CN118249173B - A vortex fiber laser based on a full-space all-dielectric metasurface - Google Patents
A vortex fiber laser based on a full-space all-dielectric metasurface Download PDFInfo
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- CN118249173B CN118249173B CN202410256164.4A CN202410256164A CN118249173B CN 118249173 B CN118249173 B CN 118249173B CN 202410256164 A CN202410256164 A CN 202410256164A CN 118249173 B CN118249173 B CN 118249173B
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Abstract
本发明提供一种基于全空间全介电超构表面的涡旋光纤激光器，包括顺序设置的泵浦光源、波分复用器、准直器、法拉第旋光器和全空间全介电超构表面；所述泵浦光源用于发出激光，所述泵浦光源与波分复用器相连接，所述波分复用器与准直器通过光纤相连接，将激光传递到准直器，所述准直器将激光传递到法拉第旋光器，所述法拉第旋光器向全空间全介电超构表面输出45°偏振光束，所述超构表面输出涡旋光束；所述超构表面均匀设置有多个超构表面单元，每个所述超构表面单元包括两个纳米柱，所述超构表面单元的两个纳米柱的输出光的y偏振的相位差等于第一设定值，所述超构表面的超构表面单元的x偏振入射下的输出光的相位差累计值为第二设定值。
The present invention provides a vortex fiber laser based on a full-space all-dielectric metasurface, comprising a pump light source, a wavelength division multiplexer, a collimator, a Faraday rotator and a full-space all-dielectric metasurface which are arranged in sequence; the pump light source is used to emit laser light, the pump light source is connected to the wavelength division multiplexer, the wavelength division multiplexer is connected to the collimator through an optical fiber, the laser light is transmitted to the collimator, the collimator transmits the laser light to the Faraday rotator, the Faraday rotator outputs a 45° polarized light beam to the full-space all-dielectric metasurface, and the metasurface outputs a vortex light beam; the metasurface is uniformly provided with a plurality of metasurface units, each of the metasurface units comprises two nanocolumns, the y-polarized phase difference of the output light of the two nanocolumns of the metasurface unit is equal to a first set value, and the phase difference cumulative value of the output light of the metasurface unit of the metasurface under x-polarized incidence is a second set value.
Description
Technical Field
The invention relates to the technical field of optics, in particular to a vortex fiber laser based on an all-space all-dielectric super-structured surface.
Background
In recent years, vortex beams have attracted attention due to their orbital angular momentum (Orbital Angular Momentum, OAM). A significant feature of the vortex beam is that it has a helical phase that is related to azimuth and helicity. In the field of optical communication, the topology protection and state unbounded characteristics of the OAM optical beam add a new degree of freedom to the information encoding, which can significantly improve the capacity and spectral efficiency of the optical communication system, especially in the case of the constraint of limited spatial bandwidth of the optical channel. In the field of optical tweezers, the vortex beam is not easy to thermally damage captured particles even under the condition of focusing because the central light intensity is close to zero in theory, and is not easy to be influenced by the relative refractive index of the captured particles, so the vortex beam has great potential in the field of optical tweezers.
The method of generating the vortex beam is often divided into intra-cavity generation of the vortex beam and extra-cavity generation of the vortex beam. Spiral phase plates are one of the most prominent methods of generating a swirling beam outside the cavity. The spiral phase plate has a spiral internal structure, can convert an incident Gaussian beam into a vortex beam, and the topological charge number of the generated vortex beam is determined by the specific structure in the spiral phase plate. The spiral phase plate has the advantages of high precision, high efficiency and the like. Other methods of extracavity generation of the swirling beam include variable swirling plates, spatial light modulators, and the like. However, the vortex beam generated outside the cavity often has many limitations, such as low purity, poor conversion efficiency, etc. [1], so the generation of the active vortex beam also becomes one of the research hotspots. Intracavity generation of the vortex beam mainly includes solid state lasers and fiber lasers, etc.
However, since conventional super-structured surfaces only affect the reflective or transmissive regions, prior art lasers typically require the use of polarizing beam splitters to separate the gaussian and vortex beams, which takes up additional space and makes the overall laser cavity less compact.
Disclosure of Invention
In view of the foregoing, embodiments of the present invention provide a vortex fiber laser based on an all-spatial all-dielectric superstructural surface that obviates or mitigates one or more of the disadvantages of the prior art.
The invention provides a vortex fiber laser based on an all-space all-dielectric super-structure surface, which comprises a pumping light source, a wavelength division multiplexer, a collimator, a Faraday rotator and the all-space all-dielectric super-structure surface which are sequentially arranged;
The pumping light source is used for emitting laser, the pumping light source is connected with the wavelength division multiplexer, the wavelength division multiplexer is connected with the collimator through an optical fiber, the laser is transmitted to the collimator, the collimator transmits the laser to the Faraday rotator, the Faraday rotator converts 67.5-degree polarized light beams output by the collimator into 45-degree polarized light beams, and the super-structure surface outputs vortex light beams;
The super-structure surface is uniformly provided with a plurality of super-structure surface units, each super-structure surface unit comprises two nano columns, the phase difference of y polarization of output light of the two nano columns of the super-structure surface unit is a first set value, and the accumulated value of the phase difference of the output light of the super-structure surface unit under the incidence of x polarization of the super-structure surface unit is a second set value.
By adopting the scheme, the patent designs the laser based on the all-dielectric all-space super-structure surface, asymmetric transmission can be realized according to the polarization state of incident light, and as the accumulated phase difference value of the output light under the incidence of the x polarization of the super-structure surface unit of the super-structure surface is a second set value, one vortex light beam is transmitted under the incidence of the x polarization light beam (the polarization states x and y of the light beams are defined according to the structural direction of the super-structure surface unit), and as the phase difference of the y polarization of the output light of the two nano-columns of the super-structure surface unit is a first set value, induced reflection is generated when the cross polarization (y polarization) light beam is incident, the super-structure surface is converted into a reflective super-structure surface, a Gaussian light beam is reflected, the separation of the Gaussian light beam and the vortex light beam is completed, the vortex light beam can be directly emitted, and one end of the laser cavity (the reflected Gaussian light beam is coupled back into the cavity to generate oscillation) and the output end of the vortex light beam can be born simultaneously.
In some embodiments of the present invention, the top plane of the super-structure surface is a rectangle, the center of gravity of the rectangle is taken as an external line of one end of the ray, the rectangle is divided into a plurality of triangle areas, the angles of each triangle area at the center of gravity of the rectangle are the same, and the structural parameters of the super-structure surface units of each triangle area are the same.
In some embodiments of the present invention, the top plane of the super-structure surface unit is a rectangle formed by two squares with the same area, and in the top plane of the super-structure surface unit, the two nano-pillars are respectively in the range of the two squares, and the center of gravity point of the rectangle formed by the nano-pillars is the same point as the center of gravity point of the square.
In some embodiments of the invention, the first set point is pi, and the phase difference of y polarization of the output light of the two nanopillars of the super-structured surface element is pi.
In some embodiments of the present invention, the second set value is 2pi, and the cumulative value of the phase difference of the output light under the x polarization incidence of the super-surface unit of the super-surface is 2pi.
In some embodiments of the present invention, the top plane of the super-structured surface is rectangular, the center of gravity of the rectangle is taken as an external line of one end of the ray, the rectangle is divided into 8 triangular areas, and the phase difference of the output light under the x-polarized incidence of each triangular area is 0.25 pi.
In some embodiments of the invention, the vortex fiber laser based on the all-space all-dielectric super-structure surface further comprises a first lens and a second lens, wherein the first lens is arranged between the Faraday rotator and the all-space all-dielectric super-structure surface, and is used for converging the light beam on the super-structure surface, the second lens is arranged at the output end of the all-space all-dielectric super-structure surface and is used for collimating the light beam, and the second lens is arranged outside the laser cavity.
In some embodiments of the present invention, the all-space all-dielectric super-structured surface based vortex fiber laser further comprises a fiber mirror, the fiber mirror being coupled to the wavelength division multiplexer.
In some embodiments of the invention, the super-structured surface element further comprises a base plate, two of the nanopillars being connected to the base plate.
In some embodiments of the present invention, the base plate is made of silicon dioxide, and the nano-pillars are made of amorphous silicon.
In some embodiments of the invention, the height of the nanopillars is 500nm.
Additional advantages, objects, and features of the invention will be set forth in part in the description which follows and in part will become apparent to those having ordinary skill in the art upon examination of the following or may be learned from practice of the invention. The objectives and other advantages of the invention may be realized and attained by the structure particularly pointed out in the written description and drawings.
It will be appreciated by those skilled in the art that the objects and advantages that can be achieved with the present invention are not limited to the above-described specific ones, and that the above and other objects that can be achieved with the present invention will be more clearly understood from the following detailed description.
Drawings
The accompanying drawings, which are included to provide a further understanding of the application and are incorporated in and constitute a part of this specification, illustrate and together with the description serve to explain the application.
FIG. 1 is a schematic diagram of one embodiment of a vortex fiber laser based on an all-space all-dielectric superstructural surface in accordance with the present invention;
FIG. 2 is a schematic diagram of a connection structure of an experimental example in the present invention;
FIG. 3 is a simulation result of a super-structured surface element under x-polarized and y-polarized light incidence;
FIG. 4 is a simulation result of a super-structured surface at 45℃incidence of a linearly polarized Gaussian beam;
Fig. 5 is a schematic view of a super-structured surface unit and an arrangement mode thereof.
Detailed Description
The present invention will be described in further detail with reference to the following embodiments and the accompanying drawings, in order to make the objects, technical solutions and advantages of the present invention more apparent. The exemplary embodiments of the present invention and the descriptions thereof are used herein to explain the present invention, but are not intended to limit the invention.
It should be noted here that, in order to avoid obscuring the present invention due to unnecessary details, only structures and/or processing steps closely related to the solution according to the present invention are shown in the drawings, while other details not greatly related to the present invention are omitted.
As shown in fig. 1, the invention provides a vortex fiber laser based on an all-space all-dielectric super-structure surface, which comprises a pumping light source, a wavelength division multiplexer, a collimator, a faraday rotator and the all-space all-dielectric super-structure surface which are sequentially arranged;
The pumping light source is used for emitting laser, the pumping light source is connected with the wavelength division multiplexer, the wavelength division multiplexer is connected with the collimator through an optical fiber, the laser is transmitted to the collimator, the collimator emits the laser, the Faraday rotator is used for changing the polarization state of a light beam, 67.5-degree polarized light input by the collimator is converted into 45 degrees, y polarized light output by the super-structure surface is changed into 67.5-degree polarized light, and the y polarized light is coupled back to the collimator, and the super-structure surface outputs vortex light;
in the implementation process, polarization-maintaining single-mode fibers are adopted for connecting all components in the vortex fiber laser, so that the light beam in a fiber light path is ensured to be in a linear polarization LP 01 mode.
In the implementation process, 976nm pump light is injected into the resonant cavity through a 980/1030nm wavelength division multiplexer. Ytterbium-doped polarization maintaining fiber is used as a gain medium. The linearly polarized light beam output from the collimator has a polarization angle of 67.5 ° with respect to the x-axis (definition of the x-axis is shown in fig. 1) and is converted into linearly polarized light in the 45 ° direction after passing through the 22.5 ° faraday rotator.
The super-structure surface is uniformly provided with a plurality of super-structure surface units, each super-structure surface unit comprises two nano columns, the phase difference of y polarization of output light of the two nano columns of the super-structure surface unit is a first set value, and the accumulated value of the phase difference of the output light of the super-structure surface unit under the incidence of x polarization of the super-structure surface unit is a second set value.
By adopting the scheme, the patent designs the laser based on the all-dielectric all-space super-structure surface, the asymmetric transmission can be realized according to the polarization state of incident light, the phase difference cumulative value of the output light under the x polarization incidence of the super-structure surface unit of the super-structure surface is a second set value, so that one vortex light beam is transmitted under the incidence of the x polarization light beam (the polarization states x and y of the light beams are defined according to the structural direction of the super-structure surface unit), and the phase difference of the y polarization of the output light of the two nano-columns of the super-structure surface unit is a first set value, so that when the cross polarization (y polarization) light beam is incident, induced reflection is generated, the super-structure surface is converted into a reflective super-structure surface, a Gaussian light beam is reflected, the separation of the Gaussian light beam and the vortex light beam is completed, the vortex light beam can be directly emitted, and the scheme has the two functions of one end of the laser cavity (the reflected Gaussian light beam is coupled back into the cavity to generate oscillation) and the output end of the vortex light beam.
In some embodiments of the present invention, the top plane of the super-structure surface is a rectangle, the center of gravity of the rectangle is taken as an external line of one end of the ray, the rectangle is divided into a plurality of triangle areas, the angles of each triangle area at the center of gravity of the rectangle are the same, and the structural parameters of the super-structure surface units of each triangle area are the same.
In some embodiments of the present invention, the top plane of the super-structure surface unit is a rectangle formed by two squares with the same area, and in the top plane of the super-structure surface unit, the two nano-pillars are respectively in the range of the two squares, and the center of gravity point of the rectangle formed by the nano-pillars is the same point as the center of gravity point of the square.
In some embodiments of the invention, the first set point is pi, and the phase difference of y polarization of the output light of the two nanopillars of the super-structured surface element is pi.
In some embodiments of the present invention, the second set value is 2pi, and the cumulative value of the phase difference of the output light under the x polarization incidence of the super-surface unit of the super-surface is 2pi.
In some embodiments of the present invention, as shown in fig. 5 (d), the top plane of the super-structured surface is rectangular, and the center of gravity of the rectangle is taken as an external line of one end of the ray, so that the rectangle is divided into 8 triangular areas, and the phase difference of the output light under x-polarized incidence of each triangular area is 0.25 pi.
In some embodiments of the invention, the vortex fiber laser based on the all-space all-dielectric super-structure surface further comprises a first lens and a second lens, wherein the first lens is arranged between the Faraday rotator and the all-space all-dielectric super-structure surface, and is used for converging the light beam on the super-structure surface, the second lens is arranged at the output end of the all-space all-dielectric super-structure surface and is used for collimating the light beam, and the second lens is arranged outside the laser cavity.
The lenses 1 and 2 in fig. 1 and 2 correspond to a first lens and a second lens, respectively.
In some embodiments of the present invention, the all-space all-dielectric super-structured surface based vortex fiber laser further comprises a fiber mirror, the fiber mirror being coupled to the wavelength division multiplexer.
In the specific implementation process, an OAM light beam of an x polarization component is emitted from an output end, a Gaussian light beam of a y polarization component is reflected by an ultra-structured surface and converted into linear polarized light in a 67.5 DEG direction through a Faraday rotator, the linear polarized light is finally coupled back into a collimator, and the optical fiber reflector and the ultra-structured surface serve as two ends of a laser cavity to ensure that the Gaussian light beam can oscillate back and forth in the linear cavity. Therefore, the characteristics of the transverse intensity distribution and the polarization state of the light beam can form self-consistent transmission in the cavity, and the polarization-maintaining gain fiber and the related optical element ensure that the laser emission is near 1030nm and corresponds to the design wavelength of the super-constructed surface.
In some embodiments of the invention, the super-structured surface element further comprises a base plate, two of the nanopillars being connected to the base plate.
In some embodiments of the present invention, the base plate is made of silicon dioxide, and the nano-pillars are made of amorphous silicon.
In some embodiments of the invention, the height of the nanopillars is 500nm.
In the implementation process, the optical super-structured surface is an optical element composed of artificial atoms with sub-wavelengths, and has the advantages of extremely thin thickness, extremely low weight and the like compared with the traditional optical element. The super-structured surface can modulate the amplitude, phase, polarization and the like of an incident light beam on the basis of low loss.
In a specific implementation process, the principle of the super-structured surface designed by the scheme is based on abnormal diffraction of induced reflection. Assuming a periodic array of super-structure atoms with a phase gradient ζ, the state of the output light, i.e. k out＝kin +ζ, can be described generally by Generalized Snell's Law (GSL), where k out and k in are the lateral momentum of the outgoing light and incoming light, respectively, and ζ is the phase gradient between the super-structure units. But when the phase gradient is greater than the wave vector in free space, GSL will not be suitable for this super-constructed surface. This condition is called the critical angle condition, where the formula describing the emerging light field needs to be replaced by K out＝kin +ζ+ (n-1) G, which is the diffraction law of parity inversion. In this formula, n represents the diffraction order of the emergent light field, and G is the reciprocal lattice vector of the superlattice surface unit structure, which is generally equivalent in value to ζ.
If the number of times light propagates back and forth within a superconstituent unit is set to δ, δ may be expressed as δ=m+n, where m represents the number of nanopillars in one superconstituent unit. When the number of nano-pillars contained in the basic unit of the super-structured surface is 2, as shown in fig. 5 (c), as long as the critical condition is satisfied, direct transmission (δ=1) cannot occur, but reflection is induced (δ=2), and the reflected light occupies most of energy.
Experimental example
The experimental example is that a vortex fiber laser based on an all-space all-dielectric super-structured surface is connected with a CCD camera
Based on the characteristics, the basic unit of the super-structured surface of the scheme consists of two amorphous silicon nano-pillars on a SiO 2 substrate. As shown in fig. 5 (a) and (b), fig. 5 (a), (b) and (c) are schematic structural diagrams of the super-structured surface unit, and each nano-pillar has a length (L) and a width (W) that are adjustable, and the height is uniformly set to h=500 nm, and the period of a single nano-pillar is p=450 nm. Amorphous silicon has a high refractive index and a low absorptivity at the wavelength of use (1030 nm), and thus this super-structured surface is generally expressed as a transmissive super-structured surface. When the y polarized light is incident on the super-structured surface, the super-structured surface presents the characteristic of the reflective super-structured surface due to breaking the critical angle condition. Because of the birefringent nature of the amorphous silicon nanopillars, each basic unit of the super-structured surface can independently regulate the phases of reflection and transmission. Depending on the requirements of the vortex laser, the super-structured surface needs to exhibit specular reflection characteristics at y-polarized incidence, while being able to output a vortex beam at x-polarized incidence. The length and width of the silicon nano-pillars were scanned step by step at 1030nm using the finite difference time domain method (FDTD), and finally 8 groups of nano-pillars were selected, and specific geometrical parameters are shown in table 1, and specific structural parameters of the 8 groups of nano-pillars are recorded in table 1. The design of the phase relation satisfiesAndWherein the method comprises the steps ofRepresenting the phase of x-polarized incidence of one nanopillar in the same super-structured surface element,Representing the phase of another nanopillar x-polarized incident in the same super-structured surface element; Representing the phase of y-polarized incidence of one nanopillar in the same super-structured surface element, Representing the phase of y-polarized incident light of another nanopillar in the same super-structured surface element. The transmittance or reflectance and phase retardation of the selected nanopillars at x-or y-polarized incidence are shown in fig. 3 (a) and 3 (b), where fig. 3 (a) is a schematic diagram of the transmittance and transmittance phase of 8 super-constituent units at x-polarized incidence at 1030nm, and fig. 3 (b) is a schematic diagram of the reflectance and reflectance phase of 8 super-constituent units at y-polarized incidence at 1030 nm. For x-polarized incidence, the diffraction mechanism of the output light follows GSL. Phase shift of transmitted lightAlmost equal toAndA high transmittance of more than 0.85 is obtained. For y-polarized incidence, the critical angle condition is satisfiedMost of the light field is reflected. Meanwhile, for the 8 groups of nano units, when y polarization is incident, the reflection phases are guaranteed to be nearly consistent on the premise of meeting the critical angle condition. When incident with x polarization, ensureOn the premise that the transmission phase between each group differs by pi/4.
TABLE 1
| Unit numbering | Length of nano-pillar L 1 (nm) | Nanometer column W 1 width (nm) | Length of nano-pillar L 2 (nm) | Nanometer column W 2 width (nm) |
| 1 | 170 | 215 | 150 | 350 |
| 2 | 200 | 200 | 170 | 320 |
| 3 | 220 | 195 | 185 | 315 |
| 4 | 235 | 190 | 200 | 290 |
| 5 | 260 | 185 | 225 | 270 |
| 6 | 310 | 175 | 250 | 265 |
| 7 | 350 | 170 | 290 | 250 |
| 8 | 130 | 230 | 145 | 355 |
According to the arrangement of fig. 5 (d), fig. 5 (d) is a schematic diagram of the distribution of the super-structure surface units on the super-structure surface, and the 8 groups of nano units are arranged, so that the phases and amplitudes of the reflected light are almost the same fixed value under the condition that the y polarized light is incident on the super-structure surface, the reflected light is ensured to be as close to the gaussian light beam as possible, and the phases of the transmitted light are sequentially increased by pi/4 under the condition that the x polarized light is incident, so that the change of the phases of the light is accumulated to 2 pi, and the OAM light with the topological charge number of 1 is output.
The invention simulates far field distribution of the transmission and reflection of the super-structured surface under 45-degree linear polarized light incidence. Fig. 4 shows the output of the super-structured surface, fig. 4 (a) is a reflected light beam intensity distribution diagram, fig. 4 (b) is a vortex light intensity distribution diagram with a transmission topological charge number of 1, fig. 4 (c) is a reflected light beam phase distribution diagram, fig. 4 (d) is a vortex light beam phase distribution diagram with a topological charge number of 1, the central intensity of the transmitted light field is close to 0, and the phase distribution is basically consistent with an OAM light beam with the topological charge number of 1. At the same time, the reflected light field is almost a perfect gaussian beam. The transmissivity is close to the reflectivity, is 45.3 percent and 41.2 percent respectively, and meets the design target.
The vortex fiber laser with compact structure is realized by embedding the full-space super-structured surface into the laser cavity. The laser consists of a plurality of key components, including 976nm laser pumping light source, polarization-maintaining ytterbium-doped fiber, super-structured surface, 22.5 DEG Faraday rotator and other standard optical elements. Through ingenious light path design, the abnormal diffraction phenomenon of the inner super-structured surface of the fiber laser is utilized for the first time, and a novel method is provided for directly emitting vortex light beams through the fiber laser. The advantages of high gain, mode filtering mechanism and super-structured surface of the fiber laser cavity, and high freedom degree, provide possibility for the laser cavity to directly output vortex beams with high purity and high power. Meanwhile, due to the characteristic of high degree of freedom of the super-structured surface, the design concept of the proposed fiber laser has commonality, for example, a similar laser cavity can be used for outputting vortex beams with other topological charges or other scalar structural beams which can be obtained through phase regulation, only the structural arrangement of the 8 groups of nano-pillars needs to be changed, and meanwhile, the similar design method can be applied to the use wavelength of the ytterbium-doped fiber laser, and can also be applied to fiber lasers with other working wavelengths, such as erbium-doped fiber lasers and the like.
By adopting the scheme, the vortex fiber laser based on the all-dielectric all-space super-structured surface is provided, and vortex light beams are directly output in a compact and simple laser cavity by utilizing the all-space super-structured surface. The super-structured surface is reasonably designed, and the degree of freedom of the super-structured surface for manipulating the light beam is introduced into the whole space from one side by utilizing abnormal diffraction, so that the super-structured surface has the functions of reflecting the Gaussian light beam and transmitting the vortex light beam according to the polarization state of the incident light. The scheme provides a novel method for directly emitting vortex beams by the fiber laser, expands the design of the vortex laser, and can become an ideal light source in the fields of optical communication, optical tweezers, special processing and the like.
Those of ordinary skill in the art will appreciate that the various illustrative components, systems, and methods described in connection with the embodiments disclosed herein can be implemented as hardware, software, or a combination of both. The particular implementation is hardware or software dependent on the specific application of the solution and the design constraints. Skilled artisans may implement the described functionality in varying ways for each particular application, but such implementation decisions should not be interpreted as causing a departure from the scope of the present invention. When implemented in hardware, it may be, for example, an electronic circuit, an Application Specific Integrated Circuit (ASIC), suitable firmware, a plug-in, a function card, or the like. When implemented in software, the elements of the invention are the programs or code segments used to perform the required tasks. The program or code segments may be stored in a machine readable medium or transmitted over transmission media or communication links by a data signal carried in a carrier wave.
It should be understood that the invention is not limited to the particular arrangements and instrumentality described above and shown in the drawings. For the sake of brevity, a detailed description of known methods is omitted here. In the above embodiments, several specific steps are described and shown as examples. The method processes of the present invention are not limited to the specific steps described and shown, but various changes, modifications and additions, or the order between steps may be made by those skilled in the art after appreciating the spirit of the present invention.
In this disclosure, features that are described and/or illustrated with respect to one embodiment may be used in the same way or in a similar way in one or more other embodiments and/or in combination with or instead of the features of the other embodiments.
The above description is only of the preferred embodiments of the present invention and is not intended to limit the present invention, and various modifications and variations can be made to the embodiments of the present invention by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.
Claims (8)
1. The vortex fiber laser based on the all-space all-dielectric super-structured surface is characterized by comprising a pumping light source, a wavelength division multiplexer, a collimator, a Faraday rotator and the all-space all-dielectric super-structured surface which are sequentially arranged;
The pumping light source is used for emitting laser, the pumping light source is connected with the wavelength division multiplexer, the wavelength division multiplexer is connected with the collimator through an optical fiber, the laser is transmitted to the collimator, the collimator transmits the laser to the Faraday rotator, the Faraday rotator outputs 45-degree polarized light beams to the full-space full-dielectric super-structured surface, and the super-structured surface outputs vortex light beams;
The plane of the super-structure surface is rectangular, the center of gravity of the rectangle is taken as an external connecting line of one end line of the ray, the rectangle is divided into a plurality of triangular areas, angles of the triangular areas at the center of gravity of the rectangle are the same, structural parameters of super-structure surface units of the triangular areas are the same, the super-structure surface is uniformly provided with a plurality of super-structure surface units, each super-structure surface unit comprises two nano columns, the phase difference of output light of the two nano columns of the super-structure surface unit under y polarization incidence is equal to a first set value, the phase difference cumulative value of the output light of the super-structure surface unit under x polarization incidence of the super-structure surface is a second set value, the plane of the super-structure surface unit is a rectangle formed by two squares with the same area, the two nano columns are respectively positioned in the range of the two squares in the plane of the super-structure surface unit, and the center of gravity of the square center of gravity of the rectangular formed by the nano columns is the same point as the center of gravity of the square.
2. The vortex fiber laser based on the all-space all-dielectric super-structured surface according to claim 1, wherein the first set value is pi, and the phase difference of y polarization of the output light of the two nano-pillars of the super-structured surface unit is equal to pi.
3. The vortex fiber laser based on the all-space all-dielectric super-structured surface according to claim 1, wherein the second set value is 2 pi, and the phase difference cumulative value of the output light under the x polarization incidence of the super-structured surface unit of the super-structured surface is 2 pi.
4. The vortex fiber laser based on the full-space full-dielectric super-structured surface according to claim 2, wherein the top plane of the super-structured surface is rectangular, the rectangular is divided into 8 triangular areas by taking the center of gravity of the rectangular as an external connecting line of one end line of a ray, and the phase difference of output light under x-polarization incidence of each triangular area is 0.25 pi.
5. The all-space all-dielectric-super-surface-based vortex fiber laser of claim 1, further comprising a first lens disposed between the faraday rotator and the all-space all-dielectric super-surface to demagnify the light beam and focus the light beam on the super-surface, and a second lens disposed at an output end of the all-space all-dielectric super-surface to collimate the light beam, the second lens being disposed outside the laser cavity.
6. The all-space all-dielectric-super-surface-based vortex fiber laser of claim 1, further comprising a fiber mirror coupled to the wavelength division multiplexer.
7. The vortex fiber laser based on an all-space all-dielectric super-structured surface according to claim 1, wherein said super-structured surface unit further comprises a base plate, two of said nano-pillars being connected to the base plate.
8. The vortex fiber laser based on the all-space all-dielectric super-structured surface according to claim 7, wherein the substrate plate is made of silicon dioxide material, and the nano-pillars are made of amorphous silicon material.
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| WO2012167447A1 (en) * | 2011-06-09 | 2012-12-13 | 天津奇谱光电技术有限公司 | External cavity tunable laser with 25ghz frequency interval |
| CN117080850A (en) * | 2023-08-15 | 2023-11-17 | 北京邮电大学 | Wavelength-tunable vortex fiber laser |
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| CN113725711B (en) * | 2021-08-25 | 2022-11-08 | 江苏科技大学 | Optical vortex optical fiber laser based on double vortex wave plates |
| CN114172009B (en) * | 2021-11-11 | 2023-07-18 | 北京邮电大学 | Vortex fiber laser and interference system based on plasmonic metasurface |
| CN116131084A (en) * | 2023-01-09 | 2023-05-16 | 中国科学院上海技术物理研究所 | High-repetition-frequency full polarization-maintaining fiber laser based on nonlinear amplification annular mirror |
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| WO2012167447A1 (en) * | 2011-06-09 | 2012-12-13 | 天津奇谱光电技术有限公司 | External cavity tunable laser with 25ghz frequency interval |
| CN117080850A (en) * | 2023-08-15 | 2023-11-17 | 北京邮电大学 | Wavelength-tunable vortex fiber laser |
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