X-lumin has announced a successful demonstration of roundtrip optical transmission between its portable optical ground terminal (OGT) and a low Earth orbit (LEO) satellite, marking a significant advancement in laser-based space communications. The test involved transmitting an optical signal from a compact 15 cm terminal to a retroreflector-equipped satellite and receiving the signal back on Earth, closing a full roundtrip optical link.
The demonstration, conducted over multiple satellite passes, is notable as the first instance of a low size, weight, and power (SWaP) portable terminal achieving such a feat. X-lumin reported that its system was capable of tracking downlink signals that are up to one million times dimmer than the conventional benchmark of 25 µW/m², highlighting its sensitivity and precision.
Roundtrip optical communication presents substantial technical challenges compared to one-way links. Signals must pass through atmospheric turbulence twice, requiring extremely precise pointing stability at the microradian level and detection sensitivity at picowatt scales. Despite these challenges, X-lumin’s OGT operated with a power consumption of less than 20 watts and a total weight under 50 kilograms, demonstrating both efficiency and portability.
According to John Stryjewski, CTO and Co-Founder of X-lumin, the system was designed as a departure from traditional large-scale astronomical telescope-based ground stations. Instead, the company focused on developing a compact, cost-effective solution that is less susceptible to atmospheric interference and easier to deploy across diverse environments.
The terminal was developed under a Direct to Phase Two Small Business Innovation Research (SBIR) Other Transaction Authority (OTA) contract with the Space Development Agency, part of the United States Space Force. It builds on X-lumin’s prior work with larger 50–70 cm terminals used in both government and commercial applications. While designed to meet SDA 3.1 specifications, the system is modem-agnostic and supports multiple communication standards, including high-speed coherent modulation schemes exceeding 100 Gbps.
The achievement comes at a time when the space industry is rapidly transitioning toward optical communication technologies to support growing data demands. Emerging space architectures—driven by initiatives such as Amazon’s LEO programs, SpaceX’s Starlink network, and projects by Axiom Space—are expected to significantly increase the volume of data transmitted between space and Earth. According to McKinsey & Company, daily data demand could grow by 3.5 times over the next four years.
Industry experts note that traditional radio frequency (RF) systems may struggle to meet these requirements due to bandwidth and spectrum limitations. Optical communication, with its higher capacity and efficiency, is increasingly viewed as a critical enabler of next-generation space infrastructure.
X-lumin’s demonstration suggests that compact optical ground terminals could play a key role in overcoming current bottlenecks, offering scalable, high-performance alternatives to large, infrastructure-heavy systems. The company is also expanding its ecosystem through collaborations with partners such as Cisco and participation in industry programs supported by Space Florida and Seraphim Space.
