Some scientific achievements are large and flashy—like imposing robots—while others are incredibly small, fast, and nearly invisible. And as a record-breaking laser pulse reported by scientists in a new study shows, even these tiny-sized advances can pack a ton of power.
For the Korean research team led by senior author Chang-hee Nam, a plasma physicist and professor at Gwangju Institute of Science & Technology, their breakthrough in laser science may be a physically small feat (striking an area the size of a micron) but will have a huge impact on how we study not only cosmic phenomena from the beginning of time but how we treat cancer as well.
After ten years of toiling, the team has demonstrated in a paper published on Thursday in the journal Optica the development of a laser with record-breaking intensity over 10²³ watts per square centimeter. Nam told Motherboard in an email that you can compare the intensity of this laser beam to the combined power of all of the sunlight across the entire planet, but pressed together into roughly the size of a speck of dust or a single red blood cell. This whole burst of power happens in just fractions of a second.
“The laser intensity of 10²³ W/cm² is comparable to the light intensity obtainable by focusing all the sunlight reaching Earth to a spot of 10 microns,” explained Nam.
To achieve this effect, Nam and colleagues at the Center for Relativistic Laser Science (CoReLS) lab constructed a kind of obstacle course for the laser beam to pass through to amplify, reflect, and control the motion of the photons comprising it. Because light behaves as both a particle (e.g. individual photons) as well as a wave, controlling the wavefront of this laser (similar to the front of an ocean wave) was crucial to make sure the team could actually focus its power.
Nam explains that the technology to make this kind of precise control possible has been years in the making.
“We have developed ultrahigh power femtosecond lasers for more than a decade, reaching the output power of 4 PW (1015 W) in 2017,” says Nam. “We then developed the laser technology to focus the beam size of 28 cm to 1 micron, for which we have to make the laser wavefront superb using a deformable mirror.”
Nam said that the ultrahigh power laser design played a role in this discovery by helping remove beam distortions while the deformable mirrors made it possible to have “extremely tight focusing without any aberrations.”
Beyond being a scientific breakthrough, Nam said that this high-intensity laser will open doors to explore some of the universe’s most fundamental questions that had previously only been explored by theoreticians.
“With such ultrahigh laser intensity we can tackle such phenomena as electron-positron pair production from light-light interactions… This kind of phenomena is supposed to happen in the early universe, plasma jets from supernova explosions and from black holes,” said Nam.
Thanks to these lasers, and even more powerful ones yet to come, Nam says that it will now be possible to explore these cosmic rays in the lab instead of just through simulations and theories. Using laser pulses, the researchers will be able to make and collide high energy electrons with photons, recreating the Compton scattering effect that scientists believe creates such high-energy cosmic rays.
Nam also said that these lasers have a more terrestrial purpose as well in the form of cancer treatment technology.
Proton therapy is a newer cancer treatment that directs positively charged proton beams to patients’ tumors using an accelerator. While this technique has shown promise, the use of an accelerator also requires a large, and expensive, radiation shield.
Nam proposes that using laser beams to direct these protons instead could be a more cost-efficient solution and may get this treatment into the hands of even more patients.
“The development of cheaper proton oncology machines will be exciting news for cancer patients,” said Nam.
The laser beam itself may strike and vanish in the blink of an eye, but it’s about to have a huge impact on the world of physics and beyond.