Optical coupling structure, optical transmitting sub-module and optical module

Abstract

The application relates to an optical coupling structure, an optical transmitting sub-module and an optical module in the technical field of optical modules in optical fiber communication. The optical coupling structure comprises a laser, a lens group and a ferrule arranged in sequence; the laser emits a light beam; the light beam is incident to the lens group; after being emitted from the lens group, the light beam forms convergent light; the convergent light is incident to the ferrule; the lens group has a virtual convergent light focus point on a side far from the laser; the ferrule has an end face; the convergent light focus point is located on a side of the end face of the ferrule far from the lens group; the lens group comprises at least one silicon lens; and the silicon lens is a convergent lens. When the temperature rises, the silicon lens has a large thermal-optical effect, the refractive index increases, the focus point of the convergent light moves to the direction close to the end face of the ferrule, the coupling light power increases, and the optical power caused by the temperature rise of the laser can be effectively balanced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of optical modules in optical fiber communication, and in particular to an optical coupling structure, an optical transmitting sub-module and an optical module. BACKGROUND

[0002] In recent years, with the maturity of 5G technology, the gradual promotion of commercialization, and the construction of base stations, a large amount of optical devices will be needed. Optical devices are functional devices that convert and transmit optical signals in optical transmission networks, and are an important part of optical transmission systems. Among them, the transmitting optical subassembly (TOSA) has always been the focus and difficulty in the production and manufacturing of optical devices due to its complex structure and process, and the cost pressure is also greater; generally speaking, the common TOSA main optical structure scheme is a combination of a laser, a glass lens and a ferrule. In the optical structure scheme of the laser, the glass lens and the ferrule, the glass lens has a high cost, and the small refractive index of the glass lens makes the product package size larger. In the use process, the temperature in the module rises, the laser light output efficiency decreases, and the optical power becomes smaller, and a TEC temperature control is usually needed.

[0003] The use of TEC temperature control increases the volume and cost of the product. SUMMARY

[0004] The present application aims to solve the problem of the existing TOSA optical structure scheme in the prior art, which needs TEC temperature control to adapt to high-temperature and high-power application scenarios, resulting in large product volume and high cost, and provides an optical coupling structure, which converges the light emitted by the laser by using a lens group containing a silicon lens, and the converging light focus point is located on the side of the ferrule end face away from the silicon lens; when the temperature rises, the converging light focus point moves towards the direction close to the ferrule end face due to the large thermo-optic effect of the silicon lens, the coupled optical power increases, and the decrease of the optical power caused by the temperature rise of the laser can be effectively balanced.

[0005] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is:

[0006] An optical coupling structure, comprising a laser, a lens group and a ferrule arranged in sequence; the laser emits a light beam, the light beam is incident to the lens group, and the converging light is formed after being emitted from the lens group, and the converging light is incident to the ferrule;

[0007] The lens group has a virtual converging light focus point on the side away from the laser; the ferrule has an end face;

[0008] The converging light focus point is located on the side of the end face of the ferrule away from the lens group;

[0009] The lens group comprises at least one silicon lens; the silicon lens is a converging lens.

[0010] When the temperature rises, the converging light focus moves towards the end face of the ferrule.

[0011] In the conventional optical coupling structure using only glass lenses, the converging light focus of the converging light is located between the lens group and the ferrule, and when the optical power received by the ferrule is adjusted, the ferrule is moved towards the lens group, and the optical power is changed from small to large until the optical power requirement is reached.

[0012] The lens group used in the scheme of the present application includes a silicon lens. When the temperature rises, the silicon lens has a large thermal-optical effect, that is, the refractive index of the lens changes sharply with the temperature, and the converging light focus moves towards the end face of the ferrule, and the coupling optical power increases, which can effectively balance the decrease of the optical power of the laser caused by the temperature rise. By using a plurality of silicon lens combinations to adjust the optical path, the requirements of the structure performance can be met.

[0013] As a preferred scheme of the present application, the silicon lens is a plano-convex lens.

[0014] As a preferred scheme of the present application, the silicon lens is a double-convex lens.

[0015] As a preferred scheme of the present application, the lens group includes a silicon lens and a glass lens.

[0016] As a preferred scheme of the present application, the glass lens is located between the silicon lens and the laser.

[0017] As a preferred scheme of the present application, the glass lens is located between the silicon lens and the ferrule.

[0018] According to the structure performance requirements, a glass lens is arranged between the silicon lens and the ferrule or between the silicon lens and the laser as a device for adjusting the optical path.

[0019] As a preferred scheme of the present application, it further includes an auxiliary device, which includes one or more of a mirror, a monitoring diode, an isolator, and a wave divider.

[0020] As a preferred scheme of the present application, it further includes a substrate having opposite first and second surfaces; the laser is connected to the first surface of the substrate, and one of the silicon lenses is connected to the second surface of the substrate.

[0021] An optical transmitting sub-module includes the optical coupling structure as described above.

[0022] An optical module includes the optical transmitting sub-module as described above.

[0023] In summary, due to the adoption of the above technical scheme, the present application has the following advantages:

[0024] 1. The optical coupling structure of the present application, by using a lens group containing a silicon lens, and the converging light focus point of the lens group is located on the side of the end face of the ferrule away from the lens group, using the silicon lens has a large thermo-optic effect when the temperature rises, the refractive index increases, the focus point of the converging light moves towards the direction close to the end face of the ferrule, the coupling light power increases, which can effectively balance the decrease of the optical power of the laser caused by the temperature rise. By using a plurality of silicon lens groups to achieve optical path adjustment to meet the requirements of the structure performance.

[0025] In the field of optical communication, the single-mode communication window is between 1000-2000nm, and the silicon lens has a transmittance of more than 99% for light waves in this range. And for this wavelength, the refractive index of the silicon lens at room temperature is 3.4-3.5, which is much larger than the refractive index of commonly used optical glass lenses, such as BK7, which is 1.5. The thermo-optic coefficient of the silicon lens is several orders of magnitude larger than that of the optical glass lens, and the temperature / optical compensation effect using the present solution is obvious.

[0026] 2. The optical transmitter sub-module or optical module of the present application, by using an optical coupling structure containing a silicon lens, the increase of optical power caused by the movement of the converging light focus point when the temperature rises can balance the decrease of the optical power of the laser caused by the temperature rise. Without using TEC temperature control, the volume of the optical module is greatly reduced, and the cost is reduced. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is a structural schematic diagram of the optical coupling structure of the present application.

[0028] Figure 2 is Figure 1 is an enlarged view schematic diagram at circle A.

[0029] Figure 3 is an optical path schematic diagram of the optical coupling structure of the present application.

[0030] Figure 4 is an optical path schematic diagram of the optical coupling structure in Example 2.

[0031] Figure 5 is a structural schematic diagram of the optical coupling structure in Comparative Example 1.

[0032] Figure 6 is Figure 5 is an enlarged view schematic diagram at circle B.

[0033] Figure 7 is a structural schematic diagram of the optical module of the present application.

[0034] Figure legend: 1-laser; 2-silicon lens; 21-converging light focus point; 3-ferrule; 31-end face; 4-glass lens; 5-substrate; 100-optical transmitter sub-module; 200-optical receiver sub-module. DETAILED DESCRIPTION

[0035] The present application will be described in detail below with reference to the drawings.

[0036] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application.

[0037] Embodiment 1

[0038] An optical coupling structure, as shown in Figure 1 and Figure 2 , comprises a laser 1, a lens group and a ferrule 3 arranged in sequence; the laser 1 emits a light beam, the light beam is incident to the lens group, and convergent light is formed after being emitted from the lens group, and the convergent light is incident to the ferrule 3; further comprising a substrate 5, the substrate 5 has opposite first and second surfaces; the laser 1 is connected to the first surface of the substrate 5, and one silicon lens 2 is connected to the second surface of the substrate 5.

[0039] The lens group has a virtual convergent light focus point 21 on the side far from the laser 1; the ferrule 3 has an end face 31; the convergent light focus point 21 is located on the side of the end face 31 of the ferrule 3 far from the lens group; the lens group comprises at least one silicon lens 2; the silicon lens 2 is a convergent lens. The silicon lens 2 is a plano-convex lens.

[0040] As shown in Figure 3 , the convergent light focus point 21 is located in the ferrule 3, and the end face 31 of the ferrule 3 is located between the convergent light focus point 21 and the silicon lens 2.

[0041] The laser 1 is bonded on the substrate 5 by eutectic welding or by glue. The silicon lens 2 is bonded on the substrate 5 by glue. The optical coupling of the TOSA refers to coupling the convergent light of the lens into the ferrule 3 and meeting the specific coupling light power requirement.

[0042] When laser 1 is working, the emitted laser light is focused by the silicon lens 2 above. During optical coupling in TOSA, the ferrule 3 is typically moved in three dimensions (XYZ) relative to the focusing beam, and the power of the light coupled into the ferrule 3 is monitored in real time. For ease of description, the optical axis direction is defined as the Z-axis direction. The ferrule 3 reaches the maximum coupled optical power P1 at the focal point 21 of the focusing beam. At this point, the ferrule 3 continues to move along the Z-axis towards the lens, and the XY axis of the ferrule 3 is finely adjusted until the real-time coupled optical power P2 meets the TOSA product specifications, thus completing the reverse defocusing of the TOSA optical coupling. P2 is generally significantly smaller than P1, meaning that the ferrule 3 will move downwards from the focal point 21, and the position of the focal point 21 will be higher than the surface of the ferrule 3.

[0043] When the temperature rises, such as Figure 1 The silicon lens 2 exhibits a significant thermo-optical effect, meaning its refractive index changes drastically with temperature. The focusing focal point 21 moves downwards along the arrow direction, reducing the distance between it and the end face 31, thus increasing the coupled optical power. Simultaneously, as temperature increases, the laser 1's output efficiency decreases, resulting in lower optical power. The reverse defocusing technique used in this scheme utilizes the thermo-optical effect to move the focusing focal point 21 downwards towards the end face 31 of the ferrule 3, thereby increasing the coupled optical power. This effectively compensates for the reduced output efficiency of the high-temperature laser 1. The TOSA of this scheme exhibits excellent high and low temperature optical power performance.

[0044] This embodiment only focuses on describing the basic structure of the optical coupling structure; in actual implementation, components such as substrate 5, laser 1, and lens are sealed in a TO-CAN package with a cap; other components in the TOSA structure are not described. It can also be packaged in COB or BOX formats.

[0045] Example 2

[0046] The difference between this embodiment and Embodiment 1 is that the lens group includes a silicon lens 2 and a glass lens 4. The glass lens 4 is located between the silicon lens 2 and the ferrule 3. The silicon lens 2 is a plano-convex lens. The glass lens 4 is a biconvex lens. The optical path diagram is as follows. Figure 4 As shown.

[0047] In other embodiments, the glass lens 4 is located between the silicon lens 2 and the laser 1.

[0048] Other solutions also include auxiliary devices, which include one or more of the following: a reflector, a monitoring diode, an isolator, and a demultiplexer.

[0049] Example 3

[0050] The difference between this embodiment and embodiment 2 is that the glass lens 4 is replaced by another silicon lens 2. That is, in this embodiment, the lens group comprises a plano-convex lens and a double-convex lens, both of which are silicon lenses 2.

[0051] Comparative example 1

[0052] As shown in Figure 5 and Figure 6 , the defocus mode of the conventional TOSA optical coupling structure is positive defocus. The position of the convergent light focus 21 is lower than the end face 31 of the ferrule 3. When the temperature rises, the convergent light focus 21 moves downward, the distance between the convergent light focus 21 and the end face 31 of the ferrule 3 increases, and the optical power decreases.

[0053] Embodiment 4

[0054] An optical module, as shown in Figure 7 , comprises a light emitting sub-module 100 and a light receiving sub-module 200. The light emitting sub-module 100 comprises the optical coupling structure in embodiment 1 or embodiment 2 or embodiment 3.

[0055] The above only describes the preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement and improvement within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. An optical coupling structure comprising, in sequence, a laser (1), a lens group and a ferrule (3); characterized in that, The laser (1) emits a light beam, the light beam is incident to the lens group, and convergent light is formed after the light beam is emitted from the lens group, and the convergent light is incident to the ferrule (3); The lens group has a virtual convergent light focus point (21) on a side away from the laser (1); and the ferrule (3) has an end face (31); The convergent light focus point (21) is located on a side of the end face (31) of the ferrule (3) away from the lens group; The lens group comprises at least one silicon lens (2), and the silicon lens (2) is a convergent lens; The auxiliary device comprises one or more of a mirror, a monitoring diode, an isolator, and a wave divider; The substrate (5) has opposite first and second surfaces; the laser (1) is connected to the first surface of the substrate (5), and one of the silicon lenses (2) is connected to the second surface of the substrate (5); When the temperature rises, the light output power of the laser (1) becomes smaller, the silicon lens (2) has a thermo-optic effect, the refractive index of the lens increases with the rise of the temperature, the convergent light focus point (21) moves towards the end face (31) of the ferrule (3), and the coupling light power becomes larger, thereby compensating for the decrease of the light output efficiency of the laser (1).

2. The optical coupling structure of claim 1, wherein, The silicon lens (2) is a plano-convex lens.

3. The optical coupling structure of claim 1, wherein, The silicon lens (2) is a double-convex lens.

4. The optical coupling structure of claim 1, wherein, The lens group comprises a silicon lens (2) and a glass lens (4).

5. The optical coupling structure of claim 4, wherein, The glass lens (4) is located between the silicon lens (2) and the laser (1).

6. The optical coupling structure of claim 4, wherein, The glass lens (4) is located between the silicon lens (2) and the ferrule (3).

7. An optical sub-assembly, characterized by, The optical coupling structure comprises the optical coupling structure according to any one of claims 1-6.

8. An optical module characterized by comprising: The optical transmitting sub-module (100) comprises the optical coupling structure according to claim 7.

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