Sci-fi is famously a starting point and inspiration for scientific breakthroughs and new technologies that have stepped out of the realms of fiction and into fact – smartphones and wearables, cloning, automatic doors, voice control and the internet, to name just a few.
Laser technology is another such example. Ray guns, for example, were depicted in science fiction long before lasers were actually invented.
Laser technology is not especially new. Theodore Maiman made the first operational laser in 1960 at the Hughes Research Laboratory in California by shining a high-power flash lamp on a ruby rod with silver-coated surfaces.
At the time, Maiman’s achievement was described as “a solution looking for a problem.” However, it wasn’t long until the intense, very narrow beam of light of a single wavelength that a laser represents was being used in science, technology and medicine.
Lasers are now everywhere. They are used in research laboratories, quantum physics, medical clinics, supermarket checkouts and communications infrastructure.
But despite being around for decades, laser technology is still developing, and more sophisticated and powerful lasers will open up new possibilities and have new applications.
The UK is building the world’s most powerful laser
The most powerful laser developed so far is currently being built in the UK at a cost of £85 million. The Vulcan 20-20 is being developed by the Science and Technology Facilities Council (STFC) Central Laser Facility (CLF) based at the STFC Rutherford Appleton Laboratory (RAL) in south Oxfordshire and funded by UK Research and Innovation.
The laser will produce a beam a million, billion, billion times brighter than the most intense sunlight, with a single laser pulse delivering more power than the entire National Grid – but for less than a trillionth of a second and be focused on a target just a few micrometres wide.
What can a laser as extraordinarily powerful as the Vulcan 20-20 be used for?
The Vulcan 20-20 is expected to be used for different applications at the cutting edge of scientific research when it is functional – which will be in 2029 if all goes to plan.
One intended application of the laser is in nuclear fusion testing – a theoretically safe, clean and spectacularly more efficient energy generation alternative to nuclear fission. While fission splits heavy, unstable atoms into smaller particles, fission binds smaller atoms together into larger ones.
In theory, the result of controlled fission is almost limitless clean energy without the toxic waste of fission reactions or the danger of nuclear meltdown – fusion reactions fizzle out almost immediately without almost perfect conditions to maintain them making them very low risk.
The greatest challenge in nuclear fusion science is generating enough power to transform a peppercorn-sized capsule of fuel into plasma, igniting the fuel in fusion reaction. Achieving the reaction mimics the reactions that happen in the centre of the sun and needs similar temperatures of around 100 million Celsius.
That’s one of the uses the £85 million laser will be put to. It will also be used for, writes The Times, “laboratory astrophysics”. Scientists will use the laser to attempt to recreate phenomena like the explosive supernova death of some types of stars.
Another application seen as potentially possible for the Vulcan 20-20 is using it to produce matter from light. In theory, colliding photons together in a way not yet achieved but thought possible with a laser as powerful as the 20-20, would create pairs of electrons and positrons – particles of matter and antimatter.
Scientists believe (but don’t yet fully understand) that these matter and antimatter particles come into being around neutron stars far out in space.
They also believe a laser as powerful as the Vulcan 20-20 might be able to recreate the conditions around neutron stars and hope this might lead to the appearance of electrons and positrons. This in turn would be hoped to lead to an improved understanding of how these particles, the building blocks of matter, appear.
The new, improved, super-strength Vulcan 20-20 laser will, therefore, mean it can be used for:
- Renewable energy research
- Plasma physics research
- Laboratory astrophysics
But what else will next generation lasers and their ability to concentrate energy into a beam with a small, sometimes tiny, surface area allow scientists to do?
What are the planned and potential applications of next generation laser technology?
Laser light already carries information in modern fiber communications networks, is used in facial recognition technology and to control self-driving vehicles. Lasers are also used in new methods in the fields of bioscience and medicine.
As well as the building of huge, extremely powerful lasers, advances in laser technology are also focused on miniaturising laser devices. One are of research in this direction is the development of lasers that do not require optical components to achieve the desired effect.
Scientists are working on new lasers that use “metasurfaces” instead of optical components, allowing the size of devices to be shrunk down and they can also be manufactured in a single process – making them cheaper, simpler to make and more energy efficient.
Creating a metasurface entails coating a material with an ultrathin film of nanoparticles in a tailored structure. Although the metasurface is thinner than the wavelength of the light, it possesses properties that govern how the light is refracted or reflected.
Metasurfaces can be designed to work as an optical lens and research is also exploring the possibility of etching metasurfaces within the part of the laser where the light itself is created.
The metasurface can then reflect a portion of the light back into the laser, potentially simplifying control of wavelength and polarization. Here, the emphasis is on VCSELs for ultraviolet light, with Åsa Haglund’s team achieving some of the shortest wavelengths in the world.
Mikael Käll, professor at Chalmers University of Technology, explains:
“If we can succeed in making the devices as compact as we hope, we’ll be able to use the technology as new light sources in for example fluorescence microscopy, which is much used in biophysics and cell biology. Hopefully, on the strength of my earlier research, we wiIl also be able to build molecular sensors in which the laser is an integral part.”
Other potential uses of lasers with metasurfaces are the future creation of miniaturised “lab-on-a-chip” laboratories.
They may also improve the technology used for facial recognition, and determining distance in self-driving vehicles.
Laser (or “directed energy”) weapons are another branch of research and many experts believe that laser technology will be crucial to future warfare.
Challenges remain
Theoretical and technological challenges remain to the development of the super and nanolasers that hold so much promise for future scientific research.
The kind of super lasers like the Vulcan 20-20, designed to emit huge volumes of concentrated, directed energy, will have to become more energy efficient if they are to be used effectively in future atomic fusion reactors. Another challenge is working out how to use a barrage of laser beams to crush a fuel pellet uniformly from all directions at once, something which may have to be achieved ten times a second in a full-scale nuclear fusion power station.
When it comes to nanolasers, Professor Käll says the theoretical calculations needed to understand how the light integrates with the metasurfaces, and the difficult nanoscale etching processes that will be required still need to be perfected. Achieving this is expected to involve leveraging cutting edge AI methods such as deep learning not previously available to scientists.
But there is still plenty to be done before the true potential of next gen laser technology is unlocked:
“Even if we do everything right, there are no guarantees it will be as effective as we hope. If the units we create are to have practical applications, they will have to be better than their current counterparts. This is a dynamic research field in which many international research teams are active, but we believe we possess the expertise to make an impression.”