A laser is a device that produces light using an optical amplification technique based on electromagnetic radiation’s stimulated emission. Before discussing the laser components, below are some types of lasers.

Types of Lasers

There are numerous varieties of lasers. A semiconductor, gas, liquid, or solid can be the laser medium. The type of lasing material used to create a laser is a typical way to identify a laser:

Solid-state lasers

A solid-state laser contains a solid matrix with lasing material dispersed (such as the ruby or neodymium: yttrium-aluminum-garnet “Yag” lasers). At 1,064 nanometers, the neodymium-Yag laser emits infrared light (nm). A nanometer is 1×10-9 meters.

Gas lasers

The main output of (helium and helium-neon HeNe, which are the most commonly used gas lasers) is visible red light. Far-infrared radiation is emitted by CO2 lasers, which are used to cut hard materials.

Excimer lasers

The name excimer is derived from the terms (excited and dimers). Excimer lasers use reactive gases, such as chlorine and fluorine, mixed with inert gases, such as argon, krypton, or xenon. When electrically stimulated, a pseudo molecule (dimer) is produced. When lased, the dimer has light in the ultraviolet range.

Dye lasers

Rhodamine 6G and other complex organic dyes are used as the lasing medium in dye lasers. They have a wide range of wavelength tuning.

Semiconductor lasers

Diode lasers, often known as semiconductor lasers, are not solid-state lasers. These electronics are often highly compact and power-efficient. Larger arrays may contain them, such as the writing source in some laser printers or CD players.

Essential Components of a Laser

A laser’s gain medium, pump source, and resonator are its essential parts. Please read through for an in-depth discussion of laser components.

Gain Medium

Gain in a laser medium can be described by considering two energy levels with population densities, N2 and N1, and an associated transition cross section σ21. In practice, it takes more than two energy levels to create a population inversion because a two-level scheme can only, at best, enable equal populations at the upper and lower levels, which prevents any amplification.

Several factors, such as radiative and non-radiative decay pathways, pumping rates, absorption, and stimulated emission rates, affect population densities dynamically.

Pump Source

To achieve population inversions, a variety of different pumping processes are employed, and the gain medium frequently constrains these. Specific lasers and their associated media are discussed in the types of lasers above. The objective is always to achieve pumping rates, or the number of atoms per unit time per unit volume, to a metastable level that is adequate to create sustained stimulated emission.

A laser system is referred to as a diode-pumped solid-state (DPSS) laser when a laser diode pumps a solid-state gain medium. Other solid-state lasers can be pumped at excessively high rates using DPSS lasers.

Resonator

The gain medium in a laser is encased in an optical resonator that offers feedback. Photons produced by stimulated emission can be reflected into the laser medium and amplified further thanks to this feedback mechanism.

For optical feedback, the resonator must be designed to be stable so that light stays inside the cavity and does not leak out.