What is a laser?
Laser is an acronym for "Light Amplification by Stimulated Emission of Radiation." Laser generation is based on the phenomenon of stimulated emission: this process occurs in specialized materials (gases, semiconductors, solids, or liquids) under the influence of external energy.
A laser beam is strictly monochromatic, meaning the radiation from the laser source is characterized by a single wavelength, without dispersion across the spectrum—essentially pure monochrome light. The laser beam propagates with high directivity, possesses concentrated energy, and maintains focus even over long distances.
Applications of lasers
Industrial production
Laser cutting, welding, and drilling technologies are characterized by high precision, productivity, and contactless processing. They are widely used in the processing of metals, plastics, wood, and other materials, reducing raw material waste and increasing production efficiency.
Medicine and biotechnology
Lasers are widely used in medicine, including laser surgery, laser cosmetology, laser therapy, and other applications. Lasers allow for precise cutting or coagulation of biological tissue while minimizing damage to healthy surrounding tissue. Lasers are also used in tumor treatment, dentistry, and physical therapy.
Communication technology
Lasers power fiber-optic communications, allowing large amounts of data to be transmitted at high speeds over vast distances. This technology is used in the internet, television, and telephone communications. Laser-based lidar (LiDAR) systems are widely used in autopilot systems, topographic surveying, and environmental monitoring.
Military affairs
Lasers have important military applications: they are used in weapons guidance systems and air defense systems, demonstrating the advantages of high precision and ultra-high speed of action.
What is a fiber laser?
A fiber laser is a type of laser in which the active medium is an optical fiber. Unlike traditional solid-state or gas lasers, its primary working element is a fiber, not a crystal or gas. Fiber lasers belong to the class of solid-state lasers.
The operating principle is as follows: light from a pump source is coupled through reflective mirrors into a fiber doped with rare-earth elements. This process causes the rare-earth ions to transition to excited energy levels, achieving a population inversion, and generating a stable laser beam at the output within the resonator.
A pump laser diode generates pump radiation with a wavelength of 980 nm; this light is coupled optically into an active fiber doped with ytterbium (Yb) ions. The ytterbium ions absorb the 980 nm radiation, and their inner electrons are released into excited orbitals. This excited state is unstable, so the electrons return to their original lower levels, emitting photons with a wavelength of 1070 nm. The photons are repeatedly reflected by two reflective elements within the fiber, amplified, and form the final laser radiation.
Optical fiber
Optical fiber is a medium for transmitting light based on the phenomenon of total internal reflection of light rays.
It consists of three layers: core, shell and protective coating.
- The core is the central part of the fiber, made of ultra-pure silicon dioxide (quartz glass), and is responsible for transmitting the light signal.
- The cladding surrounds the core and is also made of ultra-pure silicon dioxide, but has a lower refractive index. It forms a reflective boundary for light, ensures total internal reflection of light rays at the core-cladding interface, prevents light leakage, and provides mechanical protection.
- The protective coating is the outer layer of the fiber, made from acrylates, silicone rubber, and nylon, and protects the fiber from moisture, mechanical scratches, and damage.
When a light beam hits the core at a certain angle, it is reflected multiple times at the core-cladding boundary and propagates along the fiber. This results in significantly lower light signal loss than electrical signal loss in copper cables.
Pump diode
The pump diode is a key component of high-brightness fiber lasers and is critical for 976 nm pump technologies.
The pumping process itself is the transfer of electrons from atoms or molecules from lower energy levels to excited higher levels using light. This mechanism is used in laser systems to create a population inversion of the active medium levels. The pump diode, as a key element, implements this process in fiber laser designs; its high brightness allows for the creation of highly efficient fiber laser models.
