The laser, an acronym for “Light Amplification by Stimulated Emission of Radiation”, is a device that produces a unique form of light radiation. Its monochromatic, coherent and precise light makes it an essential technology in many fields. Find out more about the fundamental principles of its operation, its different types, its uses and the risks associated with its use.
Definition and meaning of the word “laser”
The word “laser” is an acronym for Light Amplification by Stimulated Emission of Radiation. It refers to a device that produces a beam of light with high spatial and temporal coherence.
This coherence means that the light waves produced by the laser are in phase with each other, in both space and time. This unique characteristic distinguishes laser light from light produced by more common sources, such as a light bulb or the sun, whose light waves are randomly in phase.
In simpler terms, a laser is a device that produces very powerful, precise and targeted light.
The role of lasers in today’s technology

Lasers are used in a multitude of areas of modern technology. Indeed, their ability to produce a concentrated, intense beam of light makes them invaluable in a variety of industries.
- In communications, lasers are used to transmit data at high speed over long distances. This is particularly true of fiber-optic telecommunications.
- In medicine, lasers have revolutionized a number of fields, including ophthalmology, dermatology and surgery. They are used for precise surgery, tumor treatment and permanent hair removal.
- In industry, lasers are used for cutting, laser marking, welding and other high-precision operations.
- They are also used in scientific research, where they play a crucial role in fields such as spectroscopy, atomic force microscopy and atom cooling, among others.
In a word, the laser’s unique properties have made it an indispensable tool in the world of modern technology.

Operating principle of a laser
Laser light production
Laser light production is based on the process of stimulated emission. In a laser, an environment – usually a gas, solid or semiconductor – is excited by an external energy source. This excitation pushes the atoms in the medium to a higher energy level. When an atom returns to its initial energy level, it emits a photon
This photon can then stimulate the emission of other identical photons, creating a cascade of photon emissions. This phenomenon, known as stimulated light amplification, is at the origin of laser light production.
The light produced is then directed through a resonant cavity, usually consisting of two mirrors, which amplifies the light by causing it to bounce back and forth several times. One of the mirrors is partially transparent, allowing the light to emerge as a laser beam.
It should be noted that the wavelength of laser light, which determines its color, depends on the nature of the environment used.
Elements required to produce a laser
To produce a laser, a specific device is required, consisting mainly of three essential elements:
- Energy source: this excites the atoms in the laser environment, taking them to a higher energy level. This source can be electrical, luminous or even chemical, depending on the type of laser.
- Laser environment: This is the material in which the atoms are excited. It can be solid (for example, ruby or Nd:YAG), liquid, gaseous (such as CO2 or helium-neon), or a semiconductor.
- Resonant cavity : Generally made up of two mirrors, it serves to amplify the light produced. One of the mirrors is partially transparent to allow the light to emerge as a laser beam.
In addition to these basic components, additional elements may be required, such as a cooling system to dissipate the heat generated by the energy source.

How physics is involved in laser operation
To better understand how lasers work, it’s essential to understand their physical principles. The key phenomenon is stimulated emission, a light-matter interaction described by Einstein in 1917.
In this process, an atom, when excited by an energy source, absorbs a photon and moves to a higher energy state. When the atom returns to its initial state, it emits a photon. If this photon encounters another excited atom, it can stimulate the emission of another identical photon, creating a chain of photon emissions.
This is the basis of light amplification in a laser. For this to happen, a necessary condition is population inversion, which means that more atoms are in an excited state than in the initial state.
The light produced is amplified in a resonant cavity, usually consisting of two mirrors. One of the mirrors allows a small proportion of the light to pass through, and emerge as a laser beam.
It should be noted that light-matter interaction in lasers implicates quantum physics phenomena. The nature of the laser environment, i.e. the type of atoms it contains, determines the color (or wavelength) of the laser.
The meaning of the acronym “laser
The acronym “laser” is made up of the initials of the English words Light Amplification by Stimulated Emission of Radiation. Each of these terms has a specific meaning in laser operation:
- Light: refers to the nature of the radiation produced by the laser.
- Amplification: refers to the process of increasing the intensity of light in the laser.
- Stimulated Emission: is the physical phenomenon behind the production of light in the laser, as described by Albert Einstein in 1917.
- Radiation: refers to the end product of the device, the laser beam, which is electromagnetic radiation.
So it’s vital to understand that the word “laser” is much more than just a term: it summarizes the operating principle of this technology.
Discovery and invention of the laser
Albert Einstein first predicted the existence of the laser in 1917, but it wasn’t until 1960 that the first laser was created. Theodore Maiman, an American physicist, succeeded in obtaining laser emission from a ruby crystal, marking a crucial step in the evolution of this technology.
Over the years, different types of lasers have been developed:
- In 1961, Ali Javan developed the first gas laser, using helium and neon.
- In 1962, the first semiconductor laser was created at General Electric.
- In 1963, Elias Snitzer invented the fiber-optic laser.
These advances unlocked a multitude of practical applications, making lasers an indispensable tool in many fields.
It should be noted that the development of the laser was the fruit of intense fundamental research, and required a thorough understanding of complex concepts and theories.

Risks and dangers associated with laser use
Risks to human health
There are many health risks associated with laser use. The most common are eye and skin lesions. Depending on the laser class, laser radiation can cause burns and irreversible damage to the retina if directed at the eyes.
- Class 3B and 4 lasers can even cause serious eye and skin injuries.
- Exposure to optical radiation can also be dangerous to the skin.
Appropriate safety precautions should therefore be taken when using lasers.
Precautionary measures when using a laser
When using a laser, certain precautions must be taken to guard against potential risks.
- Eye protection: Wearing suitable protective eyewear is essential, especially when using high-class lasers.
- User training: All laser operators must receive appropriate training in the use and safety of lasers
- Compliance with safety instructions: Safety instructions, such as avoiding pointing the laser beam at a person, must be scrupulously observed.
- Control of exposure zones: It is advisable to delimit laser exposure zones and to prohibit access by untrained persons.
- Regular maintenance: Regular maintenance of the device is necessary to ensure its proper operation and avoid any risk of accident.
It is also essential to respect current laser safety regulations.
9 common uses for lasers
Once we’ve discovered how lasers work, let’s take a look at how this technology is used in our everyday lives and in different sectors of activity.
- Barcode reading: This technology makes it easier to read prices and product information.
- Optical communication: lasers are used for high-speed data transmission in fiber-optic networks.
- Medical applications: Lasers are used in a variety of surgical procedures, such as vision correction or tumor removal.
- Industry: Lasers are used for cutting, welding, marking and laser engraving on plastic and metal.
- Hair removal: alexandrite lasers are highly effective for hair removal from light skin and dark hair.
- Tattoo removal: lasers are commonly used to remove tattoos, particularly blue and green pigments.
- Printers: Lasers are used in printers for fast, high-quality printing.
- Construction: Double-beam lasers are used for construction and earthmoving work.
- Telemetry: Lasers are used for high-precision distance measurement.