Optical coupling microsystem with fast axis beam shaping function

Abstract

The invention discloses an optical coupling microsystem with a fast axis beam shaping function. The optical coupling microsystem comprises a light emitting structure, a collimating lens, a shaping lens, a focusing lens and a light receiving structure which are sequentially arranged along a light path. The equivalent distance between the collimating lens and the shaping lens is d12, the equivalent distance between the shaping lens and the focusing lens is d23, the equivalent focal length of the collimating lens is f1, and the equivalent focal length of the front and rear curved surfaces of the fast axis of the shaping lens is f2; the equivalent focal length of the focusing lens is f3, and the formula is met: the equivalent divergence angles of the fast axis and the slow axis of the light emitting structure are respectively the equivalent divergence angles of the fast axis and the slow axis of the light receiving structure, and the relation is met. And a high aspect ratio light spot can be zoomed into a quasi-circular light spot, so that the coupling efficiency between an emergent end and a receiving end is greatly improved, and the optical lens is suitable for space-sensitive high-integration-level application, such as a high-speed optical module.

Description

Technical Field

[0001] The present invention relates to an optical coupling microsystem, and in particular to an optical coupling microsystem including fast axis beam shaping. Background Art

[0002] In the field of optical communications, an optical module typically contains active or passive optical components such as a carrier light source, modulator chip, optical fiber, and photodiodes. To minimize light loss when transmitting from one optical component to another, the mode overlap between the light emitting and light receiving components must be as high as possible, effectively achieving high coupling efficiency. However, due to significant differences in materials, processes, and structures among different optical components, especially the large ratio of fast-axis to slow-axis emission angles of lasers, it is difficult to achieve similar mode overlaps without the aid of additional designs or systems, which in turn affects coupling efficiency.

[0003] At present, the industry commonly uses the following two methods to improve optical coupling efficiency: 1. Optical microlens group, which uses spatial light to add collimating and focusing lenses between the light emitting and receiving elements to change the spot size and improve coupling efficiency. This method is often used for coupling with a small fast-slow axis ratio or relatively consistent pattern spot symmetry between the light emitting and receiving elements. However, the coupling efficiency is low for a large fast-slow axis emission angle ratio (greater than 2:1) or a large difference in pattern spot symmetry between the light emitting and receiving elements; 2. Pattern spot conversion structure, which uses special process steps to directly perform pattern spot conversion on the light emitting structure or the light receiving structure to achieve the purpose of efficient coupling, but 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 the present invention is to provide an optical coupling microsystem including fast axis beam shaping, which greatly improves the coupling efficiency between the output end and the receiving end.

[0005] Technical solution: The present invention includes a light emitting structure, a collimating lens, a shaping lens, a focusing lens and a light receiving structure arranged in sequence along the light 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 equivalent focal length of the collimating lens is f1, the equivalent focal length of the front and rear surfaces of the fast axis of the shaping lens is f2; the equivalent focal length of the focusing lens is f3, satisfying the formula: The equivalent divergence angles of the fast and slow axes of the light emitting structure are The equivalent divergence angles of the fast and slow axes of the light receiving structure are And satisfy the relationship

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

[0007]

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

[0009]

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

[0011] The geometric size parameter range of the collimating lens, shaping lens and focusing lens is: width*height*length: 0.5mm*0.5mm*0.5mm~2mm*2mm*2mm, the curvature radius range is: -2~2mm, the ellipticity coefficient range is: 0.5~2, the refractive index range is: 1.4~2, and the object-image distance range is: 3~10mm.

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

[0013] The light emitting structure is located at the focal position of the collimating lens, the emission center of the light emitting structure is located on the optical axis of the system, and 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 aspheric lens, the side facing the light emitting structure is a plane, and the side facing the shaping lens is a convex fast-slow axisymmetric aspheric surface, and the center of the collimating lens coincides with the system optical axis.

[0015] The center of the shaping lens coincides with the optical axis of the system, and the front and rear aspheric surfaces facing the fast axis of the light emitting structure are the same, and the front and rear planes facing the slow axis of the light emitting structure are the same.

[0016] The focusing lens is an aspheric lens, the side facing the shaping lens is a convex fast-slow axisymmetric aspheric surface, and the side facing the light receiving structure is a plane, the center of which coincides with the system optical axis.

[0017] Beneficial effects: The present invention has a simple structure and small size. By determining the geometric size parameter range 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 output end and the receiving end. It is suitable for space-sensitive high-integration applications, such as high-speed optical modules. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 Schematic diagram of the system of the present invention Figure 1 ;

[0019] Figure 2 Schematic diagram of the system of the present invention Figure 2 ;

[0020] Figure 3 Schematic diagram of the elliptical light spot emitted by the light emitting structure;

[0021] Figure 4 To adopt Figure 1 Schematic diagram of the light spot after system shaping. DETAILED DESCRIPTION

[0022] The present invention will be further described below 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 of 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 in sequence along the optical path. The light emitting structure 1 is located at the focal position of the collimating lens 2, the light receiving structure 5 is located at the focal position of the focusing lens 4, the fast axis of the light incident surface and the fast axis of the light exit 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 exit surface of the shaping lens 3 are both planes.

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

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

[0027] The center of the shaping lens 3 coincides with the optical axis of the system. It has two front and rear aspheric surfaces facing the fast axis of the light emitting structure 1 and two front and rear planes facing the slow axis of the light emitting structure 1.

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

[0029] The equivalent distance between the collimating lens 2 and the 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 are all greater than 0; the equivalent focal length of the collimating lens 2 is f1, the equivalent focal length of the front and rear surfaces of the fast axis of the shaping lens 3 is f2; the equivalent focal length of the 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 The equivalent divergence angles of the fast and slow axes of the light receiving structure 5 are And satisfy the relationship

[0031] When the light exiting structure 1 diverges at an angle or Less than or equal to the divergence angle of the light receiving structure 5 or Right now or The curvature radius R2 of the collimating lens 2 is less than or equal to the curvature radius R4 of the focusing lens 4, that is, |R2|≤|R4|, and the curvature radius R of the shaping lens 3 facing the collimating lens 2 is 3-f Greater than or equal to the curvature radius R of the curved surface facing the focusing lens 4 3-r , that is, |R 3-f |≥|R 3-r |; When the light exiting structure 1 diverges at an angle or Greater than or equal to the divergence angle of the light receiving structure 5 or Right now or The curvature radius R2 of the collimating lens 2 is less than or equal to the curvature radius R4 of the focusing lens 4, that is, |R2|≤|R4|, and the curvature radius R of the shaping lens 3 facing the collimating lens 2 is 3-f Less than or equal to the curvature radius R facing the focusing lens 4 3-r That is |R 3-f |≤|R 3-r |.

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

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

[0034] The curvature radius R of the incident surface of the shaping lens 33-f , curvature radius of light emitting surface R 3-r , lens thickness d and refractive index n and their 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 limit. When all lens parameters meet the above formula, a coupling efficiency of more than 80% can be achieved.

[0036] The geometric size parameter ranges of the collimating lens 2, the shaping lens 3 and the focusing lens 4 determined according to the above formula are: width*height*length: 0.5mm*0.5mm*0.5mm~2mm*2mm*2mm, the curvature radius range is: -2~2mm, the ellipticity coefficient range is: 0.5~2, the refractive index range is: 1.4~2, and the object-image distance range is: 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 range is 3 to 3.6. The refractive index n of the shaping lens 3 ranges from 1280 to 1650 nm, and the wavelength range is 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 light spot in the fast axis direction of the light beam so that the light spot is quasi-circular. The system shapes the light spot in the fast axis direction of the laser beam, such as Figure 1 As shown, it 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 in sequence along the optical path. The light emitting structure 1 is located at the focal position of the collimating lens 2, the light receiving structure 5 is located at the focal position of the focusing lens 4, and 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 direction is the same.

[0040] The light emitting structure 1 is a semiconductor laser chip with a wavelength of 1310 nanometers and an elliptical spot cross section. Figure 3 As shown in the figure, the mode spot size along the fast axis is 1 micron, with a divergence angle of 55.8°; the mode spot size along the slow axis is 5 microns, with a divergence angle of 11.25°. The light 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 aspheric lens used to collimate the incident light beam into collimated light. Its surface facing the light-emitting structure 1 is flat, while the surface facing the shaping lens 3 is a convex aspheric surface with a radius of curvature of 0.6 mm, centered on the system optical axis. It measures 1 mm (width) by 1 mm (height), is made of silicon, has a refractive index of 3.5, and is 0.5 mm thick. Antireflection coating is applied to both sides of the lens, resulting in a reflectivity of less than 1%. Its wavelength is 1260 to 1620 nm.

[0042] The shaping lens 3 is located between the collimating lens 2 and the focusing lens 4, with its center coinciding with the system 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 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 measures 0.5 mm (width) by 0.5 mm (height) and is made of N-SF11 glass with a refractive index of 1.748 and a thickness of 1 mm. The lens is coated on both sides with an antireflection coating, resulting in a reflectivity of less than 1%, and a wavelength of 1260 to 1620 nanometers.

[0043] Focusing lens 4 is an aspheric lens. After passing through it, the shaped light beam is focused onto the light receiving structure 5. The side of focusing lens 4 facing the shaping lens 3 is a convex aspheric surface, while the side facing the light receiving structure 5 is flat, with its center coinciding with the system's optical axis. The radius of curvature of the aspheric surface of focusing lens 4 is 1.14 mm. Focusing lens 4 measures 1 mm (width) by 1 mm (height). Made of silicon with a refractive index of 3.5 and a thickness of 0.5 mm, it is coated on both sides with an antireflection coating, resulting in a reflectivity of less than 1%. Its wavelength range is 1260 to 1620 nm.

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

[0045] As can be seen from the above examples, the micro-optical system proposed in the present invention can realize the shaping of high-aspect-ratio transmitting-end light beams, thereby greatly improving the coupling efficiency with various receiving-end structures.

Claims

1. An optically coupled microsystem including fast-axis beam shaping, characterized in that: The optical system comprises a light emitting structure, a collimating lens, a shaping lens, a focusing lens and a light receiving structure arranged in sequence 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 equivalent focal length of the collimating lens is f1, the equivalent focal length of the front and rear surfaces of the fast axis of the shaping lens is f2; the equivalent focal length of the focusing lens is f3, satisfying the formula: The equivalent divergence angles of the fast and slow axes of the light emitting structure are The equivalent divergence angles of the fast and slow axes of the light receiving structure are And satisfy the relationship 2. The optically coupled microsystem comprising fast-axis beam shaping according to claim 1, wherein: The curvature radius R2 and the refractive index n of the collimating lens and the corresponding equivalent focal length f1 satisfy the formula:

3. The optically coupled microsystem comprising fast-axis beam shaping according to claim 2, wherein: The curvature radius R4 and the refractive index n of the focusing lens and the corresponding equivalent focal length f3 satisfy the formula:

4. The optically coupled microsystem including fast-axis beam shaping according to claim 3, wherein: The curvature radius R of the incident surface of the plastic lens 3-f , curvature radius of light emitting surface R 3-r , lens thickness d and refractive index n and their corresponding equivalent focal length f2 satisfy the formula:

5. The optically coupled microsystem including fast-axis beam shaping according to claim 1, wherein: The geometric size parameter range of the collimating lens, shaping lens and focusing lens is: width*height*length: 0.5mm*0.5mm*0.5mm~2mm*2mm*2mm, the curvature radius range is: -2~2mm, the ellipticity coefficient range is: 0.5~2, the refractive index range is: 1.4~2, and the object-image distance range is: 3~10mm.

6. The optically coupled microsystem comprising fast-axis beam shaping according to claim 4, wherein: The refractive index n of the collimating lens and the focusing lens is in the range of 1280 to 1650 nm, and the wavelength range is 3 to 3.

6. The refractive index n of the shaping lens is in the range of 1280 to 1650 nm, and the wavelength range is 1.3 to 1.

8.

7. The optically coupled microsystem comprising fast-axis beam shaping according to claim 1, wherein: The light emitting structure is located at the focal position of the collimating lens, the emitting center of the light emitting structure is located on the optical axis of the system, and the light spot satisfies that the ratio of the fast axis to the slow axis is not equal to 1:

1.

8. The optically coupled microsystem including fast-axis beam shaping according to claim 1, wherein: The collimating lens is an aspheric lens, the side facing the light emitting structure is a plane, and the side facing the shaping lens is a convex fast-slow axisymmetric aspheric surface, and the center of the collimating lens coincides with the system optical axis.

9. The optically coupled microsystem including fast-axis beam shaping according to claim 1, wherein: The center of the shaping lens coincides with the optical axis of the system, and the front and rear aspheric surfaces facing the fast axis of the light emitting structure are the same, and the front and rear planes facing the slow axis of the light emitting structure are the same.

10. The optically coupled microsystem including fast-axis beam shaping according to claim 1, wherein: The focusing lens is an aspheric lens, the side facing the shaping lens is a convex fast-slow axisymmetric aspheric surface, and the side facing the light receiving structure is a plane, the center of which coincides with the system optical axis.

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