1.World’s First Demonstration of Airborne Laser Communication with GEO Satellites and Its Application Prospects

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The rapid iteration of space laser communication technology has made cross-platform, long-distance high-speed data transmission a key direction for upgrading aviation and national defense communication capabilities. Recently, the European Space Agency (ESA) and Airbus have joined forces to achieve a world-first demonstration breakthrough in laser link communication between an aircraft and a Geostationary Orbit (GEO) satellite. In this demonstration, a highly collimated laser beam successfully established a reliable communication link between a high-speed flying aircraft and a GEO satellite 36,000 kilometers away, with a data transmission rate of up to 2.6 Gbps—performance comparable to that of ground-based optical fiber networks. The demonstration project is jointly promoted by ESA, Airbus Defence and Space, the Netherlands Organisation for Applied Scientific Research (TNO), and Germany’s TESAT GmbH. Notably, for such scenarios with strict requirements on high-precision alignment and stable transmission of laser links, the off-axis reflective collimator can be used as the core optical support equipment. In the flight test verification carried out in Nîmes, France, Airbus’ UltraAir laser terminal demonstrated excellent operational stability, achieving zero-error transmission for several consecutive minutes. This major breakthrough further highlights the broad application prospects of laser communication technology in realizing beyond-visual-range, high-bandwidth communication in aviation, navigation, and national defense security.

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2.Technical Difficulties in High-Speed Mobile Laser Communication and Adaptation Advantages of the Instrument

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2.1Technical Difficulties of Laser Communication in High-Speed Mobile Scenarios

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Even establishing a laser link between two fixed ground terminals presents considerable technical barriers. Achieving stable communication between a high-speed moving aircraft and a GEO satellite sets extremely high standards for the dynamic accuracy of the system. GEO satellites operating at an orbit of 36,000 kilometers are stationary relative to the ground, while aircraft are constantly in a dynamic state of vibration, airflow disturbance, and continuous displacement. A laser communication system must not only resist various complex interferences such as atmospheric turbulence, cloud occlusion, and temperature variations, but also achieve ultra-high-precision real-time alignment of the laser beam.

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2.2Adaptation Advantages of the Off-Axis Reflective Collimator

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For such high-precision space laser communication scenarios, the off-axis reflective collimator is an ideal core optical instrument that provides a solid guarantee for the high-precision and stable transmission of laser links. Adopting an off-axis structure, the instrument has its primary mirror and secondary mirror arranged in a staggered manner (non-coaxial), which effectively reduces stray light interference and internal reflection, significantly optimizes optical performance, and accurately fulfills core tasks such as laser beam expansion and output of parallel light with an ultra-low divergence angle. It perfectly matches the high-precision application requirements of space laser communication.

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3.Core Demonstration Performance, Instrument Parameters and Strategic Value

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3.1Core Demonstration Performance and Technical Evaluation

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François Lombard, Head of Connected Intelligence at Airbus Defence and Space, commented on the technical challenge: “Establishing a laser link between two moving targets over a distance of tens of thousands of kilometers is undoubtedly an extremely difficult technical challenge. The continuous motion of the targets, the vibration of the platform itself, and atmospheric disturbances impose extremely high requirements on the precision control of the system.” In this demonstration, the UltraAir laser terminal onboard the aircraft successfully achieved rapid acquisition and stable tracking of the satellite and maintained a reliable connection for a sufficient duration, fully verifying its core capability of continuous high-throughput transmission.

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3.2Parameters and Supporting Role of the Off-Axis Reflective Collimator

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In similar laser communication application scenarios, the off-axis reflective collimator can provide key technical support. The instrument adopts an off-axis Newtonian reflective optical system, with a system wave aberration RMS better than 1/15λ, and parallelism controlled within 5 arcseconds. The primary mirror can be made of fused silica or microcrystalline material according to requirements. Two coating options are available: aluminum + silicon protective coating (reflectivity 85%) and silver + silicon protective coating (reflectivity 95%). Its excellent optical parameters ensure high collimation and low divergence of the laser beam, providing strong support for high-speed data transmission. At a transmission rate of 2.6 Gbps, a high-definition movie can be downloaded in just a few seconds.

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3.3Strategic Value and Security Advantages of the Technology

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In addition to its application value in the civilian field, the technology also has prominent strategic significance. Kees Buijsrogge, Director of TNO Space, stated from a geopolitical perspective: “This breakthrough fully demonstrates that our industry is continuously strengthening Europe’s security capabilities and strategic autonomy by leading technological innovation in secure laser communication.” Due to the extremely small divergence angle and invisible wavelength of the laser beam, the communication link is inherently difficult to detect or intercept. When equipped with an off-axis reflective collimator, the ultra-low divergence parallel light further enhances this security advantage, providing absolute assurance of communication resilience and operational safety for defense users operating in complex and contested environments.

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4.European Accumulation in Laser Relay Technology and Requirements of the EDRS System

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The success of this airborne laser link demonstration is not accidental, but the result of more than ten years of intensive research and development by Europe in practical laser relay technology.

The European Data Relay System (EDRS), known as the “Space Data Highway”, developed by ESA, is centered on geostationary orbit relay satellites. It receives data from Low Earth Orbit (LEO) spacecraft via laser links and forwards it to ground receiving stations, completely breaking the dependence on traditional downlink transmission windows. The stable operation of this system urgently requires high-precision optical instruments. The off-axis reflective collimator can be widely used for optical axis calibration in multi-axis systems covering visible light, infrared, and laser bands. It can also perform basic optical parameter measurement and infrared imaging quality inspection, serving as a comprehensive optical support equipment for the long-term stable operation of such laser links.

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5.EDRS Solving Transmission Bottlenecks and Multi-Scenario Adaptation of the Instrument

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5.1Principle of EDRS in Solving Transmission Bottlenecks

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A LEO satellite orbits the Earth approximately every 100 minutes, but its line-of-sight contact with a specific ground station during each pass lasts only about 10 minutes, which severely limits communication efficiency. EDRS achieves continuous optical relay through geostationary orbit nodes, effectively solving this transmission bottleneck, greatly extending communication duration, and reducing transmission latency. This process imposes extremely strict precision requirements: the laser terminal must accurately locate and lock onto the target at a distance of nearly 45,000 kilometers, while one platform can move at a speed of up to 8 km/s relative to the Earth.

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5.2Instrument Adaptation in High-Difficulty Scenarios and Technical Expansion

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In this high-precision pointing and tracking process, the off-axis reflective collimator can simulate infinite targets, assist laser terminals in achieving high-precision alignment, and effectively ensure link stability, making it highly suitable for such high-difficulty laser communication scenarios. The new laser link between aircraft and GEO satellites realized this time is essentially an important practice of successfully extending the mature aerospace laser communication concept to the aviation field.

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5.3European Optical Communication Ecosystem and Multi-Scenario Application of the Instrument

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At present, the airborne UltraAir terminal has been deeply integrated into the European optical communication ecosystem. The LaserPort optical ground station developed by Airbus Netherlands can establish two-way communication links with LEO, MEO, and GEO satellites, with transmission rates ranging from 2.5 Gbps to 100 Gbps and the potential to upgrade to terabit (Tbps)-level throughput. These systems can be widely used in trunk transmission, feeder links, and data relay. Compared with traditional RF systems, they require no frequency licensing and greatly reduce the cost per bit. When paired with an off-axis reflective collimator, its high-precision optical performance further improves transmission stability and the upper rate limit of the system. Previously, projects such as CREOLA have successfully achieved bidirectional optical feeder link transmission at 9 Gbps for several consecutive days. Such high-demand projects can also be supported by similar high-precision optical instruments.

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6.Core Advantages of Optical Links and Supporting Significance of the Instrument

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Currently, global data traffic is growing explosively. Traditional radio frequency (RF) spectrum resources are becoming increasingly scarce and regulated, placing growing transmission pressure on satellite networks. Especially in low Earth orbit, traditional RF frequency bands face severe bandwidth shortages. According to laser communication materials released by ESA, optical links demonstrate irreplaceable core advantages under this background. Compared with radio waves, laser beams have extremely low divergence, enabling larger data volumes to be transmitted over longer distances. They also feature higher security, lower interception risk, and no complicated frequency licensing procedures.

As the core optical support instrument for such scenarios, the off-axis reflective collimator’s key features—outputting parallel light with an ultra-low divergence angle and suppressing stray light interference—are critical guarantees for long-distance, high-rate, and high-security transmission of laser links. It also provides a reliable optical equipment solution for the large-scale application of space laser communication technology in the future.