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Chinese researchers have developed a two-kilowatt (kW) fibre laser capable of operating without the protection of heating or cooling systems across Earth’s most extreme climates – from temperatures of minus 50 degrees Celsius (minus 58 degrees Fahrenheit) in the Arctic to 50 degrees Celsius (122 degrees Fahrenheit) in the Sahara Desert.
The device, designed for quick and ultra-portable deployment for both defence and industrial purposes, starkly contrasts with counterparts with similar power output such as the European HELMA-P or India’s IDDIS, which require truck transport with container-sized cooling units to achieve a 1km (0.62 miles) kill range on drones.
Led by Chen Jinbao, vice-president of the National University of Defence Technology and a national award-winning pioneer in high-energy lasers, the team overcame a decades-long challenge: stabilising laser performance across 100-degree temperature swings.
Their innovation hinges on some radical design choices, including 940-nanometre pump lasers with minimal thermal drift, directly injecting light via nine forward and 18 backward fibre-coupled diodes.
They also put pump combiners outside the resonator to isolate heat-sensitive components. Coiling ytterbium-doped fibre at around 8cm (3.1 inches) diameters helps to suppress parasitic lightwaves.
“We have achieved a technological breakthrough in the performance of wide-temperature operating fibre lasers,” wrote Chen and his colleagues in a peer-reviewed paper to be published in the Chinese-language journal Higher Power Laser and Particle Beams in July, now available online.
At the laser’s core lies a dual-clad optical resonator – 99 per cent reflective gratings at both ends sandwiching ytterbium-doped fibres. When pumped, ytterbium ions emit photons amplified into a lethal 1,080nm beam, filtered and collimated through quartz caps.
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