A method for manufacturing a PVA / dye flexible random laser based on an electrospinning method

Abstract

The application belongs to the technical field of laser, and relates to a method for manufacturing a PVA / dye flexible random laser based on an electrostatic spinning method. A mixed solution of PVA, ovalbumin, rhodamine dye and Au nano-particles is adopted, the sample size and the morphology of the spinning structure are controlled by controlling the voltage, the spraying distance and the needle tip size in the electrostatic spinning technology process, and then the wavelength and the mode of laser emission and other parameters are adjusted. The design is simple and intuitive, the method is flexible and convenient, the principle is reliable, and the method is easy to realize. The obtained flexible random laser is easy to be coupled with other photon devices, and the quantitative control of the laser property is easy to be realized.

Description

Technical Field

[0001] This invention belongs to the field of laser technology and relates to a process for fabricating PVA / dye flexible random lasers, particularly a method for fabricating PVA / dye flexible random lasers based on electrospinning. Background Technology

[0002] Random lasers are a type of stimulated emission phenomenon formed by the multiple scattering and feedback amplification of light in a disordered medium. The emission pattern is related to the optical properties of the disordered medium, the scatterers, and their spatial distribution. With the deepening research into random lasers, significant progress has been made in three main areas: finding new materials, lowering the emission threshold, and controlling the emitted laser. This has led to a more in-depth understanding of the emission principle and property control of random lasers. However, currently, most materials that generate random lasers are organic and noble metal systems, many of which are toxic and have poor biocompatibility. This creates a bottleneck in the application of random lasers in biology, medicine, and other fields. Developing materials with good biocompatibility and achieving control over random lasers are problems that need to be solved.

[0003] Polyvinyl alcohol (PVA) is classified into pharmaceutical grade and chemical grade. Pharmaceutical grade PVA is an extremely safe polymer material, non-toxic to the human body, and has good biocompatibility, making it widely used in medicine. Different forms of PVA have been applied in various biomedical scenarios. For example, PVA aqueous gels are widely used in ophthalmology, wound dressings, and artificial joints, while films are used in pharmaceutical membranes and artificial kidney membranes. The safety of PVA is evident from its use in wound and skin repair products and eye drops. Some types of PVA are also commonly used in cosmetics such as masks, cleansers, toners, and lotions, serving as a commonly used and safe film-forming agent.

[0004] As a high-quality protein, ovalbumin accounts for approximately 54% of the total egg white protein. It is a typical globulin with a molecular weight of 44.5 kDa. Belonging to the phosphoglycoprotein family, it contains four free sulfhydryl groups and 385 amino acid residues. These amino acid residues intertwine and fold together to form a highly granular structure with a strong secondary structure, primarily consisting of α-helices and β-sheets. Ovalbumin has one disulfide bond and four sulfhydryl groups at its center. Heating allows intermolecular interactions to further stabilize the colloidal structure of ovalbumin.

[0005] In the research of random lasers, surface plasmon resonance enhancement based on metal nanoparticles is a commonly used approach. Surface plasmon resonance is essentially a collective oscillation state formed when photons interact with the free electrons of a metal, generating a strong local electric field that plays a crucial role in lowering the laser threshold. Random lasers often use materials such as quartz as substrates, employing spin-coating of films containing gain media and scatterers from solutions. Researchers have also successfully fabricated various types of random lasers by embedding microstructures into optical fibers, aiming to reduce laser size, improve luminous efficiency, and expand application potential. However, these methods struggle to precisely control film thickness and quality, and cannot achieve the construction of special structures in specific micro-regions. Furthermore, limitations in size and flexibility make it difficult to integrate random lasers with other optoelectronic devices, thus restricting their applications to some extent. Therefore, the design concepts and technical approaches for random lasers still require further improvement; further research is needed to reduce the threshold, decrease size, and quantitatively control laser parameters.

[0006] Invention content:

[0007] The purpose of this invention is to overcome the defects of existing technologies and address the problems existing in existing technologies by providing a novel and convenient method for fabricating PVA / dye flexible random lasers based on electrospinning. This method uses a mixture of PVA, ovalbumin, rhodamine dye, and Au nanoparticles. By controlling the voltage, spray distance, and needle tip size during the electrospinning process, the sample size and morphology of the spun structure are controlled, thereby adjusting parameters such as the wavelength and mode of the laser emission. Au nanoparticles act as scatterers to enhance the dye fluorescence effect, lowering the lasing threshold and obtaining a highly efficient and controllable random laser.

[0008] To achieve the above objectives, the specific process of fabricating a PVA / dye flexible random laser based on electrospinning technology is as follows: First, the spinning solution is loaded into the syringe of the electrospinning device and allowed to flow freely into the tip of the needle. Then, aluminum foil is fixed on the receiving device. The vertical (z-direction) movement and horizontal (xy-plane) movement are achieved by controlling the lifting and translation devices, respectively, thereby controlling the distance between the needle tip of the syringe 1 and the receiving device to achieve the spraying of the spinning solution. A high voltage is applied between the needle tip of the syringe and the receiving device to control the spinning solution to form a nanofiber structure. After spinning is completed, the nanofiber structure is peeled off from the aluminum foil to obtain the PVA / dye flexible random laser.

[0009] The spinning solution of this invention is an aqueous solution containing PVA, the organic dye Rhodamine 6G, Au nanoparticles, and ovalbumin. First, PVA particles are dissolved in deionized water, and then mixed with the well-dispersed aqueous solution of Rhodamine 6G, Au nanoparticles, and ovalbumin to obtain the spinning solution. The mass ratio of solvent to solute is adjusted according to actual needs. Ovalbumin is used to increase biocompatibility, and the concentration ratio of ovalbumin to PVA controls the characteristics of the spinning structure. Rhodamine 6G serves as a gain medium to achieve fluorescence amplification, and Au nanoparticles act as scatterers to achieve fluorescence enhancement and laser generation. The addition of Au nanoparticles enhances photon scattering in the random laser system, lowers the lasing threshold, and improves luminescence efficiency.

[0010] The syringe described in this invention uses a special injection needle tube for spinning. By adjusting the needle tip diameter, it sprays out fiber structures of different line widths. The receiving device uses an electrode plate, and a high voltage is applied between the electrode plate and the needle tip to control the spraying out of the fiber. The lifting device and the translation device are used to control the movement of the substrate (aluminum foil) to achieve the spinning spraying of different structures. The entire electrospinning equipment is placed in a normal indoor environment and does not require an ultra-clean room.

[0011] The spinning material described in this invention, polyvinyl alcohol (PVA), is a water-soluble polymer with good mechanical properties, biocompatibility, and high hydrophilicity. The spun film of PVA and ovalbumin has a certain degree of extensibility and can achieve different degrees of bending, thereby qualitatively and quantitatively changing the emission characteristics of random lasers.

[0012] All components of the PVA / dye flexible random laser prepared by this invention have good water solubility. The mixed materials are integrally jet-spun into a film by electrospinning technology to obtain a flexible random laser. The emission properties of the random laser can be adjusted by changing the film thickness, density, and curvature.

[0013] This invention is based on the electrospinning method to fabricate PVA / dye flexible random lasers. During the laser emission test, pulsed laser is required for pump excitation, and the energy change of the pump light affects the intensity of the laser emission light.

[0014] Compared with existing technologies, this invention has the following advantages: First, it achieves nanofiber fabrication through electrospinning, which is simple, flexible, and convenient. Second, by controlling the spinning parameters during electrospinning, the size and speed of the sprayed material can be freely changed, making the entire process programmed and automated, which is conducive to mass production. Third, it achieves electrospinning of mixed materials through high voltage, resulting in fewer defects, higher efficiency, less dependence on the environment, and lower requirements for substrate flatness. Fourth, all component materials used are water-soluble, and the entire spinning process and the fabrication of the random laser are carried out in an aqueous environment without the use of other organic solvents, making it non-toxic and highly biocompatible. Fifth, it utilizes PVA, ovalbumin, gain medium, and scattering medium of different components to integrally spray and spin a flexible random laser, which has good biocompatibility and can be bent and deformed as a whole. By controlling bending, stretching, or other thin film parameters, the emission mode, wavelength, threshold, and other properties of the random laser can be freely adjusted. The design is simple and intuitive, the method is flexible and convenient, the principle is reliable, and it is easy to implement. The resulting flexible random laser is easy to couple with other photonic devices, and it is easy to achieve quantitative control of laser properties. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the main structure of the electrospinning device described in this invention.

[0016] Figure 2 This is a schematic diagram of the PVA / dye flexible random laser fabricated by electrospinning according to the present invention.

[0017] Figure 3 The diagram shows the PVA / dye flexible random laser emission configuration fabricated by electrospinning as described in this invention, wherein the pump light is a pulsed laser, and the fiber collector is connected to an external spectrometer to collect the lasing spectrum.

[0018] Figure 4 This is a schematic diagram of a laser spectral measurement model for the bending of a flexible random laser, prepared for an embodiment of the present invention. Δd and Δl represent the changes in the length and width of the sample after bending, respectively. Detailed Implementation

[0019] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0020] Example:

[0021] This embodiment adopts Figure 1The electrospinning apparatus shown is used to fabricate a PVA / dye flexible random laser. First, the spinning solution is loaded into the syringe 1 of the electrospinning apparatus and allowed to flow freely into the needle tip. Then, aluminum foil is fixed to the receiving device 4. The vertical (z-direction) and horizontal (xy-plane) movements are controlled by the lifting device 2 and the translation device 3, respectively, thus controlling the distance between the needle tip of syringe 1 and the receiving device 4, achieving the jetting of the spinning solution. A high voltage of several hundred to several thousand volts is applied between the needle tip of syringe 1 and the receiving device 4 as needed. Through the action of the electric field, the droplet at the needle tip changes from a spherical shape to a conical shape, and extends from the tip of the cone to form a filament, producing a nanofiber structure. After spinning, the nanofiber structure is completely peeled off from the aluminum foil, obtaining a flexible random laser containing Au nanoparticles and dye. Figure 2 As shown.

[0022] The spinning solution described in this embodiment is an aqueous solution containing PVA, the organic dye Rhodamine 6G, Au nanoparticles, and ovalbumin. First, PVA particles are dissolved in deionized water, and then mixed with the well-dispersed aqueous solution of Rhodamine 6G, Au nanoparticles, and ovalbumin to obtain the spinning solution. The solvent-to-solute mass ratio is adjusted according to actual needs. Ovalbumin is used to increase biocompatibility. By controlling the concentrations of ovalbumin and PVA, the mixture is ensured to have a certain viscosity to facilitate the formation of fine fibers, thereby controlling the characteristics of the spinning structure and achieving stronger optical gain feedback to obtain a random laser emission ratio. The dye Rhodamine 6G acts as a gain medium to obtain a fluorescence amplification effect, and the Au nanoparticles act as a scatterer to achieve fluorescence enhancement and obtain laser light. The addition of Au nanoparticles enhances photon scattering in the random laser system, lowers the lasing threshold, and improves luminous efficiency.

[0023] This embodiment will adopt Figure 3 The optical path shown is used to pump and excite the fabricated flexible random laser sample. The pump light is a nanosecond pulsed laser with a wavelength of 532 nm. Due to the fluorescence effect of the dye, the localized plasmon enhancement of Au nanoparticles and the scattering enhancement effect on photons, as well as the scattering enhancement effect of nanofibers on photons, photons are scattered multiple times at high frequency in the nanofibers, achieving effective gain amplification and realizing laser output. The pump light is incident on the sample surface at a 45° angle. An optical fiber collector is placed perpendicular to the sample surface on the other side of the sample. The optical fiber collector converges and receives the lasing light from the sample and forms a lasing spectrum through a spectrometer, which is then transmitted to a computer.

[0024] In this embodiment, by selecting the injection speed, translation speed, voltage, and needle tip size during the electrospinning process, nanofiber structures with different morphologies and sizes can be obtained, providing variable parameters for adjusting the properties of random laser luminescence.

[0025] In this embodiment, PVA is chosen as the film-forming material. PVA itself has good biocompatibility and water solubility, and is soluble in water. No organic solvents need to be added during the preparation of the mixed solution. The water-soluble environment makes the preparation process low-cost, non-toxic, and easy to control. Furthermore, the composite film obtained through spinning has excellent flexibility; it is bendable and foldable, making it easy to couple with other photonic devices and expanding its application range. By changing the degree of bending of the film, the properties of random laser wavelength, mode, intensity, and threshold can be freely controlled. A schematic diagram of the spectral measurement model of the flexible random laser under different degrees of bending is shown below. Figure 4 As shown, a certain force is applied to a flexible structure to make it bend, and the changes in the spectrum of random laser emission are recorded. The bending magnitude is quantitatively measured by Δd and Δl, so as to realize the quantitative control of the properties of random laser by adjusting the mechanical parameters of the flexible random laser.

[0026] This embodiment uses Au nanoparticles as the scatterer mainly because they have the dual effects of localized plasmon resonance and scattering. Using Au nanoparticles as a random laser scatterer results in a stronger scattering effect on photons, which is beneficial for multiple scattering of photons in the waveguide layer, achieving higher gain and obtaining random lasers with high modulation and low threshold.

[0027] The reasons for choosing ovalbumin in this embodiment are as follows: First, proteins are the main carriers of cellular and biological functions, and participate in almost all aspects of biological activities. Based on the changes in spectral signals caused by the interaction between proteins and metal ions, information on protein content and structure can be provided. Second, the addition of ovalbumin is beneficial to further improve the biocompatibility of the random laser and promote the application of flexible random lasers in fields such as biomonitoring. Third, controlling the concentration ratio of ovalbumin and PVA can achieve control over the morphology, size, and hardness of spun fibers, obtain sample structures with different extensibility, and also achieve regulation of random laser luminescence parameters.

[0028] This embodiment uses electrospinning technology to prepare random lasers for the following reasons: First, electrospinning technology is convenient and quick to form nanofiber structures, which is low-cost and highly efficient; second, the preparation process can be programmed and automated, and the linewidth, gap size, and film density of nanofibers can be freely changed. The transformation of the mixture into nanofibers is achieved by high voltage, which is simple, has few structural defects, high quality, low dependence on the environment, and low requirements for substrate materials.

Claims

1. A method for making a PVA / dye flexible random laser based on electrospinning, characterized in that, The specific process is: firstly, the spinning solution is filled into the injector of the electrostatic spinning device and flows freely into the needle tip, then the aluminum foil paper is fixed on the receiving device, and the distance between the needle tip of the injector and the receiving device is controlled by controlling the vertical movement and horizontal movement of the lifting device and the translation device respectively, so as to realize the injection of the spinning solution, and a high voltage is applied between the needle tip of the injector and the receiving device for controlling the spinning solution to form a nanofiber structure, after the spinning is completed, the nanofiber structure is peeled off from the aluminum foil paper, and a PVA / dye flexible random laser is obtained; when the spinning solution is prepared, the PVA particles are dissolved in deionized water, and then the water solution of the dispersed rhodamine 6G, Au nanoparticles and ovalbumin is mixed to obtain the spinning solution, wherein the mixing mass ratio of the solvent and the solute is adjusted according to the actual requirement; the injector adopts a special injection needle tube for spinning, different fiber structures with different line widths are sprayed by adjusting the diameter of the needle tip, and the receiving device adopts an electrode plate.

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