A continuous domain bound state based directional micro-nano laser, and a preparation method and application thereof

Abstract

This invention relates to the field of micro-nano optoelectronics technology, specifically to a directional micro-nano laser based on continuous domain bound states, its fabrication method, and its applications. The method involves: growing and forming a perovskite single-crystal thin-film gain layer on a substrate; spin-coating photoresist onto the perovskite single-crystal thin-film gain layer to form a photoresist layer; patterning and exposure developing the photoresist layer to form a Limaçon deformable cavity structure; the Limaçon deformable cavity structure and the perovskite single-crystal thin-film gain layer together constitute a planar waveguide, resulting in a directional micro-nano laser based on continuous domain bound states. The fabrication method of this invention not only completely avoids the etching damage to perovskite materials caused by traditional etching processes but also solves the technical problem of uncontrollable laser emission direction in on-chip integration, thereby realizing an etching-free, high-performance, and directionally controllable on-chip integrated directional micro-nano laser.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of micro-nano photoelectronic technology, and in particular to a directional micro-nano laser based on a continuous domain bound state, a preparation method and an application. BACKGROUND

[0002] In the current field of optoelectronics, micro-nano lasers are the core development direction of optical communication and laser technology, and perovskite materials have become ideal gain media for microcavity lasers due to their excellent optoelectronic properties. However, the preparation of traditional perovskite microcavity lasers relies on complex etching processes, which not only have high costs and long cycles, but also easily introduce surface defects and non-radiative recombination centers during the etching process, resulting in increased material damage and optical loss.

[0003] Currently, the existing problem-solving solutions mainly have two types of bottlenecks: one is etching patterning technology. This type of technology can provide high structural precision, but has low processing efficiency and high cost, making it difficult to meet the high-density integration demand, limiting its large-scale application; more importantly, the etching process inevitably introduces surface defects and non-radiative recombination centers, which seriously damage the integrity of the perovskite single crystal film, resulting in increased optical loss and elevated laser threshold. In addition, although the circular cavity laser based on etching can greatly improve the Q value of the microcavity laser, the rotational symmetry invariance leads to omnidirectional radiation of the laser, which cannot control the emission direction and is difficult to achieve efficient directional coupling with external elements such as on-chip waveguides and optical fibers. The second is self-assembled microcavity technology. This type of technology can avoid etching damage, but the spatial position, size and orientation of the microcavity are random, which cannot meet the strict requirements of on-chip integration for positioning accuracy, and the structural stability is poor. In particular, the geometric morphology of the self-assembled microcavity cannot be precisely designed, and the emission direction of the laser cannot be actively controlled, making it difficult to achieve precise control of the laser channel. SUMMARY

[0004] In view of the deficiencies of the prior art, the present application provides a directional micro-nano laser based on a continuous domain bound state, a preparation method and an application. The present application grows and forms a perovskite single crystal film gain layer on a substrate, combines exposure development, and directly shapes a Limaçon deformed cavity structure in a low refractive index photoresist, completely avoiding the etching damage of traditional etching processes to perovskite materials. At the same time, the geometric asymmetry of the Limaçon deformed cavity induces a directional radiation channel, and the continuous domain bound state mode is formed at the interface between the low refractive index layer and the high refractive index layer relying on the coherent cancellation, achieving the organic unity of high Q value resonance, low threshold lasing and multidirectional controllable emission without etching damage, providing a high-performance and easy-to-prepare laser light source solution for on-chip integrated photonic chips.

[0005] To achieve the above purpose, the technical scheme adopted by the present application is as follows: The first object of the present application is to provide a preparation method of a continuous domain bound state-based directional micro / nano laser, comprising the following steps: S1, growing and forming a perovskite single crystal thin film gain layer on a substrate.

[0006] S2, spin-coating a photoresist on the peroviskite single crystal thin film gain layer to form a photoresist layer.

[0007] S3, performing a patterned exposure treatment on the photoresist layer to form a Limaçon deformed cavity pattern, thereby obtaining an exposed photoresist layer; wherein the boundary expression of the Limaçon deformed cavity pattern is r=R·(1+ε·cosφ), wherein R is a reference radius, the deformation degree ε is 0.4-0.5, and the azimuth angle φ∈[0, 2π]. If ε>0.5, the deformation is excessive, resulting in a decrease in Q value and disorder of the emission direction; if ε<0.4, the symmetry is not broken enough, and the emission direction still cannot meet the single-channel directional emission requirement.

[0008] S4, performing a development treatment on the exposed photoresist layer to remove the exposed photoresist layer, thereby forming a Limaçon deformed cavity structure; the Limaçon deformed cavity structure serves as a low refractive index layer, and the peroviskite single crystal thin film gain layer serves as a high refractive index layer, together forming a planar waveguide; through coherent cancellation at the interface between the low refractive index layer and the high refractive index layer, the optical field is bound in the peroviskite single crystal thin film gain layer, and a continuous domain bound state mode is formed, thereby obtaining a continuous domain bound state-based directional micro / nano laser, and the peroviskite single crystal thin film gain layer is not etched in the whole process.

[0009] Preferably, the peroviskite single crystal thin film gain layer is MAPbBr3, MAPbI3 or CsPbBr3, and the thickness of the peroviskite single crystal thin film gain layer is 80-120 nm. According to the technical solution of the present application, theoretically, any luminescent material that can grow into a single crystal thin film and has a refractive index higher than that of the photoresist can be applicable.

[0010] Preferably, the thickness of the photoresist layer is 450-500 nm.

[0011] Preferably, the refractive index of the photoresist is lower than that of the peroviskite single crystal thin film gain layer, and the photoresist is selected from ZEP photoresist, polymethyl methacrylate photoresist (PMMA photoresist) or hydrogen silsesquioxane photoresist (HSQ photoresist), which has a high sensitivity and is applicable to micro / nano optical experiments. The selection of the photoresist needs to be coordinated with the characteristics of the underlying luminescent material, and the damage degree of different developing solutions to different luminescent functional materials is comprehensively considered, so as to select a suitable combination of photoresist and developing solution to implement the technical solution of the present application.

[0012] Preferably, the photoresist layer is exposed and patterned by electron beam lithography, and the acceleration voltage is 25kV-30kV, and the exposure dose is 71μC / cm 2 ~73μC / cm 2 .

[0013] Preferably, the photoresist layer is exposed and patterned by electron beam lithography, and the acceleration voltage is 25kV-30kV, and the exposure dose is 71μC / cm

[0014] Preferably, the photoresist layer is exposed and patterned by electron beam lithography, and the acceleration voltage is 25kV-30kV, and the exposure dose is 71μC / cm

[0015] Preferably, the photoresist layer is exposed and patterned by electron beam lithography, and the acceleration voltage is 25kV-30kV, and the exposure dose is 71μC / cm

[0016] Preferably, the photoresist layer is exposed and patterned by electron beam lithography, and the acceleration voltage is 25kV-30kV, and the exposure dose is 71μC / cm

[0017] The second object of the present application is to provide a continuous domain bound state based directional micro / nano laser prepared by the above preparation method, comprising: a substrate, a perovskite single crystal thin film gain layer disposed on the substrate, a photoresist layer disposed on the perovskite single crystal thin film gain layer, a Limaçon deformed cavity structure formed on the photoresist layer by an exposure and development process, the refractive index of the photoresist layer being lower than that of the perovskite single crystal thin film gain layer, and the perovskite single crystal thin film gain layer not being etched in the patterning process, the Limaçon deformed cavity structure serving as a low refractive index layer, the perovskite single crystal thin film gain layer serving as a high refractive index layer, the low refractive index layer and the perovskite single crystal thin film gain layer together forming a planar waveguide, the light field being bound in the perovskite single crystal thin film gain layer through coherent cancellation at the interface between the low refractive index layer and the high refractive index layer, and a continuous domain bound state mode being formed, and in-plane directional laser emission being realized through the geometric asymmetry of the Limaçon deformed cavity.

[0018] Preferably, the continuous domain bound state based directional micro / nano laser emits in-plane multi-directional laser, and the emission directions include 30°, 80°, 180°, 330° and 280°.

[0019] The third object of the present application is to provide an application of the above continuous domain bound state based directional micro / nano laser in an integrated photonics chip, an optical communication system, a sensing system or an imaging system.

[0020] Preferably, the continuous domain bound state based directional micro / nano laser serves as a visible light communication on-chip laser light source.

[0021] Compared with the prior art, the present application has the following advantages: 1. This invention provides a method for fabricating a directional micro / nano laser based on continuous domain bound states. The method involves growing and forming a perovskite single-crystal thin-film gain layer on a substrate; spin-coating photoresist onto the perovskite single-crystal thin-film gain layer to form a photoresist layer; patterning and exposing the photoresist layer to form a Limaçon deformable cavity pattern, resulting in an exposed photoresist layer; developing the exposed photoresist layer to remove the exposed photoresist layer, thus forming a Limaçon deformable cavity structure. The Limaçon deformable cavity structure serves as a low-refractive-index layer, which, together with the perovskite single-crystal thin-film gain layer (which serves as a high-refractive-index layer), constitutes a planar waveguide. The geometric asymmetry of the Limaçon deformable cavity induces directional radiation channels, while coherent destructive interaction at the interface between the low-refractive-index layer and the high-refractive-index layer forms a continuous domain bound-state mode with in-plane multi-directional radiation channels, resulting in a directional micro / nano laser based on continuous domain bound states. Furthermore, the perovskite single-crystal thin-film gain layer is not etched throughout the entire process.

[0022] Compared to existing etching patterning techniques, this invention forms a Limaçon deformable cavity structure through an exposure and development process, avoiding the etching steps of optical functional materials. This successfully circumvents surface defects and non-radiative recombination centers introduced by etching, simplifying the process, reducing manufacturing difficulty and complexity, and improving optical performance and material compatibility. Simultaneously, the geometric asymmetry of the Limaçon deformable cavity induces directional radiation channels, while relying on the coherent destructive phase at the interface between the low-refractive-index and high-refractive-index layers to form a continuous domain bound state mode. This synergistically achieves the organic unity of high-Q resonance, low-threshold lasing, and multi-directional controllable emission, providing a high-performance and easily fabricated laser source solution for on-chip integrated photonic chips.

[0023] 2. This invention also provides a directional micro / nano laser based on continuous-domain bound states, comprising a substrate, a perovskite single-crystal thin-film gain layer, and a Limaçon deformable cavity stacked sequentially from bottom to top along the longitudinal structural direction. The Limaçon deformable cavity structure serves as a low-refractive-index layer, which, together with the perovskite single-crystal thin-film gain layer (a high-refractive-index layer), forms a planar waveguide. The geometric asymmetry of the Limaçon deformable cavity induces a directional radiation channel, while coherent destructive interaction at the interface between the low-refractive-index and high-refractive-index layers forms a continuous-domain bound-state mode with in-plane multi-directional radiation channels. The directional micro / nano laser based on continuous-domain bound states of this invention possesses both excellent optical performance and controllable emission direction.

[0024] Furthermore, by setting a monitoring structure on one side of its deformable cavity structure, the present invention can indirectly characterize the directional laser emission direction of the directional micro / nano laser based on the continuous domain bound state of the present invention through the scattered light. This monitoring structure is a circular cavity formed by electron beam lithography.

[0025] 3. The preparation method of the present invention is also applicable to various perovskite single crystal thin film materials such as cesium lead bromide (CsPbBr3), which can realize on-chip integration of lasing channels in different wavelength bands, and has significant cost-effectiveness, saving investment in etching equipment, improving raw material utilization, and reducing manufacturing costs; in addition, the structure is designable, and the curvature radius and symmetry of the microcavity can be flexibly controlled by adjusting the photolithography parameters. Attached Figure Description

[0026] Figure 1 This is an optical micrograph of the MAPbBr3 single crystal thin film of Example 1.

[0027] Figure 2 This is a schematic diagram of the Limaçon deformable cavity structure, and the formula is: ,in, For radius, For the degree of deformation, For angle.

[0028] Figure 3 This is a schematic diagram of the Limaçon deformable cavity structure after development, which is composed of a photoresist layer.

[0029] Figure 4 This is a cross-sectional schematic diagram of a directional micro / nano laser based on continuous domain bound states.

[0030] Figure 5 This is a schematic diagram of the femtosecond pump-laser collection optical microscopy characterization system used in this invention.

[0031] Figure 6 Fluorescence microscopy images of directional micro / nano lasers based on continuous domain bound states.

[0032] Figure 7 Laser micrographs of directional micro / nano lasers based on continuous domain bound states.

[0033] Figure 8 This is a laser / fluorescence spectrum of a directional micro / nano laser based on continuous domain bound states.

[0034] Figure 9 This is a threshold characteristic curve of a directional micro / nano laser based on continuous domain bound states.

[0035] Figure 10 This is a micrograph of the directional laser emission from a directional micro / nano laser based on a continuous domain bound state.

[0036] Figure 11 This is a cross-sectional schematic diagram of the optical microcavity and scattering boundary of a directional micro / nano laser based on continuous domain bound states.

[0037] Figure 12The images show the directional laser emission pattern and optical micrograph of a directional micro / nano laser based on a continuous domain bound state, where a is the directional laser emission pattern and b is the optical micrograph.

[0038] Figure 13 The light intensity distribution map is an angle-resolved image of the far field, showing that the directional emission is mainly concentrated at 30°, 80°, 180° and their symmetrical directions.

[0039] Figure 14 The image shows the eigenvalue simulation of the Limaçon deformable cavity, where the arrows point to the eigenvalues ​​with the highest Q values.

[0040] Figure 15 The highest Q-value eigenvalue of the Limaçon deformable cavity Field distribution map.

[0041] Figure 16 This is a schematic diagram of a 2.5D multiphysics simulation model of the actual device structure.

[0042] Figure 17 The simulation results are shown for a cavity radius of 13.4 μm. The inset is an enlarged view of the area within the white dashed frame.

[0043] Figure 18 The simulation results are shown for a cavity radius of 15.7 μm. The inset is an enlarged view of the area within the white dashed frame.

[0044] Figure 19 The simulation results are shown for a cavity radius of 35.6 μm. The inset is an enlarged view of the area within the white dashed frame. Detailed Implementation

[0045] The technical solution of the present invention will be clearly and completely described below with reference to the data in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0046] It should be noted that the technical terms used in this invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of this invention. Unless otherwise specified, all raw materials, reagents, instruments and equipment used in the following embodiments of this invention can be purchased on the market or prepared by existing methods.

[0047] Etching has always been a challenge for optical functional materials, becoming a long-standing technical bottleneck in integrated photonics. To mitigate the damage risks associated with etching, researchers have developed a novel confined-state mechanism—continuous-domain confined states, which are unconventional states that coexist with the radiation mode continuum and possess stable locality. Traditional waveguide optics theory relies on total internal reflection to confine light waves, requiring a structure composed of high-refractive-index and low-refractive-index layers to achieve low-loss transmission. Furthermore, while existing circular cavity lasers can significantly improve the Q-factor, their rotational invariance leads to uncontrollable emission directions.

[0048] This invention, based on the principle of continuous domain bound states (BIC), constructs an etch-free layered waveguide structure: It employs easily fabricated low-refractive-index ZEP photoresist (refractive index approximately 1.56) as a layer, which, together with a high-refractive-index perovskite single-crystal thin film (refractive index approximately 2.5 at 550nm), forms a low-loss planar waveguide, achieving effective confinement and transmission of photons. Furthermore, this planar waveguide is bent into a closed loop to construct an on-chip circular cavity laser. The cavity boundary is further modified using Limaçon deformation design (r = R·(1+ε·cosφ), where ε is 0.4~0.5), maintaining bound-state transmission while achieving precise control of the laser emission direction by appropriately breaking rotational symmetry.

[0049] This invention utilizes the synergistic control of the BIC mechanism and geometric deformation: on the one hand, it relies on the coherent destructive interaction at the interface between the low-refractive-index photoresist layer and the high-refractive-index layer to form an out-of-plane confinement of a symmetrically protected BIC; on the other hand, it leverages the geometric asymmetry of the Limaçon deformable cavity to induce destructive Mie scattering, forming an in-plane directional leakage channel for the BIC. This etching-free deformable cavity structure based on continuous-domain confined states avoids etching damage to high-refractive-index optical functional materials and overcomes the bottleneck of the traditional circular cavity laser's incompatibility between "high Q value" and "directional emission," providing a high-performance, easily fabricated on-chip laser source solution for novel integrated optical chips.

[0050] To enable those skilled in the art to more clearly understand the technical solution of the present invention, the following will provide a detailed description in conjunction with specific embodiments: Example 1 A method for fabricating a directional micro / nano laser based on continuous domain bound states includes the following steps: S1. Under constant temperature of 80℃, a MAPbBr3 single-crystal thin film was grown on the surface of a SiO2 substrate using a spatial confinement method, with the film thickness controlled at 80nm, to obtain a perovskite single-crystal thin film. The micrograph is shown below. Figure 1 As shown, this perovskite single-crystal thin film has a refractive index of 2.5 in the 550 nm band and serves as the gain layer for a directional micro / nano laser based on continuous-domain bound states.

[0051] S2. ZEP photoresist is dropped onto a perovskite single crystal thin film, spin-coated at 2500 rpm for 60 s, and then dried at 85°C for 2 h to obtain a photoresist layer with a thickness of 450 nm.

[0052] S3. The photoresist layer is patterned using electron beam lithography, with the process parameters set as follows: accelerating voltage of 30kV and exposure dose of 71μC / cm². 2 The exposed pattern is a Limaçon deformable cavity, whose polar coordinate boundary is determined by the formula r = R·(1 + ε·cosφ), where the reference radius R is 13.4 μm, the deformation degree ε is 0.45, φ∈[0,2π], φ is the independent variable, and r is the dependent variable. This Limaçon deformable cavity structure breaks rotational symmetry, aiming to achieve directional laser emission through a continuous domain bound state. A schematic diagram of the Limaçon deformable cavity structure is shown below. Figure 2 As shown.

[0053] S4. After exposure, develop the perovskite single crystal film for 60 seconds using ZEP developer to form a Limaçon deformable cavity structure composed of a photoresist layer on the surface of the perovskite single crystal film. At this time, the perovskite single crystal film itself is not etched; its surface is only covered by the developed photoresist to form a waveguide structure, resulting in a directional micro / nano laser based on continuous domain bound states. Its structural schematic diagram is shown below. Figure 3 As shown in the schematic cross-sectional view Figure 4 As shown.

[0054] The directional micro / nano laser based on continuous domain bound states fabricated in this embodiment consists of, from bottom to top, a SiO2 substrate, an 80 nm thick perovskite single-crystal thin-film gain layer, and a 500 nm thick Limaçon deformable cavity.

[0055] Example 2 A method for fabricating a directional micro / nano laser based on a continuous domain bound state is the same as the method in Example 1, except that the deformation degree ε in S3 is replaced with 0.45 to obtain a directional micro / nano laser based on a continuous domain bound state.

[0056] Example 3 A method for fabricating a directional micro / nano laser based on a continuous domain bound state is the same as the method in Example 1, except that the deformation degree ε in S3 is replaced with 0.5 instead of 0.45, thus obtaining a directional micro / nano laser based on a continuous domain bound state.

[0057] Example 4 A method for fabricating a directional micro / nano laser based on continuous domain bound states is the same as the method in Example 1, except that the single crystal thin film in S1 is replaced with CsPbBr3 to obtain a directional micro / nano laser based on continuous domain bound states.

[0058] Example 5 A method for fabricating a directional micro / nano laser based on continuous domain bound states is the same as the method in Example 1, except that the single crystal thin film in S1 is replaced with MAPbI3 instead of MAPbBr3, thus obtaining a directional micro / nano laser based on continuous domain bound states.

[0059] Optical characterization: Constructing a femtosecond pump-laser collection optical microscopy characterization system, such as Figure 5 As shown, optical microscopic characterization, fluorescence / laser pump excitation, and fluorescence / laser spectral characterization were performed on a directional micro / nano laser based on continuous domain bound states. The spectrum, laser threshold, and lasing direction were recorded. The results are as follows: Figure 6 , Figure 7 , Figure 8 , Figure 9 as well as Figure 10 As shown.

[0060] Figure 8 The wavelength corresponding to the highest laser peak shown in the laser spectrum is 548.22 nm, the full width at half maximum (FWHM) is 0.47 nm, and the calculated Q value is 1166.43.

[0061] from Figure 9 The threshold of the directional micro / nano laser based on continuous domain bound states in Example 1 was found to be 5 μJ / cm. 2 .

[0062] like Figure 10 As shown, the emission of the directional micro / nano laser based on continuous domain bound states in Example 1 is completely different from that of a circular cavity, exhibiting good directionality. Moreover, due to the vertical symmetry of the cavity, this directionality also exhibits vertically symmetrical emission directionality.

[0063] Further data analysis yielded a far-field angle-resolved light intensity distribution map, such as... Figure 13As shown, the in-plane emission directions of the directional micro / nano laser based on continuous domain bound states in Example 1 are mainly concentrated at 30° (330°), 80° (280°), and 180°, with the strongest emission in the 80° (280°) direction. Here, the formula for calculating lasing unidirectionality is defined as U_angle = I_unidirectional_angle I_total. Based on this, we calculate U30° = 0.085, U330° = 0.126, U80° = 0.169, U280° = 0.207, and U180° = 0.189. These five unidirectional emissions account for 77.72% of the total energy.

[0064] Since the emission direction of a directional micro / nano laser based on a continuous domain bound state propagates in-plane and cannot be directly observed, this invention designs an indirect verification method. Specifically, a circular cavity is set up as a "signal receiver" at a distance of 22 μm from the Limaçon deformable cavity, as shown in the schematic cross-sectional diagram below. Figure 11 As shown; subsequently, utilizing the waveguide properties of the perovskite single-crystal thin film itself, the directional laser emitted from the Limaçon deformable cavity was guided to the edge of the cavity, exciting observable scattered light. By observing the intensity distribution of the scattered light at the cavity edge, as shown... Figure 12 As shown, the directional emission characteristics of the directional micro / nano laser based on the continuous domain bound state of the present invention can be deduced.

[0065] Depend on Figure 12 The ability to visually observe this edge scattering demonstrates the effectiveness of the scattering boundary setting and provides a clear indication of the directionality of the directional micro / nano laser emitted by the present invention based on continuous domain bound states.

[0066] Existing technologies modify waveguides to create closed-loop circular cavity lasers. While this structure significantly improves the Q-factor of microcavity lasers, the rotational invariance of the circular cavity structure prevents control over the laser emission direction. To achieve on-chip, etch-free, directional micro / nano lasers, this invention employs a Limaçon deformable cavity as the laser resonator. Through the synergistic control of geometric deformation and continuous-domain bound states, it overcomes the bottleneck of the traditional microcavity laser's inability to simultaneously achieve both high Q-factor and directional emission.

[0067] like Figure 14 As shown, the Limaçon deformable cavity (refractive index 2.3, reference radius R=5) Deformation Simulation results with an eigenvalue of 0.45 show that, while moderately breaking the rotational symmetry, the cavity still maintains the high Q-value resonance characteristics of a whispering-gallery-like mode. Figure 14 ), and the light field is highly localized at the cavity boundary ( Figure 15 This laid the foundation for the subsequent realization of low-threshold laser emission.

[0068] To verify the feasibility of the etching-free process, this invention constructs a 2.5D multiphysics simulation model of the actual device structure (e.g., Figure 16 As shown in the diagram, a planar waveguide configuration of low-refractive-index layer-high-refractive-index layer-low-refractive-index substrate was formed by setting the ZEP photoresist layer thickness to 500 nm (refractive-index 1.54), the perovskite single-crystal film thickness to 80 nm (refractive-index 2.5), and the SiO2 substrate (refractive-index 1.45). Systematic scanning of the Limaçon deformable cavity radius of curvature from 12 μm to 40.5 μm and back to 12 μm confirmed that the Limaçon deformable cavity can achieve high-Q bound states over a wide scale range, and the Q value exhibits a robust response to radius changes. This result demonstrates that high-quality optical resonance can be obtained while preserving the integrity of the perovskite single-crystal film, without the need for precise control of the cavity dimensions, simply by accurately replicating the Limaçon geometric boundary using electron beam lithography. This simplifies the complex three-dimensional etching process to two-dimensional photoresist patterning, significantly improving the reliability and repeatability of device fabrication.

[0069] Depend on Figure 17 , Figure 18 and Figure 19 In both cases, the light field can be observed to be tightly confined within an extremely narrow range centered on the perovskite thin film.

[0070] It should be noted that when numerical ranges are involved in this invention, it should be understood that both endpoints of each numerical range, as well as any value between the two endpoints, can be selected. Since the steps and methods used are the same as in the embodiments, preferred embodiments are described here to avoid redundancy. Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this invention.

Claims

1. A method for fabricating a directional micro / nano laser based on continuous domain bound states, characterized in that, Includes the following steps: A perovskite single-crystal thin film gain layer is grown and formed on the substrate; Photoresist is spin-coated onto the gain layer of a perovskite single-crystal thin film to form a photoresist layer; The photoresist layer is patterned and exposed to form a Limaçon deformable cavity pattern, resulting in an exposed photoresist layer. The boundary expression of the Limaçon deformable cavity pattern is r=R·(1+ε·cosφ), where R is the reference radius, ε is 0.4~0.5, and φ∈[0,2π]. The exposed photoresist layer is developed and removed to form a Limaçon deformable cavity structure, resulting in a directional micro / nano laser based on continuous domain bound states.

2. The preparation method according to claim 1, characterized in that, The gain layer of the perovskite single crystal thin film is MAPbBr3, MAPbI3 or CsPbBr3, and the thickness of the perovskite single crystal thin film gain layer is 80nm~120nm.

3. The preparation method according to claim 1, characterized in that, The thickness of the photoresist layer is 450nm~500nm.

4. The preparation method according to claim 1, characterized in that, The photoresist has a lower refractive index than the perovskite single-crystal thin film gain layer, and the photoresist is selected from ZEP photoresist, polymethyl methacrylate photoresist or hydrogen silsesquioxane photoresist.

5. The preparation method according to claim 1, characterized in that, Electron beam lithography was used to pattern the photoresist layer, with an accelerating voltage of 25kV~30kV and an exposure dose of 71μC / cm. 2 ~73μC / cm 2 .

6. The preparation method according to claim 1, characterized in that, A perovskite single-crystal thin film gain layer is grown on a substrate using a spatial confinement method, wherein the growth temperature of the perovskite single-crystal thin film gain layer is 60℃~120℃.

7. The preparation method according to claim 6, characterized in that, The substrate is selected from low refractive index SiO2 or MgF2.

8. A directional micro / nano laser based on continuous domain bound states, characterized in that, The directional micro / nano laser based on continuous domain bound states is prepared by the fabrication method of any one of claims 1 to 7, wherein the substrate, perovskite single crystal thin film gain layer and Limaçon deformable cavity are stacked sequentially from bottom to top in the longitudinal structural direction.

9. The directional micro / nano laser based on continuous domain bound states according to claim 8, characterized in that, The emission directions of directional micro / nano lasers based on continuous domain bound states include 30°, 80°, 180°, 330°, and 280°.

10. The application of a directional micro / nano laser based on continuous domain bound states according to any one of claims 8 in an integrated photonics chip, optical communication system, sensing system or imaging system.

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