A fiber vortex random laser integrated with multi-orbital angular momentum modes, a preparation method thereof, and a device and method for generating vortex random laser

Abstract

The application provides a fiber vortex random laser integrated with multiple orbital angular momentum modes and a preparation method thereof, and a vortex random laser generating device and method, and belongs to the technical field of lasers; the problems of the existing vortex random laser, i.e., the radiation direction to be optimized and the system integration to be strengthened, are solved; the fiber vortex random laser integrated with multiple orbital angular momentum modes comprises a microfluid channel, a single-mode optical fiber, an optical fiber splitter and an optical fiber integrated with a spiral phase plate; a gain medium and scattering particles are arranged in the microfluid channel; one end of the single-mode optical fiber is fixed in the microfluid channel; the other end of the single-mode optical fiber is coupled with an end face of the spiral phase plate of the optical fiber integrated with the spiral phase plate through the optical fiber splitter; the spiral phase plates of different optical fibers integrated with the spiral phase plates carry different topological charges, and the vortex random lasers carrying different orbital angular momentum modes are formed; the application is applied to the random laser.

Description

Technical Field

[0001] This invention provides an integrated multi-orbit angular momentum mode fiber vortex random laser and its fabrication method, as well as a device and method for generating vortex random lasers, belonging to the field of laser technology. Background Technology

[0002] With the rapid development of coherent optics theory, partially coherent vortex beams are considered a special type of vortex beam. Compared to fully coherent vortex beams, partially coherent vortex beams possess unique physical significance and optical properties. By adjusting their coherence and orbital angular momentum modes, physical effects such as coherent singularity vanishing, beam shaping, beam self-healing, and polarization state conversion can be achieved, offering unique advantages in suppressing speckle noise, exceeding the Rayleigh diffraction limit, and resisting atmospheric turbulence disturbances. Currently, partially coherent vortex beams are mainly passively generated through dynamic scatterer methods, incoherent superposition methods, or pure digital holography. Among these, the dynamic scatterer method requires rotating a frosted glass to passively generate lasers with low spatial coherence, limiting the adjustment speed. The other two methods offer the advantage of flexible control but require complex offline computational processing. Therefore, designing a light source with low spatial coherence is essential for the real-time generation of partially coherent vortex beams.

[0003] As a novel partially coherent light source, random lasers possess the advantages of simple structure, flexible design, and low spatial coherence of radiated light, making them promising for applications in speckle-free imaging, biosensing, and information security. Currently, researchers have used spatial light modulators to control the phase of random lasers, realizing vortex random lasers covering the visible and near-infrared bands, demonstrating that partially coherent vortex beams can be generated in real-time and actively using random lasers. However, these vortex random lasers still require further improvement in radiation direction optimization and system integration. Phase control based on spatial light modulators requires multiple optical elements for beam collimation, resulting in a complex optical path system, causing energy loss, hindering system integration and miniaturization, and limiting the practical application of vortex random lasers. In recent years, researchers have proposed that the optical confinement effect of fiber waveguides can effectively optimize the radiation direction of random lasers. Simultaneously, the fiber endface is a naturally occurring platform on the order of hundreds of micrometers, compatible with some mature planar micro / nano fabrication processes. The method of generating vortex beams based on fiber endface microstructures has the advantages of compact structure, easy integration, high robustness, and long-distance transmission. This involves directly fabricating various micro-optical devices (spiral phase plates, fork gratings, or spiral axonospindles) on the fiber endface to modulate the spatial phase of the incident light. Therefore, leveraging the waveguide effect and ease of integration of optical fibers, modulating the phase of random lasers through specially designed fiber endface microstructures is beneficial for the integrated design and radiation direction optimization of vortex random lasers. Summary of the Invention

[0004] To address the issues of unoptimized radiation direction and inadequate system integration in existing vortex random lasers, this invention proposes an integrated fiber vortex random laser with multiple orbital angular momentum modes, its fabrication method, and a device and method for generating vortex random lasers. Based on the coupling between the random laser and the optical fiber, the phase of the random laser is modulated by etching phase plates with different topological charge numbers at the fiber end, resulting in the output of vortex random lasers with different orbital angular momentum modes at the fiber end.

[0005] The technical solution adopted in this invention is as follows: a fiber vortex random laser integrating multiple orbital angular momentum modes, comprising a microfluidic channel, a single-mode fiber, a fiber splitter, and an fiber with an integrated spiral phase plate. The microfluidic channel contains a gain medium and scattering particles. One end of the single-mode fiber is fixed in the microfluidic channel, and the other end of the single-mode fiber is coupled to the end face of the spiral phase plate of the fiber with the integrated spiral phase plate through the fiber splitter. The spiral phase plates of different integrated spiral phase plates carry different topological charges, thus constituting vortex random lasers carrying different orbital angular momentum modes.

[0006] Furthermore, the gain medium can be selected from laser dyes, quantum dots, perovskites, or semiconductor materials. By changing the type of gain medium, the vortex random laser can cover the visible light band.

[0007] Furthermore, the scattering particles are selected from metal nanoparticles, metal nanowires, or dielectric nanomaterials.

[0008] Furthermore, the spiral phase plate was etched using two-photon polymerization laser direct writing technology.

[0009] Furthermore, the inner diameter of the microfluidic channel is 500±15μm.

[0010] Furthermore, the single-mode fiber has a cladding diameter of 125±1.5μm, a coating diameter of 245±15μm, a numerical aperture of 0.13, and an operating wavelength of 600-770nm.

[0011] A method for fabricating a fiber vortex random laser integrating multiple orbital angular momentum modes includes the following steps:

[0012] Step 1: Mix the gain medium and scattering particles in a certain proportion in a polymethyl methacrylate solution to obtain a mixed solution;

[0013] Step 2: Utilize the capillary action of the microfluidic channel to draw the mixed solution into the microfluidic channel;

[0014] Step 3: Insert one end of the single-mode fiber into the microfluidic channel, and then place it in a drying oven to complete the curing process, thus forming a microfluidic random laser;

[0015] Step 4: Using two-photon polymerization laser direct writing technology, spiral phase plates with different topological charges are etched on the end face of the optical fiber to obtain an optical fiber with integrated spiral phase plates;

[0016] Step 5: Use an optical fiber splitter to couple the other end of the single-mode fiber to the end face of the optical fiber with the integrated spiral phase plate to form an optical fiber vortex random laser.

[0017] A device for generating a vortex random laser includes a pump source, a fiber vortex random laser integrating multiple orbital angular momentum modes, a half-wave plate, a Glan prism, a beam splitter, an optical power meter, a lens, and a fiber optic spectrometer. The laser generated by the pump source is processed by the half-wave plate and the Glan prism to adjust its power, and then split into two laser beams by the beam splitter. One laser beam is input to the optical power meter, and the other laser beam is input to the fiber optic spectrometer for measuring the radiation spectrum of the vortex random laser under different pump powers after passing through a first lens, the fiber vortex random laser, and a second lens.

[0018] Furthermore, it also includes a computer, an optical power meter, and a fiber optic spectrometer, which are connected to the computer via wires. The computer is also connected via wires to a CCD camera used to capture the output spot of a vortex random laser with different topological charges.

[0019] A method for generating a vortex random laser, employing a device for generating a vortex random laser, includes the following steps:

[0020] Step 6: Excite a microfluidic random laser using a pump source. The random laser coupled into a single-mode fiber is split into multiple fibers with integrated spiral phase plates by a fiber splitter. Under the modulation of the spiral phase plates, vortex random lasers with different orbital angular momentum modes are output from the fiber end face of the integrated spiral phase plates.

[0021] Step 7: Adjust the power of the pump source using a half-wave plate and a Glan prism, and monitor the pump power using an optical power meter, then repeat step 6;

[0022] Step 8: Measure the radiation spectrum of the vortex random laser under different pump powers using a fiber optic spectrometer.

[0023] The advantages of this invention over the prior art are as follows:

[0024] (1) Based on the easy integration of optical fiber, the integration and miniaturization of vortex random lasers are realized by etching spiral phase plates with different topological charge numbers at the end of the optical fiber, and vortex random lasers with orbital angular momentum modes of 1-5 can be output simultaneously.

[0025] (2) Based on the waveguide effect of optical fiber, the optimization of the vortex random laser radiation direction was realized. Attached Figure Description

[0026] The present invention will be further described below with reference to the accompanying drawings:

[0027] Figure 1 This is a structural diagram of the device of the present invention;

[0028] Figure 2 This is a structural diagram of the optical path system of the present invention;

[0029] Figure 3 Electron micrograph of the end face of an optical fiber with an etched spiral phase plate;

[0030] Figure 4 Electron micrographs of spiral phase plates with different topological charges etched at the fiber ends;

[0031] Figure 5 The radiation spectra of the present invention under different pump power densities are shown below.

[0032] Figure 6 Output spot patterns of vortex random lasers with different orbital angular momentum modes;

[0033] In the diagram: 100 is a microfluidic channel, 101 is a gain medium, 102 is a scattering particle, 103 is a single-mode fiber, 104 is a fiber splitter, 105 is a fiber with an integrated spiral phase plate, 200 is a pump source, 201 is a half-wave plate, 202 is a Glan prism, 203 is a beam splitter, 204 is an optical power meter, 205 is a lens, 206 is a fiber vortex random laser, 207 is a fiber spectrometer, and 208 is a computer. Detailed Implementation

[0034] like Figures 1 to 6 As shown, this invention provides an integrated multi-orbit angular momentum mode fiber vortex random laser, comprising a microfluidic channel 100, a gain medium 101, scattering particles 102, a single-mode fiber 103, a fiber splitter 104, and an fiber 105 with an integrated spiral phase plate. The gain medium 101 and scattering particles 102 are mixed in a polymethyl methacrylate solution and solidified in the microfluidic channel 100, forming the microfluidic random laser. One end of the single-mode fiber 103 is also solidified in the microfluidic channel 100, and the other end is coupled to the fiber 105 with the integrated spiral phase plate under the action of the fiber splitter 104. Under the excitation of a pump source 200, the random laser radiation from the microfluidic random laser is coupled into the single-mode fiber 103 for transmission, and then transmitted to the fiber 105 with the integrated spiral phase plate under the action of the fiber splitter 104. Finally, under the phase modulation of the spiral phase plate, vortex random lasers with different orbital angular momentum modes are output from the fiber end.

[0035] Specifically, under the excitation of the pump source 200, the radiated light is amplified by multiple scattering of randomly distributed scattering particles 102 in the gain medium 101. At the same time, the total internal reflection at the interface between the microfluidic channel 100 and the air provides positive feedback for optical amplification. When the total gain is greater than the loss, random laser radiation is realized. A portion of the random laser is coupled into a single-mode fiber 103 for transmission, and under the action of the fiber splitter 104, it is transmitted to multiple integrated spiral phase plates in the fiber 105. Finally, under the phase modulation of the spiral phase plates carrying different topological charges, the fiber ends output vortex random lasers with different orbital angular momentum modes.

[0036] The gain medium 101 can be a laser dye, quantum dot, perovskite or semiconductor material; by changing the type of gain medium 101, the vortex random laser can cover the visible light band.

[0037] The scattering particles 102 can be metal nanoparticles, metal nanowires, or dielectric nanomaterials.

[0038] The inner diameter of the microfluidic channel 100 is 500±15μm.

[0039] The single-mode fiber 103 has a cladding diameter of 125±1.5μm, a coating diameter of 245±15μm, a numerical aperture of 0.13, and an operating wavelength of 600-770nm.

[0040] The fiber optic splitter 104 is specifically a 1-to-5 splitter, which divides the random laser in the single-mode fiber 103 into five paths according to energy.

[0041] The spiral phase plates integrated at the fiber ends are fabricated using two-photon polymerization laser direct writing technology, and the spiral phase plates carry topological charges from 1 to 5 respectively.

[0042] This embodiment also proposes a method for fabricating a fiber vortex random laser integrating multiple orbital angular momentum modes, including the following steps:

[0043] Step 1: Mix the gain medium 101 and scattering particles 102 in a certain proportion in a polymethyl methacrylate solution to obtain a mixed solution;

[0044] Step 2: Using the capillary action of the microfluidic channel 100, the mixed solution is drawn into the microfluidic channel 100;

[0045] Step 3: Insert one end of the single-mode fiber 103 into the microfluidic channel 100, and then place it in a drying oven to complete the curing process, thus forming a microfluidic random laser;

[0046] Step 4: Using two-photon polymerization laser direct writing technology, spiral phase plates with different topological charges are etched on the end face of a single-mode fiber to obtain fiber 105 with integrated spiral phase plates.

[0047] Step 5: Using fiber optic splitter 104, couple the other end of single-mode fiber 103 to the end face of the spiral limiting plate of fiber 105 with integrated spiral phase plate to form a fiber optic vortex random laser, such as... Figure 1 As shown.

[0048] This embodiment also proposes a device for generating vortex random lasers, including a pump source 200, a fiber vortex random laser 206 integrating multiple orbital angular momentum modes, a half-wave plate 201, a Glan prism 202, a beam splitter 203, an optical power meter 204, a lens 205, a fiber optic spectrometer 207, and a computer 208. After the power of the pump source 200 is adjusted by the half-wave plate 201 and the Glan prism 202, the laser emitted by the pump source 200 passes through the beam splitter 203 to form two laser beams. One laser beam enters the optical power meter 204 as an auxiliary laser for detecting the pump power. Then, the computer 208 collects the pump power measured by the optical power meter 204. The other laser beam passes through a first lens, the fiber vortex random laser 206, and a second lens before entering the fiber optic spectrometer 207. The fiber optic spectrometer 207 measures the radiation spectrum of the vortex random laser 206 under different pump powers and sends the radiation spectrum to the computer 208.

[0049] This embodiment also proposes a method for generating vortex random lasers, based on the aforementioned vortex random laser generation apparatus, including the following steps:

[0050] Step 6: The microfluidic random laser is excited by the pump source 200 and coupled into the single-mode fiber 103. The random laser is split into multiple fibers 105 by the fiber splitter 104. Under the modulation of the spiral phase plate, vortex random lasers with different orbital angular momentum modes are output from the end face of the fiber 105.

[0051] Step 7: Adjust the power of pump source 200 using half-wave plate 201 and Glan prism 202, and monitor the pump power using optical power meter 204, such as... Figure 2 As shown;

[0052] Step 8: Measure the radiation spectrum of the vortex random laser under different pump powers using a fiber optic spectrometer 207;

[0053] Step 9: Use a CCD to capture the output spot of a vortex random laser with different topological charges.

[0054] Example 1:

[0055] This embodiment provides a specific method for fabricating a fiber vortex random laser with integrated multi-orbit angular momentum modes and a method for generating vortex random laser. This embodiment verifies the effectiveness of the invention. DCJTB dye is selected as the gain medium, and Ti3C2 is used as the scattering particle to generate a red vortex random laser, including the following steps:

[0056] (1) Dissolve 30g of polymethyl methacrylate in acetone solution to obtain polymethyl methacrylate dilution;

[0057] (2) Dissolve 1.5 mg of DCJTB dye and 0.2 mg of Ti3C2 in polymethyl methacrylate diluent to obtain a mixed solution; then use the capillary action of microfluidic channel 100 to draw the mixed solution into microfluidic channel 100.

[0058] (3) Insert one end of the single-mode fiber 103 into the microfluidic channel 100, and then place it in a drying oven at 60°C to complete the curing process, thus forming a microfluidic random laser;

[0059] (4) Using two-photon polymerization laser direct writing technology, spiral phase plates with a topological charge of 1-5 are etched on the end face of a single-mode fiber, such as... Figure 3-4 As shown;

[0060] (5) Using a 1-to-5 fiber optic splitter 104, the other end of the single-mode fiber 103 is coupled to the five fibers of the integrated spiral phase plate to form a fiber optic vortex random laser.

[0061] (6) A microfluidic random laser is pumped using a nanosecond laser with a wavelength of 532 nm, and the radiation spectrum is collected at the fiber end using a fiber optic spectrometer 207; for example Figure 5 As shown, when the pump power density is greater than 0.0567 MW / cm², 2 At that time, a red vortex random laser with a center wavelength of 660nm was generated;

[0062] (7) Use CCD to capture the output spot of vortex random laser with different topological charge numbers. Figure 6 The emitted beam patterns of vortex random lasers with topological charges ranging from 1 to 5 are presented. It can be seen that as the topological charge increases, a region with zero intensity appears at the center of the intensity distribution, resembling a "donut" shape, indicating the presence of a phase singularity; simultaneously, the beam diameter also gradually increases. The results show that the helical phase plate at the fiber end effectively modulates the phase of the random laser. This invention achieves the integration of vortex random lasers with different orbital angular momentum modes.

[0063] In summary, this invention proposes for the first time an integrated fiber vortex random laser with different orbital angular momentum modes. This vortex random laser effectively optimizes its radiation direction based on the waveguide effect of optical fiber. At the same time, it utilizes the ease of integration of optical fiber to achieve the integration and miniaturization of the vortex random laser. Furthermore, based on the ease of integration of optical fiber, vortex random lasers with topological charges of 1-5 can be output simultaneously, showing potential application prospects in speckle-free imaging, optical communication, and particle manipulation.

[0064] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. An integrated multi-orbital angular momentum mode fiber-optic vortex random laser, characterized in that: The fiber vortex random laser comprises a microfluid channel (100), a single-mode optical fiber (103), an optical fiber splitter (104) and an integrated spiral phase plate optical fiber (105), the microfluid channel (100) is internally provided with a gain medium (101) and scattering particles (102), one end of the single-mode optical fiber (103) is fixed in the microfluid channel (100), the other end of the single-mode optical fiber (103) is coupled with an end face of the integrated spiral phase plate optical fiber (105) through the optical fiber splitter (104), different integrated spiral phase plate optical fibers (105) carry different topological charges, and the vortex random laser carrying different orbital angular momentum modes is formed. 2.The integrated multi-orbital angular momentum mode fibered vortex random laser of claim 1, wherein: The gain medium (101) is selected from laser dyes or semiconductor materials, and the vortex random laser can cover the visible light band range by changing the type of the gain medium (101). 3.The optical fiber vortex random laser integrating multiple orbital angular momentum modes of claim 1, wherein: The scattering particles (102) are selected from metal nanoparticles, metal nanowires or dielectric nanomaterials. 4.The optical fiber vortex random laser integrating multiple orbital angular momentum modes of claim 1, wherein: The spiral phase plate is etched by using a two-photon polymerization laser direct writing technology. 5.The optical fiber vortex random laser integrating multiple orbital angular momentum modes of claim 1, wherein: The inner diameter of the microfluid channel (100) is 500±15 μm. 6.The integrated multi-orbital angular momentum mode fibered vortex random laser of claim 1, wherein: The cladding diameter of the single-mode optical fiber (103) is 125±1.5 μm, the coating layer diameter is 245±15 μm, the numerical aperture is 0.13, and the working wavelength is 600-770 nm.

7. A method of preparing the integrated multi-orbital angular momentum mode optical fiber vortex random laser according to any one of claims 1-6, characterized in that: The method comprises the following steps: Step 1: mixing the gain medium (101) and the scattering particles (102) in a polymethyl methacrylate solution at a certain ratio to obtain a mixed solution; Step 2: using the capillary action of the microfluid channel (100) to suck the mixed solution into the microfluid channel (100); Step 3: inserting one end of the single-mode optical fiber (103) into the microfluid channel (100), and then placing it in a drying box to complete the curing process, thereby forming a microfluid random laser; Step 4: etching spiral phase plates with different topological charges on the end face of the optical fiber by using a two-photon polymerization laser direct writing technology, thereby obtaining the integrated spiral phase plate optical fiber (105); Step 5: coupling the other end of the single-mode optical fiber (103) with the end face of the integrated spiral phase plate optical fiber (105) by using the optical fiber splitter (104), thereby forming a fiber vortex random laser.

8. An apparatus for vortex random laser generation, characterized by: The fiber vortex random laser (206) carrying multiple orbital angular momentum modes comprises a pump source (200), a half-wave plate (201), a Glan prism (202), a beam splitter (203), an optical power meter (204), a lens (205) and a fiber spectrometer (207), laser generated by the pump source (200) passes through the half-wave plate (201) and the Glan prism (202) to adjust the power, and then passes through the beam splitter (203) to form two beams of laser, one of which is input into the optical power meter (204), and the other of which passes through a first lens, the fiber vortex random laser (206) and a second lens and is then input into the fiber spectrometer (207) for measuring the radiation spectrum of the vortex random laser under different pump powers.

9. The device for generating a vortex random laser according to claim 8, wherein: Also included are a computer (208), an optical power meter (204) and an optical fiber spectrometer (207) are connected to the computer (208) through wires respectively, the computer (208) is also connected to a CCD camera for shooting the output spot of vortex random laser with different topological charges through wires.

10. A method of vortex random laser generation using the apparatus of vortex random laser generation according to claim 8 or 9, characterized by: The method comprises the following steps: Step 6: excite the microfluidic random laser with the pump source (200), the random laser coupled into the single-mode optical fiber (103) is branched into multiple integrated spiral phase plate optical fibers (105) under the action of the optical fiber splitter (104); under the modulation of the spiral phase plate, vortex random lasers with different orbital angular momentum modes are output from the end face of the integrated spiral phase plate optical fiber (105); Step 7: use a half-wave plate (201) and a Glan prism (202) to regulate the power of the pump source (200), and use an optical power meter (204) to monitor the pump power, and then repeat step 6; Step 8: use an optical fiber spectrometer (207) to measure the radiation spectrum of the vortex random laser under different pump powers.

Images