CN110077110B

CN110077110B - Method for manufacturing random laser system by ink-jet printing

Info

Publication number: CN110077110B
Application number: CN201910398268.8A
Authority: CN
Inventors: 吕浩; 王霞; 张帅一; 秦汉唐; 张校
Original assignee: Qingdao University of Science and Technology
Current assignee: Qingdao University of Science and Technology
Priority date: 2019-05-14
Filing date: 2019-05-14
Publication date: 2020-07-07
Anticipated expiration: 2039-05-14
Also published as: CN110077110A

Abstract

The invention belongs to the technical field of laser, and relates to a method for manufacturing a random laser system by ink-jet printing, which comprises the steps of firstly, filling printing ink into a printing needle tube, enabling the printing ink to freely flow into a tip end of a needle point, then fixing a flexible substrate on an electrode plate, applying high voltage between the needle point and the electrode plate, enabling the needle tube to freely move in the vertical direction, controlling the movement of the flexible substrate through an external computer end program, moving the flexible substrate according to a program preset at a computer end, thus realizing the printing of structures with different shapes, standing and solidifying an obtained sample after the printing is finished to obtain the random laser system of graphene reinforced dye based on the flexible substrate; the design is simple and visual, the method is flexible, convenient and fast, the principle is reliable, the realization is easy, flexible material PDMS is adopted as the substrate, the flexibility and the foldability of the random laser are increased, the coupling with other photonic devices is easier, and the quantitative control of the mechanical parameter adjustment of the substrate on the property of the random laser can be realized.

Description

Method for manufacturing random laser system by ink-jet printing

The technical field is as follows:

the invention belongs to the technical field of laser, and relates to a process for manufacturing graphene enhanced random laser, in particular to a method for manufacturing a random laser system by ink-jet printing.

Background art:

random Laser (Random Laser) is Laser generated by multiple scattering in a disordered scattering system to obtain nonlinear enhancement. Unlike conventional lasers, which require a finely tuned cavity, random lasers do not require a conventional laser cavity, but rely on photon localization. People realize the generation and regulation of random laser based on semiconductor nano structures, polymer films, quantum dots, biological tissues, photonic crystals and the like, and the random laser has the characteristics of small volume, high quality and no cavity emission and has great application potential in the aspect of optical integration. Random lasers provide a feedback mechanism by means of scattering effects, and nanostructures and nanoarrays have historically been the focus of development in scattering systems. The metal nano-structure with different energy band characteristics, the metal nano-particles with the local plasma resonance effect, the novel carbon materials such as graphene and carbon nano-tubes and the like are expected to become excellent random laser scatterers, and random laser emission with high power and low threshold is realized.

With the development of science and technology and the pursuit of people to convenient life such as intelligence wearing, the flexible display obtains scientific research personnel's favor because of advantages such as its collapsible, hi-lite, ultra-thinness. The laser device based on the flexible substrate is expected to be applied to the fields of micro sensors, flat panel display, OLED luminescence, information communication and the like. In flexible display, obtaining a light source with good quality, low loss and high brightness is still a difficult problem to be solved urgently in industrial application. The random laser is combined with the flexible substrate, so that the advantages of the random laser can be further exerted, the imaging quality is improved, the three-dimensional space laser is obtained, the integration of a random laser and different optoelectronic devices is realized, and the application of flexible display and the random laser is further promoted.

With the development and application of novel carbon materials such as graphene and carbon nanotubes, laser research and application based on carbon materials gradually come into the visual field of people. The existing researchers design a laser based on the saturable absorption characteristic of graphene, the laser pulse output of communication wavelength is realized by utilizing a ring-shaped fiber laser structure, the laser is based on the random metamaterial cavity-free laser emission of graphene, the scattering effect is greatly enhanced by the aid of the gain of dye and the feedback of graphene, the feedback efficiency of photons is effectively improved, the random laser threshold is reduced, and the improvement of the random laser performance is promoted.

The research of random laser is mainly based on a glass or quartz substrate, or the solution doped with a gain medium and a scatterer is placed in a small capillary tube, and laser emission is realized through optical pumping; personnel can embed the microstructure into the optical fiber to reduce the overall size of the laser, improve the luminous efficiency and expand the application potential. However, spin coating is often used in the manufacturing process, which is difficult to control the quality of the film layer and cannot realize the manufacturing of the specific structure in the specific area. The development and development of random laser have the challenges of reducing the pumping threshold, miniaturizing the device and quantitatively controlling the light-emitting parameters. In addition, the base material which is difficult to control not only influences the laser emitting intensity, but also limits the development and application of random laser devices to a certain extent due to the fact that the base material is large in size and inconvenient to couple.

The invention content is as follows:

the invention aims to overcome the defects in the prior art and provide a brand-new and convenient method for manufacturing a random laser system by ink-jet printing, aiming at the problems in the prior art, the array of a graphene and dye mixed material is printed on a flexible substrate material by the ink-jet printing technology, the emission of random laser is realized under the optical pumping, and the random laser system manufactured by the ink-jet printing technology can design the type, the size and the thickness of the array according to the programming, so that the parameters of the wavelength, the mode and the like of the laser emission can be effectively adjusted, the dye fluorescence effect is enhanced by taking the graphene as a scatterer, the lasing threshold is reduced, and the high-efficiency controllable random laser is obtained.

In order to achieve the above purpose, the specific process of manufacturing the random laser system by the inkjet printing technology of the invention is as follows: firstly, printing ink is filled into a printing needle tube, the printing ink freely flows into the tip of a needle point, then a flexible substrate is fixed on an electrode plate, micro-nano-level movement is realized in an x-y plane (horizontal plane) along with a precise control moving platform, and high voltage is applied between the needle point and the electrode plate for controlling the ejection and outflow state of the printing ink, so that the printing ink can be smoothly ejected and printed on the surface of the flexible substrate; the needle tube freely moves in the z direction (vertical direction) to control the distance between the needle point and the flexible substrate; the flexible substrate is moved through an external computer end program, the flexible substrate is moved according to a preset program of a computer end, printing of structures in different shapes is achieved, an obtained sample is placed statically and solidified after printing is finished, a random laser system of the graphene enhanced dye based on the flexible substrate is obtained, and excitation and testing of random laser emission are conducted.

The printing ink is prepared by respectively dispersing graphene and rhodamine 6G in different solvents and mixing the graphene and the rhodamine 6G according to a certain mass ratio to form ink required for printing, wherein the mass ratio of the solvents to the mixture is selected according to actual requirements, the rhodamine 6G is used as a gain medium to obtain a fluorescence amplification effect, the graphene is used as a scatterer to realize fluorescence enhancement to obtain laser, and due to the addition of the graphene, photon scattering in a random laser system is enhanced, the threshold value is reduced, and the efficiency is improved.

The needle tube adopts an injection needle tube, and the printing of structures with different line widths is realized by adjusting the diameter of the needle tip; applying high voltage between the electrode plate and the needle point to control the ink jet flow; the precise control mobile platform is used for controlling the movement of the substrate to realize the printing of different structures, and equipment required by the printing can be used in a common indoor environment without an ultra-clean room.

The flexible substrate is Polydimethylsiloxane (PDMS), is one of organic silicon, is low in cost and simple to use, has good adhesion to printing ink, has good chemical inertness, and can be bent and stretched to different degrees by the PDMS, so that the emission characteristic of random laser can be qualitatively and quantitatively changed.

In the graphene enhanced dye random laser system based on the flexible substrate, the printing ink is adhered to the surface of the PDMS substrate and deforms along with the bending of the substrate, so that the emission property of random laser is adjusted.

The graphene enhanced dye random laser system based on the flexible substrate needs to use pulse laser as pump light to excite pumping during excitation and test, and energy change of the pump light influences intensity of laser emitted light.

Compared with the prior art, the invention has the following advantages: firstly, the preparation of the mixed liquid of graphene and dye is realized in a printing mode, the method is flexible and convenient, and the printing of structures with different dimensions and different shapes such as linear type, dot type array, three-dimensional lattice point and the like can be realized; secondly, the line width, the ink jet speed, the printing structure layer number and the like of the printing structure can be freely changed by controlling the printing parameters in the printing process, and all the printing processes are stylized and automated, thereby being beneficial to batch production; thirdly, the jet printing of the ink is realized through high voltage, the defects are few, the efficiency is high, the dependence degree on the environment is small, and the requirement on the flatness of the substrate is low; fourthly, graphene is used as a random laser scatterer, the scattering effect on photons is stronger, and random laser with high modulation rate and low threshold is obtained; fifthly, a PDMS flexible substrate is adopted, the substrate material can be bent, and the properties of the random laser such as the emergent mode, the wavelength, the threshold value and the like can be freely adjusted through bending or stretching the substrate material; the design is simple and visual, the method is flexible, convenient and fast, the principle is reliable, the realization is easy, flexible material PDMS is adopted as the substrate, the flexibility and the foldability of the random laser are increased, the coupling with other photonic devices is easier, and the quantitative control of the mechanical parameter adjustment of the substrate on the property of the random laser can be realized.

Description of the drawings:

FIG. 1 is a schematic diagram of the main structure of an inkjet printing system according to the present invention.

Fig. 2 is a schematic diagram of a stochastic laser system based on graphene enhanced dyes with flexible substrates according to the present invention.

Fig. 3 is an emission configuration diagram of the random laser system based on graphene enhanced dye with a flexible substrate, wherein pump light is pulse laser, and an optical fiber collector is connected with an external spectrometer for collecting a lasing spectrum.

Fig. 4 is a schematic diagram of a random laser spectroscopy measurement model of a substrate with different degrees of bending according to an embodiment of the present invention, where (a) - (c) are increasingly bent, d and l respectively represent the initial width and length of a PDMS film, and Δ d and Δ l respectively represent the amount of change in length and width after bending.

The specific implementation mode is as follows:

the invention is further illustrated by the following examples in conjunction with the accompanying drawings.

Example (b):

the main structure of the ink-jet printing system comprises a needle tube, a needle tip, printing ink, high-voltage electricity, a PDMS flexible substrate, an electrode plate and a precision control moving platform, wherein the needle tip is arranged below the needle tube and is connected with the needle tube, and the needle tube freely moves in the z direction (vertical direction), so that the distance between the needle tip and the PDMS flexible substrate is controlled, and the printing ink is jetted and flows out; the PDMS flexible substrate is arranged above the electrode plate, and the micro-nano-level movement is realized along with the movement of the precise moving platform in an x-y plane, so that printing structures in different shapes are obtained; applying high voltage (generally hundreds of volts to thousands of volts) between the needle point and the electrode plate, and enabling printing ink to be ejected from the needle point and adhered to the surface of the PDMS flexible substrate by the action of the electric field force; the needle tube and the precise control mobile platform move through an external computer end to realize programmed control, and the automation and the high efficiency of the printing process are ensured.

An insulating material isolation layer is arranged between the electrode plate and the precision control moving platform, so that firstly, an electric field is generated between the electrode plate and the needle point due to the applied high voltage to promote the jet of printing ink; secondly, the high voltage is prevented from puncturing a precision control platform circuit to influence the movement of the platform in the printing process.

In the embodiment, the printing ink used in the inkjet printing process is a mixed solution containing graphene and an organic dye rhodamine 6G, the graphene is firstly dispersed in cyclohexanone/terpineol, and is mixed with an ethanol solution of the dispersed rhodamine 6G according to a mass ratio of 1:1, so that the mixed solution has a certain viscosity to facilitate printing, the strongest optical gain feedback is realized, and the emission of random laser is obtained.

The PDMS flexible substrate is a film with a smooth surface and a thickness of tens of micrometers, which is obtained by uniformly coating PDMS on the surface of silica gel glass and performing heat treatment.

In this embodiment, a PDMS flexible substrate is placed on an inkjet printing system to perform printing and manufacturing of a structure, a printing array shown in fig. 2 is obtained, after the printing is finished, an obtained sample is kept still and solidified, then the PDMS flexible substrate coated with printing ink is peeled off from the surface of silica gel glass, graphene sheets and dye molecules in the formed structure are uniformly dispersed in a printing pattern, a waveguide layer is formed in the PDMS substrate and the printing structure, and local enhancement and multiple scattering of photons are realized, so that a random laser system of a graphene enhanced dye based on a flexible substrate is obtained, a laser emission configuration diagram of the random laser system is shown in fig. 3, pulse laser with a wavelength of 532nm is used as pump light to excite the manufactured random laser system of the graphene enhanced dye based on the flexible substrate, due to the fluorescence effect of organic dye and the scattering effect of graphene on photons, multiple scattering of photons is generated in the PDMS flexible substrate and the graphene-dye layer, the gain amplification of light is realized, laser is obtained, pump light enters the surface of a sample system along an angle of 45 degrees, one side surface of a sample structure and dye faces the incident direction of the laser, an optical fiber collector is arranged on the other side of the random laser system and is vertical to the surface of a substrate, and laser light of the sample is converged and received and forms a laser spectrogram through a spectrometer.

In the embodiment, the random laser system of the graphene enhanced dye based on the flexible substrate can obtain an array with a line width of several micrometers to several hundred micrometers by selecting a needle point, controlling voltage and controlling the distance between the needle point and the substrate in the printing process, and can print planar structures such as a one-dimensional grating and a two-dimensional grid; or the three-dimensional arrays with different structures and thicknesses are obtained by adopting layer-by-layer printing.

This example selects a graphene-dye printing ink for the following reasons: the graphene is used as a random laser scatterer, so that the scattering effect on photons is stronger, the multiple scattering of the photons on the waveguide layer is facilitated, the higher gain is realized, and the random laser with the high modulation rate and the low threshold is obtained.

The embodiment adopts the flexible material PDMS as the substrate, and has two main functions: firstly, the flexibility and foldability of the random laser can be increased, the random laser can be easily coupled with other photonic devices, and the application range of the random laser is expanded; secondly, by changing the bending property of the substrate material, the properties of the random laser output such as wavelength, mode, intensity, threshold value and the like are changed, the schematic diagram of the random laser spectrum measurement model under different bending degrees of the substrate is shown in fig. 4, a certain force is applied to the flexible structure to bend the flexible structure, the change condition of the spectrum emitted by the random laser is recorded, the bending size of the flexible substrate is quantitatively measured by delta d and delta l, and the quantitative control of the mechanical parameter adjustment of the substrate on the properties of the random laser is realized.

The present embodiment selects the inkjet printing technology to realize the preparation of random laser, and has the following reasons: firstly, the ink-jet printing technology is convenient and quick to form, can realize the printing and forming of one-dimensional gratings, two-dimensional grids and three-dimensional arrays, is low in cost and high in efficiency, and can realize batch printing and manufacturing; and secondly, the printing process can realize programming and automatic control, the line width, the ink jet speed, the number of printing structure layers and the like of the printing structure can be freely changed, the ink jet printing is realized through high voltage, the defects are few, the quality is high, the dependence degree on the environment is small, and the requirement on the substrate flatness is low.

Claims

1. A method for manufacturing a random laser system by ink-jet printing is characterized in that printing ink is firstly filled into a needle tube for printing and is enabled to freely flow into a tip end of a needle point, the needle point is arranged below the needle tube and is connected with the needle tube, a flexible substrate is fixed on an electrode plate and moves in a micro-nano level in a horizontal plane along with a precise control moving platform, and high voltage is applied between the needle point and the electrode plate for controlling the jet flow state of the printing ink and ensuring that the printing ink can be smoothly ejected and printed on the surface of the flexible substrate; the needle tube freely moves in the vertical direction to control the distance between the needle tip and the flexible substrate; the movement of the flexible substrate is controlled through an external computer end program, the flexible substrate is moved according to a program preset by a computer end, so that printing of structures with different shapes is realized, an obtained sample is kept stand and solidified after printing is finished, a random laser system of the graphene enhanced dye based on the flexible substrate is obtained, and excitation and testing of random laser emission are carried out; the printing ink is prepared by respectively dispersing graphene and rhodamine 6G in different solvents and mixing the graphene and the rhodamine in a certain mass ratio to form ink required by printing, wherein the mass ratio of the solvents to the mixed solution is selected according to actual requirements; the needle tube adopts an injection needle tube, and the printing of structures with different line widths is realized by adjusting the diameter of the needle tip; applying high voltage between the electrode plate and the needle point to control the ink jet flow; the precise control mobile platform is used for controlling the movement of the flexible substrate to realize printing of different structures, and equipment required by printing is only required in a common indoor environment without an ultra-clean room; the flexible substrate is a PDMS (polydimethylsiloxane) flexible substrate.

2. The method for manufacturing a stochastic laser system according to claim 1, wherein the stochastic laser system based on the graphene enhanced dye with the flexible substrate needs to be excited and pumped by using a pulse laser as a pump light during excitation and test, and the energy change of the pump light affects the intensity of laser emission light.