A light coupling method for an optical transmitter submodule

Abstract

The present invention provides a light coupling method for an optical transmitter submodule, comprising the following steps: S1, installing and fixing a laser and a fiber optic adapter; S2, powering the laser, adjusting the position of a converging lens in the X-axis, Y-axis, and Z-axis directions so that the optical power coupled into the fiber optic adapter reaches maximum, and recording the position of the converging lens at this time as P0; S3, adjusting the position of the converging lens in the X-axis and Z-axis directions to position P1, so that the distance from the converging lens to the fiber optic adapter in the X-axis direction is the focal length F of the converging lens, and the center of the converging lens in the Z-axis direction is at the same height as the center of the fiber core of the fiber optic adapter; and gluing and fixing the converging lens at position P1. This invention determines the final position P1 of the converging lens by coupling to the converging lens position P0 at the maximum optical power point of the fiber optic adapter. This method has high positioning accuracy and greatly reduces the influence of the mounting position of the laser and fiber optic adapter on the coupling efficiency, thereby improving the coupling efficiency of the product's optical power.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical communications, and in particular relates to a light coupling method for an optical transmission sub-module. Background Art

[0002] With the development of the optical communications industry, the data traffic that needs to be transmitted is getting larger and larger, and the transmission rate requirements for optical modules are also getting higher and higher. At the same time, the optical power requirements for optical modules are also getting higher and higher. Especially for optical modules for long-distance transmission, the light emitted by the laser is required to be coupled into the optical fiber through the lens with high coupling efficiency.

[0003] The optical path structure of a typical single-channel optical module's optical transmission submodule is as follows: Figure 1 As shown, the light emitted by the laser 1 is collimated by the collimating lens 2 and then converged by the converging lens 3 into the optical fiber of the optical fiber adapter 5. Usually, an optical isolator 4 is placed between the converging lens 3 and the optical fiber adapter 5. Figure 1 The lens coupling steps of the optical emission submodule shown are as follows: S1. Install the laser 1, optical isolator 4 and optical fiber adapter 5; S2. Power on the laser 1, fix the converging lens 3 in the X-axis direction at a position where the distance from its optical center to the left end face core of the optical fiber adapter 5 is the focal length F of the converging lens 3, then adjust the position of the converging lens 3 in the Y-axis and Z-axis directions to maximize the optical power coupled into the optical fiber adapter 5, and then fix the converging lens 3; S3. Power on the laser 1, adjust the position of the collimating lens 2 in the X-axis, Y-axis and Z-axis directions to maximize the optical power coupled into the optical fiber adapter 5, and then fix the collimating lens 2 to complete the coupling.

[0004] However, the above traditional coupling method has the following problems:

[0005] 1. The mounting position deviation and angle deviation of the laser 1 will cause the coupling position of the converging lens 3 to deviate from the designed position, thereby affecting the coupling efficiency.

[0006] 2. The position deviation of the optical fiber adapter 5 will affect the coupling efficiency.

[0007] 3. In order to reduce the influence of the reflected light from the optical fiber end face of the optical fiber adapter 5 on the laser 1, the ceramic ferrule end face on the light input side of the optical fiber adapter 5 is usually ground into a bevel with a certain angle, such as Figure 2 As shown, the angle α of the bevel is usually 4-8 degrees; however, this bevel angle design will also cause the actual position of the converging lens 3 during coupling to deviate from the designed position, thereby reducing the optical power ultimately coupled into the optical fiber adapter 5. Summary of the Invention

[0008] The object of the present invention is to provide a light coupling method for an optical transmission sub-module, which can at least solve some of the defects in the prior art.

[0009] To achieve the above object, the present invention adopts the following technical solutions:

[0010] A light coupling method for an optical transmission sub-module comprises the following steps:

[0011] S1. Install and fix the laser and fiber adapter;

[0012] S2. Power on the laser and adjust the position of the converging lens in the X-axis, Y-axis, and Z-axis directions to maximize the optical power coupled into the fiber adapter. Record the position of the converging lens at this time as P0 (X0, Y0, Z0).

[0013] S3. Adjust the position of the converging lens in the X-axis and Z-axis directions to position P1 (X0+B, Y0, Z0-C), so that the distance from the converging lens in the X-axis direction to the fiber optic adapter is the focal length F of the converging lens, and the center of the converging lens in the Z-axis direction is at the same height as the center of the fiber core of the fiber optic adapter; fix the converging lens at position P1 by gluing.

[0014] Furthermore, the optical coupling method of the above-mentioned optical emission submodule also includes step S4, placing the collimating lens between the laser and the converging lens, powering on the laser, adjusting the position of the collimating lens in the three directions of X-axis, Y-axis and Z-axis to maximize the optical power entering the optical fiber adapter, and fixing the collimating lens with glue.

[0015] Furthermore, when the converging lens is located at position P0 in step S2, the light exit point of the laser, the center of the converging lens and the center of the fiber core of the optical fiber adapter are on a straight line.

[0016] Furthermore, the calculation process of the X-axis translation distance B of the converging lens from position P0 to position P1 in step S3 is as follows: Using the converging lens focal length calculation formula Combined with the designed distance between the laser and the fiber adapter in the X-axis direction = A + B + F, the X-axis translation distance B of the converging lens is calculated; where F is the focal length of the converging lens, and A is the distance between the converging lens and the laser along the X-axis at position P0.

[0017] Furthermore, in step S3, the Z-axis translation distance of the converging lens from position P0 to position P1 is Where A is the distance between the converging lens and the laser along the X-axis when the converging lens is at position P0, B is the X-axis translation distance of the converging lens from position P0 to position P1, F is the focal length of the converging lens, and β is the angle between the incident light and the X-axis when the converging lens at position P1 causes the light coupled to the fiber adapter to be emitted horizontally.

[0018] Furthermore, the end face of the optical fiber adapter on the light incident side is an inclined surface with an inclination angle α. In this case, β is calculated according to the refractive index formula n=sin(α+β) / sinα; wherein n is the core refractive index of the optical fiber adapter.

[0019] Furthermore, the step S1 further includes installing and fixing an optical isolator between the laser and the optical fiber adapter, and in the step S2, a converging lens is placed between the laser and the optical isolator.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) The light coupling method of the optical emission submodule provided by the present invention first finds the point where the optical power coupled to the optical fiber adapter is the largest, and then determines the final position of the converging lens through the position of the converging lens at this point of maximum optical power. Since the light power coupled into the optical fiber adapter is the largest, the size of the light spot converged to the optical fiber adapter is almost the same as the core diameter of the optical fiber adapter, and the positioning accuracy is very high. Therefore, the accuracy of positioning the converging lens is also very high, which greatly improves the positioning accuracy of the converging lens and improves the coupling efficiency of the product.

[0022] (2) When the optical power coupled into the adapter reaches the maximum in the optical coupling method of the optical emission submodule provided by the present invention, the light emitting point of the laser, the center of the converging lens and the center of the fiber core of the optical fiber adapter are on a straight line. Therefore, even if there is a small deviation in the mounting position of the laser and the optical fiber adapter, the position of the converging lens can be quickly found, so that the light emitting point of the laser, the center of the converging lens and the center of the fiber core of the optical fiber adapter are on a straight line. Then, the final position of the converging lens is determined according to the position of the converging lens at this time, which greatly reduces the influence of the mounting position of the laser and the optical fiber adapter on the coupling efficiency and improves the coupling efficiency of the product optical power.

[0023] The present invention will be described in further detail below with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a schematic diagram of the optical path structure of a traditional optical transmission submodule;

[0025] Figure 2 It is a structural diagram of the optical fiber adapter;

[0026] Figure 3 Schematic diagram of the optical path of the light coupling method of the light emitting sub-module of the present invention;

[0027] Figure 4 This is a schematic diagram of the optimal incident light path of light coupled to the optical fiber adapter in the present invention.

[0028] Explanation of the accompanying symbols: 1. Laser; 2. Collimating lens; 3. Converging lens; 4. Optical isolator; 5. Fiber optic adapter. DETAILED DESCRIPTION

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0030] In the description of the present invention, it should be understood that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention.

[0031] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "install", "connect" and "connect" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, a conflicting connection or an integral connection. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0032] like Figure 3 and Figure 4 As shown, this embodiment provides a light coupling method for an optical transmission sub-module, comprising the following steps:

[0033] S1. Install and fix the laser 1 and the optical fiber adapter 5.

[0034] Optionally, when an optical isolator 4 is set in the optical path of the optical emission submodule, in this step, the optical isolator 4 needs to be fixed between the laser 1 and the optical fiber adapter 5. In the subsequent coupling process of the converging lens 3, the converging lens 3 will be placed between the laser 1 and the optical isolator 4 for coupling.

[0035] S2. Power on the laser 1 and adjust the position of the converging lens 3 in the X-axis, Y-axis, and Z-axis directions to maximize the optical power coupled into the fiber adapter 5. Record the position of the converging lens 3 at this time as P0 (X0, Y0, Z0).

[0036] When the optical power coupled into the optical fiber adapter 5 reaches the maximum, Figure 3 As shown, at this time, the center of the converging lens 3 is on the line connecting the light exit point of the laser 1 and the center of the fiber core of the optical fiber adapter 5, and the actual deviation is within the range of 1-2 μm. The influence of this deviation on the subsequent calculation results can be ignored. Therefore, it can be considered that the light exit of the laser 1, the center of the converging lens 3 and the center of the fiber core of the optical fiber adapter 5 are on a straight line. Therefore, even if there is a small deviation in the mounting position of the laser 1 and the optical fiber adapter 5, the P0 position of the converging lens 3 can be quickly found, so that the light exit of the laser 1, the center of the converging lens 3 and the center of the fiber core of the optical fiber adapter 5 are on a straight line. Subsequently, the final position of the converging lens 3 is determined according to the P0 position of the converging lens 3 at this time, which greatly reduces the influence of the mounting position of the laser 1 and the optical fiber adapter 5 on the coupling efficiency and improves the coupling efficiency of the product optical power.

[0037] S3. Adjust the position of the converging lens 3 in the X-axis and Z-axis directions to position P1 (X0+B, Y0, Z0-C), so that the distance between the converging lens 3 in the X-axis direction and the optical fiber adapter 5 is the focal length F of the converging lens 3, and the center of the converging lens 3 in the Z-axis direction is at the same height as the center of the fiber core of the optical fiber adapter 5; fix the converging lens 3 at position P1 with glue.

[0038] Optionally, in the present invention, the final position P1 of the converging lens 3 is determined by the position P0 of the converging lens 3 at the point of maximum optical power, and the final coupling position of the converging lens 3 can be determined by calculating the offset distances B and C of the converging lens 3 in the X-axis and Z-axis directions relative to the converging lens 3 at position P0.

[0039] Specifically, the calculation process of the X-axis translation distance B of the converging lens 3 from position P0 to position P1 is as follows: Using the focal length calculation formula of the converging lens 3 Combined with the design distance L between the laser 1 and the fiber adapter 5 along the X-axis, L = A + B + F, where F is the focal length of the converging lens 3 and A is the distance between the converging lens 3 and the laser 1 along the X-axis at position P0, the design distance L between the laser 1 and the fiber adapter 5 along the X-axis and the focal length F of the converging lens 3 are known quantities in the above two calculation formulas. Thus, the X-axis translation distance B of the converging lens 3 can be calculated.

[0040] The calculation process of the Z-axis translation distance C of the converging lens 3 from position P0 to position P1 is as follows: Figure 3As shown, using similar triangles we can know Calculated Wherein, A is the distance between the converging lens 3 and the laser 1 along the X-axis direction when the converging lens 3 is at position P0, B is the X-axis translation distance of the converging lens 3 from position P0 to position P1, F is the focal length of the converging lens 3, and β is the angle between the incident light and the X-axis direction when the converging lens 3 at position P1 causes the light coupled to the optical fiber adapter 5 to be emitted horizontally.

[0041] Furthermore, in order to reduce the influence of the reflected light from the optical fiber end face of the optical fiber adapter 5 on the laser, the optical fiber adapter 5 is designed to have an inclined surface with an inclined angle of α, such as Figure 4 As shown, at this time, it is necessary to ensure the optimal incident angle of the light coupled to the optical fiber adapter 5, that is, the refracted light after the incident light is refracted at the fiber core end face of the optical fiber adapter 5 is along the X-axis direction. According to the refractive index formula n = sin (θ + β) / sin γ, since θ = γ = α, then n = sin (α + β) / sin α, and thus β can be calculated; where n is the core refractive index of the optical fiber adapter 5.

[0042] In this embodiment, since the optical power coupled into the optical fiber adapter 5 is at its maximum (i.e., the converging lens 3 is located at position P0), the spot size from the converging lens 3 to the optical fiber adapter 5 is approximately the same size as the core diameter of the optical fiber adapter 5, and the positioning accuracy is very high. According to theoretical calculations, the final position P1 of the converging lens 3 is obtained by translating the distances B and C along the X-axis and Z-axis directions with position P0 as the reference point. Therefore, the accuracy of the final position P1 of the converging lens 3 positioned using this method is also very high, which greatly improves the positioning accuracy of the converging lens 3 and improves the coupling efficiency of the product.

[0043] S4. Place the collimating lens 2 between the laser 1 and the converging lens 3, power on the laser 1, adjust the position of the collimating lens 2 in the X-axis, Y-axis, and Z-axis directions so that the optical power entering the fiber optic adapter 5 reaches the maximum, and fix the collimating lens 2 with glue.

[0044] The following describes the light coupling method of the optical transmitter submodule of the present invention using a specific embodiment. Assume that the distance L between the laser 1 and the optical fiber adapter 5 in the X-axis direction is 22 mm (i.e., A+B+F=22 mm), the focal length F of the converging lens 3 is 2 mm, the inclination angle α of the optical fiber adapter 5 on the light-entry side is 6 degrees, and the core refractive index n of the optical fiber adapter 5 is 1.448. The light coupling process of the optical transmitter submodule is as follows:

[0045] First, the laser 1 , optical isolator and optical fiber adapter 5 are installed and fixed.

[0046] Then, power on the laser 1 to make it emit light, as shown in the following example: Figure 3As shown, adjust the position of the converging lens 3 in the X-axis, Y-axis, and Z-axis directions to maximize the optical power coupled into the fiber adapter 5. The position of the converging lens 3 at this time is recorded as P0 (X0, Y0, Z0), that is, Figure 3 The position of the converging lens 3 (the converging lens drawn with a dotted line) on the left side of the middle is located.

[0047] According to theoretical calculation, since A+B+F=22mm, F=2mm, we can substitute From the calculation, we get B = 0.22mm; from n = 1.448, α = 6 degrees, we put it into n = sin (α + β) / sin α, and get β ≈ 2.7 degrees. Then, according to Calculation shows that C≈0.0094mm.

[0048] Then, the converging lens 3 is moved to the position P1 (X0+0.22, Y0, Z0-0.0094) with P0 as the reference point. Figure 3 At the location of the converging lens 3 (the converging lens drawn in the middle right), glue is applied to the converging lens and the converging lens is fixed by UV and baking.

[0049] Finally, power on the laser 1 and adjust the position of the collimating lens 2 in the X-axis, Y-axis, and Z-axis directions to maximize the optical power entering the fiber optic adapter 5. Then apply glue to the collimating lens 2 and fix it by UV and baking.

[0050] The above examples are merely illustrative of the present invention and do not limit the scope of protection of the present invention. Any design that is identical or similar to the present invention falls within the scope of protection of the present invention.

Claims

1. A light coupling method for an optical transmitter submodule, characterized in that: The steps include: S1. Install and fix the laser and fiber adapter; S2. Power on the laser and adjust the position of the converging lens in the X-axis, Y-axis, and Z-axis directions to maximize the optical power coupled into the fiber adapter. Record the position of the converging lens at this time as P0 (X0, Y0, Z0). S3. Adjust the position of the converging lens in the X-axis and Z-axis directions to position P1 (X0+B, Y0, Z0-C), so that the distance between the converging lens in the X-axis direction and the fiber adapter is the focal length F of the converging lens, and the center of the converging lens in the Z-axis direction is at the same height as the center of the fiber core of the fiber adapter; fix the converging lens at position P1 with glue; The calculation process of the X-axis translation distance B of the converging lens from position P0 to position P1 is as follows: Using the formula for calculating the focal length of the converging lens , and combined with the designed distance between the laser and the fiber adapter in the X-axis direction = A + B + F, the X-axis translation distance B of the converging lens is calculated; where F is the focal length of the converging lens, and A is the distance between the converging lens and the laser along the X-axis at position P0; The Z-axis translation distance of the converging lens from position P0 to position P1 Wherein, A is the distance between the converging lens and the laser along the X-axis direction when the converging lens is at position P0, B is the X-axis translation distance of the converging lens from position P0 to position P1, F is the focal length of the converging lens, and β is the angle between the incident light and the X-axis direction when the converging lens at position P1 makes the light coupled to the optical fiber adapter emerge horizontally.

2. The light coupling method of the optical transmitter sub-module according to claim 1, wherein: The process also includes step S4, placing the collimating lens between the laser and the converging lens, powering on the laser, adjusting the position of the collimating lens in the X-axis, Y-axis, and Z-axis directions to maximize the optical power entering the optical fiber adapter, and fixing the collimating lens with glue.

3. The light coupling method of the optical transmitter sub-module according to claim 1, wherein: When the converging lens is located at position P0 in step S2, the light exit point of the laser, the center of the converging lens and the center of the fiber core of the optical fiber adapter are on a straight line.

4. The light coupling method of the optical transmitter sub-module according to claim 1, wherein: The end face of the optical fiber adapter on the light incident side is an inclined surface with an inclination angle α. At this time, β is calculated according to the refractive index formula n=sin(α+β) / sinα; where n is the core refractive index of the optical fiber adapter.

5. The light coupling method of the optical transmitter sub-module according to claim 1, wherein: The step S1 further includes installing and fixing an optical isolator between the laser and the optical fiber adapter, and in step S2, a converging lens is placed between the laser and the optical isolator.

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