Silicon Optical Phased Arrays Break Speed Barriers for Aircraft-to-Satellite Communications

New pointing, acquisition, and tracking system achieves microsecond beam steering for high-speed satellite handoffs

A team of Chinese researchers has demonstrated a breakthrough in free-space optical communications that could enable high-speed internet access for aircraft through low-Earth orbit (LEO) satellite constellations. The system uses an integrated silicon optical phased array (OPA) to achieve beam steering speeds of less than 60 microseconds—fast enough to maintain stable laser links as satellites zip across the sky.

The research, led by Lei Chen and colleagues at the Chinese Academy of Sciences' Chongqing Institute of Green and Intelligent Technology, addresses a critical challenge in air-to-space laser communications: the need for rapid, precise beam steering to track fast-moving satellites while compensating for aircraft vibrations.

"The current mechanical beam steering systems using gimbals and fast steering mirrors are relatively large in size, weight, and power," the researchers write in their paper published in IEEE Photonics Journal. "The complex mechanical structure with large inertia makes scanning speed slow and control bandwidth low."

Silicon Photonics Solution

The team's solution centers on a 512-element silicon-based integrated optical phased array that steers laser beams electronically rather than mechanically. The system achieves two-dimensional beam steering by controlling thermal phase shifters for azimuth scanning and adjusting the laser wavelength for elevation scanning.

In laboratory tests, the system demonstrated beam steering rise times of less than 60 microseconds in azimuth and 46 microseconds in elevation, with pointing accuracy better than 0.05° root-mean-square error within a 5° × 5° field of view. The calculated closed-loop bandwidth exceeded 2.5 kHz.

"The experimental results show that the OPA used in this paper has the ability of fast scanning and high response speed, and can achieve efficient beam control and dynamic adjustment," the authors note.

Growing Field of Research

This work represents the latest advance in a rapidly evolving field. Recent research has shown increasing sophistication in optical phased array technology for free-space communications:

• In 2022, researchers at National Yang Ming Chiao Tung University demonstrated a 30-channel integrated optical waveguide OPA with a 17.42° scanning range
• A 2023 study from Jilin University achieved switching times under 27 microseconds with a large-aperture silicon-silicon nitride OPA
• In 2024, researchers demonstrated ±20° scanning with sub-20 microsecond rise times using a 32-channel silicon-based OPA

However, most previous research focused solely on beam steering performance rather than complete pointing, acquisition, and tracking (PAT) systems required for operational communications.

Real-World Applications

The motivation for this research stems from the explosive growth of LEO satellite constellations. These satellites move rapidly across the sky, staying in view for only short periods, requiring communication systems that can quickly establish and hand off connections between satellites.

Traditional mechanical steering systems face significant limitations in aircraft applications. Beyond their size and weight penalties, they affect aircraft aerodynamics and cannot respond quickly enough to compensate for both satellite motion and aircraft vibrations.

The integrated OPA approach offers several advantages: dramatically reduced size, weight, and power consumption; mechanical-free operation that eliminates reliability concerns; and the ability to switch between arbitrary beam angles without the limitations of mechanical inertia.

Technical Innovations

The researchers' system includes several novel technical elements. They use a wedge prism to correct the naturally curved beam pattern produced by the grating couplers, transforming it into a straight line that simplifies two-dimensional calibration. The system also employs a four-quadrant detector (QD) for angle-of-arrival detection, enabling closed-loop tracking.

The team implemented a rotating electric vector (REV) algorithm for OPA calibration, systematically adjusting the phase of each channel to optimize beam quality. This resulted in peak sidelobe ratios exceeding 12 dB across all steering angles.

Future Prospects

While the current demonstration operates over a 2-meter laboratory range, the researchers envision scaling the technology for operational aircraft-to-satellite links. The system's high bandwidth and precision make it suitable for the rapid satellite handoffs required in LEO constellation networks.

The work also has implications beyond aircraft communications. Similar OPA-based systems could enable high-speed optical links for autonomous vehicles, ship-to-satellite communications, and next-generation optical networks requiring rapid beam steering.

As LEO satellite constellations continue their rapid deployment, technologies like integrated optical phased arrays may prove essential for realizing the promise of ubiquitous high-speed internet access from aircraft and other mobile platforms.

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Sources

1. Chen, L., Zhu, L., Du, H., Wang, X., Shen, S., Wang, Y., Zhao, S., & Wang, X. (2025). Pointing Acquisition and Tracking System for Free Space Optical Communication Based on Integrated Optical Phased Array. IEEE Photonics Journal, 17(4), 7301608. https://doi.org/10.1109/JPHOT.2025.3582266
2. Poulton, C. V., et al. (2019). Long-range LiDAR and free-space data communication with high-performance optical phased arrays. IEEE Journal of Selected Topics in Quantum Electronics, 25(5), 7700108. https://doi.org/10.1109/JSTQE.2019.2908555
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7. Kaymak, Y., Rojas-Cessa, R., Feng, J., Ansari, N., Zhou, M., & Zhang, T. (2018). A survey on acquisition, tracking, and pointing mechanisms for mobile free-space optical communications. IEEE Communications Surveys & Tutorials, 20(2), 1104-1123. https://doi.org/10.1109/COMST.2018.2804323
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