An optical coupling microsystem comprising fast axis beam shaping

Abstract

This invention discloses an optical coupling microsystem including fast-axis beam shaping, comprising a light-emitting structure, a collimating lens, a shaping lens, a focusing lens, and a light-receiving structure arranged sequentially along the optical path; the equivalent distance between the collimating lens and the shaping lens is d. 12 The equivalent distance d between the shaping lens and the focusing lens 23 The collimating lens has an equivalent focal length of f1, the shaping lens has an equivalent focal length of f2 on the front and rear curved surfaces of the fast axis, and the focusing lens has an equivalent focal length of f3. These satisfy the formula: the equivalent divergence angles of the fast and slow axes of the light-emitting structure are respectively, and the equivalent divergence angles of the fast and slow axes of the light-receiving structure are respectively, and satisfy the relationship. This invention has a simple structure and small size. By determining the range of geometric dimension parameters of each lens, a light spot of the required size can be formed, and a high aspect ratio light spot can be scaled into a quasi-circular light spot, greatly improving the coupling efficiency between the emitting end and the receiving end. It is suitable for space-sensitive, highly integrated applications, such as high-speed optical modules.

Description

Technical Field

[0001] This invention relates to an optical coupling microsystem, and more particularly to an optical coupling microsystem incorporating fast-axis beam shaping. Background Technology

[0002] In the field of optical communication, an optical module typically contains active or passive optical components such as a carrier light source, a modulator chip, optical fiber, and photodiodes. To reduce light loss as it propagates from one optical component to another, the overlap rate of the light emitting and receiving elements should be as high as possible, i.e., high coupling efficiency. However, due to significant differences in materials, processes, and structures among different optical components, especially the typically large ratio of fast to slow axis emission angles in lasers, it is difficult to achieve similar modes without additional design or system support, thus affecting coupling efficiency.

[0003] Currently, the industry commonly uses the following two methods to improve optical coupling efficiency: 1. Optical microlens arrays: By adding collimating and focusing lenses between the light emitting and receiving elements using spatial light, the spot size is changed, thereby improving coupling efficiency. This method is often used for couplings with a small ratio of fast to slow axes or where the mode symmetry between the light emitting and receiving elements is relatively consistent. However, the coupling efficiency is low for couplings with a large ratio of fast to slow axis emission angles (greater than 2:1) or where the mode symmetry between the light emitting and receiving elements differs significantly. 2. Mode conversion structure: This method uses special processes to directly convert the mode on the light emitting or receiving structure to achieve efficient coupling. However, this method has certain requirements for the material system, poor versatility, and relatively high cost. Summary of the Invention

[0004] Purpose of the invention: The purpose of this invention is to provide an optical coupling microsystem that includes fast-axis beam shaping, which greatly improves the coupling efficiency between the output end and the receiver end.

[0005] Technical solution: This invention includes a light-emitting structure, a collimating lens, a shaping lens, a focusing lens, and a light-receiving structure arranged sequentially along the optical path; the equivalent distance between the collimating lens and the shaping lens is d. 12 The equivalent distance between the shaping lens and the focusing lens is d. 23 The collimating lens has an equivalent focal length of f1, the shaping lens has an equivalent focal length of f2 on the fast axis front and rear curved surfaces, and the focusing lens has an equivalent focal length of f3, satisfying the formula: The equivalent divergence angles of the fast and slow axes of the light-emitting structure are respectively The equivalent divergence angles of the fast and slow axes of the optical receiver structure are respectively And satisfy the relationship

[0006] The radius of curvature R2, refractive index n, and corresponding equivalent focal length f1 of the collimating lens satisfy the following formula:

[0007]

[0008] The radius of curvature R4, refractive index n, and corresponding equivalent focal length f3 of the focusing lens satisfy the following formula:

[0009]

[0010] The incident surface curvature radius R of the shaping lens 3-f Radius of curvature R of the light-emitting surface 3-r The lens thickness d, refractive index n, and corresponding equivalent focal length f2 satisfy the formula:

[0011] The geometric dimensions of the collimating lens, shaping lens, and focusing lens are as follows: width*height*length: 0.5mm*0.5mm*0.5mm~2mm*2mm*2mm, radius of curvature: -2~2mm, ellipticity: 0.5~2, refractive index: 1.4~2, and object-image distance: 3~10mm.

[0012] The refractive index n of the collimating lens and the focusing lens ranges from 1280 to 1650 nm, and the wavelength ranges from 3 to 3.6. The refractive index n of the shaping lens ranges from 1280 to 1650 nm, and the wavelength ranges from 1.3 to 1.8.

[0013] The light emitting structure is located at the focal point of the collimating lens, and the emission center of the light emitting structure is located on the optical axis of the system. The light spot satisfies that the ratio of the fast axis to the slow axis is not equal to 1:1.

[0014] The collimating lens is an aspherical lens, with the side facing the light-emitting structure being a plane and the side facing the shaping lens being a convex, fast-slow axisymmetric aspherical surface. The center of the collimating lens coincides with the optical axis of the system.

[0015] The center of the shaping lens coincides with the optical axis of the system. Its fast axis facing the light-emitting structure consists of two unidirectional aspherical surfaces, and its slow axis facing the light-emitting structure consists of two planes.

[0016] The focusing lens is an aspherical lens, with the side facing the shaping lens being a convex, fast-slow axis symmetric aspherical surface, and the side facing the light receiving structure being a plane, with its center coinciding with the system's optical axis.

[0017] Beneficial effects: The present invention has a simple structure and small size. By determining the range of geometric dimension parameters of each lens, a light spot of the required size can be formed. It can also scale a high aspect ratio light spot into a quasi-circular light spot, which greatly improves the coupling efficiency between the output end and the receiving end. It is suitable for space-sensitive, highly integrated applications, such as high-speed optical modules. Attached Figure Description

[0018] Figure 1 This is a system illustration of the present invention. Figure 1 ;

[0019] Figure 2 This is a system illustration of the present invention. Figure 2 ;

[0020] Figure 3 A schematic diagram of an elliptical light spot emitted by a light-emitting structure;

[0021] Figure 4 To adopt Figure 1 A schematic diagram of the light spot after system shaping. Detailed Implementation

[0022] The invention will now be further described with reference to the accompanying drawings.

[0023] Example 1

[0024] like Figure 1 and Figure 2 As shown, the optical coupling microsystem including fast-axis beam shaping in this embodiment includes a light emitting structure 1, a collimating lens 2, a shaping lens 3, a focusing lens 4, and a light receiving structure 5 arranged sequentially along the optical path. The light emitting structure 1 is located at the focal point of the collimating lens 2, and the light receiving structure 5 is located at the focal point of the focusing lens 4. The fast axis of the light-incident surface and the fast axis of the light-outcident surface of the shaping lens 3 are both aspherical surfaces, and the slow axis of the light-incident surface and the slow axis of the light-outcident surface of the shaping lens 3 are both planar surfaces.

[0025] The emission center of the light emission structure 1 is located on the optical axis of the system, and the light spot satisfies the ratio of the fast axis to the slow axis not being equal to 1:1.

[0026] Collimating lens 2 is an aspherical lens. The side facing the light-emitting structure 1 is a plane, and the side facing the shaping lens 3 is a convex aspherical surface with fast and slow axis symmetry. The center of collimating lens 2 coincides with the optical axis of the system.

[0027] The center of the shaping lens 3 coincides with the optical axis of the system. Its fast axis direction facing the light-emitting structure 1 consists of two aspherical surfaces in the same direction, and its slow axis direction facing the light-emitting structure 1 consists of two planes in the front and back.

[0028] The focusing lens 4 is an aspherical lens. The side facing the shaping lens 3 is a convex aspherical surface with fast and slow axis symmetry, while the side facing the light receiving structure 5 is a plane. The center of the aspherical lens coincides with the optical axis of the system.

[0029] The equivalent distance between collimating lens 2 and shaping lens 3 is d. 12 The equivalent distance between the shaping lens 3 and the focusing lens 4 is d. 23 ,d 12 d 23 All are greater than 0; the equivalent focal length of collimating lens 2 is f1, the equivalent focal length of the fast axis front and rear curved surfaces of shaping lens 3 is f2, and the equivalent focal length of focusing lens 4 is f3, satisfying the formula:

[0030] The equivalent divergence angles of the fast and slow axes of the light-emitting structure 1 are respectively The equivalent divergence angles of the fast and slow axes of the optical receiver structure 5 are respectively And satisfy the relationship

[0031] When the light exits the structure at an angle of 1 or The divergence angle is less than or equal to that of the light receiving structure 5. or Right now or The radius of curvature R2 of collimating lens 2 is less than or equal to the radius of curvature R4 of focusing lens 4, i.e., |R2|≤|R4|. The radius of curvature R of the shaping lens 3 facing collimating lens 2 is... 3-f The radius of curvature R of the surface facing the focusing lens 4 is greater than or equal to 3-r That is, |R 3-f |≥|R 3-r |;When the light exits the structure at a divergence angle of 1 or A divergence angle greater than or equal to 5° of the light receiving structure or Right now or The radius of curvature R2 of collimating lens 2 is less than or equal to the radius of curvature R4 of focusing lens 4, i.e., |R2|≤|R4|. The radius of curvature R of the shaping lens 3 facing collimating lens 2 is... 3-f The radius of curvature R facing the focusing lens 4 is less than or equal to 3-r That is, |R 3-f |≤|R 3-r |

[0032] The radius of curvature R2, refractive index n, and corresponding equivalent focal length f1 of collimating lens 2 satisfy the following formula:

[0033] The radius of curvature R4, refractive index n, and corresponding equivalent focal length f3 of focusing lens 4 satisfy the following formula:

[0034] The radius of curvature R of the incident surface of the shaping lens 33-f Radius of curvature R of the light-emitting surface 3-r The lens thickness d, refractive index n, and corresponding equivalent focal length f2 satisfy the formula:

[0035] When selecting the parameters of each lens, the final parameters need to be combined with the system object-image distance limit and the actual process limitation. Under the condition that all lens parameters meet the aforementioned formula, a coupling efficiency of more than 80% can be achieved.

[0036] The geometric dimensions of the collimating lens 2, the shaping lens 3, and the focusing lens 4, as determined by the above formula, are as follows: width * height * length: 0.5mm * 0.5mm * 0.5mm ~ 2mm * 2mm * 2mm, radius of curvature: -2 ~ 2mm, ellipticity: 0.5 ~ 2, refractive index: 1.4 ~ 2, and object-image distance: 3 ~ 10mm.

[0037] The refractive index n of the collimating lens 2 and the focusing lens 4 ranges from 1280 to 1650 nm and the wavelength ranges from 3 to 3.6. The refractive index n of the shaping lens 3 ranges from 1280 to 1650 nm and the wavelength ranges from 1.3 to 1.8.

[0038] Example 2

[0039] The optical coupling microsystem including fast-axis beam shaping provided in this embodiment can shape the beam spot along the fast axis, resulting in a quasi-circular spot. This system shapes the beam spot along the fast axis of the laser beam, such as... Figure 1 As shown, the light includes a light emitting structure 1, a collimating lens 2, a shaping lens 3, a focusing lens 4, and a light receiving structure 5 arranged sequentially along the light path. The light emitting structure 1 is located at the focal point of the collimating lens 2, and the light receiving structure 5 is located at the focal point of the focusing lens 4. The light incident surface and the light emitting surface of the shaping lens 3 are both aspherical surfaces only in the fast axis direction, and the bending directions are the same.

[0040] The light-emitting structure 1 is a semiconductor laser chip with a wavelength of 1310 nanometers. The laser beam cross-section is an elliptical spot, as shown below. Figure 3 As shown. The mode size along the fast axis is 1 micrometer, with a divergence angle of 55.8°; the mode size along the slow axis is 5 micrometers, with a divergence angle of 11.25°. The emission position of the semiconductor laser chip is the starting point of the optical axis of the entire system, and the center of the light source is located on the optical axis of the system.

[0041] Collimating lens 2 is an aspherical lens used to collimate the incident beam into collimated light. Its side facing the light-emitting structure 1 is flat, while its side facing the shaping lens 3 is a convex aspherical surface with a radius of curvature of 0.6 mm, and its center coincides with the system's optical axis. It measures 1 mm (width) * 1 mm (height), is made of silicon with a refractive index of 3.5, and has a thickness of 0.5 mm. Both sides of the lens are coated with anti-reflective coatings, resulting in a reflectivity of less than 1%, and a wavelength of 1260–1620 nanometers.

[0042] The shaping lens 3 is located between the collimating lens 2 and the focusing lens 4, with its center coinciding with the system's optical axis, and is used for beam shaping. In this embodiment, the shaping lens 3 has a curved surface only in the fast axis direction, with the convex surface of the curved surface facing the collimating lens 2. The radius of curvature of the incident surface is 1.3 mm; the radius of curvature of the exit surface is 0.6 mm. The shaping lens 3 has dimensions of 0.5 mm (width) * 0.5 mm (height), is made of N-SF11 glass with a refractive index of 1.748, a thickness of 1 mm, and is coated with anti-reflective coatings on both sides, resulting in a reflectivity of less than 1% and a wavelength of 1260–1620 nm.

[0043] Focusing lens 4 is an aspherical lens. The shaped beam after passing through focusing lens 4 is focused onto light receiving structure 5. The side of focusing lens 4 facing shaping lens 3 is a convex aspherical surface, while the side facing light receiving structure 5 is a flat surface. Its center coincides with the optical axis of the system. The radius of curvature of the aspherical surface of focusing lens 4 is 1.14 mm. The dimensions of focusing lens 4 are 1 mm (width) * 1 mm (height), the material is silicon, the refractive index is 3.5, the thickness is 0.5 mm, the lens is coated with anti-reflection coating on both sides, the reflectivity is less than 1%, and the wavelength is 1260–1620 nm.

[0044] The light spot obtained at point 5 of the light-receiving structure is as follows: Figure 4 As shown, the spot diameters in the fast axis direction and the slow axis direction are 10 μm * 9 μm, the object-image distance is 3.7 mm, and the coupling efficiency with the light receiving structure 5 with a pattern size of 10 μm * 10 μm is approximately 93%.

[0045] As can be seen from the above examples, the micro-optical system proposed in this invention can shape the beam of a high aspect ratio transmitter, thereby greatly improving the coupling efficiency with various receiver structures.

Claims

1. An optical coupling microsystem incorporating fast-axis beam shaping, characterized in that, It includes a light-emitting structure, a collimating lens, a shaping lens, a focusing lens, and a light-receiving structure arranged sequentially along the optical path; the equivalent distance between the collimating lens and the shaping lens is d. 12 The equivalent distance between the shaping lens and the focusing lens is d. 23 The collimating lens has an equivalent focal length of f1, the shaping lens has an equivalent focal length of f2 on the fast axis front and rear curved surfaces, and the focusing lens has an equivalent focal length of f3, satisfying the formula: The equivalent divergence angles of the fast and slow axes of the light-emitting structure are φ. 1-o φ 1-e The equivalent divergence angles of the fast and slow axes of the optical receiver structure are φ. 5-o φ 5-e And satisfy the relation , .

2. The optical coupling microsystem including fast-axis beam shaping according to claim 1, characterized in that, The radius of curvature R2, refractive index n, and corresponding equivalent focal length f1 of the collimating lens satisfy the following formula: .

3. The optical coupling microsystem including fast-axis beam shaping according to claim 2, characterized in that, The radius of curvature R4, refractive index n, and corresponding equivalent focal length f3 of the focusing lens satisfy the following formula: .

4. The optical coupling microsystem including fast-axis beam shaping according to claim 3, characterized in that, The incident surface curvature radius R of the shaping lens 3-f Radius of curvature R of the light-emitting surface 3-r The lens thickness d, refractive index n, and corresponding equivalent focal length f2 satisfy the formula: ).

5. The optical coupling microsystem including fast-axis beam shaping according to claim 1, characterized in that, The geometric dimensions of the collimating lens, shaping lens, and focusing lens are as follows: width*height*length: 0.5mm*0.5mm*0.5mm~2mm*2mm*2mm, radius of curvature: -2~2mm, ellipticity: 0.5~2, refractive index: 1.4~2, and object-image distance: 3~10mm.

6. The optical coupling microsystem including fast-axis beam shaping according to claim 4, characterized in that, The refractive index n of the collimating lens and the focusing lens ranges from 3 to 3.6, and the wavelength range is 1280 to 1650 nm. The refractive index n of the shaping lens ranges from 1.3 to 1.8, and the wavelength range is 1280 to 1650 nm.

7. The optical coupling microsystem including fast-axis beam shaping according to claim 1, characterized in that, The light emitting structure is located at the focal point of the collimating lens, and the emission center of the light emitting structure is located on the optical axis of the system. The light spot satisfies that the ratio of the fast axis to the slow axis is not equal to 1:

1.

8. The optical coupling microsystem including fast-axis beam shaping according to claim 1, characterized in that, The collimating lens is an aspherical lens, with the side facing the light-emitting structure being a plane and the side facing the shaping lens being a convex, fast-slow axisymmetric aspherical surface. The center of the collimating lens coincides with the optical axis of the system.

9. The optical coupling microsystem including fast-axis beam shaping according to claim 1, characterized in that, The center of the shaping lens coincides with the optical axis of the system. Its fast axis facing the light-emitting structure consists of two unidirectional aspherical surfaces, and its slow axis facing the light-emitting structure consists of two planes.

10. The optical coupling microsystem including fast-axis beam shaping according to claim 1, characterized in that, The focusing lens is an aspherical lens, with the side facing the shaping lens being a convex, fast-slow axis symmetric aspherical surface, and the side facing the light receiving structure being a plane, with its center coinciding with the system's optical axis.

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