Micro-nano laser and preparation method thereof

Abstract

The invention discloses a micro-nano laser and a preparation method thereof, the micro-nano laser comprises an excitation light source and a micro laser resonator, light emitted by the excitation light source is emitted through the micro laser resonator, the micro laser resonator comprises a substrate and a mixed halogen perovskite thin film arranged on one side of the substrate, and the mixed halogen perovskite thin film is arranged on the other side of the substrate. A geometric structure with a preset shape is etched on the mixed halogen perovskite thin film, and the halogen component and proportion in the geometric structure are determined according to the wavelength of the emergent laser of the micro-nano laser. The laser is easy to integrate, can be adjusted in situ, is simple and convenient to prepare, and can be widely applied to the technical field of lasers.

Description

Technical Field

[0001] This invention relates to the field of laser technology, and in particular to a micro / nano laser and its fabrication method. Background Technology

[0002] Currently, the gain medium and optical resonator of perovskite micro / nano lasers mainly rely on the crystal material itself. There are two main methods for forming the resonator: one is to grow the crystal itself into a regular shape to form the resonator structure, and the other is to artificially etch a specific shape structure into the material to form the resonator. Existing methods cannot simultaneously meet the requirements of simple fabrication, easy integration, and in-situ tuning. Summary of the Invention

[0003] In view of this, in order to solve one of the above problems, the purpose of this invention is to provide a micro / nano laser and its fabrication method, which is easy to integrate, can be adjusted in situ, and is simple to fabricate.

[0004] On one hand, embodiments of the present invention provide a micro / nano laser, including an excitation source and a micro laser resonator. The light emitted by the excitation source is emitted through the micro laser resonator. The micro laser resonator includes a substrate and a mixed halide perovskite thin film disposed on one side of the substrate. A geometric structure of a predetermined shape is etched on the mixed halide perovskite thin film. The halogen composition and proportion within the geometric structure are determined according to the emitted laser wavelength of the micro / nano laser.

[0005] Optionally, the geometry includes circles and / or regular polygons.

[0006] Optionally, the distance from the center of the geometric structure to each point ranges from 5 to 20 μm.

[0007] Optionally, the mixed halide perovskite film includes at least two of chloride ions, bromide ions, or iodide ions.

[0008] Optionally, the proportion of halogen in the mixed halide perovskite film ranges from 1% to 90%.

[0009] Optionally, the geometry on the mixed halide perovskite film includes one or more types.

[0010] The implementation of this invention includes the following beneficial effects: In this embodiment, the micro laser resonator includes a substrate and a mixed halide perovskite thin film disposed on one side of the substrate. A geometric structure of a preset shape is etched on the mixed halide perovskite thin film. The halogen composition and ratio within the geometric structure are determined according to the emitted laser wavelength of the micro / nano laser. The etched geometric structure will satisfy the conditions of the resonant cavity, so that the etched geometric structure simultaneously possesses a gain medium and a resonant cavity. Thus, by controlling the composition and ratio of halogen ions in situ, the emitted laser wavelength can be controlled, and the requirements of on-chip integration can be met.

[0011] On the other hand, embodiments of the present invention provide a method for fabricating a micro / nano laser, comprising:

[0012] The first light source is controlled to irradiate the mixed halide perovskite film so that the mixed halide perovskite film reaches a preset phase transition at a preset position, and the mixed halide perovskite film is disposed on one side of the substrate.

[0013] The second light source is controlled to perform etching, etching a geometric structure of a preset shape at a preset position on the mixed halide perovskite film to form a micro laser resonator; the halogen composition and ratio within the geometric structure are determined according to the emitted laser wavelength of the micro / nano laser.

[0014] The micro laser resonator and excitation source are assembled to form a micro / nano laser.

[0015] Optionally, controlling the first light source to irradiate the mixed halide perovskite film so that the mixed halide perovskite film reaches a preset phase transition at a preset position, specifically including:

[0016] The power and duration of the first light source irradiating the mixed halide perovskite film are controlled so that the mixed halide perovskite film reaches a preset phase transition at a preset position.

[0017] Optionally, the second light source is controlled to perform etching, etching a geometric structure of a predetermined shape at a predetermined location on the mixed halide perovskite thin film to form a micro laser resonator, specifically including:

[0018] The light trajectory of the second light source is controlled to perform etching, and a geometric structure of a preset shape is etched at a preset position on the mixed halide perovskite thin film to form a micro laser resonator.

[0019] Optionally, a femtosecond laser direct writing system is used to etch a geometric structure of a predetermined shape at a predetermined location on the mixed halide perovskite thin film.

[0020] The implementation of this invention provides the following advantages: This embodiment utilizes the halide ion migration characteristics in mixed halide perovskite films, introduces a first light source that easily induces a phase transition, controls the aggregation degree of halide ions, and uses a second light source to etch specific geometric shapes during the phase transition process. The grooves formed by the etching will block the continued migration of ions, spatially localizing the halide ions within the etching range. The etched geometry will meet the conditions of the resonant cavity. At the micro-nano scale, a method for continuously controlling the emission wavelength in situ is realized. Compared with large-area ion exchange, this method is more precise and simpler to control, and can be used for on-chip integration of multicolor micro-nano laser cavities, meeting the requirements of on-chip integration. The entire fabrication process is simple and facilitates mass production. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of a micro / nano laser provided in an embodiment of the present invention;

[0022] Figure 2 This is a schematic flowchart of a method for fabricating a micro / nano laser according to an embodiment of the present invention;

[0023] Figure 3 This is a schematic diagram of the structure of a femtosecond laser direct writing system provided in an embodiment of the present invention;

[0024] Figure 4 This is a partial view of the fabrication process of another micro / nano laser provided in an embodiment of the present invention;

[0025] Figure 5 This is a schematic flowchart of another method for fabricating a micro / nano laser provided in an embodiment of the present invention;

[0026] Figure 6 This is a schematic diagram of the emitted laser wavelength containing different proportions of halogen elements provided in an embodiment of the present invention;

[0027] Figure 7 This is a physical image and a schematic diagram of the emission spectrum of a micro laser resonator containing different proportions of halogen elements, provided by an embodiment of the present invention. Detailed Implementation

[0028] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. The step numbers in the following embodiments are only for ease of explanation and do not limit the order of the steps. The execution order of each step in the embodiments can be adapted according to the understanding of those skilled in the art.

[0029] Mixed halide perovskites: Perovskites have the expression ABX3, where A represents an organic or inorganic monovalent cation, B represents a divalent cation, and X represents a halide anion. When different types of halide ions fill the X-position, it is called a mixed halide perovskite, for example, a combination of different proportions of chloride / bromine (Cl / Br) ions or bromine / iodine (Br / I) ions. A key characteristic of mixed halide perovskites is the tunability of their band gap: a higher proportion of Cl ions corresponds to a wider band gap and a blue emission wavelength, while a higher proportion of I ions corresponds to a narrower band gap and a red emission wavelength.

[0030] Another key characteristic of mixed halide perovskites is the easy migration of halide ions within the material. External factors such as light, heat, and electricity can all induce the movement of halide ions within the material. The phenomenon where ion movement disrupts the inherent mixed distribution of ions is called a phase transition. Taking Br / I ion-doped mixed halide perovskites as an example, continuous illumination will cause the formation of a phase with a high concentration of I ions and a low concentration of Br ions in the illuminated area, i.e., I ion aggregation. Ultraviolet light is more likely to induce a phase transition; moreover, this phenomenon is reversible under the condition that the external excitation is not too strong. After being placed in darkness for a period of time, the ions in the illuminated area will redistribute. This ion migration characteristic based on external factors provides the possibility for in-situ control of ion distribution in the material. During the occurrence or recovery of the phase transition, specific shapes can be etched on the material at the micro-nano scale using lasers, blocking the channels for ion migration inside and outside the etched area. This allows for in-situ regulation of ion distribution, enabling the integration of multiple regions with different band gaps (emission wavelengths) within a small area.

[0031] Micro / nano lasers include laser resonant cavities with physical dimensions on the micrometer (nanometer) scale. With the rapid development of nanotechnology and photonics, micro / nano lasers with device physical dimensions or mode volumes on the micrometer, sub-micrometer, or even smaller than the diffraction limit have emerged. Due to their small size and ease of integration, they hold immense application potential in multiple fields.

[0032] Femtosecond laser direct writing technology has advantages such as low damage, high precision, high repeatability and controllability due to its ultra-short pulse duration and ultra-high instantaneous power. It has attracted widespread attention in the field of integrated photonic device fabrication. Using femtosecond lasers to etch micro-nano resonant cavities of specific shapes on materials is one of the ways to realize micro-nano lasers.

[0033] See Figure 1This invention provides a micro / nano laser, including an excitation source (1-1) and a micro laser resonator. The light emitted from the excitation source is emitted through the micro laser resonator. The micro laser resonator includes a substrate (1-2) and a mixed halide perovskite thin film (1-3) disposed on one side of the substrate. A geometric structure (1-4) of a preset shape is etched on the mixed halide perovskite thin film (1-3). The halogen composition and proportion in the geometric structure (1-4) are determined according to the emitted laser wavelength of the micro / nano laser.

[0034] The wavelength range of the excitation light source (1-1) is determined according to the actual application, and this embodiment does not impose specific limitations. For example, the wavelength range of the light source (1-1) is 300-400nm. The excitation light emitted by the light source (1-1) irradiates the geometric structure (1-4) on the mixed halide perovskite thin film (1-3). The geometric structure (1-4) forms a resonant cavity. After the excitation light undergoes multiple amplifications and spontaneous emission in the resonant cavity, it forms a laser beam.

[0035] It should be noted that different geometries, halogen compositions, and halogen ratios correspond to different resonant wavelengths, i.e., different emitted laser wavelengths. The substrate is determined based on the specific application, such as a glass substrate.

[0036] Optionally, the geometry includes circles and / or regular polygons.

[0037] It should be noted that the geometric structure is determined according to the actual application, and this embodiment does not impose specific restrictions. The geometric structure includes, but is not limited to, circles and / or regular polygons, such as regular hexagons or regular octagons.

[0038] Optionally, the distance from the center of the geometry to each point ranges from 5 to 20 μm.

[0039] It should be noted that the size and dimensions of the geometric structure are determined based on the actual application, and this embodiment does not impose specific limitations. The distance from the center of the geometric structure to each point is within the range of micrometers; in one optional embodiment, the distance from the center of the geometric structure to each point ranges from 5 to 20 μm. See also... Figure 1 The geometry is circular, and the diameter D of the circle is 15μm.

[0040] Optionally, the mixed halide perovskite film includes at least two of chloride ions, bromide ions, or iodide ions.

[0041] Optionally, the proportion of halogens in the mixed halide perovskite thin film ranges from 1% to 90%.

[0042] It should be noted that the types and proportions of halide ions in the mixed halide perovskite thin film are determined according to the actual application, and this embodiment does not impose specific restrictions.

[0043] Optionally, the geometry on the mixed halide perovskite film includes one or more types.

[0044] Different geometries contain different halogen elements and compositions, corresponding to different emitted laser wavelengths. When the geometric structure on the mixed halide perovskite film is of one type, the emitted laser wavelength includes one type; when the geometric structure on the mixed halide perovskite film is of multiple types, the emitted laser wavelength includes multiple types, forming a multi-wavelength output.

[0045] In one specific embodiment, the general expression for the metal halide perovskite structure is ABX3, where the A-site is an organic amine (MA+, FA+) or an inorganic cation (Cs+), and the B-site is a metal cation (Pb). 2+ The X-position is occupied by a halide anion (Cl-, Br-, I-). Metal cations and halide anions form a [BX6]4-octahedron through strong coordination bonds. The bond length of BX decreases as the radius of the halide ion decreases, with substitutions from Cl to Br and then to I. Experimentally, it has been demonstrated that the band gap of perovskite materials can be controlled by adjusting the composition and proportion of halogens. Measurements of photoluminescence spectra have revealed that photoinduced phase segregation leads to a narrowing of the band gap. From a microscopic perspective, specific illumination conditions cause a redistribution of halide ions in mixed halide perovskite materials, resulting in a redshift in their emission.

[0046] The implementation of this invention includes the following beneficial effects: In this embodiment, the micro laser resonator includes a substrate and a mixed halide perovskite thin film disposed on one side of the substrate. A geometric structure of a preset shape is etched on the mixed halide perovskite thin film. The halogen composition and ratio within the geometric structure are determined according to the emitted laser wavelength of the micro / nano laser. The etched geometric structure will satisfy the conditions of the resonant cavity, so that the etched geometric structure simultaneously possesses a gain medium and a resonant cavity. Thus, by controlling the composition and ratio of halogen ions in situ, the emitted laser wavelength can be controlled, and the requirements of on-chip integration can be met.

[0047] See Figure 2 This invention provides a method for fabricating a micro / nano laser, comprising:

[0048] S100: Control the first light source to irradiate the mixed halide perovskite film so that the mixed halide perovskite film reaches a preset phase transition at a preset position. The mixed halide perovskite film is disposed on one side of the substrate.

[0049] The first light source is determined based on the actual application, and this embodiment does not impose specific limitations. For example, the first light source can be an ultraviolet light source. By controlling the light source parameters of the first light source, the first light source is used to irradiate a preset position of the mixed halide perovskite thin film. Halogen ions in the mixed halide perovskite thin film migrate at the preset position, forming a preset phase transition.

[0050] Optionally, the first light source is controlled to irradiate the mixed halide perovskite film so that the mixed halide perovskite film reaches a preset phase transition at a preset position. Specifically, this includes controlling the power and duration of the first light source irradiating the mixed halide perovskite film so that the mixed halide perovskite film reaches a preset phase transition at a preset position.

[0051] By controlling the power and duration of the first light source irradiating the mixed halide perovskite film, the migration of halogens in the mixed halide perovskite film can be controlled, so that the mixed halide perovskite film can achieve a preset phase transition at a preset position.

[0052] S200: Control the second light source to perform etching, and etch a geometric structure of a preset shape at a preset position of the mixed halide perovskite thin film to form a micro laser resonator; the halogen composition and ratio in the geometric structure are determined according to the output laser wavelength of the micro / nano laser.

[0053] The second light source is an etching light source. The second light source is determined according to the actual application. This embodiment does not impose specific restrictions. For example, the second light source is a femtosecond laser light source.

[0054] First, the emitted light from the second light source is positioned at a preset location. Then, a geometric structure of a preset shape is etched according to the path of the emitted light to form a miniature laser resonator.

[0055] Optionally, the second light source is controlled to perform etching, etching a geometric structure of a predetermined shape at a predetermined location on the mixed halide perovskite thin film to form a micro laser resonator, specifically including:

[0056] The light trajectory of the second light source is controlled to perform etching, and a geometric structure of a preset shape is etched at a preset position on the mixed halide perovskite thin film to form a micro laser resonator.

[0057] The trajectory of the light from the second light source can be automatically controlled by a program, and the control component for the trajectory of the light from the second light source is determined according to the specific equipment.

[0058] S300, assembling micro laser resonators and excitation sources to form micro / nano lasers.

[0059] Based on the actual application requirements, the positional relationship between the micro laser resonator and the excitation source is determined, and the micro laser resonator and the excitation source are assembled according to the determined positional relationship to form a micro / nano laser.

[0060] Optionally, a femtosecond laser direct writing system is used to etch a geometric structure of a predetermined shape at a predetermined location on the mixed halide perovskite thin film.

[0061] See Figure 3The micro / nano laser resonator was fabricated using a femtosecond laser direct writing system, which includes a femtosecond laser (1), a mirror (2), a short-focal-length lens (3), a long-focal-length lens (4), an adjustable aperture (5), a half-wave plate (6), a Glan prism (7), an ultraviolet light source (8), a dichroic mirror (9), a CCD and spectrometer (10), a microscope objective (11), and a three-axis displacement platform (12). The short-focal-length lens (3) and the long-focal-length lens (4) have overlapping focal points, forming a confocal lens system, which, together with the adjustable aperture (5), is used to scale the parallel beam and control the size of the spot at the focal point. The half-wave plate (6) and the Glan prism (7) are equivalent to linear attenuators, used to adjust the power of the etching light. The dichroic mirror (9) can only reflect light above 750 nm and transmit light below 500 nm, forming a dual incident light path. The image acquired by the microscope objective (11) is reflected back to the dichroic mirror (9) and enters the CCD and spectrometer (10). Visual control and spectral analysis are achieved through relevant software. This system etches polygons of different sizes and arbitrary shapes on the surface of a perovskite thin film. The high gain property of the perovskite material, after being excited by the incident laser, generates strong amplified spontaneous emission within it. The high refractive index of the perovskite thin film makes the generated amplified spontaneous emission easily confined within the resonant cavity through multiple total internal reflections, thus providing sufficient optical feedback. When the etching quality of the micro-resonant cavity (microcavity) is ideal, such as having a regular shape and sharp edges, the gain obtained within the cavity exceeds the loss of the optical cavity, thus achieving lasing. Through system programming, an array of resonant cavities with different emitting lasers integrated on the wafer can be rapidly etched in a short time. By scanning and exciting different positions, a micro / nano laser device with continuously tunable wavelength can be realized.

[0062] See Figure 4 In the fabrication process of micro / nano lasers, a micro laser resonator is placed on a triaxial displacement platform (12). The mixed halide perovskite film (1-3) of the micro laser resonator is close to the side of the laser source being etched, and the substrate (1-2) of the micro laser resonator is closer to the first light source (13). The first light source (13) irradiates the micro laser resonator to cause the mixed halide perovskite film (1-3) to form a preset phase transition. At the same time, the emitted light from the first light source is used to etch the mixed halide perovskite film (1-3) to form a geometric structure of a preset shape.

[0063] In a specific embodiment, taking the mixed halide perovskite material MAPbBr3-xIx as an example, a beam of ultraviolet light is used to induce a photoinduced phase transition and control ion migration. A femtosecond laser is used to etch the material surface, locking the migrated ions in specific areas, thereby changing the emission wavelength. Simultaneously, a pre-defined geometric structure is etched to form a resonant cavity. By controlling different variables in the ultraviolet irradiation process, such as intensity and duration, the phase segregation process in the metal halide perovskite material can be controlled. The longer or stronger the ultraviolet irradiation, the higher the concentration of I ions in the irradiated area of ​​MAPbBr3-xIx, i.e., x~3, thus achieving continuous wavelength emission covering the visible spectrum. For details, see [link to relevant documentation]. Figure 5 By using a laser etching system to directly write resonant cavities of different shapes and sizes onto a metal-halide perovskite material, the irreversible phase segregation is fixed at a certain degree, achieving the desired emission wavelength. Simultaneously, the number of reflections is increased to enhance the material's luminescence gain, thus obtaining the emitted laser light. (See also...) Figure 5 and Figure 6 When etching is performed after 10 seconds of ultraviolet light irradiation, 20 seconds of irradiation, and so on, the concentration of I ions in the etched region increases with the irradiation time, resulting in a continuous redshift of the emitted light wavelength. This ion aggregation can be controlled by ultraviolet light, and the ion distribution in the etched region is irreversible. (See also...) Figure 7 Different regions are etched after being irradiated with phase-change light for different durations. The ultraviolet pump laser is then focused on the etched region to generate multimode lasers of different wavelengths (with varying degrees of redshift relative to the initial state).

[0064] The implementation of this invention includes the following beneficial effects: This embodiment utilizes the halide ion migration characteristics in mixed halide perovskite films, introduces a first light source that easily induces a phase transition, controls the degree of halide ion aggregation, and uses a second light source to etch specific geometric shapes during the phase transition process. The grooves formed by the etching will block the continued migration of ions, spatially localizing the halide ions within the etching range. The etched geometric structure will meet the conditions of the resonant cavity, thereby achieving wavelength modulation of the emitted laser and meeting the requirements of on-chip integration. The entire fabrication process is simple and facilitates mass production.

[0065] The above is a detailed description of the preferred embodiments of the present invention. However, the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention. All such equivalent modifications or substitutions are included within the scope defined by the claims of this application.

Claims

1. A micro / nano laser, characterized in that, The device includes an excitation source and a micro laser resonator. The light emitted from the excitation source is emitted through the micro laser resonator. The micro laser resonator includes a substrate and a mixed halide perovskite film disposed on one side of the substrate. The mixed halide perovskite film has a geometric structure of a predetermined shape etched on it. The halogen composition and proportion within the geometric structure are determined according to the emitted laser wavelength of the micro / nano laser.

2. The micro / nano laser according to claim 1, characterized in that, The geometry includes circles and / or regular polygons.

3. The micro / nano laser according to claim 1, characterized in that, The distance from the center of the geometric structure to each point ranges from 5 to 20 μm.

4. The micro / nano laser according to claim 1, characterized in that, The mixed halide perovskite film includes at least two of chloride ions, bromide ions, or iodide ions.

5. The micro / nano laser according to claim 1, characterized in that, The halogen content in the mixed halogen perovskite thin film ranges from 1% to 90%.

6. The micro / nano laser according to claim 1, characterized in that, The geometry on the mixed halide perovskite film includes one or more types.

7. A method for fabricating a micro / nano laser, characterized in that, include: The first light source is controlled to irradiate the mixed halide perovskite film so that the mixed halide perovskite film reaches a preset phase transition at a preset position, and the mixed halide perovskite film is disposed on one side of the substrate. The second light source is controlled to perform etching, etching a geometric structure of a preset shape at a preset position on the mixed halide perovskite film to form a micro laser resonator; the halogen composition and ratio within the geometric structure are determined according to the emitted laser wavelength of the micro / nano laser. The micro laser resonator and excitation source are assembled to form a micro / nano laser.

8. The preparation method according to claim 7, characterized in that, The step of controlling the first light source to irradiate the mixed halide perovskite film so that the mixed halide perovskite film reaches a preset phase transition at a preset position specifically includes: The power and duration of the first light source irradiating the mixed halide perovskite film are controlled so that the mixed halide perovskite film reaches a preset phase transition at a preset position.

9. The preparation method according to claim 7, characterized in that, The process of controlling the second light source to perform etching, etching a geometric structure of a predetermined shape at a predetermined position on the mixed halide perovskite thin film to form a micro laser resonator, specifically includes: The light trajectory of the second light source is controlled to perform etching, and a geometric structure of a preset shape is etched at a preset position on the mixed halide perovskite thin film to form a micro laser resonator.

10. The preparation method according to claim 7, characterized in that, A femtosecond laser direct writing system is used to etch a geometric structure of a predetermined shape at a predetermined location on the mixed halide perovskite thin film.

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