A double-focus ring-pumped multi-orbital angular momentum vortex hollow laser

Abstract

The application discloses a kind of based on double focal ring pumping multiple orbital angular momentum vortex hollow laser, including fiber coupling output's semiconductor laser array (1), plano-convex lens (2), double focal ring pumping beam generation system (3), conical mirror (4), gain medium (5) and V-shaped crystal conical mirror (6).The application realizes high-order Laguerre-Gaussian intensity, tangential (or radial) polarization state multiple orbital angular momentum superposition state vortex phase distribution laser, which can simulate the entangled state of multiple particles and multiple degrees of freedom, making it possible to develop high-dimensional multi-channel high-capacity quantum and classical optical communication technology, and can also revolutionize traditional optical tweezers and particle manipulation technology.The laser resonator structure is simple and easy to adjust, simplifying the multi-dimensional laser generation system, advancing the practical process and the expansion of new technology, and creating conditions for the application of multi-degree-of-freedom optical field.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of lasers, and particularly relates to a double-focus-ring-pumped multi-orbital angular momentum vortex hollow laser. BACKGROUND

[0002] Light field modulation has shown many novel optical effects and physical phenomena, and has expanded the application field of lasers. Light field modulation is divided into time domain modulation and space domain modulation. Light frequency comb is a typical example of time domain modulation of light field frequency. High-precision light frequency comb has a milestone significance in the fields of optical communication, laser radar, laser frequency measurement, development of high-precision clock, and improvement of positioning system. The space domain modulation of light field mainly reflects the amplitude, phase and polarization parameters, and its application has also sprung up in recent years, such as in super-resolution microscopic imaging, particle manipulation, quantum optics, high-capacity optical communication, and biological tissue imaging and detection. People have designed and implemented a multi-degree-of-freedom intrinsic mode hollow laser (patent 202111665250.3), which can produce a hollow laser with three degrees of freedom of intrinsic mode, i.e. non-Gaussian intensity distribution with larger inner light intensity gradient than outer light intensity gradient, cylindrical vector polarization state and vortex phase, breaking through the limitation of spatial structure light field laser in two dimensions of spin angular momentum and orbital angular momentum, and greatly expanding the application field of lasers. However, the application inserts a Brewster cone in the cavity, and only when the Brewster angle is incident can a cylindrical vector polarization state be generated, and the element needs to be strictly aligned, so the structure is complex and difficult to adjust. In addition, in the aspects of communication coding and information transmission processing, a composite light field with diversified phase distribution is needed, for example, the superposition state of multi-orbital angular momentum of vortex laser can ensure the transmission of multi-channel signals, improve the communication capacity and security, and the light field obtained by single-ring pumping cannot meet the demand. SUMMARY

[0003] The application aims to provide a double-focus-ring-pumped multi-orbital angular momentum vortex hollow laser.

[0004] In order to solve the technical problems, the technical scheme of the application is as follows:

[0005] A double-focus-ring-pumped multi-orbital angular momentum vortex hollow laser, comprising a fiber-coupled semiconductor laser array, and further comprising a plano-convex lens arranged along the optical axis of the emitted light beam, a double-focus-ring-pumped beam generation system, a first conical mirror, a gain medium and a V-shaped crystal conical mirror.

[0006] The bifocal ring pumping beam generating system is sequentially arranged along the incident-to-emergent direction: a trapezoidal conical mirror, a second conical mirror and a convex lens; the collimated light beam passing through the trapezoidal conical mirror is divided into two beams of divergent and parallel light, the divergent light is focused into a ring beam on the focal plane by the convex lens, and the parallel light is focused by the second conical mirror to form another ring beam after the focal depth, and then diverges; the trapezoidal conical mirror has a conical angle α which is not equal to the conical angle β of the second conical mirror, and the divergence angle of the trapezoidal conical mirror is different from that of the other beam of light, so that another ring beam is formed on the focal plane after passing through the convex lens, thereby forming a bifocal ring beam.

[0007] Further, the fiber-coupled output semiconductor laser array is a pumping source of the laser; the plano-convex lens is a pumping beam collimating lens; the conical surface of the first conical mirror and the positive conical surface of the V-shaped crystal conical mirror constitute a resonant cavity of the laser.

[0008] Further, the first conical mirror is an input mirror of the resonant cavity, and has a conical angle φ=90 o The bottom surface is coated with an antireflection film for the pumping light and the laser, and the conical surface is coated with a high-reflection film for the laser and an antireflection film for the pumping light.

[0009] Further, the light passing surface of the trapezoidal conical mirror is coated with an antireflection film for the pumping light.

[0010] Further, the light passing surface of the second conical mirror is coated with an antireflection film for the pumping light.

[0011] Further, the positive conical surface of the V-shaped crystal conical mirror is an output coupling mirror of the resonant cavity, and has an optical axis which is parallel to the cylindrical surface of the V-shaped crystal conical mirror; the negative conical surface is coated with an antireflection film for the laser, and the positive conical surface is coated with a dielectric film having a transmittance of 5-10% for the laser.

[0012] Further, the conical angle γ of the V-shaped crystal conical mirror and the refractive index n o of o light in the crystal satisfy n o =ctan(γ / 2), so that a tangential polarization state is generated.

[0013] Further, the conical angle γ of the V-shaped crystal conical mirror and the refractive index n e of e light in the crystal satisfy n e =ctan(γ / 2), so that a radial polarization state is generated.

[0014] Further, the conical angle γ of the V-shaped crystal conical mirror and the refractive index n o of o light in the crystal satisfy n o =ctan(γ / 2), so that the o light in the cavity forms a traveling wave cavity set closed loop operation, at this time the birefringence generates e light which does not satisfy n e =ctan(γ / 2), and cannot form a closed loop operation, and the set of o light from the 2π direction forms a tangential polarization, on the contrary, when the conical angle γ of the V-shaped crystal conical mirror and the refractive index ne satisfy n e =ctan(γ / 2) when, the cavity e light forms a closed loop running from the 2π direction, the collection of e light forms radial polarization, Laguerre-Gaussian beam (LG pl ) is the eigenmode of the laser resonator, p and l are the radial and angular parameters respectively, when the size of the ring-shaped pump beam and its mode match, the specific LG pl mode laser operation can be excited.

[0015] Further, the light transmission surface of the gain medium is coated with a transmittance film for pump light and laser; the pump source and gain medium crystal are cooled by TEC.

[0016] Compared with the prior art, the advantages of the present application are:

[0017] The present application adopts a double-focus ring pumping system to realize a multi-dimensional optical field laser with high-order Laguerre-Gaussian intensity, tangential (or radial) polarization state and vortex phase distribution multi-orbital superposition state, increases the degrees of freedom of the optical field (such as orbital degeneracy, orbital phase and orbital combination number), can simulate the entangled state of multiple particles and multiple degrees of freedom, makes it possible to develop high-dimensional multi-channel large-capacity quantum and classical optical communication technology, and can also revolutionize traditional optical tweezers and particle manipulation technology (multiple particles can be captured by the same light and control their multi-degree-of-freedom motion), so that the optical field has more exotic shapes and more abundant properties. In addition, the laser resonator structure of the present application is simple and easy to adjust, greatly simplifies the generation system of multi-dimensional structured light field, promotes the practicalization process and the expansion of new technologies, and will open up new research and application fields of structured light field, creating more opportunities for the application of multi-degree-of-freedom optical field. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 It is a schematic diagram of the laser structure of the present application;

[0019] Figure 2 It is a double-ring zoom pumping beam generation system;

[0020] Figure 3 It is a tangential polarization state schematic diagram;

[0021] Figure 4 It is a radial polarization state schematic diagram;

[0022] Figure 5 It is a Laguerre-Gaussian beam intensity distribution schematic diagram.

[0023] Reference signs:

[0024] 1-fiber coupled output semiconductor laser array; 2-plano-convex lens; 3-double focal ring pump beam generating system; 4-first conical mirror; 5-gain medium; 6-V-shaped crystal conical mirror; 7-trapezoidal conical mirror; 8-second conical mirror; 9-convex lens. DETAILED DESCRIPTION

[0025] The specific embodiments of the present application will be described below in conjunction with examples:

[0026] It should be noted that the structures, proportions, sizes, etc. shown in the present specification are merely used to cooperate with the content disclosed in the present specification for the understanding and reading of those skilled in the art, and are not used to limit the defined conditions under which the present application can be implemented. Any modification of the structure, change of the proportional relationship, or adjustment of the size, which does not affect the effects that can be produced by the present application and the purposes that can be achieved, should still fall within the scope of the technical content disclosed by the present application.

[0027] Meanwhile, the terms such as "upper", "lower", "left", "right", "middle", and "one" cited in the present specification are merely for the clear understanding of the description, and are not used to limit the scope in which the present application can be implemented. The change or adjustment of the relative relationship without substantial change of the technical content is also regarded as the scope in which the present application can be implemented.

[0028] Example 1:

[0029] A double focal ring pumped multiple orbital angular momentum vortex hollow laser, as shown in Figure 1 from left to right in order to set fiber coupled output semiconductor laser array 1, plano-convex lens 2, double focal ring pump beam generating system 3, first conical mirror 4, gain medium 5 and V-shaped crystal conical mirror 6. Fiber coupled output semiconductor laser array 1 is the pump source of the laser; plano-convex lens 2 is the pump beam collimation lens; the conical surface of the first conical mirror 4 and the positive conical surface of the V-shaped crystal conical mirror 6 constitute the resonant cavity of the laser. Double focal ring pump beam generating system 3, as shown in Figure 2 from left to right in order to set trapezoidal conical mirror 7, second conical mirror 8 and convex lens 9. After collimated light passes through trapezoidal conical mirror 7, it is divided into two beams of divergent and parallel light. The divergent light is focused into a ring beam (radius r1) on the focal plane after passing through convex lens 9. The parallel light passes through the focusing beam generated by the second conical mirror 8 and is divergent after the focal depth. Because the conical angle α of the trapezoidal conical mirror 7 is not equal to the conical angle β of the second conical mirror 8, the divergence angle is different from that of the other beam, so another ring beam (radius r2) is formed on the focal plane after passing through convex lens 9, thereby forming a double focal ring beam.

[0030] The conical angle φ of the first conical mirror 4 of the laser resonant cavity is 90 oThe bottom surface of the V-shaped crystal conical mirror 6 is coated with an anti-reflection film for the pump light and laser, while the conical surface is coated with a high-reflection film for the laser and an anti-reflection film for the pump light. The light-transmitting surface of the gain medium 5 is coated with an anti-reflection film for both the pump light and laser. The pump source and the crystal of the gain medium 5 are TEC cooled. The light-transmitting surface of the trapezoidal conical mirror 7 is coated with an anti-reflection film for the pump light. The light-transmitting surface of the second conical mirror 8 is coated with an anti-reflection film for the pump light. The positive conical surface of the V-shaped crystal conical mirror 6 serves as the output coupling mirror of the resonant cavity, with its optical axis parallel to the cylindrical surface of the conical mirror. The negative conical surface is coated with an anti-reflection film for the laser, and the positive conical surface is coated with a dielectric film with a transmittance of 5-10%. The cone angle γ of the V-shaped crystal conical mirror 6 and the refractive index n of the o-light in the crystal are also considered. o Satisfying n o When γ = ctan(γ / 2), the o-ray within the cavity forms a traveling wave cavity assembly operating in a closed loop. At this time, the birefringence producing e-ray does not satisfy n. e =ctan(γ / 2), cannot form a closed-loop operation. Viewed from the 2π direction (rotating one revolution along the system axis), the collection of light forms a tangential polarization distribution, such as Figure 3 As shown. Conversely, when the cone angle γ and the refractive index n of the e-ray in the crystal... e Satisfying n e When γ = ctan(γ / 2), the e-beams within the cavity form a traveling wave cavity array operating in a closed loop. Viewed from the 2π direction (rotating one revolution along the system axis), the array of e-beams forms a radial polarization distribution, as shown in the figure. Figure 4 As shown. Laguerre-Gaussian beam (LG pl ) is the eigenmode of the laser resonator, and p and l are the radial and angular parameters, respectively. When the size of the ring pump beam is matched with its mode, a specific LG carrying a vortex phase can be excited. pl Mode laser operation, such as Figure 5 For different orders of LG pl The light intensity distribution diagram is shown.

[0031] Example 2:

[0032] A hollow laser based on a dual-focal-ring pumped multiple orbital angular momentum vortex (polarization distribution as follows) can be implemented using the following unit devices. Figure 3 (As shown): The specific parameters of the fiber-coupled semiconductor laser array 1 are as follows: output wavelength of 808nm, fiber core diameter of 400μm, and numerical aperture of 0.22; the focal length of the plano-convex lens 2 is 200mm, and its light-transmitting surface is coated with an 808nm anti-reflection film; the first conical mirror 4, the trapezoidal conical mirror 7, and the second conical mirror 8 are all made of K9 glass; the cone angle of the first conical mirror 4 is φ=90°. o The bottom surface is coated with 808nm and 1064nm antireflection films, and the conical surface is coated with a 1064nm antireflection film and an 808nm antireflection film; the gain medium 5 is made of Nd:YAG crystal, Nd 3+The doping concentration is 1.0%, and the light-transmitting surface is coated with 808nm and 1064nm antireflection films; the fiber-coupled semiconductor laser array 1 and the Nd:YAG crystal are cooled by TEC, and the temperature is controlled within the range of 15 o ±0.5 o The taper angle of the trapezoidal conical mirror 7 is 120 o , and the light-transmitting surface is coated with 808nm antireflection film; the taper angle of the second conical mirror 8 is 100 o , and the light-transmitting surface is coated with 808nm antireflection film; the V-shaped crystal conical mirror 6 is made of a negative uniaxial calcite crystal, the taper angle is 61 o , the optical axis is parallel to the cylindrical surface of the conical mirror, the negative taper surface is coated with 1064nm antireflection film, and the positive taper surface is coated with 1064nm dielectric film with a transmittance of 10%.

[0033] Embodiment 3:

[0034] A kind of based on double focus ring pumping multiple orbital angular momentum vortex hollow laser (polarization distribution as shown in Figure 4 ) can be realized by using the following unit devices: the specific parameters of the fiber-coupled semiconductor laser array 1 are as follows: the output wavelength is 940nm, the fiber core diameter is 400μm, and the numerical aperture is 0.22; the focal length of the plano-convex lens 2 is 200mm, and the light-transmitting surface is coated with 940nm antireflection film; the first conical mirror 4, the trapezoidal conical mirror 7 and the second conical mirror 8 are all made of K9 glass; the taper angle of the first conical mirror 4 is 90 o , the bottom surface is coated with 940nm and 1030nm antireflection films, the taper surface is coated with 1030nm antireflection film and 940nm antireflection film; the gain medium 5 is made of Yb:YAG crystal, and the Yb 3+ doping concentration is 0.5%, and the light-transmitting surface is coated with 940nm and 1030nm antireflection films; the fiber-coupled semiconductor laser array 1 and the Yb:YAG crystal are cooled by TEC, and the temperature is controlled within the range of 15 o ±0.5 o ; the taper angle of the trapezoidal conical mirror 7 is 120 o , and the light-transmitting surface is coated with 940nm antireflection film; the taper angle of the second conical mirror 8 is 100 o , and the light-transmitting surface is coated with 940nm antireflection film; the V-shaped crystal conical mirror 6 is made of a positive uniaxial quartz crystal, the taper angle is 66 o , the optical axis is parallel to the cylindrical surface of the conical mirror, the negative taper surface is coated with 1030nm antireflection film, and the positive taper surface is coated with 1030nm dielectric film with a transmittance of 5%.

[0035] The preferred embodiments of the present application are described in detail above, but the present application is not limited to the above-mentioned embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the spirit of the present application.

[0036] Many other changes and modifications can be made to the application without departing from the spirit and scope of the application. It is to be understood that the application is not limited to particular embodiments described, and is intended in its broadest aspect to cover all such changes and modifications thereof. The scope of the application is defined by the appended claims.

Claims

1. A dual-focal-ring-pumped multi-orbital angular momentum vortex hollow laser, characterized in that, The application relates to a fiber-coupled semiconductor laser array (1) comprising a plano-convex lens (2) arranged along the optical axis of the outgoing light beam, a bifocal annular pumping beam generating system (3), a first conical mirror (4), a gain medium (5) and a V-shaped crystal conical mirror (6). The bifocal annular pumping beam generating system (3) is sequentially arranged along the incident direction to the outgoing direction: a trapezoidal conical mirror (7), a second conical mirror (8) and a convex lens (9); the collimated light beam passing through the plano-convex lens (2) is divided into two beams of divergent and parallel light after passing through the trapezoidal conical mirror (7), the divergent light is focused into an annular light beam on the focal plane after passing through the convex lens (9), the parallel light is focused by the second conical mirror (8) to generate a divergent light beam after passing through the focal depth, the trapezoidal conical mirror (7) has a conical angle alpha which is not equal to the conical angle beta of the second conical mirror (8), the divergence angle of the trapezoidal conical mirror (7) is different from that of the other light beam, and another annular light beam is formed on the focal plane after passing through the convex lens (9), so that a bifocal annular light beam is formed. The fiber-coupled semiconductor laser array (1) is a pumping source of the laser; the plano-convex lens (2) is a pumping beam collimating lens; the conical surface of the first conical mirror (4) and the positive conical surface of the V-shaped crystal conical mirror (6) constitute a resonant cavity of the laser.

2. The dual-focal-ring pumped multi-orbital angular momentum vortex hollow laser according to claim 1, wherein, The light transmission surface of the trapezoidal conical mirror (7) is coated with an antireflection film for the pumping light.

3. The dual-focal-ring pumped multi-orbital angular momentum vortex hollow laser of claim 1, wherein, The first conical mirror (4) is an input mirror of the resonant cavity, with a conical angle φ = 90 o The bottom surface is coated with a laser anti-reflection film and a pump light anti-reflection film, and the conical surface is coated with a laser high-reflection film and a pump light anti-reflection film.

4. The dual-focal-ring pumped multi-orbital angular momentum vortex hollow laser of claim 1, wherein, The light transmission surface of the second conical mirror (8) is coated with an antireflection film for the pumping light.

5. The dual-focal-ring pumped multi-orbital angular momentum vortex hollow laser of claim 1, wherein, The positive conical surface of the V-shaped crystal conical mirror (6) is an output coupling mirror of the resonant cavity, the optical axis of the V-shaped crystal conical mirror (6) is parallel to the cylindrical surface of the V-shaped crystal conical mirror (6); the negative conical surface is coated with an antireflection film for the laser, and the positive conical surface is coated with a dielectric film with a transmittance of 5-10% for the laser.

6. The dual-focal-ring pumped multi-orbital angular momentum vortex hollow laser of claim 1, wherein, The light transmission surface of the gain medium (5) is coated with an antireflection film for the pumping light and the laser; and the pumping source and the gain medium (5) crystal are cooled by a TEC.

7. The dual-focal-ring pumped multi-orbital angular momentum vortex hollow laser of claim 1, wherein, The V-shaped crystal conical mirror (6) has a conical angle γ and a refractive index n of o light in the crystal o Satisfies n o = ctan(γ / 2) when the tangential polarization state is generated.

8. The dual-focal-ring pumped multi-orbital angular momentum vortex hollow laser of claim 7, wherein, The V-shaped crystal conical mirror (6) has a conical angle γ and a refractive index n of e light in the crystal e satisfies n e = ctan(γ / 2), a radial polarization state is generated.

9. The dual-focal-ring pumped multi-orbital angular momentum vortex hollow laser of claim 8, wherein, The cone angle γ of the V-shaped crystal conical lens (6) and the refractive index n of the o-ray in the crystal. o Satisfying n o When γ = ctan(γ / 2), the o-ray within the cavity forms a traveling wave cavity assembly operating in a closed loop. At this time, the birefringence producing e-ray does not satisfy n. e =ctan(γ / 2), cannot form a closed-loop operation. Looking at the 2π direction, the collection of o-rays forms tangential polarization. Conversely, when the cone angle γ and the refractive index n of the e-ray in the crystal... e Satisfying n e When γ = ctan(γ / 2), the e-beams within the cavity form a traveling wave cavity collection in a closed loop. Viewed from the 2π direction, the collected e-beams exhibit radial polarization, resulting in a Laguerre-Gaussian beam (LG). pl ) is the eigenmode of the laser resonator, and p and l are the radial and angular parameters, respectively. When the size of the ring pump beam is matched with its mode, a specific LG carrying a vortex phase can be excited. pl The laser operates in a specific mode.

10. The dual-focal-ring pumped multi-orbital angular momentum vortex hollow laser of claim 1, wherein, ​

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