An ultrastable laser for space applications

Abstract

The present invention discloses an ultra-stable laser for space applications, including: a main optical path module, a physical module, an active vibration isolation module, an electronic drive control module, a sound insulation module, a liquid cooling plate and a main substrate. The ultra-stable laser for space applications of the present invention has a compact and stable structure, can withstand greater mechanical vibrations, and through modular design, the system has stronger maintainability. The laser between modules is transmitted through an integrated fiber collimator, which can effectively overcome the laser pointing changes caused by fiber plugging and unplugging. The eight-point support method is used to maintain low vibration sensitivity while making the cubic reference cavity have stronger adaptability to the mechanical environment. The energy absorption design of installing a shock-absorbing spring or a vibration-absorbing pad at the bottom of the vacuum chamber helps to further reduce the influence of vibration on the reference cavity and the optical path pointing during mechanical testing and launch.

Description

Technical Field

[0001] The invention belongs to the field of lasers, and in particular relates to an ultra-stable laser for space applications. Background Art

[0002] Ultrastable lasers with extremely high frequency stability have important application prospects in the fields of atomic optical clocks, gravitational wave detection, and precision spectral measurement. The Pound-Drever-Hall (PDH) frequency stabilization technology based on an optical reference cavity is one of the most commonly used methods to achieve ultrastable lasers. Using this method to lock the laser frequency to the resonant frequency of the optical reference cavity, the laser frequency stability of the ultrastable laser has reached the order of 10-17, and the laser linewidth is less than 10mHz. With the rapid development of space science, the demand for ultrastable lasers for space applications such as space optical clocks and space gravitational wave detection is becoming increasingly urgent.

[0003] Compared with ultra-stable lasers operating on the ground, ultra-stable lasers for space environment applications have strict resource constraints in terms of spatial size, mass, power consumption, etc., and especially have extremely stringent requirements on mechanical structure. Once a certain degree of structural deformation occurs during the emission process, it may cause the reference cavity position to deflect or the optical path to change, resulting in lower coupling efficiency between the laser and the optical reference cavity, weaker error signal-to-noise ratio, or even failure to lock. It will also reduce the coupling efficiency of the laser entering the fiber collimator, causing the output laser power to drop significantly, which cannot meet the system operation or user needs. However, existing lasers cannot be applied to scenarios facing space environments. Summary of the invention

[0004] In order to solve the above problems existing in the prior art, the present invention provides an ultra-stable laser for space applications. The technical problem to be solved by the present invention is achieved through the following technical solutions:

[0005] An ultra-stable laser for space applications, comprising:

[0006] Main optical path module, physical module, active vibration isolation module, electronic drive control module, sound insulation module, liquid cooling plate and main base plate;

[0007] A lightening groove is provided on the main substrate, and the main optical path module is arranged in the lightening groove below the main substrate; the lightening groove above the main substrate forms a first cavity and a second cavity through an isolating member, and the liquid cooling plate is arranged in the first cavity; the electronic drive control module is arranged on the liquid cooling plate, and the electronic drive control module is fixed on the main substrate; the active vibration isolation module is arranged in the second cavity, and the physical module is fixed on the active vibration isolation module; the sound insulation module is a box structure with one side open, and the opening surface of the sound insulation module covers the physical module and the active vibration isolation module and is fixed on the main substrate;

[0008] The surface of the liquid cooling plate is provided with a heat conducting coating.

[0009] In a specific embodiment, the main optical path module includes a laser, a polarization beam splitter, an electro-optic modulator, an acousto-optic modulator, a double-pass acousto-optic modulator, a first fiber collimator, and a second fiber collimator;

[0010] A polarization beam splitter prism, an electro-optic modulator, an acousto-optic modulator and a first optical fiber collimator are connected in sequence, and the polarization beam splitter prism, a double-pass acousto-optic modulator and a second optical fiber collimator are connected in sequence;

[0011] The polarization beam splitter prism is used to split the laser into a first optical signal and a second optical signal. The first optical signal is outputted through an electro-optic modulator, an acousto-optic modulator and a first optical fiber collimator in sequence and then transmitted to an optical reference cavity to stabilize the laser frequency. The second optical signal is outputted through an acousto-optic modulator and a second optical fiber collimator in sequence twice.

[0012] In a specific embodiment, the FC interface of the first fiber optic collimator is an oblique head connector to avoid noise generated by laser return; and when the fiber length of the second fiber optic collimator is greater than 3m, the FC interface of the second fiber optic collimator is a flat head connector, and the fiber end face of the second fiber optic collimator is coated with a reflective film to utilize the reflected laser to suppress the fiber phase noise; or when the fiber length of the second fiber optic collimator is less than 3m, the FC interface of the second fiber optic collimator is an oblique head connector.

[0013] In a specific embodiment, the reflectivity of the reflective film is 10%-20%.

[0014] In a specific embodiment, the active vibration isolation module includes a stator, a float and an electronic control unit, the stator is fixed on a main substrate, and the stator and the float are connected by a spring; a captive screw is installed and fixed on the stator of the active vibration isolation module so that by tightening the captive screw, the thread of the captive screw and the threaded hole on the float are completely fixed and engaged to achieve locking, or by loosening the captive screw, the float is unlocked by the support of the spring.

[0015] In a specific embodiment, the physical module includes a cylindrical vacuum chamber, a front-cavity matching optical path module arranged at the lower end of the cylindrical vacuum chamber, and a rear-cavity detection optical path module arranged at the upper end of the cylindrical vacuum chamber;

[0016] The cylindrical vacuum chamber has a heat shielding layer inside and a heating film and heat wrap outside;

[0017] The lower part of the cylindrical vacuum chamber is evenly distributed with mounting columns, and the mounting columns are fixed to the float of the active vibration isolation module through metal-based shock-absorbing springs or rubber shock-absorbing pads to increase the damping between the cylindrical vacuum chamber and the outside world;

[0018] The input end of the pre-cavity matching optical path module is connected to a third optical fiber collimator, and the collimating lens end of the third optical fiber collimator is fixed on the pre-cavity matching optical path module to stabilize the direction of the input laser.

[0019] In a specific embodiment, the heating film is arranged on the upper end surface, the lower end surface and the side surface outside the cylindrical vacuum chamber, and the heating modules on the upper end surface, the lower end surface and the side surface are independently controlled.

[0020] In a specific embodiment, the main substrate is a metal structural plate with a thickness of not less than 50 mm and a base frequency of the main substrate of not less than 120 Hz.

[0021] In a specific embodiment, both sides of the main substrate further include mounting holes for fixing the ultra-stable laser.

[0022] In a specific embodiment, the optical reference cavity of the cylindrical vacuum chamber is a cubic reference cavity with eight vertex corners cut and fixed.

[0023] Beneficial effects of the present invention:

[0024] The ultra-stable laser for space applications of the present invention has a compact and stable structure and can withstand greater mechanical vibrations. The modular design makes the system more maintainable. The laser between modules is transmitted through an integrated fiber collimator, which can effectively overcome the changes in laser pointing caused by fiber plugging and unplugging. The eight-point support method is used to make the cubic reference cavity have stronger adaptability to the mechanical environment while maintaining low vibration sensitivity. The energy absorption design of installing shock-absorbing springs or vibration-absorbing pads at the bottom of the vacuum chamber helps to further reduce the influence of vibration on the reference cavity and the direction of the optical path during mechanical testing and launch.

[0025] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1This is a schematic diagram of an explosion structure of an ultra-stable laser for space applications provided by an embodiment of the present invention;

[0027] Figure 2 1 is a schematic diagram of the structure of an ultra-stable laser for space applications provided by an embodiment of the present invention;

[0028] Figure 3 This is a block diagram of a main optical path module of an ultra-stable laser for space applications provided by an embodiment of the present invention;

[0029] Figure 4 It is a schematic diagram of the structure of a physical module of an ultra-stable laser for space applications provided by an embodiment of the present invention;

[0030] Figure 5 It is a schematic diagram of the structure of an ultra-stable laser optical reference cavity for space applications provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below with reference to specific embodiments, but the embodiments of the present invention are not limited thereto.

[0032] Embodiment 1

[0033] See also Figure 1 , an ultra-stable laser for space applications, comprising: a main optical path module 1, a physical module 2, an active vibration isolation module 3, an electronic drive control module 4, a sound insulation module 5, a liquid cooling plate 6 and a main substrate 7;

[0034] A lightening groove is provided on the main substrate 7, and the main optical path module 1 is arranged in the lightening groove below the main substrate 7 and is non-airtightly sealed with a metal sheet, so as to reduce the influence of air flow and sound on the main optical path; the lightening groove above the main substrate 7 forms a first cavity 72 and a second cavity 73 through an isolation piece 71, and the liquid cooling plate 6 is arranged in the first cavity 72. The surface of the liquid cooling plate 6 has a thermal conductive coating to reduce the thermal resistance between the upper and lower surfaces and the contacted objects through the thermal conductive coating. The liquid cooling plate 6 is used to take away the heat generated by the electronic drive control module and the optoelectronic devices in the system, wherein the optoelectronic devices will transfer heat to the liquid cooling plate 6 through media with high thermal conductivity such as heat pipes, graphite conductive belts, and copper plates. The electronic drive control module 4 is arranged on the liquid cooling plate 6, and the electronic drive control module 4 is fixed on the main substrate 7; the active vibration isolation module 3 is arranged in the second cavity 73, and the physical module 2 is fixed on the active vibration isolation module 3; the sound insulation module 5 is a box structure with one side open, and the opening surface of the sound insulation module 5 covers the physical module 2 and the active vibration isolation module 3 and is fixed on the main substrate 7, and the side of the sound insulation module 5 without the sound insulation board is inverted above the main substrate, covering the physical module 2 and the active vibration isolation module 3 inside, reducing the influence of external sound on the physical module 2 and the active vibration isolation module 3, thereby improving the length stability of the optical reference cavity 24 in the physical module 2.

[0035] In one specific embodiment, see Figure 3 The main optical path module 1 includes a laser 10, a polarization beam splitter prism 11, an electro-optic modulator 12, an acousto-optic modulator 13, a double-pass acousto-optic modulator 14, a first fiber collimator 15, and a second fiber collimator 16;

[0036] The polarization beam splitter prism 11, the electro-optic modulator 12, the acousto-optic modulator 13 and the first fiber collimator 15 are connected in sequence, and the polarization beam splitter prism 11, the double-pass acousto-optic modulator 14 and the second fiber collimator 16 are connected in sequence;

[0037] The polarization beam splitter prism 11 is used to split the laser into a first optical signal and a second optical signal. The first optical signal is outputted through the electro-optic modulator 12, the acousto-optic modulator 13 and the first optical fiber collimator 15 in sequence and then transmitted to the optical reference cavity to stabilize the laser frequency. The second optical signal is outputted through the acousto-optic modulator 14 and the second optical fiber collimator 16 twice in sequence.

[0038] It should be noted that the main optical path module 1 first generates a laser, and then divides the generated laser into two parts through a polarization beam splitter prism 11. The smaller power part, about 0.5 mW, is phase- and frequency-modulated by an electro-optic modulator 12 and a first acousto-optic modulator 13, and then coupled into a first fiber collimator 15 for stabilizing the laser frequency; the larger power part is coupled into one or more second fiber collimators 16 after passing through the acousto-optic modulator 14 twice, and is delivered to the user for use. Passing through the acousto-optic modulator 14 twice can make the acousto-optic modulator coupling efficiency relatively insensitive to the laser pointing, and can increase the frequency shift of the laser, so that the user has more frequency adjustment margin; the above-mentioned fiber collimators are all integrated designs, and the two ends of the integrated fiber collimator are respectively a collimating lens and an FC connector, wherein the collimating lens and the optical fiber are completely fixed together by a connecting structure, and the relative position offset between the collimating lens and the optical fiber is not easy to occur during mechanical tests and rocket launches, thereby avoiding a reduction in the efficiency of laser coupling into the optical fiber. The FC connector of the first fiber collimator 15 is an angled head to prevent the laser return from generating noise; the FC connector of the second fiber collimator 16 is a flat head, and a reflective film is coated on the fiber end face, and the reflectivity is usually 10%-20%, and the reflected laser is used to suppress the fiber phase noise; if the fiber length of the second fiber collimator 16 is less than 3m, that is, the noise introduced by the fiber is not sufficient to affect the output laser performance, the fiber end face of its FC connector can also be an angled head without a reflective film.

[0039] In a specific embodiment, the active vibration isolation module 3 includes a stator, a float and an electronic control unit. The stator is fixed on a main substrate, and the stator and the float are connected by a spring. The captive screw is installed and fixed on the stator of the active vibration isolation module so that by tightening the captive screw, the thread of the captive screw and the threaded hole on the float are completely fixed and engaged to achieve locking, or by loosening the captive screw, the float is unlocked by the support of the spring.

[0040] During mechanical tests and rocket launches, it is kept in a locked state to maintain a high stiffness to resist the corresponding vibrations. After unlocking, the active vibration isolation is turned on for performance testing. When performing performance testing on the ground, the float of the active vibration isolation module 3 needs to be suspended together with the physical module 2 through a suspension device to simulate the on-orbit microgravity environment. When performing performance testing on-orbit, it is only necessary to unlock and then turn on the active vibration isolation.

[0041] In one specific embodiment, see Figure 4 and Figure 5 The physical module 2 includes a cylindrical vacuum chamber 21, a front-cavity matching optical path module 22 arranged at the lower end of the cylindrical vacuum chamber 21, and a back-cavity detection optical path module 23 arranged at the upper end of the cylindrical vacuum chamber 21;

[0042] The cylindrical vacuum chamber 21 has a heat shielding layer inside and a heating film and heat wrap outside;

[0043] The lower part of the cylindrical vacuum chamber 21 is evenly distributed with mounting columns 26, and the mounting columns 26 are fixed to the float of the active vibration isolation module 3 through metal-based shock-absorbing springs or rubber shock-absorbing pads to increase the damping between the cylindrical vacuum chamber 21 and the outside world;

[0044] The input end of the pre-cavity matching optical path module 22 is connected to a third optical fiber collimator 27 , and the collimating lens end of the third optical fiber collimator 27 is fixed on the pre-cavity matching optical path module 22 to stabilize the direction of the input laser.

[0045] It should be noted that the optical reference cavity 25 is completely fixed on the heat shielding layer, and the front-cavity matching optical path module 22 and the cylindrical vacuum chamber 21 are completely fixedly installed, thereby reducing the relative position change between the two; the heating film outside the cylindrical vacuum chamber 21 is divided into three loops of the upper and lower end faces and the side faces, which are independently temperature controlled, and can adjust the target temperature according to the different temperature distributions around the vacuum chamber, so that the temperature control of unidirectional heating will not fail due to the target temperature being higher than the set temperature; the evenly distributed mounting columns under the cylindrical vacuum chamber 21 are fixed to the float of the vibration isolation module 2 through metal-based shock-absorbing springs or rubber shock-absorbing pads. The use of metal-based shock-absorbing springs or rubber shock-absorbing pads can effectively increase The damping between the optical reference cavity 25 and the outside world allows the kinetic energy generated during mechanical testing or launching to be greatly absorbed, ensuring that the optical reference cavity 25 has a more stable mechanical environment; the input of the pre-cavity matching optical path module 22 is the third optical fiber collimator 27, and the collimating lens end is fixed on the pre-cavity matching optical path module 22, which can ensure that the direction of the input laser does not change; the optical reference cavity 25 is a cubic reference cavity formed by a support frame 24 cut based on eight vertex corners. Compared with the traditional four-vertex fixing method, the eight-vertex fixing method is adopted to make the optical reference cavity 25 more firmly fixed, enough to withstand higher-intensity mechanical vibrations, and at the same time, the vibration sensitivity can be changed by adjusting the cutting depth of the eight vertex corners.

[0046] The electronic drive control module includes electronic functions such as laser drive, RF drive, feedback control circuit, etc. required for the ultra-stable laser. Circuits with different functions are independently installed in a metal box, and then all the metal boxes are fixed on a metal base plate in turn to form an electronic drive control module structure; the metal base plate of the electronic drive control module is located on the liquid cooling plate for heat conduction, and the main substrate 7 is the one that actually bears the installation force of the electronic drive control module.

[0047] In a specific embodiment, the main substrate 7 is a metal structural plate with a thickness of not less than 50 mm and the base frequency of the main substrate 7 is not less than 120 Hz. The high-rigidity main substrate can provide high-strength support for the whole machine, so that it can withstand the huge vibration during mechanical tests and rocket launches; there are mounting holes on both sides of the bottom surface of the main substrate 7, which can conveniently fix the ultra-stable laser on the satellite platform or the experimental cabinet of the space station, or install it on the transport tooling for quick transportation. In addition, if the working environment of the whole machine is a manned space station environment, it is fixed with captive screws, which is conducive to the on-orbit maintenance and replacement of the whole machine.

[0048] The ultra-stable laser for space applications in this embodiment has a compact and stable structure and can withstand greater mechanical vibrations. The modular design makes the system more maintainable. The laser between modules is transmitted through an integrated fiber collimator, which can effectively overcome the changes in laser pointing caused by fiber plugging and unplugging. The eight-point support method is used to make the cubic reference cavity more adaptable to the mechanical environment while maintaining low vibration sensitivity. The energy absorption design of installing shock-absorbing springs or vibration-absorbing pads at the bottom of the vacuum chamber helps to further reduce the influence of vibration on the reference cavity and the direction of the optical path during mechanical testing and launch.

[0049] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0050] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "plurality" is two or more, unless otherwise clearly and specifically defined.

[0051] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0052] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0053] In the description of this specification, the description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine different embodiments or examples described in this specification.

[0054] Although the present application is described herein in conjunction with various embodiments, in the process of implementing the present application for which protection is claimed, those skilled in the art may understand and implement other variations of the disclosed embodiments by viewing the drawings, the disclosure, and the appended claims. In the claims, the word "comprising" does not exclude other components or steps, and "one" or "an" does not exclude multiple situations. A single processor or other unit may implement several functions listed in a claim. Certain measures are recorded in mutually different dependent claims, but this does not mean that these measures cannot be combined to produce good results.

[0055] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.

Claims

1. An ultra-stable laser for space applications, characterized in that: include: A main optical path module (1), a physical module (2), an active vibration isolation module (3), an electronic drive control module (4), a sound insulation module (5), a liquid cooling plate (6) and a main base plate (7); The main substrate (7) is provided with a lightening groove, and the main optical path module (1) is arranged in the lightening groove below the main substrate (7); the lightening groove above the main substrate (7) forms a first cavity (72) and a second cavity (73) through an isolating member (71), and the liquid cooling plate (6) is arranged in the first cavity (72); the electronic drive control module (4) is arranged on the liquid cooling plate (6), and the electronic drive control module (4) is fixed on the main substrate (7); the active vibration isolation module (3) is arranged in the second cavity (73), and the physical module (2) is fixed on the active vibration isolation module (3); the sound insulation module (5) is a box structure with one side open, and the opening surface of the sound insulation module (5) covers the physical module (2) and the active vibration isolation module (3) and is fixed on the main substrate (7); The surface of the liquid cooling plate (6) has a heat-conducting coating; The main optical path module (1) comprises a laser (10), a polarization beam splitter prism (11), an electro-optic modulator (12), an acousto-optic modulator (13), a double-pass acousto-optic modulator (14), a first optical fiber collimator (15), and a second optical fiber collimator (16); A polarization beam splitter prism (11), an electro-optic modulator (12), an acousto-optic modulator (13) and a first optical fiber collimator (15) are connected in sequence, and the polarization beam splitter prism (11), a double-pass acousto-optic modulator (14) and a second optical fiber collimator (16) are connected in sequence; The polarization beam splitter prism (11) is used to split laser light into a first light signal and a second light signal, the first light signal being outputted through an electro-optic modulator (12), an acousto-optic modulator (13) and a first optical fiber collimator (15) in sequence and then transmitted to an optical reference cavity to stabilize the laser frequency, and the second light signal being outputted through acousto-optic modulator (14) and a second optical fiber collimator (16) in sequence for double passes.

2. The ultra-stable laser for space applications according to claim 1, characterized in that: The FC interface of the first optical fiber collimator (15) is an oblique joint to avoid noise generated by laser return; and when the optical fiber length of the second optical fiber collimator (16) is greater than 3m, the FC interface of the second optical fiber collimator (16) is a flat joint, and the optical fiber end face of the second optical fiber collimator (16) is coated with a reflective film to utilize the reflected laser to suppress optical fiber phase noise; or when the optical fiber length of the second optical fiber collimator (16) is less than 3m, the FC interface of the second optical fiber collimator (16) is an oblique joint.

3. The ultra-stable laser for space applications according to claim 2, characterized in that: The reflectivity of the reflective film is 10%-20%.

4. The ultra-stable laser for space applications according to claim 1, characterized in that: The active vibration isolation module (3) comprises a stator, a float and an electric control unit, wherein the stator is fixed on a main substrate, and the stator and the float are connected via a spring; a captive screw is installed and fixed on the stator of the active vibration isolation module so that by tightening the captive screw, the thread of the captive screw and the threaded hole on the float are completely fixed and engaged to achieve locking, or by loosening the captive screw, the float is unlocked by the support of the spring.

5. The ultra-stable laser for space applications according to claim 1, characterized in that: The physical module (2) comprises a cylindrical vacuum chamber (21), a front-cavity matching optical path module (22) arranged at the lower end of the cylindrical vacuum chamber (21), and a back-cavity detection optical path module (23) arranged at the upper end of the cylindrical vacuum chamber (21); The cylindrical vacuum chamber (21) has a heat shielding layer inside and a heating film and heat wrap outside; The lower part of the cylindrical vacuum chamber (21) is evenly distributed with mounting columns (26), and the mounting columns (26) are fixed to the float of the active vibration isolation module (3) through metal-based shock-absorbing springs or rubber shock-absorbing pads to increase the damping between the cylindrical vacuum chamber (21) and the outside world; The input end of the pre-cavity matching optical path module (22) is connected to a third optical fiber collimator (27), and the collimating lens end of the third optical fiber collimator (27) is fixed on the pre-cavity matching optical path module (22) to stabilize the direction of the input laser.

6. The ultra-stable laser for space applications according to claim 5, characterized in that: The heating film is arranged on the upper end surface, the lower end surface and the side surface outside the cylindrical vacuum chamber (21), and the heating modules on the upper end surface, the lower end surface and the side surface are independently controlled.

7. The ultra-stable laser for space applications according to claim 1, characterized in that: The main substrate (7) is a metal structural plate with a thickness of not less than 50 mm and a base frequency of not less than 120 Hz.

8. The ultra-stable laser for space applications according to claim 1, characterized in that: Both sides of the main substrate (7) also include mounting holes for fixing the ultra-stable laser.

9. The ultra-stable laser for space applications according to claim 5, characterized in that: The optical reference cavity of the cylindrical vacuum chamber (21) is a cubic reference cavity with eight vertex corners cut and fixed.

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