Heating element, heating module and heater for annealing fiber bragg grating
The variable temperature gradient annealing of the fiber grating is achieved through heating elements and modules, which solves the problem of traditional low annealing efficiency, improves the stability and yield of the fiber grating, and conforms to the optical fiber light sensitivity characteristics.
Patent Information
- Application Number
- CN202422531834.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-21
- Publication Date
- 2025-08-22
- Estimated Expiration
- 2034-10-21
AI Technical Summary
The traditional fiber grating annealing process is inefficient and cannot efficiently remove residual hydrogen molecules, which affects the stability and service life of the grating optical characteristics. The conventional annealing method does not conform to the optical fiber photosensitive characteristics.
Using heating elements and heating modules, the fiber grating is directly heated and annealed through strips, combined with thermocouple and PLC control, to achieve variable temperature gradient annealing, and the temperature gradient is maintained by the insulation board, and the fiber grating is gradually adaptively annealed in the moving channel.
It improves the efficiency and stability of fiber grating annealing, has more stable optical characteristics, high yield, and conforms to the optical fiber photosensitive characteristics, and is simple and convenient to operate.
Smart Images
Figure CN223255129U_ABST
Abstract
Description
Technical Field
[0001] The utility model belongs to the technical field of grating annealing, and more specifically relates to a heating element, a heating module and a heater for annealing an optical fiber grating. Background Art
[0002] In the field of high-power fiber lasers, as the laser output power increases, the extremely high power density in the fiber core can stimulate the fiber core to produce Raman scattering, which in turn affects the increase in laser power and the laser beam quality. To suppress Raman scattering, ultraviolet writing is often used to create Raman gratings. This method requires sensitization treatment of the fiber, such as hydrogen loading.
[0003] After hydrogen-loaded writing, the Raman grating has unstable optical properties due to the presence of residual hydrogen molecules. Constant high-temperature annealing is often used to remove the incompletely reacted hydrogen molecules. In addition, annealing can eliminate the internal stress on the grating, improve the mechanical properties of the grating and increase the service life of the grating. For some high-power fiber Bragg gratings, such as Bragg gratings, annealing treatment is required. If annealing is not performed, the operating temperature will rise and it is easy to heat up.
[0004] The traditional annealing process places the fiber Bragg grating in a closed furnace for constant high-temperature annealing. The process takes a long time and the furnace must be cooled to the appropriate temperature before the furnace can be opened to remove the fiber, resulting in low work efficiency. Utility Model Content
[0005] In response to the above-mentioned defects or improvement needs of the prior art, the present invention provides a heating element, a heating module and a heater for annealing a fiber Bragg grating. The fiber Bragg grating can be placed directly on top of a strip block, and the fiber Bragg grating can be directly heated and annealed through the strip block. After annealing is completed, the fiber Bragg grating can be directly removed. The operation is simple, convenient and efficient.
[0006] To achieve the above-mentioned purpose, according to the utility model, a heating element for annealing of optical fiber Bragg gratings is provided, which is characterized in that it includes a bar block, and the bar block is provided with an electric heating rod mounting hole and a thermocouple mounting hole. The electric heating rod mounting hole is installed with an electric heating rod for heating the bar block, and the thermocouple mounting hole is installed with a thermocouple for obtaining the temperature of the bar block.
[0007] Preferably, the electric heating rod and the thermocouple are both connected to a PLC.
[0008] Preferably, the electric heating rod mounting hole and the thermocouple mounting hole are parallel to each other.
[0009] Preferably, there are two thermocouple mounting holes on the strip block and they are respectively arranged on two end faces in the length direction of the strip block, and a thermocouple is respectively mounted on each of the thermocouple mounting holes.
[0010] According to another aspect of the present invention, a heating module for fiber Bragg grating annealing is provided, characterized in that it comprises a plurality of the aforementioned heating elements, wherein the strip blocks of the heating elements are arranged side by side and the strip blocks are fixed together to form a heating table.
[0011] Preferably, a spacing groove is provided between any two adjacent strip blocks to reduce heat transfer between the two adjacent strip blocks.
[0012] According to another aspect of the present invention, a heater for annealing a fiber Bragg grating is provided, comprising the heating module described above, and characterized in that it further comprises a heat preservation plate, wherein the heat preservation plate and the heating platform are fixedly connected together, a space is present between the heat preservation plate and the heating platform, and the heat preservation plate is located above the heating platform to maintain the temperature of the space between the heat preservation plate and the heating platform, and the space between the heat preservation plate and the heating platform serves as a moving channel for the fiber Bragg grating, and the moving channel has an entrance and exit so that the fiber Bragg grating can enter and exit the heater.
[0013] Preferably, the material of the bar block is stainless steel, 6061 aluminum alloy or alumina ceramic.
[0014] Preferably, some of the strip blocks close to the entrance and exit of the moving channel have fin-shaped grooves.
[0015] Preferably, the area where all the bar blocks with a temperature less than T1 are located is a low-temperature area, the area where all the bar blocks with a temperature greater than T1 and less than T2 are located is a medium-temperature area, and the area where all the bar blocks with a temperature greater than T2 are located is a high-temperature area, where T1<T2, and T1 and T2 are set thresholds.
[0016] The distribution density of the fin-shaped grooves on each strip block in the low temperature area is greater than the distribution density of the fin-shaped grooves on each strip block in the medium temperature area;
[0017] The groove width of the fin-shaped groove on each strip block in the low temperature area is smaller than the groove width of the fin-shaped groove on each strip block in the medium temperature area;
[0018] No fin-shaped groove is provided on each strip block in the high-temperature area.
[0019] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects compared with the prior art:
[0020] 1. The utility model is a heating element for annealing a fiber Bragg grating. The fiber Bragg grating can be placed directly on top of a strip block, and the fiber Bragg grating is directly heated and annealed by the strip block. After the annealing is completed, the fiber Bragg grating can be directly removed without waiting for the strip block to cool down before removing the fiber Bragg grating. The operation is simple, convenient and efficient.
[0021] 2. The utility model provides a heating element for annealing a fiber Bragg grating, which can keep the position of the fiber Bragg grating above a single strip block unchanged, and gradually increase the temperature of the strip block from low temperature to high temperature, thereby directly performing variable temperature annealing on the fiber Bragg grating.
[0022] 3. The utility model provides a heating table for annealing a fiber Bragg grating (FBG), which is composed of a plurality of strip blocks. The temperature of each strip block can be easily controlled, and different temperature zones can be arranged and gradient-changed in the space above the same heating table. The fiber Bragg grating is annealed in a gradient-changing temperature range, so that the fiber Bragg grating can be adaptively annealed gradually from low temperature to high temperature, and the optical properties are more stable. Compared with the conventional constant high-temperature resistance wire or flame annealing method, this temperature gradient annealing method above the heating table is more in line with the photosensitivity characteristics of the optical fiber and has a higher grating yield rate.
[0023] 4. The utility model is a heater for annealing a fiber Bragg grating. The insulation plate can maintain the temperature of the space between the insulation plate and the heating platform to prevent heat loss, thereby allowing the fiber Bragg grating to be better annealed in various temperature ranges in the moving channel. BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Figure 1 This is a front view of one of the heating elements in the present invention;
[0025] Figure 2 This is a schematic diagram of the heating module of the present invention after the thermocouple is removed;
[0026] Figure 3 This is a schematic diagram of the heater in the present invention after the thermocouple is removed;
[0027] Figure 4 It is a three-dimensional schematic diagram of the variable temperature annealing equipment of the present utility model;
[0028] Figure 5 This is a schematic diagram of the electric translation stage, optical fiber clamp and heater installed on the base in the utility model;
[0029] Figure 6 It is a schematic diagram of one of the optical fiber clamping devices in the present invention;
[0030] Throughout the drawings, the same reference numerals are used to denote the same elements or structures, wherein:
[0031] 1-Annealing indicator light, 2-Thermocouple, 3-Strip block, 4-Electric heating rod, 5-Fiber clamping device, 6-Emergency stop button, 7-Touch screen, 8-Heating fins, 9-Thermocouple mounting hole, 10-Electric heating rod mounting hole, 11-Spacer groove, 12-Fin-type heat dissipation groove, 13-Insulation plate, 14-Base, 15-Electric translation stage, 16-U-shaped support plate, 17-Fiber support frame, 18-Strip block support frame, 19-Slide rail, 20-Stop screw, 21-Fiber clamp, 22-Micrometer head, 23-Heater, 24-Strip block, 25-Moving channel. DETAILED DESCRIPTION
[0032] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.
[0033] Reference Figure 1 A heating element for annealing optical fiber Bragg gratings comprises a strip block 24, on which an electric heating rod mounting hole 10 and a thermocouple mounting hole 9 are provided. An electric heating rod 4 is mounted at the electric heating rod mounting hole 10 for heating the strip block 24, and a thermocouple 2 is mounted on the thermocouple mounting hole 9 for obtaining the temperature of the strip block 24, so as to facilitate adjustment of the temperature zone above the strip block 24. The electric heating rod mounting hole 10 and the thermocouple mounting hole 9 are parallel to each other. There are preferably two thermocouple mounting holes 9 on each of the strip blocks 24, and they are respectively arranged on the two end faces in the longitudinal direction of the strip block 24, and a thermocouple 2 is respectively mounted on each of the thermocouple mounting holes 9. The material of the strip block 24 is preferably stainless steel, 6061 aluminum alloy or alumina ceramic, which has a fast heating speed, good effect, uniform temperature and short heating time. The stainless steel is preferably 304 stainless steel.
[0034] The electric heating rod 4 and the thermocouple 2 are both connected to a PLC. The thermocouple 2 transmits the temperature of the bar block 24 to the PLC's temperature transmitter. The PLC uses PID control to adjust the heating on / off time of the electric heating rod 4 and the temperature of the bar block 24, thereby achieving precise control over the multiple temperature zones of the bar block 24. PID is implemented by the PLC calculating and then sending a pulse signal to the SSR solid-state relay, which generates heat for the electric heating rod 4.
[0035] According to another aspect of the present invention, a heating module for fiber Bragg grating annealing is provided, comprising a plurality of the aforementioned heating elements, wherein the strip blocks 24 of the heating elements are arranged side by side and are fixedly connected together to form a heating platform 3. The heating platform 3 is preferably integrally formed, and the strip blocks 24 are thus part of the heating platform 3.
[0036] Furthermore, a spacing groove 11 and / or a heat insulating pad is provided between any two adjacent strip blocks 24 to reduce heat transfer between the two adjacent strip blocks 24. The heat insulating pad can be installed in the spacing groove 11.
[0037] According to another aspect of the present invention, a heater 23 for annealing a fiber Bragg grating (FBG) is provided, comprising a heating platform 3 and a heat preservation plate 13. The heat preservation plate 13 and the heating platform 3 are fixedly connected together, with a space between the heat preservation plate 13 and the heating platform 3. The heat preservation plate 13 is located above the heating platform 3 to maintain the temperature of the space between the heat preservation plate 13 and the heating platform 3. The space between the heat preservation plate 13 and the heating platform 3 serves as a moving channel 25 for the fiber Bragg grating (FBG). When the fiber clamp 21 moves with the optical fiber, the heating platform 3 heats and anneals the fiber Bragg grating (FBG) in the moving channel 25. The entrance and exit of the moving channel 25 are located at one end of the heater 23 to facilitate the fiber Bragg grating (FBG) to enter and exit the heater 23. The arrangement of the heat preservation plate 13 and the heating platform 3 results in the heater 23 being U-shaped, with one end of the heater 23 open to facilitate the fiber Bragg grating (FBG) to enter the moving channel 25 on the heater 23. The heater 23 is preferably mounted on the base 14 via a heater support frame 18.
[0038] Furthermore, a strip block 24 farthest from the entrance and exit of the moving channel has a step, and the top of the step is connected to the insulation board 13 so that there is space between the insulation board 13 and all the strip blocks 24.
[0039] During heating and annealing of the fiber Bragg grating (FBG), the temperature of the strips 24 gradually increases as they move away from the entrance and exit of the moving channel 25, thereby forming multiple temperature zones arranged from low to high within the moving channel 25. The heating of the strips 24 enables temperature zone control and a temperature gradient within the moving channel 25.
[0040] Figure 1 、 Figure 2The heating platform 3 shows a total of 10 strip blocks 24, which are arranged in the direction away from the entrance and exit of the moving channel 25, namely 1# strip block to 10# strip block. The area above each strip block 24 of the heating platform 3 has different temperatures through program control, thereby forming different temperature zones, and the temperatures of the temperature zones change in a trapezoidal manner. For example, there are currently 10 strip blocks 24, the temperature zone above the 1# strip block is 50°C, the temperature zone above the 2# strip block is 100°C, the temperature zone above the 3# strip block is 150°C...the temperature zone above the 10# strip block is 500°C, and the temperature zone above the 10# strip block is uniform. That is, the moving channel 25 is divided into 10 temperature zones with temperature gradient changes. Along the direction away from the entrance and exit of the moving channel 25, the temperature of the temperature zone increases from 50°C to 500°C, driving the fiber grating to move in the moving channel 25. The time for moving in each temperature zone can be customized according to process requirements. The entire process is to gradually move from the low temperature area to the high temperature area, maintain a process residence time after reaching the high temperature area, and then the fiber Bragg grating moves in the opposite direction and quickly exits the moving channel 25, thereby also exiting the heater 23.
[0041] Furthermore, some of the strip blocks 24 near the entrance and exit of the moving channel 25 are equipped with fin-shaped grooves 12 for heat dissipation. To reduce the installation space and achieve temperature control in smaller strip blocks 24, the heating platform 3 is thermally redesigned to incorporate fin-shaped grooves 12 to increase ventilation in each temperature zone and reduce heat conduction between each zone. A fin-shaped groove 12 is formed between two adjacent heat dissipation fins 8.
[0042] Furthermore, the area where all the bar blocks 24 with a temperature less than T1 are located is a low-temperature area, the area where all the bar blocks 24 with a temperature greater than T1 and less than T2 are located is a medium-temperature area, and the area where all the bar blocks 24 with a temperature greater than T2 are located is a high-temperature area, where T1<T2, and T1 and T2 are set thresholds.
[0043] The distribution density of the fin-type grooves 12 on each strip block 24 in the low temperature area is greater than the distribution density of the fin-type grooves 12 on each strip block 24 in the medium temperature area, and the groove width of the fin-type grooves 12 on each strip block 24 in the low temperature area is smaller than the groove width of the fin-type grooves 12 on each strip block 24 in the medium temperature area.
[0044] The above arrangement enables the bar blocks 24 in the low temperature area to dissipate heat relatively quickly, and the temperature is not easily affected by the adjacent bar blocks 24 with higher temperatures and thus rises, and the temperature can always be maintained at a set lower temperature.
[0045] No fin-shaped groove 12 is provided on each strip block 24 in the high-temperature area, so that the heat of the strip blocks 24 in the high-temperature area is dissipated more slowly and the temperature can be kept high all the time.
[0046] Therefore, in terms of the structure of the heating platform 3, the strip blocks 24 in the low-temperature area adopt high-density, small-sized fin-shaped grooves 12; the strip blocks 24 in the medium-temperature area adopt low-density, large-sized fin-shaped grooves 12; and the strip blocks 24 in the high-temperature area do not have fin-shaped grooves 12. There are three structural types.
[0047] According to another aspect of the present invention, a variable temperature annealing device is provided, comprising a base 14, an optical fiber clamp 21 and a heater 23, wherein:
[0048] The optical fiber clamp 21 is slidably mounted on the base 14 to clamp the optical fiber and move the optical fiber, wherein the optical fiber grating on the optical fiber clamped by the optical fiber clamp 21 is exposed from the optical fiber clamp 21; the utility model preferably also includes an electric translation stage 15 mounted on the base 14, and the electric translation stage 15 is connected to the optical fiber clamp 21 to push the optical fiber clamp 21 to move.
[0049] The optical fiber clamp 21 preferably includes an optical fiber support frame 17 and an optical fiber clamping device 5. The optical fiber support frame 17 is slidably mounted on the base 14. The optical fiber clamping device 5 is fixedly mounted on the optical fiber support frame 17 to clamp the optical fiber. Preferably, there are two optical fiber clamping devices 5, each for clamping both ends of the optical fiber, with each optical fiber clamping device 5 mounted on a respective optical fiber support frame 17. The optical fiber clamp 21 also includes a U-shaped support plate 16, with each optical fiber support frame 17 mounted at one end of the U-shaped support plate 16. The U-shaped support plate 16 is mounted on a guide rail 19 via a slider. The guide rail 19 is mounted on the base 14. When the U-shaped support plate 16 slides along the guide rail 19, it can move the two optical fiber clamping devices 5 simultaneously, thereby moving the optical fiber grating. The electric translation stage 15 is connected to the U-shaped support plate 16 of the optical fiber clamp 21 via a slider. The optical fiber clamping device 5 has a slide, a set screw 20, and a micrometer head 22 to facilitate adjustment and fixation of the optical fiber position.
[0050] The heater 23 is located between the two optical fiber clamping devices 5 so that the optical fiber Bragg grating between the two optical fiber clamping devices 5 enters the moving channel of the heater 23 for annealing treatment.
[0051] The utility model also provides a method for temperature-variable annealing of a fiber Bragg grating, comprising the following steps:
[0052] 1) Fix the optical fiber on the optical fiber clamp 21 and expose the fiber Bragg grating on the optical fiber from the optical fiber clamp 21 to facilitate the subsequent heater 23 to perform annealing treatment on the fiber Bragg grating.
[0053] 2) The fiber clamp 21 moves, allowing the fiber grating to enter the movable channel 25 (and also enter the heater 23) from the entrance and exit of the movable channel 25. The fiber clamp 21 can be moved manually or electrically. The present invention preferably uses an electrically driven method to drive the fiber clamp 21 to move via the electric translation stage 15.
[0054] 3) The fiber Bragg grating moves intermittently or continuously in a direction away from the entrance and exit of the moving channel 25 until it moves to above the bar block 24 with the highest temperature. The fiber Bragg grating has a corresponding annealing treatment time above each bar block 24. Intermittent movement means that the optical fiber pauses to stay in the temperature zone for a set time, and then moves to the temperature zone above the next bar block 24 for annealing.
[0055] 4) The fiber clamp 21 moves the fiber Bragg grating (FBG) toward the entrance and exit of the movable channel 25, and finally allows the fiber Bragg grating to exit the heater from the entrance and exit of the movable channel 25, thereby completing the annealing of the fiber Bragg grating. This annealing method is a variable temperature gradient annealing, which will not damage the cladding or make the fiber Bragg grating material brittle.
[0056] 5) Remove the optical fiber from the optical fiber clamp 21. Since the optical fiber is removed in an exposed atmospheric environment, away from the highest temperature bar block 24 and the temperature zone, it is safer to remove the optical fiber and is not likely to burn the operator.
[0057] The annealing device of this utility model includes a touch screen 7, an annealing indicator light 1, and an emergency stop button 6. Pressing the run button on the touch screen 7 illuminates the annealing indicator light 1, and the optical fiber is transported to the heater 23 via the motorized translation stage 15. The fiber's movement speed and dwell time in each temperature zone are set according to process requirements, and the fiber is gradually moved from low to high temperature zones. After reaching the high temperature zone, the fiber remains in the zone for the required time, after which it is quickly returned to its starting point via the motorized translation stage 15.
[0058] It will be easily understood by those skilled in the art that the above description is only 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 shall be included in the scope of protection of the present invention.
Claims
1. A heating element for annealing a fiber Bragg grating, characterized in that: The utility model comprises a strip block, which is provided with an electric heating rod mounting hole and a thermocouple mounting hole. The electric heating rod mounting hole is installed with an electric heating rod for heating the strip block, and the thermocouple mounting hole is installed with a thermocouple for obtaining the temperature of the strip block.
2. The heating element for annealing a fiber Bragg grating according to claim 1, characterized in that: The electric heating rod and the thermocouple are both connected to the PLC.
3. The heating element for annealing a fiber Bragg grating according to claim 1, characterized in that: The electric heating rod mounting hole and the thermocouple mounting hole are parallel to each other.
4. The heating element for annealing a fiber Bragg grating according to claim 1, characterized in that: There are two thermocouple mounting holes on the strip block and they are respectively arranged on two end faces in the length direction of the strip block, and a thermocouple is respectively mounted on each of the thermocouple mounting holes.
5. The heating element for annealing a fiber Bragg grating according to claim 1, characterized in that: The material of the strip block is stainless steel, 6061 aluminum alloy or alumina ceramic.
6. A heating module for annealing a fiber Bragg grating, characterized in that: The heating device comprises a plurality of heating elements according to any one of claims 1 to 5, wherein the strip blocks of the heating elements are arranged side by side and are fixedly connected together to form a heating table.
7. A heating module for annealing fiber Bragg gratings according to claim 6, characterized in that: A spacing groove is provided between any two adjacent strip blocks to reduce heat transfer between the two adjacent strip blocks.
8. A heater for annealing a fiber Bragg grating, comprising the heating module according to claim 6 or 7, characterized in that: It also includes a heat preservation plate, which is fixedly connected to the heating platform. There is a space between the heat preservation plate and the heating platform, and the heat preservation plate is located above the heating platform to maintain the temperature of the space between the heat preservation plate and the heating platform. The space between the heat preservation plate and the heating platform serves as a moving channel for the fiber grating.
9. The heater for annealing a fiber Bragg grating according to claim 8, characterized in that: Some of the strip blocks close to the entrance and exit of the moving channel have fin-shaped grooves.
10. The heater for annealing fiber Bragg gratings according to claim 9, characterized in that: The area where all bars with a temperature less than T1 are located is the low temperature area, the area where all bars with a temperature greater than T1 but less than T2 are located is the medium temperature area, and the area where all bars with a temperature greater than T2 are located is the high temperature area, where T1 < T2, and T1 and T2 are the set thresholds; The distribution density of the fin-shaped grooves on each strip block in the low temperature area is greater than the distribution density of the fin-shaped grooves on each strip block in the medium temperature area; The groove width of the fin-shaped groove on each strip block in the low temperature area is smaller than the groove width of the fin-shaped groove on each strip block in the medium temperature area; No fin-shaped groove is provided on each strip block in the high-temperature area.