A spaceborne coherent optical module for low-Earth orbit satellites

Abstract

A coherent optical module for a low-Earth orbit satellite includes: a printed circuit board, the inner layer of which includes a copper foil layer; a copper foil winding disposed on the copper foil layer; and a switch, wherein the switch and the copper foil winding are connected in series between the positive and negative terminals of a power supply that powers the onboard coherent optical module. The switch is configured to close when the temperature of the onboard coherent optical module is below a first threshold and to open when the temperature of the onboard coherent optical module is above a second threshold. This expands the low-temperature specification of the coherent optical module by more than 20°C, solving the problem of the operating temperature range of the coherent optical module not matching the satellite's ambient temperature.

Description

Technical Field

[0001] This invention relates to the field of temperature control for onboard coherent optical modules of low-Earth orbit satellites, and more specifically, to an onboard coherent optical module for low-Earth orbit satellites. Background Technology

[0002] Currently, the default operating temperature range of spaceborne coherent optical modules is significantly mismatched with the extreme environment of satellites, manifesting as insufficient temperature range coverage, weak temperature control capabilities, and inadequate device tolerance. Direct use can lead to link interruptions, performance degradation, or even permanent damage. Coherent optical modules, due to the integration of precision components such as digital signal processors (DSPs), lasers, and coherent modulation receivers, have much higher temperature control requirements than ordinary incoherent optical modules. Currently, mainstream commercial coherent optical modules primarily operate within a range of 0-70℃, with some telecom-grade modules capable of operating at -5-75℃, mainly depending on the core optoelectronic devices used. Temperature mismatch can lead to the following specific risks: Laser wavelength drift and power attenuation: For every 10°C drop in temperature, the laser threshold current increases by about 20%, and the output power decreases by 15%-20%; at low temperatures, the wavelength shift exceeds 0.5nm, causing inter-satellite coherent reception to be unable to lock onto the carrier, resulting in no signal in the link; DSP and coherent receiver component failure: The lower limit of operation for ordinary commercial DSPs is -10℃, at which temperature register flipping and algorithm lag may occur; the intelligent character recognition (ICR) component of coherent receivers experiences a 30% decrease in photoelectric conversion efficiency and a sharp increase in bit error rate below -20℃. The thermoelectric cooler (TEC) temperature control system malfunctioned: extreme temperatures in the satellite environment (such as below -20°C) exceeded the heating capacity of a typical TEC, causing core components to be unable to maintain their operating temperature; and Long-term reliability failure: Temperature cycling shock (-40℃→85℃) will accelerate the fatigue of the solder joints inside the optical module and the cracking of the package. Since there are no maintenance conditions on the satellite in orbit, a single failure will lead to the paralysis of the entire satellite's communication link.

[0003] Faced with the temperature range of -180℃ to 150℃ during a single orbit of a low-Earth orbit satellite, the satellite platform can help control the temperature between -20℃ and 50℃, so the temperature mismatch in the low-temperature range is particularly significant.

[0004] Traditional temperature control methods typically use TEC (Thermal Control and Temperature Coefficient). While TEC is suitable for low-power, single-point temperature control, it is no longer appropriate for controlling the temperature of the entire onboard coherent optical module, mainly due to the following issues: The conversion efficiency of high-power TECs is around 90%. For example, to control the temperature of a 25W optical module, the power consumption generated by the TEC itself is about 27.8W, which is not worthwhile. The operating temperature range of the TEC itself is generally -10℃ to 50℃, which is also incompatible with the spaceborne environment. In the spaceborne environment below -20℃, the TEC temperature control system faces the risk of collapse. Summary of the Invention

[0005] In view of this, embodiments of the present invention provide a spaceborne coherent optical module for low-orbit satellites, which can achieve a significant increase in temperature in extremely low-temperature environments.

[0006] The onboard coherent optical module of a low-Earth orbit satellite according to an embodiment of the present invention includes: A printed circuit board, wherein the inner layer of the printed circuit board includes a copper foil layer; Copper foil winding is disposed on the copper foil layer; A switch, which is connected in series with the copper foil winding between the positive and negative terminals of the power supply that powers the spaceborne coherent optical module, is provided. The switch is configured to close when the temperature of the onboard coherent optical module is below a first threshold, and to open when the temperature of the onboard coherent optical module is above a second threshold.

[0007] Furthermore, the length of the copper foil winding is between 0.5 meters and 1.5 meters, the width is between 0.8 millimeters and 1.2 millimeters, and the thickness is between 20 micrometers and 40 micrometers.

[0008] Furthermore, the copper foil windings are arranged in a serpentine pattern along one side of the printed circuit board.

[0009] Furthermore, there are multiple through holes between the copper foil layer and the first surface of the printed circuit board, wherein the first surface is the side of the printed circuit board on which the cooling device is disposed.

[0010] Furthermore, the spaceborne coherent optical module also includes: a laser disposed on the surface of the printed circuit board; and a heating element disposed around the laser, wherein the heating element, together with the switch and the copper foil winding, is connected in series between the positive and negative terminals of the power supply that powers the spaceborne coherent optical module.

[0011] Furthermore, the heating element is a polyimide film type resistance heating element.

[0012] Furthermore, the thickness of the heating element is between 0.1 mm and 0.2 mm, and the length and width are both between 1 cm and 3 cm.

[0013] Furthermore, the heating element is disposed between the surface of the printed circuit board and the laser, or between the laser and the encapsulation material of the spaceborne coherent optical module.

[0014] Furthermore, the spaceborne coherent optical module also includes a current-limiting fuse, which is connected in series with the heating element, the switch, and the copper foil winding between the positive and negative terminals of the power supply that powers the spaceborne coherent optical module.

[0015] Furthermore, the first threshold is between -15 degrees and -25 degrees, and the second threshold is between 0 degrees and 10 degrees.

[0016] According to the solution in this application embodiment, by connecting copper foil wires in series with a heating element, the low-temperature specification of the coherent optical module can be extended by more than 20°C, solving the problem of the mismatch between the operating temperature range of the coherent optical module and the satellite ambient temperature. Furthermore, this method is low-cost, easy to implement, and does not affect terrestrial telecommunications-grade use. Attached Figure Description

[0017] Figure 1 This is a schematic diagram illustrating the cooling principle of a spaceborne coherent optical module according to an embodiment of the present invention.

[0018] Figure 2 This is a schematic diagram of the wiring arrangement of the copper foil winding according to an embodiment of the present invention.

[0019] Figure 3 This is a schematic diagram of another copper foil winding arrangement according to an embodiment of the present invention.

[0020] Figure 4 This is a schematic diagram of another cooling principle for a spaceborne coherent optical module according to an embodiment of the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the spirit of the content disclosed in this application will be clearly explained below with reference to the accompanying drawings and detailed description. After understanding the embodiments of this application, any person skilled in the art can make changes and modifications based on the technology taught in this application without departing from the spirit and scope of this application.

[0022] The illustrative embodiments and descriptions provided in this application are for explaining the application, but are not intended to limit the application. Furthermore, elements / components using the same or similar reference numerals in the drawings and embodiments are used to represent the same or similar parts.

[0023] The terms “first,” “second,” etc., used in this document are not intended to specifically refer to order or sequence, nor are they used to limit this application; they are merely used to distinguish elements or operations described using the same technical terms.

[0024] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0025] The term "and / or" as used herein includes any or all of the things mentioned.

[0026] The term "multiple" in this article includes "two" and "more than two"; the term "multiple groups" in this article includes "two groups" and "more than two groups".

[0027] Certain terms used to describe this application will be discussed below or elsewhere in this specification to provide additional guidance to those skilled in the art in describing the application.

[0028] This application provides a coherent optical module for a low-orbit satellite, which can extend the low-temperature specification of the coherent optical module by more than 20°C by connecting the copper foil winding to the heating plate in series, thus solving the problem of mismatch between the operating temperature range of the coherent optical module and the satellite ambient temperature.

[0029] Figure 1 A schematic diagram illustrating the cooling principle of a spaceborne coherent optical module according to an embodiment of this application is shown. Figure 1 As shown, the spaceborne coherent optical module includes: a printed circuit board 1, the inner layer of which includes a copper foil layer; a copper foil winding 2 disposed on the copper foil layer; and a switch 3, the switch 3 and the copper foil winding 2 being connected in series between the positive and negative terminals of a power supply 4 that supplies power to the spaceborne coherent optical module. The switch 3 is configured to close when the temperature of the spaceborne coherent optical module is below a first threshold, and to open when the temperature of the spaceborne coherent optical module is above a second threshold. As described above, in a low-temperature environment, controlling the switch to close and utilizing the heating of the copper foil winding can achieve a significant temperature increase.

[0030] Low-Earth orbit satellites often face ambient temperatures as low as -20 degrees Celsius. Therefore, in one embodiment, the first threshold is between -15 and -25 degrees Celsius, and the second threshold is between 0 and 10 degrees Celsius. Preferably, the first threshold is -25 degrees Celsius, and the second threshold is 5 degrees Celsius. That is, when the temperature is below -20 degrees Celsius, the switch is closed to initiate copper foil winding heating, and when the temperature is above 5 degrees Celsius, the switch is opened to stop heating. Here, the first and second threshold temperatures are the temperatures of the onboard coherent optical module, specifically, the surface temperature of the printed circuit board 1.

[0031] Specifically, the resistance value of the copper foil winding is calculated according to the following formula: r = ρ * l / (w * t). Where r represents the resistance value of the copper foil winding, ρ represents the resistivity of the copper foil winding, l represents the length of the copper foil winding, w represents the width of the copper foil winding, and t represents the thickness of the copper foil winding. In one embodiment, the length of the copper foil winding is between 0.5 meters and 1.5 meters, the width is between 0.8 millimeters and 1.2 millimeters, and the thickness is between 20 micrometers and 40 micrometers. This allows for heating to meet the low-temperature environment requirements of this application. Furthermore, the arrangement of the copper foil winding 3 within the copper foil layer can be as follows: Figure 2 As shown, the copper foil winding 2 is arranged in a serpentine pattern along one side of the printed circuit board 1, or it can be arranged as follows: Figure 3 As shown, the copper foil winding 2 is arranged in a spiral on the printed circuit board 1, thereby increasing the trace area (heat dissipation surface) and resistance.

[0032] Furthermore, considering that the laser is a module independent of the printed circuit board 1, this embodiment of the application also performs further cooling treatment on the laser of the coherent optical module. Specifically, as Figure 4 As shown, the spaceborne coherent optical module also includes: a laser, disposed on the surface of the printed circuit board 1; and a heating element 5, disposed around the laser, the heating element 5 being connected in series with the switch 3 and the copper foil winding 1 between the positive and negative terminals of the power supply 4 that supplies power to the spaceborne coherent optical module. The heating element 5 being disposed around the laser means that the heating element 5 is located within a predetermined range from the laser, which may be, for example, 5 centimeters.

[0033] In one embodiment, the heating element 5 may be a polyimide film-type resistance heating element. Aerospace-grade polyimide film-type resistance heating elements are lightweight, customizable in shape, and capable of achieving high resistance density.

[0034] In one embodiment, the thickness of the heating element 5 is between 0.1 mm and 0.2 mm, and its length and width are both between 1 cm and 3 cm. The heating element 5 can be disposed between the surface of the printed circuit board 1 and the laser, or between the laser and the encapsulation material of the spaceborne coherent optical module.

[0035] In this way, by using copper foil winding and heating elements, the printed circuit board and laser can be heated significantly in a low-temperature environment.

[0036] In addition, in one embodiment, the spaceborne coherent optical module may also include a current-limiting fuse, which is connected in series with the heating element 5, the switch 3 and the copper foil winding 2 between the positive and negative terminals of the power supply 4 that supplies power to the spaceborne coherent optical module.

[0037] The following is a specific example to illustrate this in detail.

[0038] The printed circuit board 1 of the coherent optical module adopts a standard CFP2 package, with a length and width of 117.5mm and 41.5mm respectively. Excluding the structural housing and the 104-pin connector, the length and width of printed circuit board 1 are 88.6mm and 38.2mm respectively. Based on this, the copper foil winding width w is designed to be 1mm, with a serpentine winding along the length direction and a 1mm spacing between traces, for a total of 12 loops, occupying a total width of 2mm × 12 = 24mm (with a 14.2mm margin over the total width of the printed circuit board). The total winding length is 88.6mm × 12 = 1063.2mm. Furthermore, ρ is the resistivity of the copper foil, which is 1.72E-8Ωm. In the standard CFP2 package, the thickest copper foil layer on the printed circuit board is 1oz, or 36um; therefore, the designed trace thickness t is 36um. Substituting the above parameters into the formula r=ρ*l / (w*t), the resistance of the copper foil winding is calculated to be r=1.72E-8*1.0632 / (0.001*36E-6)=0.51Ω.

[0039] Furthermore, the heating element 5 is an aerospace-grade polyimide film type resistance heating element, which is attached between the surface of the printed circuit board 1 and the bottom of the laser. The heating element 5 has a size of 2cm × 2cm and a thickness between 0.1mm and 0.2mm. The resistance density of the heating element is 0.125Ω / cm². Therefore, the total resistance of the heating element 5 is: R = 0.125Ω / cm² * 2cm * 2cm = 0.5Ω.

[0040] The onboard coherent optical module is powered by the host board via a standard CFP2 connector, which is a 3.3V rail. Therefore, the voltage of power supply 4 is 3.3V. From this, the path current can be calculated as: I = V / (R + r) = 3.3 / (0.51 + 0.5) = 3.27A.

[0041] Therefore, the power of the copper foil winding of printed circuit board 1 is: P r =I 2 *r=5.44W. The power of heating element 5 is: P R =I 2 *R=5.36W.

[0042] When the first threshold is -20 degrees and the second threshold is 5 degrees, a temperature rise of 25 degrees is required, which is generated by the power of the copper foil winding 2. For this temperature rise, the required thermal resistance of the material between the copper foil winding 2 and the first surface of the printed circuit board 1 is: R θ=△T / Pr=25 / 5.44=4.59℃ / W. Here, the first surface is the side of the printed circuit board where the device to be cooled is located. To achieve a thermal resistivity greater than 4.59℃ / W, it can be achieved, for example, by drilling a through-hole between the copper foil layer and the first surface of the printed circuit board.

[0043] Furthermore, in this specific example, at low temperatures, the power consumption of the coherent optical module during normal operation is approximately 24W. For a 3.3V rail, the operating current of the coherent optical module is: I 模块 =24 / 3.3=7.27A. Adding the current of the temperature control system, the total current on the 3.3V rail is: I 总 =7.27 + 3.27 = 10.54A. The 104-pin connector for the optical module has 8 pins on the 3.3V rail, each with a current carrying capacity of 1.8A, totaling 14.4A, which can meet the above current requirements.

[0044] In summary, to address the current issue of mismatched low-temperature specifications of spaceborne optical modules, this invention proposes for the first time a method of connecting printed circuit board copper foil windings and heating elements in series, with a total heating power of 10.8W. This method can broaden the low-temperature specifications of coherent optical modules by more than 20°C, solving the problem of mismatch between the operating temperature range of coherent optical modules and satellite ambient temperature. This method is low-cost, easy to implement, and does not affect ground-based telecommunications-grade use.

[0045] The above description is a further detailed explanation of the present invention in conjunction with specific preferred embodiments. It should not be considered that the specific embodiments of the present invention are limited to this. For those skilled in the art, several simple deductions or substitutions can be made without departing from the concept of the present invention, and all such deductions or substitutions should be considered to fall within the scope of protection of the present invention as defined by the submitted claims.

Claims

1. A spaceborne coherent optical module for a low-Earth orbit satellite, characterized in that, include: A printed circuit board, wherein the inner layer of the printed circuit board includes a copper foil layer; Copper foil winding is disposed on the copper foil layer; A switch, which is connected in series with the copper foil winding between the positive and negative terminals of the power supply that powers the spaceborne coherent optical module, is provided. The switch is configured to close when the temperature of the onboard coherent optical module is below a first threshold, and to open when the temperature of the onboard coherent optical module is above a second threshold.

2. The spaceborne coherent optical module according to claim 1, characterized in that, The copper foil winding has a length between 0.5 meters and 1.5 meters, a width between 0.8 millimeters and 1.2 millimeters, and a thickness between 20 micrometers and 40 micrometers.

3. The spaceborne coherent optical module according to claim 1, characterized in that, The copper foil windings are arranged in a serpentine pattern along one side of the printed circuit board.

4. The spaceborne coherent optical module according to claim 1, characterized in that, There are multiple through holes between the copper foil layer and the first surface of the printed circuit board, wherein the first surface is the side of the printed circuit board on which the device to be cooled is disposed.

5. The spaceborne coherent optical module according to claim 1, characterized in that, The spaceborne coherent optical module also includes: A laser is disposed on the surface of the printed circuit board; and A heating element is disposed around the laser and is connected in series with the switch and the copper foil winding between the positive and negative terminals of the power supply that powers the spaceborne coherent optical module.

6. The spaceborne coherent optical module according to claim 5, characterized in that, The heating element is a polyimide thin-film type resistance heating element.

7. The spaceborne coherent optical module according to claim 5, characterized in that, The thickness of the heating element is between 0.1 mm and 0.2 mm, and the length and width are both between 1 cm and 3 cm.

8. The spaceborne coherent optical module according to claim 5, characterized in that, The heating element is disposed between the surface of the printed circuit board and the laser, or between the laser and the encapsulation material of the spaceborne coherent optical module.

9. The spaceborne coherent optical module according to claim 5, characterized in that, The spaceborne coherent optical module also includes a current-limiting fuse, which is connected in series with the heating element, the switch, and the copper foil winding between the positive and negative terminals of the power supply that powers the spaceborne coherent optical module.

10. The spaceborne coherent optical module according to claim 1, characterized in that, The first threshold is between -15 degrees and -25 degrees, and the second threshold is between 0 degrees and 10 degrees.

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