Preparation method of organic flexible single-crystal micro-ring and laser and application thereof

Abstract

The application discloses an organic flexible single-crystal micro-ring, a preparation method of a laser and application of the organic flexible single-crystal micro-ring. The organic flexible single-crystal micro-ring is obtained by self-assembly of organic molecules with multiple gain states and flexible groups, and can be used as a laser. The prepared micro-ring cavity has a high-quality ring resonant structure and multiple gain energy levels, and can simultaneously output a dual-color laser signal. The relative strength of the dual-color laser signal can sense a degree of strain, and a function of sensing stress deformation based on the laser signal is realized. The single-crystal micro-ring laser can reflect the degree of deformation through the relative strength ratio of different laser signals, is more intuitive, and has a larger range of sensed deformation. The self-assembly method for the ring structure provided by the application has less lattice defects of the prepared material compared with a semiconductor micro-processing technology (such as evaporation, etching, etc.), and can provide a molecular-level smooth crystal surface, and reduce optical loss.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic nanophotonics, and in particular relates to a preparation method of an organic flexible single crystal microring and a laser and applications thereof. Background Art

[0002] Flexible wearable devices have attracted widespread attention in cutting-edge fields such as future displays and chemical and biological sensing, particularly in interactive consumer electronics, artificial photoelectric skin, and devices for monitoring human motion and vital signs. However, most current flexible sensors utilize electronics as their working medium, making them susceptible to interference from complex external electromagnetic fields. This results in a decrease in the signal-to-noise ratio (SNR) of the sensing information, limiting their practical application. Coherent optical signals (laser signals) are electromagnetically immune, immune to electromagnetic crosstalk and path delays, and offer unique advantages such as fast transmission speed and parallel transmission. Furthermore, the laser signal's extremely narrow half-width (FWHM) makes it easy to identify and detect. Therefore, developing strain sensors using lasers as signal sources is key to the design and development of new wearable devices with both high stability and high sensitivity. However, most current strain sensing lasers are limited by factors such as the narrow bandgap of the gain medium and the rigidity of their materials, resulting in a limited strain sensing range that is generally lower than the deformation range of human skin. Therefore, there is an urgent need to explore and develop new flexible laser materials to expand the response range of strain sensing lasers. Summary of the Invention

[0003] The present invention has discovered through research that molecular systems with excited-state intramolecular proton transfer (ESIPT) have multiple gain states, and the compound skeleton with an intramolecular proton ring is easily affected by the external environment and produces torsion, which is conducive to achieving reversible switching between multiple vibrational energy levels and providing the possibility of exhibiting broadband strain sensing performance. The van der Waals force between flexible groups (such as pentyloxy, hexyl, etc. and chlorine groups, etc.) can effectively absorb stress, thereby avoiding crystal breakage; the two-dimensional annular microcavity has the characteristics of high quality factor and easy deformation, which is helpful to analyze the deformation degree and laser signal change of the flexible crystal microcavity under different degrees of strain, and realize the controllable construction of strain sensing crystal lasers. Based on the above ideas, the present invention provides an organic flexible single crystal microring, a method for preparing a laser and its application.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] The present invention first provides an organic flexible single crystal microring, which is obtained by self-assembly of organic molecules with multiple gain states and flexible groups, and can provide a two-color laser signal. At the same time, the relative intensity of the laser signal can sense the degree of strain.

[0006] The organic molecule is an organic crystal material with multiple vibration energy level signal output and good mechanical flexibility. The organic crystal material is a Schiff base derivative, a hydroxyphenylazole derivative, and a hydroxyacetophenone derivative having a long-chain alkane group or multiple chlorine groups, and their structural formulas are as follows:

[0007]

[0008] Where R1 and R2 are any of the following:

[0009] As a preferred embodiment, the organic molecule is a Schiff base derivative. R2=-Cl, that is, the organic molecule is (E)-4-chloro-2-(((4-n-pentylphenyl ketone)imino)methyl)phenol, and its structural formula is as follows;

[0010]

[0011] The preparation method of the (E)-4-chloro-2-(((4-n-pentylphenyl ketone)imino)methyl)phenol is as follows: 5-chloro-2-hydroxybenzaldehyde and 4-pentylaniline are added to ethanol and stirred evenly; a 1 g / ml NaOH aqueous solution is added, and the mixture is refluxed and stirred at 55-65° C. for 15-17 hours; after the reaction is completed, the mixture is cooled to room temperature, the pH is adjusted to 1±0.1 with hydrochloric acid, and a solid is obtained by filtration; and the solid is recrystallized using a mixed solvent of chloroform and ethanol to obtain the (E)-4-chloro-2-(((4-n-pentylphenyl ketone)imino)methyl)phenol.

[0012] Furthermore, the organic flexible single crystal microring is a crystalline structure.

[0013] Furthermore, the diameter of the organic flexible single crystal microring is 1 to 50 μm, preferably 2 to 20 μm.

[0014] Furthermore, the ring arm height of the organic flexible single crystal microring is 0.5 to 3 μm, preferably 1 to 2 μm, which can effectively confine the light field and reduce the optical loss of the substrate.

[0015] The present invention also provides a method for preparing an organic flexible single-crystal microring laser. Organic molecules are uniformly dissolved in an organic solvent. When the organic solvent evaporates, the organic molecules self-assemble into a flexible ribbon structure. At this time, liquid phase self-assembly assisted by the surface tension of the droplets is used to bend and assemble the organic flexible ribbon structure. The method specifically includes the following steps:

[0016] 1) uniformly dissolving the raw organic molecules in an organic solvent to obtain an organic solution;

[0017] 2) Place a hydrophobic horizontal substrate in a confined space, drip the organic solution onto the substrate, and allow it to stand to evaporate the solvent;

[0018] 3) Drying the enclosed space causes the solution to form droplets. The surface tension of the droplets induces the organic molecules to bend and grow, resulting in an organic flexible single crystal microring.

[0019] 4) Transferring the organic flexible single crystal microring to a flexible and stretchable substrate to complete the microring assembly (or, in step 2, directly using a flexible substrate and completing the microring assembly directly on the flexible substrate), ultimately obtaining a stretchable and deformable organic flexible single crystal microring that can be used as a laser.

[0020] Furthermore, the organic solvent is one or more of ethanol, methanol, ethanol / dichloromethane mixed solution, ethanol / water mixed solution, and ethanol / trichloroethane mixed solution.

[0021] Furthermore, the concentration of the organic molecule in the organic solution is 0.5-2 mg / mL.

[0022] Furthermore, the enclosed space is a cylindrical space with a diameter of 5 cm and a height of 2 cm.

[0023] Furthermore, the volume of the single dripping organic solution is 400 μL.

[0024] Furthermore, the base is various commonly used substrates, such as a glass substrate, a quartz substrate, a silicon substrate, a conductive glass substrate, a magnesium fluoride substrate, a metal film or an enhanced reflector.

[0025] Furthermore, the flexible substrate is polydimethylsiloxane (SPDM).

[0026] Preferably, the drying means waiting for the complete evaporation of the solvent. During the drying process of the system, the organic ribbon structure grows in a curved manner in the droplet on the substrate due to the surface tension of the droplet, and gradually closes to form a ring structure.

[0027] The organic flexible single crystal microring can realize laser output above dual visible light bands, and can regulate the relative intensity values ​​of dual-band signals according to power.

[0028] The organic flexible single-crystal microring laser can sense a deformation degree of 20% based on laser signals.

[0029] In the present invention, the size of the resonant cavity is controlled by changing the concentration of the organic molecules, thereby obtaining output signals of lasers in different modes.

[0030] The organic flexible single-crystal microring laser can be applied in the following fields: (1) to realize ultra-small size high-throughput information light source; (2) to be used for high-throughput information processing of optoelectronic information circuits, such as wavelength division multiplexers, optical routers, etc.; (3) to be used for preparing dual-color switchable laser signal light source; (4) to be used for mechanical information sensing such as deformation and strain.

[0031] Beneficial effects of the present invention:

[0032] 1. The present invention provides an organic flexible single-crystal microring laser. The main material of the organic flexible single-crystal microring laser is an excited-state intramolecular proton transfer (ESIPT) derivative with multiple gain states and flexible groups, which can simultaneously provide broadband gain and mechanical flexibility. The main material has excellent controllable self-assembly properties and can be processed into a high-quality annular whispering gallery resonator. Such a resonator is extremely sensitive to external mechanical deformation and can achieve dynamic response of the laser spectrum. The organic flexible single-crystal microring laser achieves adjustable dual-band laser output and has a high quality factor. Under external mechanical action, the organic flexible single-crystal microring laser can complete deformation, and the laser signal can also be switched accordingly. Therefore, the ratio of the laser intensity of the two bands can reflect the degree of deformation of the optical cavity, ultimately realizing mechanical deformation sensing based on the laser signal. Unlike previous deformation laser sensors that rely on small wavelength shifts to determine the degree of deformation, the device provided by the present invention can reflect the degree of deformation through the relative intensity ratio of different laser signals, which is more intuitive and can sense a wider range of deformation.

[0033] 2. This invention provides a simple and easy-to-use method for fabricating organic flexible single-crystal microring lasers. Using liquid-phase self-assembly assisted by droplet surface tension, high-quality organic flexible single-crystal microrings are prepared. This ring structure efficiently confines the light field, while the tall ring arms reduce substrate-induced optical losses, significantly improving the optical performance of the organic flexible single-crystal microring laser. Furthermore, this method allows for the direct assembly of an organic flexible microdisk cavity onto a flexible substrate, facilitating mechanical deformation of the organic flexible single-crystal microring laser and enhancing the mechanical deformation sensing performance based on laser signals.

[0034] 3. The organic flexible single-crystal microring laser provided by the present invention can be applied in the following fields: (1) for realizing ultra-small size high-throughput information light source; (2) for high-throughput information processing in optoelectronic information circuits, such as wavelength division multiplexers, optical routers, etc.; (3) for preparing dual-color switchable laser signal light source; (4) for mechanical information sensing such as deformation and strain. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1The fluorescence spectrum and absorption spectrum of (E)-4-chloro-2-(((4-n-pentylphenylketone)imino)methyl)phenol.

[0036] Figure 2 Schematic diagram of the preparation process of the organic flexible single crystal microring of the present invention.

[0037] Figure 3 Scanning electron micrograph of an organic flexible single crystal microring based on (E)-4-chloro-2-(((4-n-pentylphenyl ketone)imino)methyl)phenol.

[0038] Figure 4 This is a fluorescence micrograph of an organic flexible single crystal microring based on (E)-4-chloro-2-(((4-n-pentylphenyl ketone)imino)methyl)phenol under ultraviolet light excitation.

[0039] Figure 5 The photoluminescence spectrum of the organic flexible single crystal microring based on (E)-4-chloro-2-(((4-n-pentylphenyl ketone)imino)methyl)phenol changes with the pump power.

[0040] Figure 6 Comparison of laser spectra of the organic flexible single-crystal microring laser based on (E)-4-chloro-2-(((4-n-pentylphenyl ketone)imino)methyl)phenol before and after deformation.

[0041] Figure 7 is the ratio of the 576 nm to 634 nm laser intensities of the organic flexible single-crystal microring laser based on (E)-4-chloro-2-(((4-n-pentylphenyl ketone)imino)methyl)phenol under different degrees of tensile deformation. DETAILED DESCRIPTION

[0042] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, should be understood that after reading the content of the present invention being recorded, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the limited scope of the present invention equally.

[0043] Example 1

[0044] In a preferred embodiment of the present invention, the organic molecule for constructing the organic flexible single crystal microring laser is a Schiff base derivative (E)-4-chloro-2-(((4-n-pentylphenyl ketone)imino)methyl)phenol, and its structural formula is as follows

[0045]

[0046] The preparation method is as follows:

[0047] 3.08 g of 5-chloro-2-hydroxybenzaldehyde and 2.98 g of 4-pentylaniline were added to 60 ml of ethanol and stirred uniformly; 2 ml of a 1 g / ml aqueous solution of NaOH was added; the mixture was heated under reflux at 60° C. with stirring and reacted for 16 hours; after completion of the reaction, the mixture was cooled to room temperature, the pH was adjusted to 1 with hydrochloric acid, and filtered to obtain a pale yellow solid; the pale yellow solid was placed in a 100 mL beaker and recrystallized from a mixed solvent of chloroform and ethanol to obtain (E)-4-chloro-2-(((4-n-pentylphenyl ketone)imino)methyl)phenol in an 80% yield.

[0048] Figure 1 The fluorescence spectrum and absorption spectrum of (E)-4-chloro-2-(((4-n-pentylphenyl ketone)imino)methyl)phenol. Figure 1 It can be seen that the Stokes shift of this organic molecule is large, and the absorption and emission overlapping area is small, which can effectively reduce optical self-absorption, provide higher optical emission efficiency, and provide a good gain foundation for achieving effective output of dual-band laser wavelengths.

[0049] Example 2

[0050] Fabrication of organic flexible single crystal microrings and organic flexible single crystal microring lasers

[0051] The present invention adopts a droplet-assisted liquid phase self-assembly method to prepare a (E)-4-chloro-2-(((4-n-pentylphenyl ketone)imino)methyl)phenol crystal micro-ring structure. The preparation steps are as follows: a mixed solution of ethanol and dichloromethane (the volume ratio of ethanol to dichloromethane is 1:1) containing 2 mg / mL (E)-4-chloro-2-(((4-n-pentylphenyl ketone)imino)methyl)phenol is prepared and subjected to ultrasonic treatment; 400 μL of the mixed solution is dripped onto a PDMS substrate; due to the faster evaporation rate of dichloromethane, the remaining solution is The method mainly contains ethanol with strong interfacial tension, forming a microliquid, which provides a template with a confining effect for the ring-shaped self-assembly of (E)-4-chloro-2-(((4-n-pentylphenyl ketone)imino)methyl)phenol; (E)-4-chloro-2-(((4-n-pentylphenyl ketone)imino)methyl)phenol first nucleates at the edge of the microdroplet. As the solvent continues to evaporate, the crystal continues to bend and grow, and finally closes into a ring crystal, thus obtaining an organic flexible single crystal microring based on (E)-4-chloro-2-(((4-n-pentylphenyl ketone)imino)methyl)phenol.

[0052] Figure 3 The following is a scanning electron micrograph of an organic flexible single crystal microring based on (E)-4-chloro-2-(((4-n-pentylphenyl ketone)imino)methyl)phenol. Figure 3It can be seen that the organic flexible single-crystal microring assembled and synthesized using the above method has high crystallinity and atomically smooth surface, which helps to reduce optical defect loss and provides a good cavity for optical confinement of multi-wavelength signals.

[0053] Figure 4 This is a fluorescence micrograph of an organic flexible single-crystal microring based on (E)-4-chloro-2-(((4-pentylphenylketone)imino)methyl)phenol under ultraviolet light excitation. The organic flexible single-crystal microring emits uniform light, without obvious local dimming or brightening due to defects, indicating that some of the emitted fluorescence is effectively confined within the system, exhibiting excellent two-dimensional optical waveguiding behavior. This property suggests that these organic flexible single-crystal microrings may function as both gain materials and optical microresonators.

[0054] Figure 5 The photoluminescence spectrum of an organic flexible single-crystal microring based on (E)-4-chloro-2-(((4-pentylphenylketone)imino)methyl)phenol varies with pump power. The organic flexible single-crystal microring synthesized in this invention, which combines broadband gain with mechanical flexibility, provides an opportunity to study laser behavior. When a pulsed laser beam (400nm, ~150fs) is focused on the organic flexible single-crystal microring, a series of sharp peaks are observed in the luminescence spectrum, such as Figure 5 As shown in Figure 2, the luminescence intensity of the 634nm and 576nm peaks in the gain region is significantly amplified with the increase of pump flux. The graph of luminescence peak intensity and pump flux shows that the luminescence peak intensity is significantly amplified at 1μJcm -2 and ∼2 μJ cm -2 A distinct knee feature is present at the threshold, indicating lasing. Above the lasing threshold, the full width at half maximum (FWHM) at both 634 nm and 576 nm shrinks significantly to ~0.4 nm, demonstrating the high quality of the resonator and relatively good spectral purity.

[0055] An organic flexible single-crystal microring based on (E)-4-chloro-2-(((4-n-pentylphenylketone)imino)methyl)phenol can be used as a laser to realize sensing behavior based on changes in laser signals under mechanical stimulation. Figure 6This is a comparison of the laser spectra of an organic flexible single-crystal microring laser based on (E)-4-chloro-2-(((4-n-pentylphenyl ketone)imino)methyl)phenol before and after deformation. By comparing the laser spectra before and after stretching, it can be found that the 576nm laser is the dominant signal when not stretched, while the laser at 634nm is in a suppressed state; after stretching, the 576nm laser is in a suppressed state, while the laser at 634nm is the dominant signal. This may be due to the induction of some crystal defects during the stretching process, while at the same time aggravating the optical sub-absorption behavior of the crystal, prompting a gain conversion. Based on this, the organic flexible single-crystal microring laser based on (E)-4-chloro-2-(((4-n-pentylphenyl ketone)imino)methyl)phenol has demonstrated the ability to regulate laser signals by stress and deformation.

[0056] Figure 7 The ratio of the 576nm and 634nm laser intensities of an organic flexible single-crystal microring laser based on (E)-4-chloro-2-(((4-n-pentylphenyl ketone)imino)methyl)phenol under different degrees of tensile deformation. The intensity ratio of the laser signals at 576nm and 634nm changes accordingly with varying degrees of stretching, effectively reflecting the degree of tensile deformation experienced by the ring laser. Ultimately, this demonstrates the controllable construction of a strain-sensing crystal laser and expands the strain sensing range.

[0057] The above describes the embodiments of the present invention. However, the present invention is not limited to the above embodiments. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included in the scope of protection of the present invention.

Claims

1. An organic flexible single crystal microring, characterized in that: It is obtained by self-assembly of organic molecules with multiple gain states and flexible groups, and can provide dual-color laser signals. At the same time, the relative intensity of the laser signals can sense the degree of strain. The organic molecule is (E)-4-chloro-2-(((4-n-pentylphenyl)imino)methyl)phenol, and its structural formula is as follows: 。 2. The organic flexible single crystal microring according to claim 1, wherein: The preparation method of (E)-4-chloro-2-(((4-n-pentylphenyl ketone)imino)methyl)phenol is as follows: 5-chloro-2-hydroxybenzaldehyde and 4-pentylaniline are added to ethanol and stirred evenly; a 1g / ml NaOH aqueous solution is added, and the mixture is refluxed and stirred at 55-65°C for 15-17 hours; after the reaction is completed, the mixture is cooled to room temperature, the pH is adjusted to 1±0.1 with hydrochloric acid, and a solid is obtained by filtration; and the solid is recrystallized using a mixed solvent of chloroform and ethanol to obtain (E)-4-chloro-2-(((4-n-pentylphenyl ketone)imino)methyl)phenol.

3. The organic flexible single crystal microring according to claim 1, wherein: The diameter of the organic flexible single crystal microring is 1-50 μm, and the height of the ring arm is 0.5-3 μm.

4. A method for preparing an organic flexible single-crystal microring laser, characterized in that: The steps include: 1) uniformly dissolving the organic molecule according to claim 1 in an organic solvent to obtain an organic solution; 2) Place a hydrophobic horizontal substrate in a confined space, drip the organic solution onto the substrate, and allow it to evaporate. 3) When the confined space is dried, the solution forms droplets. The surface tension of the droplets induces the organic molecules to bend and grow, resulting in an organic flexible single crystal microring. 4) The organic flexible single crystal microring is transferred to a flexible and stretchable substrate to complete the microring assembly, and finally a stretchable and deformable organic flexible single crystal microring is obtained, which can be used as a laser.

5. The method for preparing an organic flexible single-crystal microring laser according to claim 4, characterized in that: The organic solvent is one or more of ethanol, methanol, ethanol / dichloromethane mixed solution, ethanol / water mixed solution, and ethanol / trichloroethane mixed solution.

6. The method for preparing an organic flexible single-crystal microring laser according to claim 4, wherein: The concentration of the organic molecule in the organic solution is 0.5-2 mg / mL.

7. The method for preparing an organic flexible single-crystal microring laser according to claim 4, characterized in that: The substrate is a glass substrate, a quartz substrate, a silicon substrate, a conductive glass sheet, a magnesium fluoride sheet, a metal film or an enhanced reflector, the flexible substrate is polydimethylsiloxane, and the drying refers to completely volatilizing the solvent.

8. An organic flexible single-crystal microring laser obtained according to the preparation method according to any one of claims 4 to 7.

9. The use of the organic flexible single crystal microring laser according to claim 8, characterized in that: Organic flexible single-crystal microring lasers are used to realize ultra-small high-throughput information light sources; or, for high-throughput information processing in optoelectronic information circuits; or, for the preparation of dual-color switchable laser signal light sources; or, for mechanical information sensing.

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