CN218824795U - Coupling device - Google Patents
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- CN218824795U CN218824795U CN202223083952.3U CN202223083952U CN218824795U CN 218824795 U CN218824795 U CN 218824795U CN 202223083952 U CN202223083952 U CN 202223083952U CN 218824795 U CN218824795 U CN 218824795U
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Abstract
The present disclosure provides a coupling device for coupling two optical waveguides; the optical path between the two optical waveguides sequentially comprises a first super lens, a reflecting surface and a second super lens; the first super lens and the second super lens are arranged in parallel and each comprise a substrate and a nano structure on the surface of the substrate; based on the phase distribution of the nanostructure, the first superlens is configured to receive incident light from the first optical waveguide and modulate the incident light into collimated light with a deflection angle; the reflecting surface is used for receiving and reflecting the collimated light, so that the collimated light is incident to the second super lens; the second superlens is configured to converge the collimated light from the reflection surface to the second optical waveguide to achieve coupling of the first optical waveguide and the second optical waveguide. The technical scheme has the advantages that the light path is folded through the reflecting surface, the whole volume of the coupling device is effectively reduced, the super lens is utilized, the coupling can be carried out based on the telecentric light path principle, and the coupling can also be carried out through the oblique incident light path under a specific angle.
Description
Technical Field
The present disclosure relates to the field of optical devices, and in particular, to a coupling device.
Background
In the prior art, there are many techniques for realizing coupling between optical waveguides (such as optical fibers), and one of them is to collimate and focus light emitted from the optical fibers by using a self-focusing lens (Grin-lens or Grin lens). The above-described technique using a GRIN lens generally employs a combination of GRIN lenses to solve the problem of aberration of a single GRIN lens. A combined GRIN lens, such as a dual GRIN lens, can focus a beam to a smaller spot and reduce aberrations.
It can be seen that in the prior art described above, a single GRIN lens has aberration problems; although the double GRIN lens can reduce aberration, the number of coupling devices is increased, the size is increased, and the alignment, miniaturization and integration of optical fibers (the diameter of a single-mode optical fiber is generally 125 um) are more difficult to realize; in addition, GRIN lens thickness dimensions are on the order of millimeters (mm), which is large relative to the fiber.
SUMMERY OF THE UTILITY MODEL
In order to solve the defects that coupling is difficult due to aberration in the prior art, and the problems that a coupling device is complex, large in size and low in integration level, the embodiment of the disclosure provides a coupling device based on a super surface.
The coupling device is used for coupling the first optical waveguide and the second optical waveguide; along the light path from the first light waveguide to the second light waveguide, the coupling device sequentially comprises a first super lens, a reflecting surface and a second super lens;
wherein the first superlens and the second superlens are arranged in parallel in normal, and each comprise a substrate and a nanostructure of the surface of the substrate;
based on the phase distribution of the nanostructure, the first superlens is configured to receive incident light from the first optical waveguide and modulate the incident light into collimated light with a deflection angle;
the reflecting surface is used for receiving and reflecting the collimated light, so that the collimated light is incident to the second super lens;
based on the phase distribution of the nanostructure, the second superlens is configured to converge the collimated light from the reflection surface to the second optical waveguide to achieve coupling of the first optical waveguide and the second optical waveguide.
According to the technical scheme, the light path is folded through the reflecting surface, the whole volume of the coupling device is effectively reduced, the integration level is improved, and the input optical fiber and the output optical fiber are both positioned on the same side of the device. In addition, the super lens is utilized, the size of the super lens can reach the micron (mum) magnitude, the super lens is obviously superior to the mm magnitude of a GRIN lens, the optical waveguide is easier to align, and meanwhile, the super lens has the advantages of lightness, thinness, simplicity, cheapness and better robustness.
Optionally, the coupling device has an exit surface and a coupling surface, wherein,
the emergent light spots of the first optical waveguide and the second optical waveguide are both positioned in the emergent plane, and the optical axes of the emergent light spots of the first optical waveguide and the second optical waveguide are parallel;
the first super lens and the second super lens are arranged in the coupling surface;
the emergent surface, the coupling surface and the reflecting surface are arranged in parallel;
the scheme aims to set the optical waveguide (two optical fibers), the two superlenses and the reflecting surface in three parallel surfaces, so that the system is clear and stable in structure and is more beneficial to integration.
The phase distribution of the first superlens and the second superlens satisfies:
in the formula, x and y are surface coordinates of the first superlens or the second superlens, λ is the wavelength of incident light, and f is the focal length of the first superlens or the second superlens.
Optionally, the mode field of the first optical waveguide is coaxial with the first superlens, and the mode field of the second optical waveguide is coaxial with the second superlens;
the value range of y in the phase distribution of the first superlens is as follows:
y 0 -d 2 /2≤y≤y 0 +d 2 /2
the value range of y in the phase distribution of the second superlens is as follows:
-y 0 -d 2 /2≤y≤-y 0 +d 2 /2
wherein, y 0 ＝d 3 /2，d 2 Spot diameter, d, of the first optical waveguide projected onto the first superlens 3 Is the center distance of the first optical waveguide and the second optical waveguide.
Further, the deflection angle θ of collimated light 2 Satisfies the following conditions:
furthermore, the distance between the emergent surface and the coupling surface is L 1 The distance between the coupling surface and the reflecting surface (03) is L 2 Wherein, in the step (A),
L 1 ＝L 2 ＝f
f is the focal length of the first superlens or the second superlens.
The above-mentioned scheme makes the embodiment have the characteristic of a telecentric light path, that is, the coupling between the optical fibers can be carried out based on the principle of the telecentric light path.
Furthermore, to achieve coupling of oblique incident light paths at a particular angle, embodiments further include the following alternatives:
the mode field axis of the first optical waveguide and the center of the first superlens, and the mode field axis of the second optical waveguide and the center of the second superlens have an offset delta y in the y direction;
wherein the distance L between the emergent surface and the coupling surface 1 Equal to the focal length f of the first superlens or the second superlens;
distance between coupling surface and reflecting surfaceL 2 Satisfies the following conditions:
wherein d is 3 Is the center distance of the first optical waveguide and the second optical waveguide, theta 2 Is the deflection angle of the collimated light.
Optionally, focal lengths f and d 2 The following relationship is satisfied:
wherein, theta 1 A divergence angle of incident light provided for the first optical waveguide;
and theta 1 And the mode field diameter d of the first optical waveguide 1 The following relationship is satisfied:
in each of the above technical solutions and their alternatives and preferences, the nanostructures are cylinders, have a diameter of 180nm to 500nm, and are periodically arranged on the surface of the substrate in a hexagonal form. The nanostructures of the first superlens and the nanostructures of the second superlens are located in different regions of the same substrate.
Optionally, the coupling surface and the reflecting surface are located on two opposite surfaces of the substrate, respectively, wherein,
the substrate is transparent to the working waveband, and the reflecting surface is a reflecting layer formed on the surface of the substrate.
In the technical scheme of the disclosure, the optical path modulation for coupling is performed through the superlens, the superlens is small in size and is a planar device, the aberration of a focal point light spot is small, perfect focusing can be realized, the optical coupling is better than that of a GRIN lens, the robustness and the integration are better, and the cost is lower. And the coupling can be carried out based on the principle of a telecentric light path, and can also be carried out through an oblique incident light path under a specific angle.
Drawings
The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated into and constitute a part of this specification. The drawings illustrate embodiments of the present disclosure and, together with the description, serve to explain the principles of the technical solutions in the present disclosure.
FIG. 1 shows a schematic diagram of the structure and optical path of an embodiment of a telecentric optical path in the present disclosure;
FIG. 2 shows a schematic structural and optical path diagram of an embodiment of an oblique incidence optical path in the present disclosure;
FIG. 3 is a graph of the transmittance and phase of nanostructures versus the diameter of a cylinder in an embodiment of a cylindrical nanostructure of the present disclosure;
fig. 4, 5 and 6 are graphs showing the results of software simulation of the coupling effect in the embodiment, in which:
FIG. 4 is a light field distribution diagram for the yx plane;
FIG. 5 is a light field distribution diagram for the yz plane;
FIG. 6 shows spot size at the focal plane;
FIG. 7 is a schematic representation of an arrangement of nanostructures on a super surface in an embodiment of the disclosure;
FIG. 8 is an exemplary illustration of one form of nanostructures in an embodiment of the disclosure;
in the drawings, reference numerals denote:
01 an exit surface; 02 a coupling surface; 03 a reflecting surface;
11 a first optical waveguide; 12 a second optical waveguide;
21 a first superlens; 22 a second superlens;
201 a substrate; 202 nanostructure.
It will be appreciated that the boundaries of the optical paths are indicated in figures 1 and 2 by thin solid lines and the central axis of the optical waveguide/superlens/coupling arrangement as a whole is indicated by dashed lines.
Detailed Description
The present disclosure now will be described more fully hereinafter with reference to the accompanying drawings, in which embodiments are shown. This disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Like reference numerals refer to like parts throughout. Also, in the drawings, the thickness, ratio and size of the components are exaggerated for clarity of explanation.
The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used herein, "a," "an," "the," and "at least one" do not denote a limitation of quantity, but rather are intended to include both the singular and the plural, unless the context clearly dictates otherwise. For example, "a component" means the same as "at least one component" unless the context clearly dictates otherwise. "at least one of" should not be construed as limited to the quantity "one". "or" means "and/or". The term "and/or" includes any and all combinations of one or more of the associated listed items.
Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art. Terms defined in commonly used dictionaries should be interpreted as having the same meaning as in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
The meaning of "comprising" or "comprises" indicates a property, a quantity, a step, an operation, a component, a part, or a combination thereof, but does not exclude other properties, quantities, steps, operations, components, parts, or combinations thereof.
Embodiments are described herein with reference to cross-sectional views that are idealized embodiments. Variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and/or tolerances, are to be expected. Thus, embodiments described herein should not be construed as limited to the particular shapes of regions as illustrated herein but are to include deviations in shapes that result, for example, from manufacturing. For example, regions shown or described as flat may typically have rough and/or nonlinear features. Also, the acute angles shown may be rounded. Thus, the regions illustrated in the figures are schematic in nature and their shapes are not intended to illustrate the precise shape of a region and are not intended to limit the scope of the claims.
Hereinafter, exemplary embodiments according to the present disclosure will be described with reference to the accompanying drawings.
In order to solve the problems and disadvantages of the prior art, embodiments of the present disclosure provide a coupling device for coupling a first optical waveguide and a second optical waveguide, and it should be understood that the first optical waveguide and/or the second optical waveguide may be a single-mode optical fiber, an on-chip waveguide, or other devices used in the prior art, which are not listed hereinafter.
As shown in fig. 1 or 2, such a coupling device comprises the following basic configuration:
along the optical path between the first optical waveguide 11 to the second optical waveguide 12, such coupling means comprise, in order, a first superlens 21, a reflecting surface 03 and a second superlens 22;
wherein the first and second superlenses 21 and 22 are arranged in a normal parallel manner and each include a substrate 201 and a nanostructure 202 of a substrate surface;
it should be understood by those skilled in the art that although the drawings show that the incident light is turned by 180 ° and output to the second optical waveguide 12 by the reflecting surface 03, the disclosure is not limited thereto, and the reflecting surface 03, the first superlens 21 and the second superlens 22 may be flexibly arranged to form a desired optical path form according to actual requirements, such as that the first optical waveguide 11 and the second optical waveguide 12 are horizontally opposite, obliquely opposite, at an angle of 90 ° or at any other angle, and the like, which are not listed herein.
The reflecting surface 03 may be a mirror surface or a device capable of reflecting at least a part of incident light, and may include a reflective coating/plating or the like. The reflecting surface 03 is configured to receive and reflect the collimated light, so that the collimated light is incident on the second superlens 22.
The first superlens 21 and the second superlens 22 mentioned above in the embodiments belong to the super-surface optical device, and for the sake of understanding, the following explanatory explanation is made for the super-surface.
The super surface is a layer of sub-wavelength artificial nano-structured film, the typical implementation of which is as two super lenses involved in the disclosed embodiments, the amplitude, phase and polarization of incident light can be modulated by the nano-structured units disposed thereon, wherein it should be noted that the nano-structure can be understood as a sub-wavelength structure containing all medium or plasmon and capable of causing phase jump, and the nano-structured unit is a structural unit obtained by dividing the super lens and taking each nano-structure as the center. The nanostructures are periodically arranged on the substrate in the superlens, wherein the nanostructures in each period form a superstructure unit, wherein the superstructure unit is in a close-packed pattern, such as a regular quadrangle, a regular hexagon and the like, each period comprises a group of nanostructures, and the vertexes and/or centers of the superstructure unit can be provided with the nanostructures, for example. In the case where the superstructure unit is a regular hexagon, at least one nanostructure is provided at each vertex and center position of the regular hexagon. Alternatively, in the case where it is a square, each vertex and central position of the square is provided with at least one nanostructure. Ideally, the superstructure unit should be a hexagon vertex and center arranged nanostructure, or a square vertex and center arranged nanostructure, and it should be understood that the practical product may have a nanostructure loss at the edge of the superlens due to the limitation of the superlens shape, so that it does not satisfy the complete hexagon/square. Specifically, as shown in fig. 7, the superstructure units are formed by regularly arranging nanostructures, and a plurality of superstructure units are arranged in an array to form a super surface structure.
As shown in fig. 7 (a), the superstructure unit comprises a central nanostructure 202 and 6 peripheral nanostructures surrounding the central nanostructure at equal distances, and the peripheral nanostructures are uniformly distributed along the periphery to form a regular hexagon, which can also be understood as a combination of regular triangles formed by a plurality of nanostructures.
As one example, shown in part (b) of fig. 7, a superstructure unit comprises one central nanostructure 202 and 4 peripheral nanostructures surrounding it at equal distances, forming a square.
The superstructure unit and its close-packed/array may also be in the form of a circumferentially arranged sector, as shown in part (c) of fig. 7, comprising two arcuate sides, or a sector of one arcuate side, as shown in the lower left corner region of part (c) of fig. 7, with nanostructures 202 disposed at the intersection and center of the sides of the sector.
For the sake of brevity and clarity, only the nanostructures 202 disposed at the centers of the superstructure units are depicted in the drawings, it being understood that the nanostructures should also be disposed at the vertices/intersections of the hexagonal, square, or fan-shaped outlines in fig. 7.
Based on the principle of the above-described super-surface, the first super-lens 21 is configured to be able to receive incident light from the first optical waveguide 11 and modulate the incident light into collimated light having a deflection angle, based on the phase distribution of its own nanostructure; the second superlens 22 is configured to condense the collimated light from the reflection surface 03 to the second optical waveguide 12 to realize coupling of the first optical waveguide 11 and the second optical waveguide 12.
To achieve the above configuration, illustratively, the phase distributions of the first and second superlenses 21 and 22 each satisfy:
in the formula, x and y are surface coordinates of the first superlens or the second superlens, λ is the wavelength of the incident light, and f is the focal length of the first superlens or the second superlens.
The basic configuration in the disclosure, the light path is folded through the reflecting surface, the overall volume of the coupling device is effectively reduced, the integration level is improved, and the input and output optical fibers are both positioned at the same side of the device. In addition, the size of the super lens can reach the mum order, the super lens is obviously superior to the mm order of a GRIN lens, the optical waveguide is easier to align, and meanwhile, the super lens is light, thin, simple, cheap and better in robustness.
In a preferred embodiment, the coupling means also have an exit face 01 and a coupling face 02, wherein,
the emergent light spots of the first optical waveguide 11 and the second optical waveguide 12 are both positioned in the emergent surface 01, and the optical axes of the emergent light spots of the first optical waveguide 11 and the second optical waveguide 12 are parallel;
the first superlens 21 and the second superlens 22 are both arranged in the coupling surface 02;
the emission surface 01, the coupling surface 02, and the reflection surface 03 are arranged in parallel.
The preferred embodiment aims at arranging the light waveguide (two optical fibers), the two superlenses and the reflecting surface in three parallel planes in a set mode, so that the system structure is clear and stable, and integration is facilitated.
On the basis of the basic configuration described above or its preferred embodiments, an example based on a telecentric optical path is provided as follows.
As shown in fig. 1, the mode field of the first optical waveguide 11 is coaxial with the first superlens 21, and the mode field of the second optical waveguide 12 is coaxial with the second superlens 22;
the phase distributions of the first and second superlenses 21 and 22 in the present embodiment still satisfy:
however, the y value has the following value requirements:
the value range of y in the phase distribution of the first superlens is as follows:
y 0 -d 2 /2≤y≤y 0 +d 2 /2
the value range of y in the phase distribution of the second superlens is as follows:
-y 0 -d 2 /2≤y≤-y 0 +d 2 /2
wherein, y 0 ＝d 3 /2，d 2 The spot diameter projected to the first superlens for the first optical waveguide (in the embodiment, the first optical waveguide 11 emits a gaussian spot according to whichCan be obtained at L according to the divergence angle and the transmission distance 1 Spot size), d 3 Is the center distance of the first optical waveguide and the second optical waveguide.
Deflection angle theta of collimated light 2 Satisfies the following conditions:
the means for forming the telecentric optical path in the scheme is also embodied as follows: the distance between the emergent surface 01 and the coupling surface 02 is set to be L 1 The distance between the coupling surface 02 and the reflecting surface 03 is set to L 2 Wherein, in the process,
L 1 ＝L 2 ＝f
f is the focal length of the first superlens or the second superlens.
In this embodiment, the light emitted by the first optical waveguide 11 has d 1 Spot size (spot size is defined herein as the drop in intensity to peak 1/e) 2 Spot size of 10.5 μm for single mode fiber, also referred to as the mode field diameter of the fiber), and θ 1 Divergence angle of magnitude, propagation distance in free space L 1 After the length, the beam is modulated to a spot size d by the first superlens 21 2 And has a deflection angle of theta 2 The collimated light of (a). Propagation in free space L 2 After the distance, the light is reflected by the reflecting surface 03, and then is converged into the first optical waveguide 12 through the second superlens 22, so that a better coupling effect is achieved when the size of a converged light spot is matched with the diameter of the optical fiber mode field.
On the basis of the above-described basic configuration or its preferred embodiment, an example of coupling an obliquely incident light waveguide is provided as follows.
As shown in fig. 2, the mode field axis of the first optical waveguide 11 and the center of the first superlens 21, and the mode field axis of the second optical waveguide 12 and the center of the second superlens 22 have an offset Δ y in the y direction; specifically, as shown in FIG. 2, Δ y is expressed in terms of a difference θ 2 At angular incidence, the center of the focused spot is offset by a distance beyond the center of the lens. I.e. the distance between the upper dark and light dashed lines in fig. 2; root of herbaceous plantsAccording to the principle of reversible light path, the distance between the lower dark and light dotted lines is also delta y.
Wherein the distance L between the emergent surface 01 and the coupling surface 02 1 Equal to the focal length f of the first superlens 21 or the second superlens 22;
distance L between coupling surface 02 and reflecting surface 03 2 Satisfies the following conditions:
wherein d is 3 Is the center distance, θ, of the first optical waveguide 11 and the second optical waveguide 12 2 Is the deflection angle of the collimated light.
The phase distributions of the first and second superlenses 21 and 22 in the present embodiment still satisfy:
however, it should be noted that, referring to FIG. 2, the two superlenses are denoted by d 3 The position shown by the two dotted lines marked by-2 Δ y is taken as the coordinate position when y = 0.
In this embodiment, the light emitted by the first optical waveguide 11 has d 1 Spot size (spot size is defined herein as the drop in intensity to peak 1/e) 2 Spot size of 10.5 μm for single mode fiber, also referred to as the mode field diameter of the fiber), and θ 1 Divergence angle of magnitude, propagation distance in free space L 1 After the length, the beam is modulated into a spot size d by the first superlens 21 2 And has a deflection angle of theta 2 The collimated light of (2). Propagation in free space L 2 After the distance, the light is reflected by the reflecting surface 03, and then is converged into the first optical waveguide 12 through the second superlens 22, so that a good coupling effect is achieved when the size of the converged light spot is matched with the diameter of the optical fiber mode field.
The method for focusing the light path in the embodiment is embodied in that: l is 1 = f, f is the focal length of the superlens, i.e. the distance L between the exit face 01 and the coupling face 02 1 And the first superlens 21Or the focal length f of the second superlens 22 is equal. L is 2 And angle theta 2 Correlation, θ 2 And may vary according to actual needs.
It is emphasized that the difference with the "telecentric beam path" embodiment is that the "telecentric beam path" embodiment is a telecentric beam path, so L 2 = f, at this time θ 2 Angle is composed of L 2 Determine, in this example, theta 2 Angle adjustable, theta 2 Angle determination L 2 。
In addition, the embodiment or the optimization thereof further has the following parameter relationship:
wherein, theta 1 A divergence angle of incident light provided for the first optical waveguide 11;
and theta 1 And the mode field diameter d of the first optical waveguide 11 1 The following relationship is satisfied:
further, an embodiment of coupling an obliquely incident light waveguide is provided as follows.
Based on the optical path structure as shown in fig. 2, in this example:
the spot size d emitted by the first optical waveguide 11 1 =10.5 μm, wavelength 1.33 μm, d 2 Set at 100 μm according to:
and
the focal length f of the superlens to be designed can be obtained.
Theta according to demand 2 From simulation, can be obtained at θ 2 At angular incidence, the spot deviates by a distance Δ y, which is defined by
The distance L of the reflecting surface relative to the super lens can be obtained 2 。
For light with the wavelength of 1.33 mu m, the super lens with the cylindrical nano structure 202 is designed in the embodiment, the nano structure has a hexagonal period, the period is 850nm, the height is 1100nm, and the diameter of the cylinder is from 180nm to 500nm. The cylindrical material is amorphous silicon, and the substrate is silicon dioxide. The transmittance and phase of the nanostructures is plotted against the diameter of the cylinder as shown in figure 3.
According to the above, the overall transmittance of the nanostructure is 90% or more, and the phase distribution is 2 π.
Obtaining the phase distribution of the superlens according to the designed focal length f
In FDTD software to theta 2 The simulation is carried out on the condition that light with an angle of =5 ° enters the super lens, and the deviation distance Δ y is obtained, as shown in fig. 4 and 5.
The offset distance is about 30 μm as can be derived from the above simulation.
The spot size at the focal plane is shown in FIG. 6, the intensity drops to 1/e of peak value 2 The spot diameter is about 10 μm.
The transmittance of the superlens is 94%, and the transmittance can be further improved by optimizing the nano structure.
Setting d 3 =200 μm, i.e. L is obtained 2 Length of (d).
According to the requirement, corresponding superlens phase distribution is designed, and after the distances among the reflecting surface, the superlens and the optical fiber light-emitting end face are selected, the optical coupling from the first optical waveguide 11 to the second optical waveguide 12 can be obtained. And L is 1 +L 2 + d is about 2mm (d denotesThe thickness of the superlens) so that the entire system is compact. Meanwhile, the aberration of the light spot of the focusing point of the super lens is smaller, and the optical fiber coupling is facilitated.
In order to improve the coupling efficiency, the structure can be optimized to improve the transmittance and the focusing efficiency, or an antireflection film is plated on the substrate.
Further, the reflecting surface can be integrated on the super lens substrate by the distance L 2 Is reduced to L 2 And/n, n represents the refractive index of the substrate.
It should be noted that the superlens provided by the embodiments of the present disclosure can be processed by a semiconductor process, and has the advantages of light weight, thin thickness, simple structure and process, low cost, high consistency of mass production, and the like, and has the expansibility of wafer level packaging.
In summary, the coupling device provided in the embodiment of the present disclosure performs optical path modulation for coupling through the superlens, the superlens has a small size and is a planar device, the focal point spot aberration is smaller, perfect focusing can be achieved, the coupling device is better than the GRIN lens in optical coupling, and has better robustness and integration, and at the same time, the cost is lower. And the coupling can be carried out based on the principle of a telecentric light path, and can also be carried out through an oblique incident light path under a specific angle.
The above description is only a specific implementation of the embodiments of the present disclosure, but the scope of the embodiments of the present disclosure is not limited thereto, and any person skilled in the art can easily conceive of changes or substitutions within the technical scope of the embodiments of the present disclosure, and all the changes or substitutions should be covered by the scope of the embodiments of the present disclosure. Therefore, the protection scope of the embodiments of the present disclosure shall be subject to the protection scope of the claims.
Claims (10)
1. A coupling device, characterized by being arranged for coupling a first optical waveguide (11) and a second optical waveguide (12); along the optical path between the first optical waveguide (11) and the second optical waveguide (12), the coupling device sequentially comprises a first super lens (21), a reflecting surface (03) and a second super lens (22);
wherein the first and second superlenses (21, 22) are arranged normal-parallel and each comprise a substrate (201) and a nanostructure (202) of a substrate surface;
based on the phase distribution of the nanostructure, the first superlens (21) is configured to be capable of receiving incident light from the first optical waveguide (11), and modulating the incident light into collimated light having a deflection angle;
the reflecting surface (03) is used for receiving and reflecting the collimated light, so that the collimated light is incident to the second super lens (22);
based on the phase distribution of the nanostructure, the second superlens (22) is configured to converge collimated light from the reflecting surface (03) to the second optical waveguide (12) to enable coupling of the first optical waveguide (11) and the second optical waveguide (12).
2. A coupling device according to claim 1, characterized by an exit face (01) and a coupling face (02), wherein,
the emergent light spots of the first optical waveguide (11) and the second optical waveguide (12) are both positioned in the emergent surface (01), and the emergent light spot optical axes of the first optical waveguide (11) and the second optical waveguide (12) are parallel;
the first superlens (21) and the second superlens (22) are both arranged in the coupling surface (02);
the emergent surface (01), the coupling surface (02) and the reflecting surface (03) are arranged in parallel;
the phase distribution of the first superlens (21) and the second superlens (22) satisfies:
in the formula, x and y are surface coordinates of the first superlens or the second superlens, λ is the wavelength of the incident light, and f is the focal length of the first superlens or the second superlens.
3. The coupling device according to claim 2, wherein the mode field of the first optical waveguide (11) is coaxial with the first superlens (21), and the mode field of the second optical waveguide (12) is coaxial with the second superlens (22);
the value range of y in the phase distribution of the first superlens is as follows:
y 0 -d 2 /2≤y≤y 0 +d 2 /2
the value range of y in the phase distribution of the second superlens is as follows:
-y 0 -d 2 /2≤y≤-y 0 +d 2 /2
wherein, y 0 ＝d 3 /2，d 2 A spot diameter, d, of the first optical waveguide projected onto the first superlens 3 Is the center distance of the first optical waveguide and the second optical waveguide.
4. A coupling device according to claim 3, wherein the deflection angle θ of the collimated light is 2 Satisfies the following conditions:
5. a coupling device according to claim 3 or 4, characterized in that the distance between the exit face (01) and the coupling face (02) is L 1 The distance between the coupling surface (02) and the reflecting surface (03) is L 2 Wherein, in the process,
L 1 ＝L 2 ＝f
f is the focal length of the first super lens or the second super lens.
6. The coupling device according to claim 2, wherein the mode field axis of the first optical waveguide (11) and the center of the first superlens (21), and the mode field axis of the second optical waveguide (12) and the center of the second superlens (22), each have an offset Δ y in the y-direction;
wherein the distance L between the emission surface (01) and the coupling surface (02) 1 A focus with the first super lens (21) or the second super lens (22)The distances f are equal;
a distance L between the coupling surface (02) and the reflecting surface (03) 2 Satisfies the following conditions:
wherein, d 3 Is the center distance theta of the first optical waveguide (11) and the second optical waveguide (12) 2 Is the deflection angle of the collimated light.
7. Coupling device according to claim 3 or 6,
the focal lengths f and d 2 The following relationship is satisfied:
wherein, theta 1 A divergence angle of incident light provided for the first optical waveguide (11);
and said theta 1 And a mode field diameter d of the first optical waveguide (11) 1 The following relationship is satisfied:
8. the coupling device according to any one of claims 1, 2, 3 or 6, wherein the nanostructures (202) are cylinders, have a diameter of 180nm to 500nm, and are periodically arranged on the surface of the substrate in the form of hexagons.
9. The coupling device according to any of claims 2, 3 or 6, wherein the nanostructures of the first superlens (21) and the nanostructures of the second superlens (22) are located in different regions of the same substrate.
10. Coupling device according to claim 9, characterized in that the coupling surface (02) and the reflecting surface (03) are located on two opposite surfaces of the substrate, respectively, wherein,
the substrate is transparent to the working waveband, and the reflecting surface (03) is a reflecting layer formed on the surface of the substrate.
Priority Applications (1)
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| CN202223083952.3U CN218824795U (en) | 2022-11-21 | 2022-11-21 | Coupling device |
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