The Common Laser

• Bena Optics provides high-quality optical components for various types of laser systems, suitable for different power levels and damage thresholds. Their products are designed to meet the stringent requirements of diverse laser applications, ensuring optimal performance and reliability. Whether for continuous lasers, pulsed lasers, or specialized systems like Raman and metal-vapor lasers, Bena Optics offers solutions that cater to the specific needs of each laser technology.

There are many methods for classifying lasers, which can be divided into several types such as solid-state, gas, liquid, semiconductor, dye, and fiber lasers.

(1) Solid-state lasers are generally small and robust, with relatively high pulse radiation power and a wide range of applications. Examples include Nd:YAG lasers. Nd (Neodymium) is a rare earth element, and YAG stands for Yttrium Aluminum Garnet, which has a crystal structure similar to that of ruby. Other examples include Tm:YAG, Ho:YAG, and Er:YAG lasers.

(2) Semiconductor lasers are small in size, lightweight, long-lasting, and have a simple structure, making them particularly suitable for use in airplanes, warships, vehicles, and spacecraft. The wavelength of semiconductor lasers can be altered by applying external electric fields, magnetic fields, temperature, pressure, etc. They can directly convert electrical energy into laser energy, which is why they have developed rapidly.

(3)Gas lasers are lasers that generate coherent light by passing an electric current through a gas. They have good monochromaticity and coherence, with laser wavelengths that can reach thousands of types, making them widely applicable. Gas lasers have a simple structure, are inexpensive to produce, and are easy to operate. They are widely used in fields such as industry and agriculture, medicine, precision measurement, and holography. Gas lasers can be excited by various energy sources, including electrical energy, thermal energy, chemical energy, light energy, and nuclear energy.

(4) Dye lasers, which use liquid dye as the working substance, were introduced in 1966 and are widely used in various scientific research fields. Approximately 500 types of dyes capable of producing laser light have been discovered. These dyes can be dissolved in alcohol, benzene, acetone, water, or other solvents. They can also be embedded in organic plastics to appear in solid form or sublimated into vapor to appear in gaseous form. Therefore, dye lasers are also referred to as “liquid lasers.” A notable feature of dye lasers is their continuously tunable wavelength. Dye lasers come in many varieties, are inexpensive, highly efficient, and their output power can rival that of gas and solid-state lasers. They are used in spectroscopy, photochemistry, medicine, and agriculture.

(5) Chemical lasers generate laser action through chemical reactions that produce a sufficient number of high-energy atoms, releasing a large amount of energy. These lasers are primarily used in weapon applications. For example, hydrogen fluoride (HF) lasers can provide continuous output power in the megawatt range.

(6) Free electron lasers (FELs) are more suitable than other types of lasers for generating very high-power radiation. Their operating mechanism is unique: they obtain high-energy electron beams, typically in the range of tens of millions of volts, from an accelerator. These electron beams pass through a periodic magnetic field, creating energy levels with different states and producing stimulated emission.

(7) Excimer lasers (which are actually a type of gas laser) are ultraviolet gas lasers. They generate laser light through the transition of excited-state molecules formed by a mixture of an inert gas and another gas (either another inert gas or a halogen) to their ground state. Excimer lasers are characterized as low-energy lasers with no thermal effects. They produce highly directional, high-purity wavelength, and high-output power pulsed laser beams. The photon energy wavelength range is from 157 to 353 nanometers, with pulse durations of tens of nanoseconds, falling within the ultraviolet spectrum. The most common wavelengths are 157 nm, 193 nm, 248 nm, 308 nm, and 351-353 nm.

(8) Fiber lasers utilize a gain medium within an optical fiber, typically doped with rare earth elements, to amplify light signals. There are two types of fiber laser pumping configurations: single-end pumping and double-end pumping, with the latter capable of achieving higher output power. Additionally, coherent beam combining technology, which is still under development, has the potential to further increase the output power of fiber lasers.

(9) Based on continuity, lasers can be classified into continuous lasers and pulsed lasers (including ultrashort pulsed lasers). Pulsed lasers can be further categorized by their pulse durations: nanosecond lasers (10^-9 seconds), picosecond lasers (10^-12 seconds), femtosecond lasers (10^-15 seconds), and even attosecond lasers (10^-18 seconds).

(10) There are many other types of lasers, including Raman lasers and metal-vapor lasers, among others. Depending on the specific application, there are numerous specialized technologies and subcategories. For instance, Raman lasers utilize the Raman scattering effect to generate laser light, while metal-vapor lasers use the vapor of metals such as copper or gold as the lasing medium. Each type of laser has unique properties and advantages that make it suitable for particular applications, ranging from scientific research and medical treatments to industrial processing and telecommunications.