A laser can reshape the eye in more than one way. For decades, corneal laser vision correction was

This week, the US Army used a high-energy multipurpose laser to shoot down three drones near the US-Mexico border, which official reports claimed were “posing a physical threat to US military personnel and CBP partners,” referring to Customs and Border Patrol.

The operation took place between the night of August 25 and the early morning of August 26 in the vicinity of the Rio Grande Valley in Texas and was led by the Joint Task Force Southern Border (JTF-SB), which operates under US Northern Command. Authorities confirmed that, during the operation, agents used technology derived from the Army’s High-Energy Multipurpose Laser (AMP-HEL) system, a military program focused on implementing high-energy lasers for new defense capabilities.

Available information suggests that this initiative began in September 2025, when AeroVironment, a company specializing in defense technology, delivered the first two functional prototypes of these laser-based weapons to the US Armed Forces. Two new, improved systems were delivered as the program was expanded in December of the same year. According to the manufacturer, this particular platform, called the Locust Laser Weapon System, is designed to be mounted on military vehicles, as the Army has done with the versions it has received.

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Remote uncrewed aerial vehicles (UAVs), or drones, equipped with solar cells could be wirelessly charged using laser beams directed at them from the ground, rather than relying on traditional onboard batteries. The problem until now, however, has been keeping the drones cool – since laser light heats them up, so reducing the efficiency of the photovoltaic cells they carry on their wings. A team of researchers at the Civil Aviation University of China has now overcome this problem by incorporating a heat blocking technology based on antimony selenide (Sb₂Se₃) nanorods into these solar cells.

As drones take on longer missions, battery life has become one of the biggest barriers, explains Jianhua Han, who led this new research study. “Our team has been looking into laser wireless power transmission, which is a leading approach for long-distance wireless energy transfer, to replace these batteries.”

Laser wireless power transmission is particularly suited to aerospace applications such as UAVs equipped with photovoltaic cells. Perovskite solar cells show much promise in this context because they are cheap to manufacture, absorb light strongly in the visible part of the electromagnetic spectrum and have long charge-carrier diffusion lengths.

A perovskite laser cell-thermoelectric tandem device

In the new work, detailed in Matter & Light, Han and colleagues studied a type of solar cell known as a perovskite laser cell-thermoelectric (PLC-TE) tandem device, which consists of a carbon-based CsPbBr₃ perovskite as the PLC and bismuth telluride (Bi₂Te₃) as the TE material. The TE module is directly fixed beneath the laser cell and a carbon electrode is attached to its negative terminal  to create a series connection. When laser light is shone onto the device, the carbon electrode converts a portion of the incident laser energy into heat. The TE then harvests this heat, converting it into electricity through the thermoelectric effect.

And that’s not all: since one side of the device ends up being warmer than the other, this temperature gradient also helps convert the thermal energy into electricity. The larger the temperature gradient, the more electricity the TE layer can generate.

There is a problem though: while the carbon in the hybrid structure dissipates some of the heat produced by the laser, the structure can still heat up – reaching temperatures of up to 90°C, says Han. “That was much higher than we expected and made us realize that heat buildup was a far more serious problem than we had imagined.”

Sb₂Se₃ behaves like a thermal barrier

To overcome this problem, the researchers turned to Sb₂Se₃, which is a promising photovoltaic material. As well as its good optoelectronic properties, this semiconductor also has a low thermal conductivity, which allows it to behave like a thermal barrier when embedded in a device.

Han’s team synthesized nanorods from the Sb₂Se₃ and incorporated them into the upper portion of the CsPbBr₃ layer. The Sb₂Se₃ reduces heat dissipation in the carbon electrode and so helps maintain a significant temperature gradient in the TE device, thereby improving its overall energy conversion efficiency. Its thermal barrier properties also help decrease the PLC’s overall operating temperature during prolonged laser exposure.

The team then inserted the tandem device containing the Sb₂Se₃ nanorods beneath the wing of a stationary drone and carved out air channels through the wing to simulate real-world airflow conditions. When illuminated with high-power green laser light with a wavelength of 520 nm, they found that the device converted 38.49% of the incoming laser energy into electricity and successfully powered the drone’s propellor blade. This power conversion efficiency, says Han, is among the highest reported for this class of technology operating under similar conditions.

Device could help UAVs stay airborne for longer

“In terms of concept, this is the first time that a system-level scheme of the devices has been applied to a UAV power supply, expanding the work from pure materials research to application-oriented system design,” Han tells Physics World. “It demonstrates that powering UAVs with light is not just a theoretical concept, but an engineering pathway that can be practically implemented.”

The device could help UAVs stay airborne for longer, something that will be useful for applications like forest patrol, disaster monitoring and delivering packages, he says. But there is still much work to do before such applications become a reality. For one, the researchers will need to integrate the PLC-TE device into a lightweight drone for flight testing outdoors and to assess the safety of their technology. They will also need to find a way of accurately tracking moving drones with laser beams.

“Going from the ground-based proof stage to the real flight validation stage will require solving many engineering challenges,” says Han, “but our technology is a good starting point and verifying its viability is the core objective for the next phase in our study”.

The post Semiconducting nanorods help laser-powered drones keep cool appeared first on Physics World.

When a team of physicists in Paris fabricated the world’s first temporal photonic crystal, they added a new dimension to humanity’s quest to control light: time. From lighting our homes to advanced fiber optics and lasers, humans have long worked to control light, and now researchers say that can be achieved in a fourth dimension.

Yannis Laplace led the team at the Laboratory of Irradiated Solids (LSI) in demonstrating the temporal photonic crystal, with the help of other European institutions, which was revealed in a recent paper published in Nature.

As light hits the crystal, a terahertz electromagnetic wave rapidly modulates its optical properties, producing a device that controls light over time without expending energy.

Crystal Power

Controlling the properties of light for applications in telecommunications, sensors, and light sources is an active research field and is often reliant on crystals. In technical terms, a crystal is simply a regularly and periodically organized system. While we primarily think of translucent, shining crystals, they can be constructed of other forms of matter, such as gas or liquids, so long as their atoms arrange into regular, well-defined intervals.

How atoms arrange to form crystals grants their electrons and the photons they emit unique properties, including color and energy. Targeting photons specifically became an interest of scientists in the 1980s, with the development of photonic crystals, whose alternating materials each had unique effects on photons. These photonics gave rise to modern lasers, optical fibers, and photodetectors, technologies that have advanced considerably in recent decades.

Into the Time Dimension

In the last decade, researchers have experimented with a new kind of crystal: the time crystal. They are comprised of a unique form of matter in which particles repeat a continuous sequence—not just in the three physical dimensions, but also in time, without expending any energy.

The LSI team sought to combine photonic crystals with time crystals to develop a temporal photonic crystal that would control a light-matter interaction by alternating over time. Their work represents the first time such an idea has moved from the theoretical realm into the physical.

The device the researchers constructed operates in the high terahertz range, pushing light to oscillate 1000 billion times a second. It consists of micrometer-scale gold structures, shaped like battlements, leaving open cavities separated from an indium-antimony semiconductor by an insulating layer. The cavities between the gold structures trap light photons.

Testing a Temporal Photonic Crystal

To demonstrate their device in the real world, the LSI team bombarded it with terahertz laser pulses and recorded the material’s optical properties, modulating light over time. The effect was incredibly powerful, creating a strong modulation that alternated one billionth of a billionth of a second.

At the semiconductor layer, the researchers observed electrons forming from the light waves in what are called “surface plasmons,” oscillating with their effective mass. The greater their speed, the heavier these electrons become, producing the device’s optical modulations.

Beyond this observed phenomenon, the researchers suspect other interesting conditions may be occurring within the crystal. Some indirect evidence suggests that photons trapped inside the structure are amplified, although presently no direct observations have confirmed this. The team is continuing with experiments in hopes of eventually capturing this photon trapping phenomenon.

Laplace and his colleagues see these unique time crystals as eventually being a pathway toward the creation of terahertz-scale light sources and detectors, which would fit between those of electronics and visible light frequencies.

The paper, “Plasmonic Metamaterial Time Crystal,” appeared in Nature on July 29, 2026.

Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org.

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