Tunable optical filter assembly and optical transmit-receive subassembly structure

Abstract

This invention discloses a tunable optical filter assembly, including a tunable optical filter, a substrate, a flexible circuit board, a temperature sensor, a heat sink, and a thermoelectric cooler. The flexible circuit board is disposed on the substrate. The tunable optical filter, temperature sensor, and thermoelectric cooler are all disposed on the metal layer of the flexible circuit board. The thermoelectric cooler is in close contact with the tunable optical filter, with its hot side in contact with the metal layer of the flexible circuit board and its cold side in contact with the heat sink. The heat sink is disposed on the thermoelectric cooler, and the heat sinks on both sides of the thermoelectric cooler contact the surface of the flexible circuit board while avoiding the metal layer of the flexible circuit board. Advantages: This invention uses irregularly shaped heat sinks, mounted in reverse using a TEC (thermal energy transfer circuit) onto a flexible strip containing a substrate. The total thickness is only 1.75 mm. Due to the large chamfer of the heat sink, the lens can penetrate deep into the center of the tunable optical filter assembly, increasing the actual thickness by 1.2~1.5 mm.

Description

Technical Field

[0001] This invention relates to the field of optical transmitter-receiver subassemblies (hereinafter referred to as BOSA), specifically to a tunable optical filter assembly. Background Technology

[0002] With the development of optical communication technology, the requirements for PON optical modules are becoming increasingly stringent. In order to increase the transmission distance, users are encouraged to use wavelength division multiplexers instead of splitters to reduce insertion loss; this necessitates tunable optical filters at the receiving end to filter out unwanted wavelengths.

[0003] However, the complex structure and excessive thickness make BOSA design extremely difficult, even preventing the use of low-cost traditional BOSA structures. Therefore, reducing the thickness of tunable optical filter assemblies has become an urgent problem to be solved. Summary of the Invention

[0004] The technical problem to be solved by this invention is: how to reduce the thickness of tunable optical filter assemblies.

[0005] To address the aforementioned technical problems, this invention proposes a tunable optical filter assembly. It employs an irregularly shaped heat sink, mounted in reverse using a thermoelectric cooler (TEC) on a flexible circuit board containing a substrate. The total thickness is only 1.75 mm. Due to the large chamfered edges of the heat sink, the lens of the light-receiving component within the optical module can extend deep into the center of the tunable optical filter assembly, increasing the actual thickness by 1.2 to 1.5 mm. Therefore, it can easily adopt a traditional BOSA structure, significantly reducing costs.

[0006] The specific technical solutions adopted are as follows:

[0007] A tunable optical filter assembly includes a tunable optical filter, a substrate, a flexible circuit board, a temperature sensor, a heat sink, and a thermoelectric cooler. The flexible circuit board is disposed on the substrate. The tunable optical filter, temperature sensor, and thermoelectric cooler are all disposed on the metal layer of the flexible circuit board. The thermoelectric cooler is in close contact with the tunable optical filter, with its hot side in contact with the metal layer of the flexible circuit board and its cold side in contact with the heat sink. The heat sink is disposed on the thermoelectric cooler, with the heat sinks on both sides of the thermoelectric cooler contacting the surface of the flexible circuit board and avoiding the metal layer of the flexible circuit board. The heat sink does not obstruct the tunable optical filter and the temperature sensor.

[0008] A further preferred embodiment of the technical solution of the present invention includes an L-shaped heat sink body with three arc surfaces on its outer surface. These three arc surfaces are located at the outermost two ends of the L-shaped heat sink body and at the right-angle bend. The purpose of these three arc surfaces is to allow the tunable optical filter assembly of the present invention to be installed into the mounting holes of the BOSA body.

[0009] A further preferred embodiment of the technical solution of the present invention includes a partition groove formed on each of two adjacent arc surfaces along the height direction of the L-shaped heat sink body. Thermally conductive adhesive is coated on the outer surface of the L-shaped heat sink body between the two partition grooves. The partition grooves prevent the thermally conductive adhesive from overflowing onto the thermoelectric cooler, thus avoiding a short hot-cold surface.

[0010] In a further preferred embodiment of the technical solution of the present invention, the upper end face of the heat sink is recessed to avoid the chamfer of the lens inside the light receiving component. The chamfer is to avoid the lens of the light receiving component, so that the light receiving component can use the space inside the tunable optical filter, making the tunable optical filter component of the present invention applicable to the conventional BOSA structure.

[0011] In a further preferred embodiment of the technical solution of the present invention, the lower end face of the heat sink is concavely cut to form a notch for installing the thermoelectric cooler, and grooves are cut on the lower end face of the heat sink on both sides of the notch to avoid the metal layer on the flexible circuit board.

[0012] In a further preferred embodiment of the technical solution of the present invention, the lower end face of the heat sink is provided with a first ground pin and a second ground pin; in order to better fix the heat sink, both the first ground pin and the second ground pin are glued to the flexible circuit board and avoid the metal layer of the flexible circuit board.

[0013] In a further preferred embodiment of the technical solution of the present invention, the temperature sensor is located close to the tunable optical filter and soldered onto the metal layer of the flexible circuit board. The temperature sensor is positioned very close to the tunable optical filter to accurately reflect its temperature.

[0014] A further preferred embodiment of the technical solution of the present invention is that metal layers are symmetrically arranged on the flexible circuit board, and a bottleneck area is provided between the metal layers.

[0015] In a further preferred embodiment of the technical solution of the present invention, the substrate is made of FRP glass fiber reinforced resin board.

[0016] The present invention also proposes a BOSA structure, comprising a BOSA body, an optical receiving component, an optical emitting component, and a tunable optical filter component as described in any one of claims 1-9, wherein the optical emitting component is installed in and coupled to the BOSA body, the tunable optical filter component is installed in the BOSA body, and the optical receiving component is installed in and coupled to the BOSA body.

[0017] The advantages of this invention compared to the prior art are as follows:

[0018] The tunable optical filter assembly of the present invention employs an irregularly shaped heat sink, which is mounted in reverse on a flexible strip containing a substrate using a TEC (Transformer Electrode Array). The total thickness is only 1.75 mm. Due to the large chamfer of the heat sink, the lens can penetrate deep into the center of the tunable optical filter assembly, increasing the actual thickness by 1.2 to 1.5 mm.

[0019] The BOSA structure of the tunable optical filter assembly of the present invention can be conveniently adopted from the traditional BOSA structure, which greatly reduces the cost. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the structure of the tunable optical filter assembly in the first direction of Embodiment 1;

[0021] Figure 2 This is a schematic diagram of the second direction structure of the tunable optical filter assembly in Embodiment 1;

[0022] Figure 3 This is a front view of the tunable optical filter assembly of Embodiment 1;

[0023] Figure 4 yes Figure 3 AA section view;

[0024] Figure 5 yes Figure 3 A front view of the tunable optical filter assembly in this embodiment, with the heat sink hidden;

[0025] Figure 6 yes Figure 5 BB section view;

[0026] Figure 7 This is a three-dimensional schematic diagram of the heat sink in the first direction;

[0027] Figure 8 This is a three-dimensional schematic diagram of the heat sink from a second direction;

[0028] Figure 9 This is a three-dimensional diagram of the heat sink from a third-angle perspective;

[0029] Figure 10 This is the front view of the BOSA structure in this embodiment;

[0030] Figure 11 yes Figure 10 CC section view;

[0031] Figure 12 This is a front view of the tunable optical filter assembly of Embodiment 2;

[0032] Among them, 1-flexible circuit board, 2-heating resistor, 3-tunable optical filter, 4-temperature sensor, 5-substrate, 51-light-passing hole, 6-heat sink, 61-chamfer, 62-insulating groove, 63-first ground pin, 64-second ground pin, 65-arc surface, 66-notch, 67-groove, 7-thermoelectric cooler, 8-tunable optical filter assembly, 9-45-degree filter, 10-light receiving assembly, 10-1, lens, 11-light emitting assembly, 12-BOSA body. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the following description is provided in conjunction with the appendix. Figures 1-12 The present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. Example 1

[0034] like Figure 1-6 As shown, this embodiment is a tunable optical filter assembly, including a flexible circuit board 1, a tunable optical filter 3, a temperature sensor 4, a substrate 5, a heat sink 6, and a thermoelectric cooler 7.

[0035] like Figure 7-9 As shown, the heat sink 6 is irregularly shaped. In this embodiment, the tunable optical filter assembly uses an irregularly shaped heat sink mounted on a flexible circuit board 1 containing a substrate 5 via a thermoelectric cooler 7 (TEC).

[0036] The total thickness of the tunable optical filter assembly is only 1.75 mm. Due to the large chamfer on the heat sink 6, the lens can extend deep into the center of the tunable optical filter assembly, increasing the actual thickness by 1.2 to 1.5 mm. Therefore, the traditional BOSA structure can be easily adopted, greatly reducing costs.

[0037] like Figure 5-6 As shown, the relative positions of the flexible circuit board 1, the tunable optical filter 3, the temperature sensor 4, the substrate 5, and the thermoelectric cooler 7 are as follows: The flexible circuit board 1 and the substrate 5 are glued together. The substrate 5 is a heat-insulating material, preferably made of FRP (fiberglass reinforced resin). In actual manufacturing, it is fabricated from a single piece by the manufacturer of the flexible circuit board 1, and has a light-transmitting hole 51 in the middle.

[0038] like Figure 5 As shown, the flexible circuit board 1 has a bottleneck area 1-1, which is to reduce the heat transferred to the outside and improve the heating and cooling efficiency.

[0039] like Figure 5-6As shown, the tunable optical filter 3, temperature sensor 4, and thermoelectric cooler 7 are all mounted on the metal layer 1-2 of the flexible circuit board 1. The temperature sensor 4 is located close to the tunable optical filter 3 to accurately reflect its temperature. Because the thermoelectric cooler 7 is relatively tall, it can only be placed on the side of the tunable optical filter 3. Therefore, the hot side of the thermoelectric cooler 7 can only transfer heat to the tunable optical filter 3 through the metal layer on the flexible circuit board 1. Simultaneously, the cold side of the thermoelectric cooler 7 is attached to the heat sink 6, which is the opposite of the traditional thermoelectric cooler structure. This is because this mounting arrangement allows the electrodes of the thermoelectric cooler to face upwards, facilitating wire bonding.

[0040] like Figure 7-9 As shown, the heat sink 6 is irregularly shaped and made of aluminum alloy. It includes an L-shaped heat sink body. The heat sink 6 is generally L-shaped, with a large chamfer on the inner side. Specifically, the upper surface of the L-shaped heat sink body is recessed to avoid the chamfer 61 of the inner lens of the light receiving component 10. The chamfer 61 is to avoid the lens of the light receiving component, allowing the light receiving component to utilize the space within the tunable optical filter, thus effectively reducing the space occupied.

[0041] like Figure 3 and 9 As shown, the side of the L-shaped heat sink body is bonded to the inner cavity of the BOSA with thermally conductive adhesive. Specifically, three arc surfaces 65 are provided on the outer surface of the L-shaped heat sink body, namely the outermost two ends and the right-angle bend of the L-shaped heat sink body. An adhesive-separating groove 62 is formed along the height direction of the L-shaped heat sink body on each of two adjacent arc surfaces 65. Thermally conductive adhesive is coated on the outer surface of the L-shaped heat sink body between the two adhesive-separating grooves 62. The two adhesive-separating grooves 62 prevent thermally conductive adhesive from overflowing onto the thermoelectric cooler 7, which could cause a short circuit between the hot and cold surfaces of the thermoelectric cooler 7.

[0042] like Figure 7 and 8 As shown, the lower end face of the L-shaped heat sink body is concavely cut to form a notch 66 for mounting the thermoelectric cooler 7. Grooves 67 are then cut on the lower end faces of the heat sink 6 on both sides of the notch 66 to avoid the metal layer on the flexible circuit board 1. Figure 7-9 As shown, the remaining portion on the lower end face of the heat sink 6 is provided with a first ground pin 63 and a second ground pin 64; both the first ground pin 63 and the second ground pin 64 are glued to the flexible circuit board 1 and avoid the metal layer of the flexible circuit board 1; both the first ground pin 63 and the second ground pin 64 are very narrow.

[0043] like Figure 10-11 As shown, this embodiment proposes a BOSA structure.

[0044] Since the SFP optical module size is fixed, the traditional BOSA structure only has a little over 1 millimeter of space left, making it impossible to fit into typical structures. The traditional BOSA structure is very mature, with low component costs, readily available tooling and fixtures, and low manufacturing costs.

[0045] Therefore, the design proposed in this invention can use the traditional 45-degree filter BOSA structure, which greatly reduces costs and has good economic benefits.

[0046] The tunable optical filter assembly 8 in this embodiment has a total thickness of only 1.75 mm. Because the heat sink 6 has a large chamfer 61, which is designed to avoid obstructing the lens 10-1 of the light receiving assembly 10, the light receiving assembly can utilize the space within the tunable optical filter, effectively reducing the space occupied. The lens 10-1 can extend deep into the center of the tunable optical filter assembly, increasing the actual thickness by 1.2~1.5 mm. Therefore, a traditional BOSA structure can be easily adopted, significantly reducing costs.

[0047] The BOSA structure of this embodiment includes a BOSA body 12, an optical receiving component 10, an optical emitting component 11, and a tunable optical filter component 8. The optical emitting component 11 is installed in the BOSA body 12 and coupled, the tunable optical filter component 8 is installed in the BOSA body 12, and the optical receiving component 10 is installed in the BOSA body 12 and coupled and fixed.

[0048] As shown in the figure, light entering the BOSA structure from the outside on the right is reflected by the 45-degree filter 9, then passes through the tunable optical filter assembly 8, and enters the optical receiving assembly 10. This achieves narrowband reception of the optical signal. Meanwhile, the optical signal emitted by the optical transmitting assembly 11 passes through the 45-degree filter 9 and is transmitted to the external optical fiber, thus achieving optical signal transmission. Example 2

[0049] like Figure 12 As shown, this embodiment also proposes a tunable optical filter assembly, including a flexible circuit board 1, an electrothermal resistor 2, a tunable optical filter 3, a temperature sensor 4, and a substrate 5.

[0050] The difference between this embodiment and Embodiment 1 is that a heating resistor 2 with a small adjustment range is used instead of the thermoelectric cooler 7. Since the thermoelectric cooler 7 is not used, its internal temperature is not high, and a heat sink 6 is not required. The rest of the structure is the same as in Embodiment 1.

[0051] In this embodiment, the heating resistor 2 is glued to the tunable optical filter 3. In order to improve the heating efficiency, the temperature of the tunable optical filter 3 is changed by heating, thereby changing the center wavelength of its wave.

[0052] The tunable optical filter assembly of this embodiment has the advantage of being cheaper than that of Embodiment 1. As is known to those skilled in the art, the thermoelectric cooler 7 is expensive, while the heating resistor 2 is inexpensive. The disadvantage is that it has a smaller adjustment range and can only heat. In contrast, the thermoelectric cooler 7 has a larger adjustment range and can both heat and cool.

[0053] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A tunable optical filter assembly, comprising a tunable optical filter (3) and a substrate (5), characterized in that, It also includes a flexible circuit board (1), a temperature sensor (4), a heat sink (6) and a thermoelectric cooler (7). The flexible circuit board (1) is disposed on a substrate (5). The tunable optical filter (3), the temperature sensor (4) and the thermoelectric cooler (7) are all disposed on the metal layer of the flexible circuit board (1). The thermoelectric cooler (7) is in close contact with the tunable optical filter (3), and the hot side of the thermoelectric cooler (7) is in contact with the metal layer of the flexible circuit board (1), and the cold side of the thermoelectric cooler (7) is in contact with the heat sink (6). The heat sink (6) is disposed on the thermoelectric cooler (7), and the heat sink (6) located on both sides of the thermoelectric cooler (7) contacts the surface of the flexible circuit board (1) and avoids the metal layer of the flexible circuit board (1); the heat sink (6) does not block the tunable optical filter (3) and the temperature sensor (4). Among them, the heat sink (6) is irregularly shaped, including an L-shaped heat sink body. The upper end face of the L-shaped heat sink body is recessed to avoid the chamfer (61) of the inner lens of the light receiving component (10).

2. The tunable optical filter assembly according to claim 1, characterized in that, Three arc surfaces (65) are provided on the outer surface of the L-shaped heat sink body. The three arc surfaces (65) are the outermost two ends of the L-shaped heat sink body and the right angle turn point, respectively.

3. The tunable optical filter assembly according to claim 2, characterized in that, A partition groove (62) is opened on each of the two adjacent arc surfaces (65) along the height direction of the L-shaped heat sink body, and thermally conductive adhesive is coated on the outer surface of the L-shaped heat sink body between the two partition grooves (62).

4. The tunable optical filter assembly according to claim 2, characterized in that, The lower end face of the heat sink (6) is recessed to form a notch (66) for installing the thermoelectric cooler (7). On the lower end face of the heat sink (6) on both sides of the notch (66), grooves (67) are cut to avoid the metal layer on the flexible circuit board (1).

5. The tunable optical filter assembly according to claim 4, characterized in that, The lower end face of the heat sink (6) is provided with a first ground pin (63) and a second ground pin (64); the first ground pin (63) and the second ground pin (64) are both glued to the flexible circuit board (1) and avoid the metal layer of the flexible circuit board (1).

6. The tunable optical filter assembly according to claim 1, characterized in that, The temperature sensor (4) is placed close to the tunable optical filter (3) and soldered onto the metal layer of the flexible circuit board (1).

7. The tunable optical filter assembly according to claim 1, characterized in that, Metal layers are symmetrically arranged on the flexible circuit board (1), and a bottleneck area (11) is provided between the metal layers.

8. The tunable optical filter assembly according to claim 1, characterized in that, The substrate (5) is made of glass fiber reinforced resin board.

9. A structure for an optical transmitter-receiver sub-assembly, characterized in that, The device includes an optical transmitter-receiver sub-assembly body (12), an optical receiver assembly (10), an optical transmitter assembly (11), and a tunable optical filter assembly (8) as described in any one of claims 1-8. The optical transmitter assembly (11) is installed in the optical transmitter-receiver sub-assembly body (12) and coupled thereto. The tunable optical filter assembly (8) is installed inside the optical transmitter-receiver sub-assembly body (12), and the optical receiver assembly (10) is installed in the optical transmitter-receiver sub-assembly body (12) and coupled thereto.

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