polymer-based optical waveguide amplifier according to claim 1, characterized in that, Specifically, Step 1 includes the following content: A1: Prepare core-multi-shell rare earth nanoparticles MREF4 by hydrothermal method, high-temperature pyrolysis method or precipitation method, where RE is a rare earth element and M is an alkali metal. A2: Doping different positions of the core and the shell with various luminescent center ions respectively; the luminescent center ions include Er 3+ , Tm 3+ , Pr 3+ , Nd 3+ , Ho 3+ , Eu 3+ or Tb 3+ ; A3: Prepare an intermediate barrier layer in the shell layers doped with different luminescent center ions. A4: Adjust the doping position and doping ratio of different luminescent center ions and control the thickness of the growth barrier layer so that the emission peak intensities of the luminescent center ions in each shell layer match in their characteristic emission bands, obtaining a broadband luminescence spectrum covering multiple bands in the same rare earth nanoparticle, and the spectra of each band are relatively flat, laying a foundation for the broadband optical amplifier to obtain gain in each band.

3. The manufacturing method of a broadband polymer-based optical waveguide amplifier as described in claim 2, characterized in that, In Step A2, the concentration of the luminescent center ions is defined as: the amount of substance of each luminescent center ion / the total amount of substance of the rare earth element in the rare earth nanoparticles, with a range of 0% - 2%; the total concentration of the luminescent center ions is defined as: the sum of the concentrations of all types of luminescent center ions, with a range not exceeding 10%, the concentration of the sensitizer ions is defined as: the amount of substance of the sensitizer ions / the total amount of substance of the rare earth element in the rare earth nanoparticles, specifically 20%; and the sum of the total concentration of the luminescent center ions and the concentration of the sensitizer ions does not exceed 30%; the thickness of the barrier layer ≥ 3 nm, and the barrier layer is a fluoride matrix material or SiO2, TiO2 oxide material.

4. The preparation method of a broadband polymer-based optical waveguide amplifier according to claim 1, characterized in that, The physical doping method in Step 2 specifically includes the following content: B1: Disperse the rare earth nanoparticles prepared in Step 1 in an organic solvent under ultrasonic dispersion or high-speed stirring to obtain a solution in which the rare earth nanoparticles are uniformly dispersed. B2: Mix the dispersion obtained in Step B1 with a polymer photoresist at a mass percentage of 10% - 30%; ultrasonically disperse or high-speed stir the mixture to obtain a gain medium in which the rare earth nanoparticles are uniformly dispersed.

5. The preparation method of a broadband polymer-based optical waveguide amplifier according to claim 4, wherein The organic solvents in Step B1 include: alcohols, ketones, esters or heterocyclic compounds; the alcohols include methanol, ethanol, ethylene glycol or glycerol; the ketones include acetone, butanone or cyclohexanone; the esters include methyl formate, ethyl acetate, ethyl formate or butyl acetate; the heterocyclic compounds include furan, thiophene, pyrrole, thiazole or imidazole; the polymer photoresists in Step B2 include SU-8 series, BPO or BP212.

6. The preparation method of a broadband polymer-based optical waveguide amplifier as described in claim 1, characterized in that, The chemical bonding method in Step 2 specifically includes the following content: C1: Disperse the rare earth nanoparticles prepared in Step 1 in a solvent, add a polymer monomer and an initiator, and the mass of the initiator is 0.01%-1% of the mass of the polymer monomer; C2: Polymerize the nanoparticles in a polymer matrix by bulk polymerization, solution polymerization, suspension polymerization or emulsion polymerization to obtain a gain medium; the doping concentration of the rare earth nanoparticles in the polymer after polymerization is 0.01%-50%.

7. The preparation method of a broadband polymer-based optical waveguide amplifier according to claim 6, characterized in that, In Step C1, the polymer monomer is a monomer capable of undergoing addition polymerization or a monomer capable of undergoing condensation polymerization; the monomers capable of undergoing addition polymerization include: ① monomers with unsaturated double bonds and triple bonds: such as unsaturated acid esters, olefin monomers; ② monomers with epoxy groups: glycidyl methacrylate, epoxy resin monomers, 1,2-epoxybutane, 1,2-epoxy-9-decene, 1,2-epoxyheptane, glycidyl methyl ether; the monomers capable of undergoing condensation polymerization include phenolic resin monomers, polyesters, lactide monomers.

8. The preparation method of a broadband polymer-based optical waveguide amplifier according to claim 6, characterized in that In Step C2, the polymerization temperature is controlled at 10°C to 120°C, the polymerization time is 0.5 hours to 48 hours, and the degree of polymerization of the composite polymer gain medium is adjusted according to the changes in the manufacturing process of the optical waveguide device, and the degree of polymerization of the composite polymer is controlled at 5%-95%.

9. The preparation method of a broadband polymer-based optical waveguide amplifier according to claim 1, characterized in that, Step three specifically includes the following content: Use the broadband polymer gain medium obtained in Step two as the core layer, and prepare a rectangular waveguide amplifier, an inverted ridge waveguide amplifier or a loaded strip waveguide amplifier by spin coating, evaporation coating, photolithography, plasma etching, ultraviolet imprinting.

10. A broadband polymer-based optical waveguide amplifier, characterized in that, Prepared by the method according to any one of claims 1-9.

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