A thermal conductivity testing device and method for a gain fiber potting and encapsulation

Abstract

The present invention relates to the technical field of optical fiber testing, and provides a thermal conductivity testing device and method for potting and encapsulating a gain fiber. The device includes: a water cooling system with a monitoring function, a first monitoring optical power meter, a control main board, and a pump source, a gain fiber, a laser output module, and a second monitoring optical power meter that are sequentially connected along the laser output direction. The first monitoring optical power meter is connected to the pump source. The gain fiber is covered with a potting glue layer and fixed to the water cooling system through the potting glue layer. The control main board is respectively connected to the pump source and the water cooling system, realizing the testing of the heat dissipation ability of the gain fiber and the comparison of the thermal conductivity of different potting glue layers.

Description

Technical Field

[0001] The present invention relates to the technical field of optical fiber testing, and in particular to a thermal conductivity testing device and method for potting and encapsulating a gain optical fiber. Background Art

[0002] As the core component of a high-power fiber laser, the gain optical fiber will generate a large amount of heat while converting the input pump light into high-quality fiber laser during operation. If this heat is not removed in time to cool the gain optical fiber, it will cause serious consequences such as a decrease in the conversion efficiency of the gain optical fiber, difficulty in controlling the laser mode, a decrease in the fiber life, and even fiber burnout. As a result, the output power of the laser will decrease, the beam quality will deteriorate, the output power will fluctuate, and the laser cannot be output, thus affecting the final processing speed, processing quality, and even unable to process. Therefore, the heat dissipation ability of the gain optical fiber is also one of the key factors restricting the further improvement of the output power of high-power fiber lasers.

[0003] The main material of the gain optical fiber is quartz glass, and a corresponding protective coating is coated on the outside of the quartz glass. A large amount of heat is generated by the quantum deficit in the core. The heat in the core needs to be conducted through the cladding to the coating layer before being transferred to the heat dissipation substrate. However, since the gain optical fiber is circular and the coating is not pressure-resistant, in order to increase the heat dissipation area and accelerate heat conduction without damaging the optical fiber, it is often necessary to fill a glue with thermal conductivity as the heat transfer medium between the gain optical fiber and the heat dissipation substrate. After absorbing the heat on the surface of the gain optical fiber, it is then conducted to the heat dissipation substrate to finally achieve the purpose of dissipating heat and cooling the gain optical fiber. This type of glue filled between the gain optical fiber and the heat dissipation substrate can effectively protect the gain optical fiber while conducting heat, and is often called a potting glue layer. The process of filling the glue between the gain optical fiber and the heat dissipation substrate is usually called potting and encapsulating the gain optical fiber. Therefore, it is very important to evaluate the heat dissipation ability of the gain optical fiber and the heat conduction ability of different potting glue layers for the gain optical fiber, and to select a potting glue with suitable heat dissipation performance for the gain optical fiber. Summary of the Invention

[0004] Based on this, the present invention provides a thermal conductivity testing device and method for potting and encapsulating a gain optical fiber, which can be used to evaluate the heat dissipation ability of the gain optical fiber and the heat conduction ability of different potting glue layers for the gain optical fiber.

[0005] In a first aspect, the present invention provides a thermal conductivity testing device for a gain fiber potting package, comprising: a water cooling system with a monitoring function, a first monitoring optical power meter, a control main board, and a pump source, a gain fiber, a laser output module, and a second monitoring optical power meter that are connected in sequence along the laser output direction. The first monitoring optical power meter is connected to the pump source. The gain fiber is covered with a potting glue layer and fixed to the water cooling system through the potting glue layer. The control main board is respectively connected to the pump source and the water cooling system, wherein,

[0006] the first monitoring optical power meter is used to monitor the pump optical power output from the pump source, the second monitoring optical power meter is used to monitor the laser power output from the laser output module, the water cooling system with a monitoring function is used to absorb and monitor the conduction heat of the gain fiber, and the control main board is used to respectively control the operation of the pump source and the water cooling system.

[0007] In a second aspect, the present invention provides a thermal conductivity testing method for a gain fiber potting package, which is tested using the thermal conductivity testing device for a gain fiber potting package, comprising:

[0008] Step S11: Monitor, through the first monitoring optical power meter, the pump optical power output by the pump source when different pump optical powers are output, obtain the corresponding monitored pump optical power, and obtain the ratio γ of the pump optical power to the monitored pump optical power according to the different pump optical powers and the corresponding monitored pump optical powers;

[0009] Step S12: Connect the pump source, the gain fiber, and the laser output module in sequence, and cover the gain fiber with a potting glue layer and fix it to the water cooling system with a monitoring function through the potting glue layer;

[0010] Step S13: Control the pump source to emit pump light and the water cooling system with a monitoring function to operate. Monitor, through the first monitoring optical power meter, the pump light output by the pump source to obtain the monitored pump optical power P1, monitor and obtain the laser power P2 output from the laser output module through the second monitoring optical power meter, and monitor the conduction heat of the gain fiber through the water cooling system with a monitoring function.

[0011] Advantages of the present invention:

[0012] The present invention provides a thermal conductivity testing device for a gain fiber with potting encapsulation, comprising: a water-cooling system with monitoring function, a first monitoring optical power meter, a control main board, and a pump source, a gain fiber, a laser output module, and a second monitoring optical power meter connected in sequence along the laser output direction. The first monitoring optical power meter is connected to the pump source. The gain fiber is covered with a potting glue layer and fixed to the water-cooling system through the potting glue layer. The control main board is respectively connected to the pump source and the water-cooling system. Among them, the first monitoring optical power meter is used to monitor the pump optical power output from the pump source, the second monitoring optical power meter is used to monitor the laser power output from the laser output module, the water-cooling system with monitoring function is used to absorb and monitor the conduction heat of the gain fiber, and the control main board is used to respectively control the operation of the pump source and the water-cooling system. Compared with the prior art, the present invention can evaluate the heat dissipation ability of the gain fiber and the thermal conductivity ability of the thermal conductive glue layer to the gain fiber.

[0013] A thermal conductivity testing method for a gain fiber with potting encapsulation provided by the present invention is tested by using the above thermal conductivity testing device for a gain fiber with potting encapsulation, which can realize the testing of the heat dissipation ability of the gain fiber and the thermal conductivity ability of the thermal conductive glue layer to the gain fiber, and has high accuracy. Description of the Drawings

[0014] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following will briefly introduce the drawings required for description in the embodiments. Obviously, the following drawings are only some embodiments of the present invention. For those skilled in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0015] Figure 1 Structural block diagram of a thermal conductivity testing device for a gain fiber with potting encapsulation provided by an embodiment of the present invention;

[0016] Figure 2 Specific structural diagram of a thermal conductivity testing device for a gain fiber with potting encapsulation provided by an embodiment of the present invention;

[0017] Figure 3 Flowchart of a thermal conductivity testing method for a gain fiber with potting encapsulation provided by an embodiment of the present invention. Detailed Embodiments

[0018] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present invention.

[0019] It should be noted that when an element is expressed as "provided in" / "arranged in" another element, it can be directly on the other element, or there can be one or more intermediate elements therebetween. In addition, in this specification, the terms "first" and "second" do not limit the data and execution order, but only distinguish items or similar items with basically the same function and role. The present invention defines the position of components with reference to the output / emission direction of the laser.

[0020] An embodiment of the present invention provides a thermal conductivity testing device 1 for gain fiber potting and encapsulation, as Figure 1 shown, including: a water cooling system 11 with monitoring function, a first monitoring optical power meter 12, a control main board 13, and a pump source 14, a gain fiber 15, a laser output module 16, and a second monitoring optical power meter 17 connected in sequence along the laser output direction. The first monitoring optical power meter 12 is connected to the pump source 14. The gain fiber 15 is covered with a potting glue layer 18 and fixed on the water cooling system 11 through the potting glue layer 18. The control main board 13 is respectively connected to the pump source 14 and the water cooling system 11. Among them,

[0021] The first monitoring optical power meter 12 is used to monitor the power of the pump light output from the pump source 14, the second monitoring optical power meter 17 is used to monitor the laser power output from the laser output module 16, the water cooling system 11 with monitoring function is used to absorb and monitor the conduction heat of the gain fiber 15, and the control main board 13 is used to respectively control the operation of the pump source 14 and the water cooling system 11.

[0022] Furthermore, as Figure 2 shown, the thermal conductivity testing device 1 for gain fiber potting and encapsulation in the embodiment of the present invention further includes: an optical fiber reel 22, a high-reflection fiber grating 19, a low-reflection fiber grating 20, and a cladding mode stripper 21. The high-reflection fiber grating 19, the gain fiber 15, the low-reflection fiber grating 20, and the cladding mode stripper 21 are arranged in sequence along the laser output direction. The gain fiber 15 is wound around the optical fiber reel 22 through the potting glue layer 18. Among them, the optical fiber reel 22 is made of a material with good thermal conductivity, such as copper or aluminum alloy, to ensure that the heat dissipated by the gain fiber 15 can be quickly transferred to the water cooling system 11 through the optical fiber reel 22.

[0023] Further, as Figure 2 shown, the water-cooling system 11 with a monitoring function described in the embodiment of the present invention includes: a water chiller 111, a water-cooling plate 115, a water inlet pipe 112 and a water outlet pipe 113 respectively arranged on the water chiller 111. The optical fiber reel 22 is fixed on the water-cooling plate 115. A flow meter 114 is arranged on the water inlet pipe 112. The water-cooling plate 115 is provided with a water inlet 117, a water outlet 117 and a cooling channel (not shown) inside. A first temperature detector 119 is arranged on the water inlet 117, and a second temperature detector 118 is arranged on the water outlet 116. The cooling water in the water chiller 111 sequentially passes through the water outlet pipe 113, the water inlet 117, the cooling channel (not shown), the water outlet 116 and the water inlet pipe 112 and returns to the water chiller. The first temperature detector 119 is used to monitor the temperature of the cooling water when it flows into the water-cooling plate 115, and the second temperature detector 118 is used to monitor the temperature of the cooling water when it flows out of the water-cooling plate 115. Among them, the flow meter 114 is used to monitor the flow rate of the cooling water passing through the water outlet pipe, and the flow rate refers to the volume of the cooling water flowing per unit time.

[0024] It should be noted that the water chiller 111 in the embodiment of the present invention includes a refrigeration system (not shown) and a water pump (not shown). The refrigeration system is used to refrigerate the cooling water returned to the water chiller 111 to keep the temperature of the cooling water flowing out of the water chiller through the water outlet pipe 113 stable. The water pump (not shown) is used to stably discharge the cooling water from the water outlet pipe 113, so as to maintain the stability of the operation of the water chiller and further ensure the accuracy of the thermal conductivity testing device 1 for the gain fiber potting and encapsulation during the testing process. Further, in this embodiment, the thermal conductivity testing device 1 for the gain fiber potting and encapsulation further includes a first driving circuit (not shown) and a second driving circuit (not shown) connected to the control main board. The first driving circuit (not shown) is connected to the pump source 14, and the second driving circuit (not shown) is connected to the water-cooling system 11 with a monitoring function, specifically, connected to the water chiller 111.

[0025] In addition, in this embodiment, the laser output module 16 is a laser output head (QBH) or a laser collimator (QCS). If the gain fiber 15 is applied to a medium-high power laser, the laser output module 16 is a laser output head (QBH); if the gain fiber is applied to a low-power laser, the laser output module 16 is a laser collimator (QCS).

[0026] The embodiment of the present invention also provides a method for testing the thermal conductivity of the gain fiber potting and encapsulation, which is tested by using the thermal conductivity testing device 1 for the gain fiber potting and encapsulation. Please refer to Figure 3 and in combination with Figure 1 andFigure 2 , including:

[0027] Step S11: When the pump source 14 outputs different pump optical powers, monitor the corresponding pump monitoring optical power through the first monitoring optical power meter 12, and obtain the ratio γ of the pump optical power to the pump monitoring optical power according to the different pump optical powers output by the pump source 14 and the corresponding pump monitoring optical powers.

[0028] Step S12: Connect the pump source 14, the gain fiber 15, and the laser output module 16 in sequence, cover a potting glue layer on the gain fiber 15, and fix it on the water-cooling system 11 with monitoring function through the potting glue layer 18.

[0029] Step S13: Control the pump source 14 to emit pump light and the water-cooling system with monitoring function to work. Monitor the pump monitoring optical power P1 of the pump light output by the pump source 14 through the first monitoring optical power meter 12, monitor the laser power P2 output from the laser output module through the second monitoring optical power meter 17, and measure the conduction heat of the gain fiber 15 through the water-cooling system 11 with monitoring function.

[0030] Specifically, in step S11, as the pump optical power output by the pump source 14 gradually increases, monitor the different pump optical powers output by the pump source 14 through the first monitoring optical power meter 12, and the obtained pump monitoring optical power also gradually increases. Use the least squares method for fitting calculation according to the gradually increasing pump optical power and pump monitoring optical power to obtain the ratio γ of the pump optical power to the pump monitoring optical power. According to the ratio γ, when the pump monitoring optical power P1 is known, the pump optical power γP1 output by the pump source 14 can be deduced.

[0031] Furthermore, the thermal conductivity test device 1 for potting and encapsulating the gain fiber in the embodiment of the present invention further includes: an optical fiber reel 22, a high-reflection fiber grating 19, a low-reflection fiber grating 20, and a cladding mode stripper 21. Specifically, in step S12, building a complete test device includes: connecting the pump source 14, the high-reflection fiber grating 19, the gain fiber 15, the low-reflection fiber grating 20, the cladding mode stripper 21, and the laser output module 16 in sequence, and fixing the gain fiber 15 on the water-cooling system 11 with monitoring function through the potting glue layer 18.

[0032] Furthermore, before step S13, it further includes: debugging the water-cooling system with monitoring function until it can work stably and normally to ensure the accuracy of the test results during the test of the thermal conductivity test device 1 for potting and encapsulating the gain fiber.

[0033] Such as Figure 2As shown, specifically, in step S13 of this embodiment, measuring the heat conducted by the gain fiber through the water-cooling system 11 with a monitoring function includes: detecting the stable temperature T1 of the water inlet 117 through the first temperature detector 119, detecting the stable temperature T2 of the water outlet 116 through the second temperature detector 118, and measuring the flow rate L of the cooling water passing through the outlet pipe through the flow meter 114, so as to obtain the heat cρ(T2 - T1)L conducted by the cooling system from the gain fiber, where c is the specific heat capacity of water and ρ is the density of water.

[0034] Further, the method for testing the thermal conductivity of the gain fiber encapsulated with glue in this embodiment further includes: obtaining the thermal conductivity coefficient β of the gain fiber. The larger the β value, the stronger the self-thermal conduction ability of the gain fiber, that is, the stronger its self-heat dissipation ability, where

[0035] .

[0036] Specifically, the gain fiber 15 converts the input pump power into laser. In this process, there is energy loss, and the lost energy is converted into heat. Also, since the cross-section of the gain fiber 15 is circular and the contact area with the fiber disk 22 is small, a potting glue layer 18 is used to cover the gain fiber and is fixed on the fiber disk 22 through the potting glue layer 18. Therefore, this part of the heat is first transferred to the potting glue layer 18, and then sequentially transferred to the fiber disk 22 and the water-cooling plate 115 through the potting glue layer 18. The cooling water entering the water-cooling plate 115 continuously carries the heat to the water-cooling machine 111, and finally the water-cooling machine 111 convects the transferred heat to the air. Then, the thermal power that the gain fiber 15 needs to consume or take away in this process is P2 - γP1, while the actual thermal power taken away or consumed by the gain fiber by the water-cooling plate 115 is cρ(T2 - T1)L. It can be understood that the thermal conductivity coefficient β of the gain fiber 15 is defined as the ratio of the actual heat power excluded by the gain fiber 15 to the heat power it needs to take away. That is, the larger the thermal conductivity coefficient of the gain fiber 15, the stronger its heat dissipation ability can be understood.

[0037] In order to obtain a more accurate thermal conductivity coefficient β of the gain fiber and eliminate the interference of different types of potting glue layers 18 on the test results, this embodiment further includes step S15: controlling the pump source 14 to output different pump optical powers, obtaining the corresponding thermal conductivity coefficient β of the gain fiber 15 and averaging and fitting it to obtain the final thermal conductivity coefficient β value.

[0038] In addition, the thermal conductivity test method for the gain fiber potting and encapsulation provided in this embodiment can also determine the thermal conduction ability of different potting glue layers to the gain fiber. Based on the above steps, this embodiment further includes step S16. In step S16, the potting glue layer 18 in step S12 is replaced with other types of potting glue layers, and the thermal conduction ability of the gain fiber 15 in the case of other types of potting glue layers is continuously tested according to steps S13 to S15, that is, the thermal conductivity coefficient β is obtained. The thermal conduction abilities of different types of potting glue layers are compared and judged according to the magnitude of the obtained thermal conductivity coefficient β. If the thermal conductivity coefficient β is larger, the thermal conduction ability of the corresponding potting glue layer 18 is stronger.

[0039] In summary, a thermal conductivity test device 1 for gain fiber potting and encapsulation provided by an embodiment of the present invention includes: a water cooling system 11 with a monitoring function, a first monitoring optical power meter 12, a control main board 13, and a pump source 14, a gain fiber 15, a laser output module 16, and a second monitoring optical power meter 17 that are sequentially connected along the laser output direction. The first monitoring optical power meter 12 is connected to the pump source 14. The gain fiber 15 is covered with a potting glue layer 18 and fixed on the water cooling system 11 through the potting glue layer 18. The control main board 13 is respectively connected to the pump source 14 and the water cooling system 11. Compared with the prior art, the test of the heat dissipation ability of the gain fiber and the comparison of the thermal conductivity of different potting glue layers are realized.

[0040] In addition, a thermal conductivity test method for gain fiber potting and encapsulation provided by the present invention is tested by using the above thermal conductivity test device 1 for gain fiber potting and encapsulation, which can realize the test of the heat dissipation ability of the gain fiber 15 and the thermal conduction ability of the thermal conductive glue layer to the gain fiber, and has high accuracy.

[0041] The above has introduced in detail a thermal conductivity test device and method for gain fiber potting and encapsulation provided by an embodiment of the present invention. Specific examples are used in this article to elaborate on the principle and implementation manner of the present invention. The description of the above embodiments is only used to help understand the method and its core idea of the present invention; at the same time, for those skilled in the art, according to the idea of the present invention, there will be changes in the specific implementation manner and application scope. In summary, the content of this specification should not be construed as a limitation to the present invention.

Claims

1. A thermal conductivity testing device for a gain fiber with glue injection encapsulation, characterized in that, Including: A water-cooling system with a monitoring function, a first monitoring optical power meter, a control main board, and a pump source, a gain fiber, a laser output module, and a second monitoring optical power meter connected in sequence along the laser output direction. The first monitoring optical power meter is connected to the pump source. The gain fiber is covered with a potting glue layer and fixed to the water-cooling system through the potting glue layer. The control main board is respectively connected to the pump source and the water-cooling system. Among them, The first monitoring optical power meter is used to monitor the pump optical power output from the pump source, and is used to perform fitting calculation according to the least square method to obtain the ratio γ of the pump optical power to the pump monitoring optical power. The second monitoring optical power meter is used to monitor the laser power output from the laser output module. The water-cooling system with a monitoring function is used to absorb and monitor the conduction heat of the gain fiber. The control main board is used to respectively control the operation of the pump source and the water-cooling system. The thermal conductivity coefficient of the gain fiber is obtained through the pump optical power, the laser power, and the conduction heat of the gain fiber, and the thermal conduction ability of the corresponding potting glue layer is judged.

2. The thermal conductivity testing device for a gain fiber with glue injection encapsulation according to claim 1, characterized in that, Further including: An optical fiber reel, a high-reflection fiber grating, a low-reflection fiber grating, and a cladding mode stripper. The high-reflection fiber grating, the gain fiber, the low-reflection fiber grating, and the cladding mode stripper are arranged in sequence along the laser output direction. The gain fiber is wound in the optical fiber reel through the potting glue layer.

3. The thermal conductivity testing device for a gain fiber with glue injection encapsulation according to claim 2, characterized in that, The water-cooling system with a monitoring function includes a water chiller, a water-cooling plate, and a water inlet pipe and a water outlet pipe respectively arranged on the water chiller. The optical fiber reel is fixed to the water-cooling plate. A flow meter is arranged on the water inlet pipe. The water-cooling plate is provided with a water inlet, a water outlet, and a cooling channel therein. A first temperature detector is arranged on the water inlet, and a second temperature detector is arranged on the water outlet. The cooling water in the water chiller sequentially returns to the water chiller through the water outlet pipe, the water inlet, the cooling channel, the water outlet, and the water inlet pipe. The first temperature detector is used to monitor the temperature when the cooling water flows into the water-cooling plate, and the second temperature detector is used to monitor the temperature when the cooling water flows out of the water-cooling plate. The flow meter is used to monitor the flow rate of the cooling water passing through the water outlet pipe.

4. The thermal conductivity testing device for a gain fiber with glue injection encapsulation according to any one of claims 1-3, characterized in that, Further including a first driving circuit and a second driving circuit connected to the control main board. The first driving circuit is connected to the pump source, and the second driving circuit is connected to the water-cooling system with a monitoring function. The laser output module is one of a laser output head or a laser collimator.

5. A thermal conductivity testing method for a gain fiber with glue injection encapsulation, which is tested by using a thermal conductivity testing device for a gain fiber with glue injection encapsulation, and the thermal conductivity testing device includes: A water chiller, a water-cooling plate, and a water inlet pipe and a water outlet pipe respectively arranged on the water chiller. The gain fiber is fixed to the water-cooling plate through a potting glue layer. A flow meter is arranged on the water outlet pipe. The water-cooling plate is provided with a water inlet, a water outlet, and a cooling channel therein. A first temperature detector is arranged on the water inlet, and a second temperature detector is arranged on the water outlet. The cooling water in the water chiller sequentially returns to the water chiller through the water outlet pipe, the water inlet, the cooling channel, the water outlet, and the water inlet pipe. Characterized by including: Step S11: Monitor the pump source at different output pump optical powers through a first monitoring optical power meter to obtain the corresponding monitored pump optical power. Then, perform fitting calculations using the least squares method based on the gradually increasing pump optical power and the monitored pump optical power to obtain the ratio γ of the pump optical power to the monitored pump optical power. Step S12: Connect the pump source, the gain fiber, and the laser output module in sequence. Then, cover a potting glue layer on the gain fiber and fix it to a water-cooling system with monitoring functions through the potting glue layer. Step S13: Control the pump source to emit pump light and the water-cooling system with monitoring functions to operate. Monitor the pump light output by the pump source through a first monitoring optical power meter to obtain the monitored pump optical power P1, monitor and obtain the laser power P2 output from the laser output module through a second monitoring optical power meter, and monitor the heat conducted by the gain fiber through the water-cooling system with monitoring functions. Specifically, detect the stable temperature T1 at the water inlet through a first temperature detector, detect the stable temperature T2 at the water outlet through a second temperature detector, and measure the flow rate L of the cooling water passing through the outlet pipe through the flow meter to obtain the heat conduction power cρ(T2 - T1)L absorbed by the cooling system from the gain fiber, where c is the specific heat capacity of water and ρ is the density of water. Step 14: Obtain the thermal conductivity coefficient β of the gain fiber, where ； Step S15: Control the pump source to output different pump optical powers, obtain the corresponding thermal conductivity coefficient β of the gain fiber, and perform average fitting on it to obtain the final value of the thermal conductivity coefficient β.

6. The thermal conductivity testing method for a gain fiber with glue injection encapsulation according to claim 5, characterized in that, Before the step S13, it also includes: debugging the water-cooling system with monitoring functions until it can operate stably and normally.

7. The thermal conductivity testing method for a gain fiber with glue injection encapsulation according to claim 5, characterized in that, Step S16: After replacing the potting glue layer in step S12 with another type of potting glue layer, continue to test the thermal conductivity coefficient of the gain fiber in the case of the other type of potting glue layer according to steps S13 to S15, and judge its heat conduction ability.

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