Spatial light-optical fiber coupling device

Abstract

The invention discloses a spatial light-optical fiber coupling device which comprises a reflecting mirror, a piezoelectric ceramic fast reflecting mirror, a beam splitter, a camera lens group, an infrared camera, a coupling mirror group, a beam expanding optical fiber and a communication machine. The piezoelectric ceramic fast reflecting mirror is positioned on a reflecting light path of the reflecting mirror; the beam splitter, the coupling mirror group and the beam expanding optical fiber are sequentially arranged along an emergent light path of the piezoelectric ceramic fast reflecting mirror; the camera lens group and the infrared camera are sequentially arranged along a reflection light path of the beam splitter; the beam expanding optical fiber is a TEC optical fiber; and the coupling mirror group is used for converting an optical mode field of the light transmitted from the beam splitter into an optical mode field which is the same as the mode field of the beam expanding optical fiber. According to the invention, spatial light coupling is carried out on the optical fiber with a large mode field diameter through the TEC beam expanding optical fiber, and the receiving area of the receiving optical fiber is increased, so that the coupling efficiency of spatial light-optical fiber and the tolerance to alignment errors are improved.

Description

Technical Field

[0001] The present invention relates to the field of satellite integration technology, and in particular to a space light-fiber coupling device. Background Art

[0002] At present, the communication between satellites and between satellite and ground stations mainly adopts microwave means. There are mainly problems such as limited frequency resources and insufficient communication bandwidth, which cannot meet the current satellite constellation networking requirements for high communication rate and high communication bandwidth. Space laser communication technology uses laser to replace traditional microwave as a carrier. The communication terminal has the characteristics of wide bandwidth, small size, light weight, low power consumption, good confidentiality, and no spectrum restrictions. It has become an effective means to solve the bandwidth bottleneck of satellite microwave communication and alleviate the shortage of satellite spectrum resources, and realize high-speed satellite communication. Therefore, laser communication technology has become one of the key technologies for future satellite communications. Laser communication technology is a carrier that uses space light for information exchange. The information carried by space light enters the back-end demodulation system through space light-fiber coupling to complete information transmission. Since the coupling efficiency of space light-fiber is a key indicator that directly determines the performance of laser communication. Therefore, space light-fiber coupling has become one of the key technologies that need to be solved for the mature application of laser communication in the field of satellite communication.

[0003] For satellite free-space laser communication systems, the space beam is captured by the receiving end of the communication system after long-distance transmission. In order to detect and process the received signal beam, the receiving end first needs to couple the beam into the optical fiber. If the coupling efficiency of the space light into the optical fiber is low, the energy loss coupled into the optical fiber will be extremely large, which will seriously affect the communication efficiency of the communication system and the reliability of the communication link. At present, the technical solution of coupling to single-mode optical fiber is widely used at home and abroad. However, due to the limitation of the fiber core size of the single-mode optical fiber (generally 8μm~10μm), it is difficult to accurately align the focused light spot with the center of the optical fiber core, and there are high requirements for the alignment error and system error of the whole machine and optical system. This brings about many requirements such as high processing accuracy, high assembly accuracy, high structural stiffness and high thermal stability. These requirements bring about problems such as high processing difficulty, high assembly difficulty, and sensitivity to mechanical and thermal environments. It also leads to problems such as high product development cost and long cycle. Summary of the invention

[0004] In order to solve the above problems existing in the prior art, the present invention provides a spatial light-fiber coupling device. The technical problem to be solved by the present invention is achieved through the following technical solutions:

[0005] A first aspect of an embodiment of the present invention provides a spatial light-fiber coupling device, comprising: a reflector, a piezoelectric ceramic fast reflector, a beam splitter, a camera lens group, an infrared camera, a coupling mirror group, a beam expanding optical fiber, and a communication machine;

[0006] The reflector is used to receive the spatial light emitted by the spatial light receiving antenna;

[0007] The piezoelectric ceramic fast reflection mirror is located on the reflection light path of the reflection mirror;

[0008] The piezoelectric ceramic fast-reflecting mirror, the beam splitter, the coupling mirror assembly and the beam-expanding optical fiber are coaxially arranged in sequence and spaced apart;

[0009] The spatial light is reflected by the reflector and then incident on the piezoelectric ceramic fast reflector. The light emitted by the piezoelectric ceramic fast reflector passes through the beam splitter and the coupling mirror group in sequence and enters the beam expanding optical fiber. Part of the light passing through the beam splitter is reflected and then enters the infrared camera through the camera lens group.

[0010] The beam expansion optical fiber is a TEC optical fiber;

[0011] The coupling mirror assembly is used to convert the optical mode field of the light transmitted from the beam splitter into an optical mode field that is the same as the mode field of the beam expanding optical fiber.

[0012] In one embodiment of the present invention, the coupling lens assembly includes: a first biconvex lens, a first biconcave lens, and a second biconvex lens which are sequentially coaxially spaced apart.

[0013] In one embodiment of the present invention, it further includes: an industrial computer;

[0014] The industrial computer is electrically connected to the infrared camera.

[0015] In one embodiment of the present invention, it further comprises: a piezoelectric actuator;

[0016] The piezoelectric actuator is electrically connected to the industrial computer and the piezoelectric ceramic fast reflection mirror.

[0017] In one embodiment of the present invention, the camera lens group includes: a third biconvex lens, a second biconcave lens, a fourth biconvex lens and a third biconcave lens which are coaxially spaced in sequence.

[0018] Beneficial effects of the present invention:

[0019] The present invention spatially couples optical fibers with large mode field diameters through TEC beam expansion fibers, thereby increasing the receiving area of ​​the receiving optical fiber and improving the coupling efficiency of spatial light-optical fiber. Although the TEC optical fiber changes the refractive index profile of the optical fiber, the normalized frequency does not change, so the single-mode state is maintained during the transmission process. At the same time, after the optical signal is transmitted to the ordinary single-mode optical fiber at the rear end, it can be conveniently connected to other mature optoelectronic devices. In addition, the coupling mirror group can match the optical mode field of the light before the incident beam expansion fiber with the mode field of the beam expansion fiber, thereby improving the light receiving efficiency and further improving the coupling efficiency.

[0020] Other features and advantages of the present invention will be described in the following description, and partly become apparent from the description, or understood by practicing the present invention. The purpose and other advantages of the present invention can be realized and obtained by the structures particularly pointed out in the written description, claims, and drawings.

[0021] The technical solution of the present invention is further described in detail below through the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0023] Figure 1 A schematic structural diagram of a spatial light-fiber coupling device provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0024] 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.

[0025] like Figure 1 As shown, an embodiment of the present invention provides a spatial light-fiber coupling device, including: a reflector, a piezoelectric ceramic fast reflector, a beam splitter, a camera lens group, an infrared camera, a coupling mirror group, a beam expanding optical fiber and a communication machine.

[0026] The reflector is used to receive the spatial light emitted by the spatial light receiving antenna and reflect it to the piezoelectric ceramic fast reflector. The piezoelectric ceramic fast reflector, the beam splitter, the coupling mirror group and the beam expanding optical fiber are coaxially arranged in sequence. The spatial light is reflected by the reflector and then enters the piezoelectric ceramic fast reflector. The light emitted by the piezoelectric ceramic fast reflector passes through the beam splitter and the coupling mirror group in sequence and enters the beam expanding optical fiber; among them, part of the light passing through the beam splitter is reflected and then enters the camera lens group and the infrared camera in sequence. The beam expanding optical fiber is a TEC optical fiber.

[0027] The coupling mirror set is used to convert the optical mode field of the light transmitted from the beam splitter into the same optical mode field as the mode field of the beam expansion fiber.

[0028] Furthermore, the coupling lens group includes: a first biconvex lens, a first biconcave lens and a second biconvex lens which are coaxially arranged in sequence and spaced apart.

[0029] The camera lens group comprises: a third biconvex lens, a second biconcave lens, a fourth biconvex lens and a third biconcave lens which are coaxially arranged in sequence and spaced apart.

[0030] Among them, part of the light passing through the beam splitter is transmitted and then passes through the third biconvex lens, the second biconcave lens, the fourth biconvex lens and the third biconcave lens in sequence before entering the beam expanding optical fiber, and the other part of the light passing through the beam splitter is reflected and then enters the first biconvex lens, the first biconcave lens, the second biconvex lens and the infrared camera in sequence.

[0031] In this embodiment, Thermally Expanded Core (TEC) optical fiber is used as a receiving optical fiber in the coupling device of satellite space laser communication, and spatial optical coupling is performed through an optical fiber with a large mode field diameter, thereby improving the coupling efficiency. At the same time, after the optical signal is transmitted to the ordinary single-mode optical fiber at the back end, it can be conveniently connected to other mature optoelectronic devices. TEC optical fiber is obtained by heating (generally 1300℃~1650℃) ordinary single-mode optical fiber to cause Ge doped ions to diffuse into the cladding, which can expand the core diameter of ordinary single-mode optical fiber from 8μm~10μm to 20μm~30μm (depending on the heating time). This increases the receiving area of ​​the receiving optical fiber, thereby improving the coupling efficiency of spatial light-optical fiber. TEC optical fiber also has a feature that although the refractive index profile of the optical fiber is changed, the normalized frequency does not change, so the single-mode state is maintained during the transmission process.

[0032] The coupling mirror group is used to convert the optical mode field of the light transmitted from the beam splitter. After conversion, it is the same as the mode field of the beam expansion fiber, which improves the light receiving efficiency and further improves the coupling efficiency.

[0033] It should be noted that according to the fiber coupling formula The coupling efficiency of common single-mode fiber and TEC fiber at different alignment offsets is calculated:

[0034] The wavelength used in the calculation is 1550nm, the core diameter of ordinary single-mode fiber is 9μm, the core diameter of TEC fiber is 18μm, the NA value of ordinary single-mode fiber is 0.12, and the NA value of TEC fiber is 0.06. In engineering applications, the coupling efficiency is generally required to reach 30% or above for the system to be considered to be working properly. The lower limit of the coupling efficiency is set to 35%. According to the calculation, when the alignment offset reaches ±21.5μm, the coupling efficiency of the TEC fiber drops to 35%. Under the same conditions, the coupling efficiency of ordinary single-mode fiber drops to 35% when the offset is ±9.5μm. By comparison, it can be seen that the tolerance of TEC fiber to alignment errors is 2.26 times that of ordinary single-mode fiber.

[0035] In this embodiment, the TEC fiber is used as a space light receiving fiber, which improves the space light-fiber coupling efficiency and tolerance to alignment errors of satellite space laser communication, reduces the difficulty of space light-fiber coupling processing, control accuracy requirements and costs, and thus improves the communication efficiency of the satellite laser communication system and the reliability of the communication link. At the same time, it reduces the processing accuracy requirements, assembly accuracy requirements, structural rigidity and thermal stability requirements of the device, reduces the difficulty of processing, assembly difficulty, thermal and mechanical environment sensitivity, and reduces the product development cost and cycle.

[0036] Furthermore, the infrared camera is also electrically connected to the industrial computer. The industrial computer is also electrically connected to the piezoelectric actuator, and the piezoelectric actuator is electrically connected to the piezoelectric ceramic fast reflector (FSM).

[0037] In this embodiment, when aligning, the infrared camera collects the position of the incident light spot, and the centroid coordinates are output through the industrial computer. When the piezoelectric ceramic fast mirror rotates, the light spot position will move. When the centroid coordinates of the light spot almost coincide with the preset zero-position centroid coordinates, the spatial light can be aligned to enter the coupling mirror group and the beam expansion fiber. If the position of the light moves during the normal operation of the device, the centroid coordinates of the light spot collected by the infrared camera will be offset. At this time, the industrial computer sends a command to adjust the position to the piezoelectric actuator, and the piezoelectric actuator controls the piezoelectric ceramic fast mirror to rotate and adjust the position. At this time, the light spot position will change accordingly until the light spot position is within the normal range.

[0038] In this embodiment, while improving the spatial light-fiber coupling efficiency and tolerance to alignment errors of satellite space laser communications, the focal length of the infrared camera can be reduced, and the field of view corresponding to a single pixel is increased, thereby reducing the size of the device. At the same time, the control accuracy range of the piezoelectric ceramic fast-reflecting mirror is increased, reducing the control difficulty and system control error.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A spatial light-fiber coupling device, characterized in that: include: Reflectors, piezoelectric ceramic fast-reflecting mirrors, beam splitters, camera lens sets, infrared cameras, coupling mirror sets, beam-expanding optical fibers and communication devices; The reflector is used to receive the spatial light emitted by the spatial light receiving antenna; The piezoelectric ceramic fast reflection mirror is located on the reflection light path of the reflection mirror; The piezoelectric ceramic fast-reflecting mirror, the beam splitter, the coupling mirror assembly and the beam-expanding optical fiber are coaxially arranged in sequence and spaced apart; The spatial light is reflected by the reflector and then incident on the piezoelectric ceramic fast reflector. The light emitted by the piezoelectric ceramic fast reflector passes through the beam splitter and the coupling mirror group in sequence and enters the beam expanding optical fiber. Part of the light passing through the beam splitter is reflected and then enters the infrared camera through the camera lens group. The beam expansion optical fiber is a TEC optical fiber; The coupling mirror assembly is used to convert the optical mode field of the light transmitted from the beam splitter into an optical mode field that is the same as the mode field of the beam expanding optical fiber.

2. A spatial light-fiber coupling device as claimed in claim 1, characterized in that: The coupling lens group comprises: a first biconvex lens, a first biconcave lens and a second biconvex lens which are coaxially arranged in sequence and spaced apart.

3. A spatial light-fiber coupling device as claimed in claim 2, characterized in that: Also includes: Industrial computer; The industrial computer is electrically connected to the infrared camera.

4. A spatial light-fiber coupling device as claimed in claim 2, characterized in that: Also includes: Piezoelectric actuators; The piezoelectric actuator is electrically connected to the industrial computer and the piezoelectric ceramic fast reflection mirror.

5. The spatial light-fiber coupling device according to claim 2, characterized in that: The camera lens group includes: a third biconvex lens, a second biconcave lens, a fourth biconvex lens and a third biconcave lens which are coaxially arranged in sequence and spaced apart.

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