There are many types of lasers.

 In the following, the laser working substances and excitation methods will be classified and introduced respectively.

working substance

According to the different states of working substances, all lasers can be divided into the following categories: ①Solid-state lasers (crystal and glass). ②Gas lasers, the working substance they use is gas, and according to the different properties of the working particles that actually produce stimulated emission in the gas, they are further divided into atomic gases Lasers, ion gas lasers, molecular gas lasers, excimer gas lasers, etc.; ③Liquid lasers, the working substances used in this type of laser mainly include two types, one is organic fluorescent dye solution, and the other is liquid containing rare earth metal ions. Inorganic compound solution, in which metal ions (such as Nd) act as working particles, while inorganic compound liquid (such as SeOCl2) acts as a matrix; ④Semiconductor lasers, such lasers use certain semiconductor materials as working substances to generate stimulated The principle of emission is achieved by exciting non-equilibrium carriers between the energy bands of semiconductor materials or between the energy bands and impurity levels through a certain excitation method (electrical injection, optical pumping or high-energy electron beam injection). The number of particles is reversed, resulting in stimulated emission of light; ⑤ free electron laser, which is a special type of new laser, the working substance is a directional free electron beam moving at high speed in a spatially periodic changing magnetic field, as long as the free electrons are changed The speed of the beam can produce tunable coherent electromagnetic radiation. In principle, its coherent radiation spectrum can transition from the X-ray band to the microwave region, so it has very attractive prospects.

gas laser

A laser in which the medium is a gas, which is excited by an electric discharge.

Helium-neon laser: the most important source of red light emission (632.8 nm).

Carbon dioxide laser: wavelength of about 10.6 μm (infrared), important industrial laser.

Carbon monoxide laser: the wavelength is about 6-8 μm (infrared), and it only works under cooling conditions.

Nitrogen Laser: 337.1 nm (UV).

Argon Ion Lasers: Available in multiple wavelengths, 457.9 nm (8%), 476.5 nm (12%), 488.0 nm (20%), 496.5 nm (12%), 501.7 nm (5%), 514.5 nm (43%) (from blue light to green light).

Helium cadmium laser: the most important blue light (442nm) and near ultraviolet laser source (325nm).

Krypton ion laser: with multiple wavelengths, 350.7nm, 356.4nm, 476.2nm, 482.5nm, 520.6nm, 530.9nm, 586.2nm, 647.1nm (the strongest), 676.4nm, 752.5nm, 799.3nm (from blue to deep red light).

oxygen ion laser

xenon ion laser

Mixed gas laser: Contains no pure gas, but a mixture of several gases (usually argon, krypton, etc.).

Excimer lasers: such as KrF (248 nm), XeF (351-353 nm), ArF (193 nm), XeCl (308 nm), F2 (157 nm) (all UV).

Metal vapor laser: such as copper vapor laser, the wavelength is between 510.6-578.2 nm. Due to the good reinforcement, the resonant mirror can be omitted.

Metal halide lasers: such as copper bromide lasers, the wavelength is between 510.6-578.2 nm. Due to the good reinforcement, the resonant mirror can be omitted.

A chemically excited laser is a special form. Excitation occurs by chemical reaction in the medium. The medium is single-use and is consumed after use. It is ideal for high power conditions and military fields.

hydrochloric acid laser

iodine laser

solid state laser

The medium is a solid-state laser, and this working substance is excited by light pumping from lamps, semiconductor laser arrays, and other lasers. Thermal lensing is a drawback of most solid-state lasers.

Ruby laser: the first laser in the world. On July 7, 1960, Maiman, a young American scientist, announced the birth of the world’s first laser. This laser is a ruby laser. The working wavelength is generally 6943, and the working state is single Pulse type, each pulse is in the order of 1ms, and the output energy is in the order of joules.

Nd:YAG (neodymium-doped yttrium aluminum garnet): the most commonly used solid-state laser, the operating wavelength is generally 1064nm, this wavelength is a four-level system, and there are other energy levels that can output lasers of other wavelengths.

Nd:YVO4 (Nd-doped yttrium vanadate): the most widely used low-power solid-state laser, the working wavelength is generally 1064nm, and can generate 532nm green light after frequency doubling by KTP and LBO nonlinear crystals.

Yb: YAG (ytterbium-doped yttrium aluminum garnet): Suitable for high power output, the disk laser of this material has a strong advantage in the field of laser industrial processing.

Titanium sapphire laser: with a wide wavelength adjustment range (670nm ~ 1200nm)

A semiconductor laser

Fiber Green Diode Laser Module

Fiber Green Diode Laser Module

Semiconductor lasers are also called semiconductor laser diodes, or laser diodes (Laser Diode, LD) for short. Due to the specificity of the material structure of the semiconductor material itself and the particularity of the movement of electrons in the semiconductor material, the working characteristics of the semiconductor laser have its particularity.

A semiconductor laser is a device that produces stimulated emission by using a certain semiconductor material as a working substance. .Its working principle is to achieve non-equilibrium loading between the energy band (conduction band and valence band) of the semiconductor material, or between the energy band of the semiconductor material and the energy level of impurities (acceptor or donor) through a certain excitation method. The particle population inversion of the fluid, when a large number of electrons and holes in the particle population inversion state recombine, stimulated emission will occur. There are three main excitation methods for semiconductor lasers, namely electrical injection, optical pumping and high-energy electron beam excitation. Electric injection semiconductor lasers are generally semiconductor surface junction diodes made of materials such as gallium arsenide (GaAs), cadmium sulfide (CdS), indium phosphide (InP), zinc sulfide (ZnS), etc., along the forward bias The voltage injection current is used for excitation, and stimulated emission is generated in the junction plane region. Optically pumped semiconductor lasers generally use N-type or P-type semiconductor single crystals (such as GaAs, InAs, InSb, etc.) N-type or P-type semiconductor single crystal (such as PbS, CdS, ZhO, etc.) is used as the working material, which is excited by injecting high-energy electron beams from the outside. Among semiconductor laser devices, the performance is better and the most widely used is the electric injection GaAs diode laser with double heterostructure.

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