Space laser communication is a communication technology that uses laser as carrier to realize high-speed and reliable data transmission in space. Its fundamental concept is to support efficient data transmission between platforms in space, on earth, and at sea through high transmission rates, strong anti-interference abilities, and excellent confidentiality. Currently, the cutting edge of space laser communication technology lies in the development of networking capabilities. This transition moves from the traditional point-to-point communication model to a multi-node collaborative network architecture, aiming to establish an intelligent, full-coverage communication network. However, in the current space laser communication networking scenario, the classic point-to-point laser communication terminal remains the core configuration. Multi-node chain networking is achieved by increasing the number of laser terminals. To realize a set of laser communication terminals capable of adapting to different types and numbers of laser links, the system should undergo software and hardware reconstruction. This will allow the establishment of laser links with multiple communication nodes to enable information transmission. We propose an optical theory and network architecture based on rotating parabolic multi-mirror splicing and discuss the challenges and breakthroughs in key technologies such as multi-beam isolation and multi-node acquisition and tracking. We provide a reference for technological progress in space optical communication networking.

To use a set of laser terminals and establish laser links with multiple communication nodes simultaneously, information transmission is realized. The optical theory and networking configuration of multi-mirror splicing based on the rotating paraboloid are proposed. The core theory is the optical principle of the rotating paraboloid. The paraboloid is rotated 180° around its axis of symmetry, and the resulting curved surface is the rotating paraboloid. The increase in the number of mirror splices, or “planes”, brings the system closer to the ideal rotating paraboloid. This ensures effective beam energy utilization and communication link margin while allowing more laser communication nodes to be dynamically reconstructed. The ultimate goal is to create a hardware system that can support optical communication networking with any number of nodes through software configuration. The theory and configuration of the one-to-many laser communication networking architecture based on the rotating paraboloid provides a 360° omnidirectional field of view and a theoretical pitch field of view above 100°. This setup can enable multi-point duplex simultaneous laser communication over a larger range and at longer distances.

The scientific research team successfully carries out a high-altitude multi-node laser communication networking test in Lulang, Xizang, and verified the key technology for dynamic networking of space platforms. The test adopts the self-developed optical transceiver system: the master optical transceiver provides 360° omnidirectional coverage and ±30° pitch scanning of a 200 μrad narrow beam through a rotating parabolic array antenna, while the slave optical transceiver uses a 90 mm aperture antenna with a 100 μrad divergence angle design. In the experiment, a three-node network is established, consisting of the master optical transceiver on the ground, the airship-based slave optical transceiver at 3300 m, and the mountaintop slave optical transceiver. A 2.5 Gbit/s high-speed transmission has been achieved over a link distance of 2 km, and synchronized returns of the gondola, unmanned aerial vehicle (UAV) aerial photography, and ground monitoring video has been successfully completed. The measured data shows that the coarse-fine composite tracking system provides a dynamic tracking accuracy better than 6 μrad (Fig. 8), and the fine tracking system significantly improves communication quality. Compared to the non-fine tracking system, the bit error rate increases from 10^-5 to better than 10^-9 (Fig. 9), which verifies the capability for rapid multi-node chain-building and stable transmission in harsh environments. This achievement provides important technical support for building a space-based high-speed laser communication network, marking a breakthrough in the field of space laser networking.

Compared to traditional point-to-point laser communication terminals, the rotating paraboloid configuration offers a similar 360° azimuth and 100° elevation beam control range, with millisecond-level mechanical servo speed. Its effective transmitting and receiving aperture exceeds 50 mm, and its multi-mirror splicing control and single sub-optical path integrated transmitting and receiving capabilities are unprecedented. As the number of nodes increases, the volume and weight advantages of this configuration will become more apparent. In comparison with non-mechanical solid-state scanning laser communication networking configuration, the rotating paraboloid multi-mirror splicing optical antenna configuration provides a wider beam control range than the liquid crystal phased array (±12° azimuth and elevation) and a larger effective transmitting and receiving aperture than the optical waveguide phased array (8 mm). This is achieved while maintaining the ability to transmit and receive multiple beams simultaneously. Additionally, unlike polarization/energy diversity networking terminals based on classical optics, which require an additional set of polarization/energy diversity devices for each node, the rotating paraboloid formed by multiple mirrors offers excellent scalability. It allows for the addition of more nodes to the laser communication networking without changing the hardware structure. In conclusion, the multi-reflector antenna configuration based on the rotating paraboloid and the associated laser communication networking device introduced in this paper offers high antenna gain and link margin, scalable software reconfiguration for large-scale networking, and a relatively mature technical system, which can provide a reference for the technological progress of space optical communication networking.