Breakthrough crystal brings China closer to ground-based anti-satellite lasers

Chinese scientists have successfully produced the world’s largest barium gallium selenide (BGSe) crystal, a milestone that could dramatically advance the development of ultra-high-power laser systems, including weapons capable of targeting satellites from Earth.

The breakthrough crystal, measuring 60 millimetres (2.3 inches) in diameter, was unveiled by researchers led by Professor Wu Haixin from the Hefei Institutes of Physical Science under the Chinese Academy of Sciences, Caliber.Az reports, referencing Chinese media.

BGSe is a synthetic material capable of converting short-wave infrared lasers into mid- and far-infrared beams, which are ideal for long-range transmission through the atmosphere. According to the research, the newly manufactured crystal can endure laser power as intense as 550 megawatts per square centimetre, ten times the threshold of current military-grade crystals, allowing for significantly more powerful and stable laser systems.

The new laser frequency converter created from this crystal measures 10×10×50 mm (0.4×0.4×2 inches), vastly outscaling conventional optical components that are typically far smaller and thinner. “This represents the largest specimen reported globally to date,” Wu’s team wrote.

Self-damage has long been a limiting factor for laser weapons, compromising both range and performance. One prominent example was the US Navy’s 1997 MIRACL test, in which a mid-infrared laser melted part of its own equipment during an anti-satellite trial. The high resilience of the new BGSe crystal addresses this long-standing challenge.

BGSe was first discovered by Chinese researchers in 2010, stunning the global defence and scientific communities with its superior properties. Efforts by Western defence companies to replicate the crystal met with difficulties, particularly in scaling production to usable sizes.

The manufacturing process developed by Wu’s team is highly complex and demands extreme precision. It begins with the vacuum-sealed combination of ultra-pure barium, gallium, and selenium in quartz tubes using a method called zone refining. These tubes are heated in a dual-zone furnace to 1,020°C (1,868°F), creating a molten region where crystals begin to grow as the tubes are slowly lowered into cooler areas over the course of a month.

After formation, the crystals are annealed — held at 500°C (932°F) for several days, then cooled at a controlled rate of 5°C per hour — to remove internal defects. Final polishing is done with diamond saws and cerium oxide slurry to achieve optically smooth surfaces.

The team emphasised that success hinges on excluding oxygen and moisture at every stage, maintaining precise temperature controls, and applying defect-erasing thermal treatment techniques to ensure structural and optical integrity at this unprecedented scale.

This advancement aligns with China’s rapidly expanding directed-energy weapons program, which has gained urgency amid growing concerns over Starlink’s role in Ukraine and broader competition in space. China has also made notable progress in related areas such as energy storage and thermal management for high-energy systems.

While the technology has clear military applications, the research team noted that large BGSe crystals also offer promise for civilian uses, including advanced medical diagnostics and ultra-sensitive infrared systems for missile tracking and aircraft identification.

Wu’s team confirmed that since 2020, these ultra-large crystals — described as “structurally intact, free of cracks and optically transparent” — have already been integrated into various cutting-edge research and development projects.

Although this 60mm crystal is the largest of its kind, even larger crystals exist in non-weapon laser systems. For example, the University of Michigan’s ZEUS laser — one of the world’s most powerful — relies on a titanium-doped sapphire crystal nearly 18 centimetres (seven inches) wide, which took four and a half years to produce.

By Tamilla Hasanova