[Reading Science] From Drone Hunting to Nuclear Fusion... The Era of Ultra-High-Power Lasers Is Coming

Can Produce Tremendous Output in an Instant
Various Applications from Drone Countermeasures to Nuclear Fusion
Korea Currently Possesses 4 Petawatt-Class, Considering Tens to Hundreds of Petawatt-Class

A 4-petawatt ultra-high-power laser research facility operated by the Institute for Basic Science (IBS) and Gwangju Institute of Science and Technology (GIST). Photo by GIST.

[Asia Economy Reporter Kim Bong-su] Laser, once seen only in SF movies, has already become an essential item not only in ultra-precision products such as semiconductors but across the entire industry. Recently, its range of applications has expanded to include weapons of war and even the exploration of the secrets of space. It is called the darling of future industries. In South Korea, research and development (R&D) to commercialize ultra-high-power lasers for anti-drone weapons, space solar power generation, and nuclear fusion energy is actively underway. What exactly is a laser, how is it made and utilized, and how will it change the future of humanity?

What is a Laser?

In Korean, it is defined as the amplification of light by stimulated emission. In English, LASER is an acronym for 'Light Amplification by Stimulated Emission of Radiation.' It refers to light energy created by injecting high-power electrical energy into a certain device (oscillator) to produce light with high energy density, high brightness, monochromaticity, directivity, and coherence. Unlike natural light, which decomposes into seven colors, laser light has a single color. It does not spread and travels straight in a fixed direction. Coherence is also an important property.

Lasers have uniform phase, so even when they hit slight obstacles, they immediately cause interference. They are used in communications, radar, surgery, processing, measurement, and 3D image production. A laser oscillator consists of a medium, an excitation mechanism, and an optical resonator (a pair of parallel mirrors). The medium can be gases such as carbon dioxide (CO2), solids like optical fibers, or liquids such as inorganic solutions containing organic chelates or rare earth ions. The active atoms in the medium absorb energy transferred from the excitation source and return to their original state while emitting energy (the seed of the laser). This light is amplified and emitted as it bounces between the mirrors. The light energy generated through this stimulated emission process is the laser. Depending on the characteristics of the medium, the output and speed of the light can be varied, making lasers widely used across industries. Since non-contact material processing is possible, lasers have become essential tools for marking, cutting, and welding metals and non-metals without deformation or wear.

Recently, ultra-high-power lasers have attracted attention. These are lasers with an enormous output of petawatts, i.e., over 1,000 trillion watts. Considering that the total global power generation was 2.6 petawatts in 2012 and the solar energy delivered to Earth is 174 petawatts, one can understand how powerful this output is. Therefore, infrastructures that produce petawatt-level high output only for an extremely short time, called femtoseconds (one quadrillionth of a second), are being developed. One femtosecond is an extremely brief time during which light, the fastest material in the universe, travels only about 300 nanometers (nm). The laser output is determined by dividing the injected energy by the duration of emission. The principle is to make the duration extremely short and maximize the energy injected at that moment to produce high output. Researcher Lee Sung-gu from the Institute for Basic Science (IBS) Ultra-High-Power Laser Research Group explained, "Nanosecond (10^-9 seconds) lasers, used for a long time, are widely used in industrial fields, and picosecond (10^-12 seconds) lasers are also in use. Currently, South Korea's 4-petawatt-class laser uses a medium doped with titanium sapphire, which allows for long use and has good optical properties."

Anti-Drone Weapons and Battlefield Arms

The military sector is the foremost candidate for the commercialization of ultra-high-power laser technology. It is being developed as equipment to neutralize enemy electronic devices such as small drones and unmanned robots. In South Korea, the Gwangju Institute of Science and Technology (GIST) recently began developing femtosecond laser weapons. Although the time is fleeting, it fires powerful pulse lasers of terawatt (one trillion watts) class or higher to disable enemy electronic devices. The research team believes this can overcome the limitations of existing laser weapons, which require enormous power and must irradiate a specific area for at least several minutes. Moreover, by rapidly scanning the direction of ultra-high-power femtosecond lasers, a filament plasma shield structure can be formed in the air, enabling the development of defensive weapons that damage the core parts of attacking weapons passing through the shield area. Also, when ultra-high-power femtosecond lasers are focused in the air and irradiate heavy metals, high electromagnetic field plasma and radiation are generated, producing an intense electromagnetic pulse (EMP) momentarily. This becomes a weapon that can paralyze enemy communication devices, computers, networks, and military equipment. Kim Hyung-taek, senior researcher at GIST's Advanced Photonics Research Institute (APRI), explained, "It can neutralize multiple small weapons at high speed, effectively responding to the threat of smart attacks by the enemy."

Peering into the Secrets of Space

Ultra-high-power lasers are also emerging as essential tools in R&D for basic science, energy, and space defense. They can generate enormous energy in a fleeting moment to reproduce and measure the extreme environments of space. Particle accelerators using lasers enable much faster and more efficient electron acceleration than conventional accelerators.

In particular, they are actively researched as a key means for nuclear fusion, a clean, infinite, and pollution-free next-generation energy source. Professor Gong Hong-jin, emeritus professor of physics at KAIST, recently stated at a forum, "It is uncertain whether magnetic confinement fusion or laser fusion will be realized first, but advanced countries worldwide are accelerating laser fusion, with four venture companies founded, moving toward commercialization. Laser fusion has the advantages of easier maintenance and excellent economic feasibility." Ultra-high-power lasers are also used for power transmission in space solar power plants, development of quantum new materials, plasma materials, high-efficiency EUV light sources, and materials and technologies with dramatically improved energy efficiency.

Accordingly, the construction of ultra-high-power laser infrastructure is active worldwide. China is already building a 100-petawatt-class laser, and Russia is designing a 200-petawatt-class laser. Currently, South Korea is utilizing a 4-petawatt-class laser built by GIST's Advanced Photonics Research Institute and IBS Ultra-High-Power Laser Research Group, but infrastructure for ultra-high-power lasers of at least tens to hundreds of petawatts is needed. The Korean government also began preliminary planning research earlier this year with a budget of 1 billion won and has started full-scale review. A Ministry of Science and ICT official said, "At present, the required scale of ultra-high-power laser infrastructure has not been determined, and we are gathering opinions from academia. This is to understand the current status of domestic ultra-high-power and high-energy lasers and to conduct feasibility studies, conceptual research, and design."