What is a laser?

The word ‘laser’ is an acronym for Light Amplification by Stimulated Emission of Radiation. Unlike conventional light sources, a laser generates a light beam that is monochromatic (only one wavelength), coherent (in phase) and highly directional. These properties make laser light particularly focused, powerful and precise, which is a decisive advantage in many fields of application.

How does a laser work?

The functioning of a laser is based on the principle of stimulated emission, which was first described theoretically by Albert Einstein in 1917. Every laser consists of three basic components:

• an active medium (e.g. gas, crystal or fibre) in which electrons are raised to a higher energy level by the supply of energy,
  
• a pump that transfers this energy into the medium, such as through light or electric current
  
• and a resonator consisting of mirrors that amplifies the light by repeatedly reflecting it through the medium.

When a photon hits an excited electron, it can cause it to fall back to its ground state. This produces two identical photons. These reinforce each other in the resonator until an intense beam of light is produced, forming the characteristic laser light. This structure produces a beam with high intensity, sharp focusing and a narrow frequency range.

Laser types

The most important types of lasers can be distinguished according to the active medium used:

CO₂ laser

These gas lasers generate infrared light and are known for their high performance. They are mainly used for cutting, engraving and welding materials, particularly in plastics and wood processing as well as sheet metal working.

Nd: YAG laser

A solid-state laser that uses neodymium-doped yttrium aluminium garnet (YAG) as its active medium. It is suitable for precision applications in metalworking, medicine (e.g. in ophthalmology or tissue ablation) and for scientific and military purposes.

Fibre laser

These lasers use a special glass fibre containing tiny amounts of certain metals such as ytterbium. These so-called ‘rare earths’ ensure that the laser light is amplified. They are characterised by their high energy efficiency, durability and compact design and are mainly used in industrial manufacturing, for example in cutting, welding or marking.

Excimer laser

These gas lasers emit ultraviolet light in the form of very short pulses. They are particularly precise and are therefore used in microlithography for the manufacture of microchips and in refractive eye surgery (e.g. LASIK), among other things.

Ultra-short pulse laser (USP laser)

UKP lasers emit extremely short light pulses in the femtosecond or picosecond range. Their high intensity combined with minimal thermal stress enables particularly gentle and precise processing of a wide variety of materials, even sensitive or transparent ones. Compared to CO₂ lasers, they offer the advantage of introducing virtually no heat into the material, which allows for micrometre-precise cuts without melting or burr formation.

Applications of laser technology

Laser technology has become indispensable in many areas of life:

In industry

Lasers perform key tasks in material processing: cutting, welding, drilling or engraving at high speed and with high precision. They are also used in quality assurance (e.g. with laser sensors or 3D scanners). Thanks to their precision, UKP lasers in particular offer decisive advantages in micro and precision machining.

In medicine

Lasers enable minimally invasive procedures with high precision. They are used in ophthalmology, dermatology, cancer therapy, tattoo removal and dental treatment. Their ability to treat tissue with pinpoint accuracy makes them a versatile medical tool.

In communication

Modern fibre optic technology is based on lasers that send light pulses to transmit data. Without them, fast internet connections, global networks and satellite communication would be inconceivable.

In research

Lasers are fundamental in spectroscopy, quantum physics and materials science. Their controllable wavelength, intensity and coherence enable researchers to address fundamental questions, such as in the study of quantum effects or the generation of plasma for simulating nuclear fusion processes.

Innovative fields of research

Laser technology is significantly advancing current key technologies:

• In quantum computer research, lasers are used to manipulate quantum states in a targeted manner.
  
• Plasma physics uses high-power lasers to investigate the possibility of controlled nuclear fusion.
  
• Optical tweezers use laser light to move and examine tiny particles, cells or DNA structures without touching them.
  

These areas of research demonstrate the enormous potential of laser technology for future technological breakthroughs.

Historical development

Albert Einstein laid the foundation for laser technology with his theory of stimulated emission. The first functioning laser was developed in 1960 by Theodore Maiman a ruby laser. Building on this pioneering achievement, a wide variety of laser types were developed in the following decades for industrial, medical and scientific purposes.

Future prospects

Laser technology is only just beginning to realise its potential. Future developments promise even more compact, powerful and energy-efficient systems. The focus is on new fields of application such as quantum communication, space technology and the processing of highly specialised materials. Combining laser technology with artificial intelligence for process automation also opens up completely new dimensions for industry and research.

Conclusion

Laser technology has become an integral part of our modern everyday lives. Its unique ability to precisely focus light and use it in a controlled manner makes it an indispensable tool in numerous fields. With increasingly powerful and compact systems, it not only advances existing technologies, but also opens up new perspectives in research and development. The future of laser technology remains promising as a driving force for innovation and progress.