A nonlinear micro / nano waveguide device, its fabrication method, and a controllable light emission method.

Abstract

This invention discloses a nonlinear micro / nano waveguide device, its fabrication method, and a controllable light emission method, relating to the interdisciplinary fields of nanophotonics and nonlinear optics. The device includes: a first fiber laser, a second fiber laser, a first tapered fiber, a second tapered fiber, a micro / nano waveguide, and a microscope objective. Two pump beams are injected in opposite directions into the micro / nano waveguide via the tapered fibers, forming a standing wave field within the waveguide and exciting a transverse nonlinear effect, generating transversely emitted light perpendicular to the axial direction, which is collected by the objective. This device utilizes the combined transverse nonlinear effect of a single nonlinear micro / nano waveguide, selectively exciting the nonlinear process by adjusting the pump beam parameters, and achieving real-time control of the wavelength and color of the transversely emitted light. Compared to traditional technologies, it does not require changes to the waveguide material or structure, offering advantages such as flexible control and high integration.

Description

Technical Field

[0001] This invention relates to the field of interdisciplinary technology of nanophotonics and nonlinear optics, and in particular to a nonlinear micro / nano waveguide device, its fabrication method, and a controllable light emission method. Background Technology

[0002] Micro- and nano-waveguides, with their superior properties such as low transmission loss, strong field confinement, significant evanescent field, and tunable dispersion, have become excellent carriers for realizing micro-light emission. In existing technologies, light emission technology based on micro- and nano-waveguides is mainly based on two different approaches: micro- and nano-waveguide arrays and single micro- and nano-waveguides. For light emission technology based on micro- and nano-waveguide arrays, color-controllable light emission is typically achieved by controlling the material composition, size, or geometric arrangement of the micro- and nano-waveguides within the array. For light emission technology based on single micro- and nano-waveguides, specific wavelength emission is typically generated by adjusting the material bandgap and structural defects. Both methods rely on intrinsic material properties or structural parameters; their light emission characteristics are fixed after the structure is fabricated and cannot be dynamically adjusted during use, limiting their application in scenarios such as real-time displays and spectral coding. Summary of the Invention

[0003] The purpose of this invention is to provide a nonlinear micro / nano waveguide device, a fabrication method, and a controllable light emission method, aiming to solve or improve at least one of the above-mentioned technical problems.

[0004] To achieve the above objectives, the present invention provides the following solution: A nonlinear micro / nano waveguide device, its fabrication method, and a controllable light emission method are disclosed, comprising: First fiber laser, second fiber laser, first tapered fiber, second tapered fiber, micro / nano waveguide and microscope objective; The first fiber laser and the second fiber laser serve as pump sources and are connected to the micro / nano waveguide via the first tapered fiber and the second tapered fiber, respectively. Two pump lights propagating in opposite directions meet and overlap in the micro / nano waveguide, exciting a transverse nonlinear effect and generating transverse emission light in the transverse direction perpendicular to the waveguide axis, which is collected by the microscope objective.

[0005] Furthermore, a nonlinear micro / nano waveguide device also includes: The first and second tapered optical fibers are arranged parallel to the waveguide axis along the micro / nano waveguide, and light is coupled into the micro / nano waveguide through evanescent field coupling.

[0006] Furthermore, the coupling efficiency is greater than 50%.

[0007] A method for fabricating a micro / nano waveguide device includes: The first and second tapered optical fibers were tilted and fixed on a three-dimensional displacement stage and placed on the focal plane of the microscope objective. The micro / nano waveguide was placed on the substrate, and the tip of the tapered optical fiber was manipulated through the nanowire by the displacement stage to lift and suspend the micro / nano waveguide. The displacement stage was adjusted to make the nanowire and the tapered optical fiber fit tightly together to ensure that the coupling efficiency is >50%.

[0008] Furthermore, the micro / nano waveguide is fabricated using a nonlinear material with third-order nonlinearity, and the constraint condition between the diameter and the maximum wavelength of the pump light is: In the formula, The diameter of the micro / nano waveguide; This is the maximum wavelength of the pump light.

[0009] Furthermore, the micro-nano waveguides utilize third-order nonlinear materials, including AlGaAs, ZnO, metal nanowires, and Si3N4; the waveguide structures include rectangular and cylindrical shapes, with a length of not less than 10 μm and a diameter or lateral dimension of not less than 100 nm; the fabrication methods for the micro-nano waveguides include chemical vapor deposition, photolithography, ion beam etching, and solution stretching.

[0010] Furthermore, the first tapered fiber and the second tapered fiber are fabricated using the flame taper method, and the constraint condition between the tip diameter and the maximum wavelength of the pump light is as follows: In the formula, The tip diameters of the first and second tapered optical fibers; This is the maximum wavelength of the pump light.

[0011] A controllable optical emission method based on micro / nano waveguide devices includes: When either the first fiber laser or the second fiber laser outputs pump light, the micro / nano waveguide outputs transverse fluorescence emission induced by two-photon absorption. When both the first and second fiber lasers output pump light with the same wavelength, the micro / nano waveguide output includes transverse second harmonic emission and transverse fluorescence emission induced by two-photon absorption. When both the first and second fiber lasers output pump light with different wavelengths, the micro / nano waveguide output includes transverse combined light, transverse second harmonic emission, and transverse fluorescence emission induced by two-photon absorption.

[0012] Further methods for controllable light emission include: By adjusting the output power of the first and second fiber lasers, the relative strength of different nonlinear effects is changed, and the intensity ratio of emitted light at different wavelengths is adjusted, thereby achieving the control of the color of the transverse emitted light.

[0013] Furthermore, when the center wavelengths of the first and second fiber lasers are in the wavelength range of 300nm-1500nm, and pump light is simultaneously input at both ends, the transverse emission light in the spectral range of 380nm-780nm has at least two peaks.

[0014] According to specific embodiments provided by the present invention, the present invention discloses the following technical effects: This invention discloses a nonlinear micro / nano waveguide device, its fabrication method, and a controllable light emission method. The device utilizes the composite transverse nonlinear effect in a single nonlinear micro / nano waveguide. By changing parameters such as the power and wavelength of the pump light, specific nonlinear effects are selectively excited, and the relative strengths of different effects are altered, thereby achieving control over the wavelength and color of the transverse emitted light. Compared to traditional micro / nano waveguide light emission technology, this invention does not require changes to the waveguide's material composition, structural dimensions, or array geometry, and enables real-time control of emitted light. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the micro / nano waveguide device structure in this invention; Figure 2 This is a schematic diagram of the suspended coupling structure between the micro / nano waveguide and the tapered optical fiber in this embodiment; Figure 3 This is a schematic diagram of the transverse emission spectrum when the pump light is input from one end in this embodiment; Figure 4 This is a schematic diagram of a camera image taken when the pump light is input at one end in this embodiment. Figure 5 This is a schematic diagram of the transverse emission spectrum when pump light of equal wavelength is simultaneously input at both ends in this embodiment; Figure 6 This is a schematic diagram of a camera image taken when pump light of equal wavelength is simultaneously input at both ends in this embodiment. Figure 7 This is a schematic diagram of the transverse emission spectrum when pump light of different wavelengths is simultaneously input at both ends in this embodiment; Figure 8 This is a schematic diagram of a camera image taken when pump light of different wavelengths is simultaneously input at both ends in this embodiment. Figure 9 This is a schematic diagram showing the color gamut that can be covered by the laterally emitted light in this embodiment; In the figure, 1-1, first fiber laser; 1-2, second fiber laser; 2-1, first tapered fiber; 2-2, second tapered fiber; 3, micro / nano waveguide; 4, microscope objective. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] The purpose of this invention is to provide a nonlinear micro / nano waveguide device, a fabrication method, and a controllable light emission method, aiming to solve or improve at least one of the above-mentioned technical problems.

[0019] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0020] like Figure 1 As shown, the present invention provides a nonlinear micro / nano waveguide device, comprising: a first fiber laser 1-1, a second fiber laser 1-2, a first tapered fiber 2-1, a second tapered fiber 2-2, a micro / nano waveguide 3, and a microscope objective lens 4. The first fiber laser 1-1 and the second fiber laser 1-2 serve as pump sources and are connected to the micro / nano waveguide 3 through the first tapered fiber 2-1 and the second tapered fiber 2-2, respectively. The two pump lights propagating in opposite directions meet and overlap in the micro / nano waveguide 3, exciting a transverse nonlinear effect and generating transverse emission light in the transverse direction perpendicular to the waveguide axis, which is collected by the microscope objective 4.

[0021] The first tapered optical fiber 2-1 and the second tapered optical fiber 2-2 are arranged parallel to the waveguide 3 along the waveguide axis, and light is coupled into the micro / nano waveguide 3 through evanescent field coupling. The coupling efficiency is >50%.

[0022] The center wavelengths of the first fiber laser 1-1 and the second fiber laser 1-2 are in the wavelength range of 300-1500nm, and the spectrum of the output light contains one or more center wavelengths.

[0023] The fabrication process of micro / nano waveguide devices includes: The first tapered optical fiber 2-1 and the second tapered optical fiber 2-2 were tilted and fixed on a three-dimensional displacement stage, placed on the focal plane of the microscope objective. A CdTe micro / nano waveguide was placed on a MgF2 substrate. The tip of the tapered optical fiber was manipulated through the nanowire using the displacement stage, lifting and suspending the micro / nano waveguide 3. The displacement stage was adjusted to ensure close contact between the nanowire and the tapered optical fiber, guaranteeing a coupling efficiency >50%. Figure 2 As shown.

[0024] The micro / nano waveguide 3 is fabricated using a nonlinear material with third-order nonlinearity. The constraint condition between its diameter and the maximum wavelength of the pump light is as follows: In the formula, The diameter of the micro / nano waveguide 3; This is the maximum wavelength of the pump light.

[0025] The micro / nano waveguide 3 utilizes third-order nonlinear materials, including but not limited to AlGaAs, ZnO, metal nanowires (Au), and Si3N4. The waveguide structure of the micro / nano waveguide 3 includes, but is not limited to, rectangular and cylindrical structures. The length is not less than 10 μm, and the diameter or lateral dimension is not less than 100 nm. The fabrication methods for the micro / nano waveguide 3 include, but are not limited to, chemical vapor deposition, photolithography, ion beam etching, and solution stretching.

[0026] The first tapered fiber 2-1 and the second tapered fiber 2-2 were fabricated using the flame taper method. The constraint condition between the tip diameter and the maximum wavelength of the pump light is as follows: In the formula, The tip diameters of the first tapered optical fiber 2-1 and the second tapered optical fiber 2-2 are denoted as . This is the maximum wavelength of the pump light.

[0027] A method for laterally controllable optical emission based on a nonlinear micro / nano waveguide device includes: The transverse nonlinear effects occurring in the micro / nano waveguide 3 include, but are not limited to, transverse second harmonic generation, transverse combination frequency, and two-photon absorption-induced fluorescence.

[0028] By changing the wavelength and power of the emitted light from the first fiber laser 1-1 and the second fiber laser 1-2, the nonlinear effect in the micro / nano waveguide 3 is selectively excited, thereby achieving the modulation of the transverse emission wavelength and color, including: By adjusting the output power of the first fiber laser 1-1 and the second fiber laser 1-2, the relative strength of different nonlinear effects is changed, and the intensity ratio of emitted light of different wavelengths is adjusted, thereby achieving the control of the color of transverse emitted light.

[0029] The relationship between transverse fluorescence emission intensity and single-end output intensity of the fiber laser is as follows: In the formula, The transverse fluorescence emission intensity; The single-end output intensity of the fiber laser; The relationship between the intensity of the transverse second harmonic and the output intensity of the first fiber laser 1-1 and the second fiber laser 1-2 is as follows: In the formula, The intensity generated by the transverse second harmonic; The output intensity of the first fiber laser 1-1 and the second fiber laser 1-2; The relationship between the intensity of the transversely combined beam and the output intensity of the first fiber laser 1-1 and the second fiber laser 1-2 is as follows: In the formula, The intensity of the transversely combined beam; The transverse fluorescence frequency is expressed as: in, The transverse fluorescence frequency; This represents the optical frequency corresponding to the bandgap of the nonlinear waveguide material.

[0030] The transverse second harmonic generates the emission frequency, expressed as: In the formula, The light emission frequency is generated by the transverse second harmonic; The first fiber laser 1-1 and the second fiber laser 1-2 emit light at the same wavelength. The emission frequency produced by transversely combined light is expressed as: In the formula, To generate emission frequencies for transversely combined light; and The frequencies at which the first fiber laser 1-1 and the second fiber laser 1-2 emit light at different wavelengths are respectively.

[0031] When either the first fiber laser 1-1 or the second fiber laser 1-2 outputs pump light, transverse fluorescence emission induced by two-photon absorption is output in the micro / nano waveguide 3. When the first fiber laser 1-1 and the second fiber laser 1-2 simultaneously output pump light with the same wavelength, the micro / nano waveguide 3 outputs transverse fluorescence emission containing transverse second harmonics and two-photon absorption. When the first fiber laser 1-1 and the second fiber laser 1-2 simultaneously output pump light with different wavelengths, the micro / nano waveguide 3 outputs transverse combined light, transverse second harmonics, and transverse fluorescence emission induced by two-photon absorption.

[0032] In this embodiment, the parameters of each component are as follows: the micro-nano waveguide is a CdTe micro-nano waveguide with a length of ~100µm, a diameter of 280~385nm, a smooth surface, and low optical loss. The first fiber laser 1-1 and the second fiber laser 1-2 are respectively selected as a 1064nm continuous laser (maximum output power 300mW) and a 980nm continuous laser (maximum output power 20mW). The tip diameter of the tapered optical fiber is 50 nm; The spectrometer has a detection range of 200~1100nm; The CCD camera has a pixel size of 2.4μm×2.4μm and is used to accurately detect the emission light spectrum and chromaticity characteristics.

[0033] The first fiber laser 1-1 is connected to the rear end of the first tapered fiber 2-1, allowing pump light with a wavelength of 1064 nm to be input into the CdTe micro / nano waveguide 3 through evanescent field coupling from one end of the first tapered fiber 2-1. After filtering out the pump light using an 850 nm short-pass filter, the transverse emission light is analyzed using a spectrometer to generate a transverse emission spectrum of 1064 nm wavelength pump light input at one end, as shown below. Figure 3 As shown; and using a CCD camera to create an image, such as... Figure 4 As shown.

[0034] like Figure 3 As shown, a strong peak appears near ~713 nm in the transverse emission spectrum, and the emission color is red. At this point, the nonlinear effect in the waveguide is mainly two-photon absorption-induced fluorescence emission.

[0035] The output light from the first fiber laser 1-1 is split into two beams via a 1:1 fiber coupler. These beams are coupled into the CdTe micro / nano waveguide 3 from both ends via the first tapered fiber 2-1 and the second tapered fiber 2-2, respectively. The beams propagate in opposite directions within the waveguide. After filtering out the pump light using an 850nm short-pass filter, the transverse emission light is analyzed using a spectrometer to generate a transverse emission spectrum when 1064nm wavelength pump light is simultaneously input at both ends. Figure 5As shown, and imaged using a CCD camera, such as Figure 6 As shown.

[0036] like Figure 5 As shown, two peaks appear in the spectrum near wavelengths of ~713 nm and ~532 nm. As the input power changes from 0 to 1.8 mW, the emission color changes between green and orange-red. At this time, the nonlinear effects in the waveguide are mainly two-photon absorption-induced fluorescence emission and transverse frequency second harmonication.

[0037] The first fiber laser 1-1 and the second fiber laser 1-2 are connected to the rear ends of the first tapered fiber 2-1 and the second tapered fiber 2-2, respectively. Pump lights with wavelengths of 1064 nm and 980 nm are input from both ends of the CdTe micro / nano waveguide 3 through evanescent field coupling via the front ends of the first tapered fiber 2-1 and the second tapered fiber 2-2, respectively, and propagate in opposite directions within the waveguide. After filtering out the pump light using an 850 nm short-pass filter, a spectrometer is used to perform spectral analysis on the transverse emission light, generating transverse emission spectra when 1064 nm and 980 nm pump lights are input at both ends, respectively. Figure 7 As shown, and imaged using a CCD camera, such as Figure 8 As shown.

[0038] like Figure 7 As shown, three peaks appear in the spectrum near wavelengths of ~713 nm, ~532 nm, and ~510 nm. The input power of the 980 nm pump light remains at ~2.20 mW. As the input power of the 1064 nm pump light changes from 1.6 mW to 2.4 mW, the emission color changes between yellow-green and orange-red. At this time, the nonlinear effects in the waveguide are mainly two-photon absorption-induced fluorescence emission and transverse frequency second harmonication.

[0039] Through various methods such as wavelength control, input selection, and power modulation, selective excitation of different nonlinear effects such as two-photon absorption and transverse frequency second harmonication can be achieved, and the emitted light color can be controlled in real time. This allows for a CIE 1931 xy chromaticity diagram color gamut coverage greater than 20%, such as... Figure 9 As shown.

[0040] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0041] This document uses specific examples to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the core ideas of the present invention. Furthermore, those skilled in the art will recognize that, based on the ideas of the present invention, there will be changes in the specific implementation methods and application scope. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A nonlinear micro / nano waveguide device, characterized in that, include: First fiber laser (1-1), second fiber laser (1-2), first tapered fiber (2-1), second tapered fiber (2-2), micro / nano waveguide (3), and microscope objective (4). The first fiber laser (1-1) and the second fiber laser (1-2) are used as pump sources and are connected to the micro / nano waveguide (3) through the first tapered fiber (2-1) and the second tapered fiber (2-2), respectively. The two pump lights propagating in opposite directions meet and overlap in the micro / nano waveguide (3), exciting a transverse nonlinear effect and generating transverse emission light in the transverse direction perpendicular to the waveguide axis, which is collected by the microscope objective (4).

2. The nonlinear micro / nano waveguide device according to claim 1, characterized in that, Also includes: The first tapered fiber (2-1) and the second tapered fiber (2-2) are arranged parallel to the waveguide axis along the micro / nano waveguide (3) and the light is coupled into the micro / nano waveguide (3) by evanescent field coupling.

3. A nonlinear micro / nano waveguide device according to claim 2, characterized in that, The coupling efficiency is greater than 50%.

4. A method for fabricating a micro / nano waveguide device based on claims 1-3, characterized in that, include: The first tapered optical fiber (2-1) and the second tapered optical fiber (2-2) are tilted and fixed on a three-dimensional displacement stage and placed on the focal plane of the microscope objective. The micro / nano waveguide is placed on the substrate, and the tip of the tapered fiber is manipulated through the nanowire by the displacement stage to lift and suspend the micro / nano waveguide (3). The displacement stage is adjusted to make the nanowire and the tapered fiber fit tightly together to ensure that the coupling efficiency is >50%.

5. The preparation method according to claim 4, characterized in that, The micro / nano waveguide (3) is fabricated using a nonlinear material with third-order nonlinearity, and the constraint condition between its diameter and the maximum wavelength of the pump light is: In the formula, The diameter of the micro / nano waveguide (3) is given. This is the maximum wavelength of the pump light.

6. The preparation method according to claim 4, characterized in that, The micro / nano waveguide (3) uses third-order nonlinear materials, including AlGaAs, ZnO, metal nanowires, and Si3N4; the waveguide structure of the micro / nano waveguide (3) includes rectangular and cylindrical structures with a length of not less than 10 μm and a diameter or lateral dimension of not less than 100 nm; the fabrication methods of the micro / nano waveguide (3) include chemical vapor deposition, photolithography, ion beam etching, and solution stretching.

7. The preparation method according to claim 4, characterized in that, The first tapered optical fiber (2-1) and the second tapered optical fiber (2-2) are fabricated by flame taper method, and the constraint condition between the tip diameter and the maximum wavelength of the pump light is: In the formula, The tip diameters of the first tapered optical fiber (2-1) and the second tapered optical fiber (2-2); This is the maximum wavelength of the pump light.

8. A controllable optical emission method based on the micro / nano waveguide device according to claims 1-3, characterized in that, include: When one of the first fiber laser (1-1) and the second fiber laser (1-2) outputs pump light, transverse fluorescence emission induced by two-photon absorption is output in the micro / nano waveguide (3); when the first fiber laser (1-1) and the second fiber laser (1-2) simultaneously output pump light with the same wavelength, the micro / nano waveguide (3) outputs transverse fluorescence emission containing transverse second harmonics and two-photon absorption; when the first fiber laser (1-1) and the second fiber laser (1-2) simultaneously output pump light with different wavelengths, the micro / nano waveguide (3) outputs transverse combined light, transverse second harmonics and two-photon absorption induced transverse fluorescence emission.

9. The controllable light emission method according to claim 8, characterized in that, Also includes: By adjusting the output power of the first fiber laser (1-1) and the second fiber laser (1-2), the relative strength of different nonlinear effects is changed, and the intensity ratio of emitted light of different wavelengths is adjusted, thereby achieving the control of the color of transverse emitted light.

10. The controllable light emission method according to claim 8, characterized in that, include: The center wavelengths of the first fiber laser (1-1) and the second fiber laser (1-2) are in the wavelength range of 300nm-1500nm, and when pump light is simultaneously input at both ends, the transverse emission light in the spectral range of 380nm-780nm has at least two peaks.

Images